Baron Services DSSR-250C Host Computer Commands

RVP8 User’s Manual
March 2006

Host Computer Commands

6. Host Computer Commands

This chapter describes the digital commands that the host computer must use to set up and
control the RVP8 processor for recording data. Each command is described in detailed in a
separate section of this chapter. Note that a command mnemonic, or shorthand reference name,
is given in each section heading. These names are frequently used to refer to particular
commands.

The write–up for each command includes a description of what the command does and a
pictorial layout of the bits in the 16-bit command word. Commands consist of an initial
command word containing an opcode in the low five bits. If additional arguments are required,
they are listed as “Input 1”, “Input 2”, etc. Finally, if the command produces output, those
words are listed as “Output 1”, “Output 2”, etc. Often each word is broken down into several
independent fields, each consisting of one or more bits. In such cases, the pictorial layouts show
the placement of the bit fields within the word, and each field is described individually. All data
transferred to or from the RVP8 are in the form of 16-bit words.

Before attempting to program the RVP8, it is a good idea to at least skim through the
descriptions of every command. The instruction set has been designed to be as concise and
orthogonal as possible. User programs should always execute the IOTEST command on
power-up to ensure that the interface connections are all intact. The diagnostic result registers
from GPARM should also be checked initially to verify that the RVP8 passed all internal checks.
Since all internal RVP8 tables and parameters are set to reasonable values on power-up, it is
conceivable that PROC commands could be issued immediately to acquire and process radar
data. More realistically, however, the default information is first modified to meet the users
needs.

To set up for data acquisition and processing the following sequence of commands might be
executed. Trigger and pulse width are first established using the SETPWF commands. Range
bin placement and processor options are then chosen using LRMSK, and SOPRM, and receiver
noise samples are taken with SNOISE. The noise levels are not automatically sampled on
power-up, so SNOISE must be issued at least once by the user. LFILT is executed if clutter
filters are needed. If data rays are to be synchronized with antenna motion, then LSYNC is used
to specify a table of antenna angles. After all setups are complete, PROC commands are issued
to actually collect, process, and output the data. Errors detected during the execution of
commands are noted by the RVP8 and can be monitored using GPARM.

The RVP8 contains a 4096-word first-in-first-out (FIFO) buffer through which all output data
flow. This buffer is included to simplify the requirements of the user’s interface hardware. The
FIFO holds each sequential word generated by the RVP8 until such time as the user is ready to
accept it. Thus, when reading from the processor, it is permissible to fall behind by as many as
4096 words before any slowdown in performance occurs. The RVP8 writes to the FIFO at full
speed as long as it is not full, and the internal processing is not affected by the exact speed at
which user I/O actually occurs. This continues as long as the average I/O rate on, perhaps 10ms
intervals, matches the average rate at which data are being produced.

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The sequence of events described above is altered when the FIFO becomes completely full.
Then, when the processor generates the next output word, it waits in an idle loop until the user
makes room in the FIFO by reading out one or more words. Until this space becomes available,
the RVP8 simply waits and does not proceed any further with its internal processing. This, of
course, leads to a slowdown in performance, but it is not a disastrous one. The user always
obtains correct data no matter how long it takes to read it. One could take advantage of this fact
to synchronize the acquisition of data by the RVP8 with the post-processing and display of that
data by the user. In this case, RVP8 would be instructed to output data at the maximum rate, the
user would read these words at the user’s maximum rate, and the overall system would
automatically run at the slower of those two speeds.

When the output FIFO is full and the RVP8 has the next word ready for output, there is another
way that the idle wait loop can be exited, that is, if the processor detects that the user is
performing a write I/O cycle. Since the user should have been reading data by now, the presence
of a write cycle is taken to mean that some more important condition has arisen. As such, the
wait loop is terminated and the RVP8 accepts the write data soon afterward. If the new data are
commands, they are executed right away, but any output they try to produce may be lost in a
similar manner. The net effect is that the processor continues to execute all commands correctly,
but that their output is discarded.

The discarded output data are not in fact lost. Rather, the data are eventually replaced with an
equal number of zeros. Each time the RVP8 discards an output word, it also increments an
internal 24-bit count. When FIFO space becomes available in the future, the processor replaces
all of the missing data with zero-valued placeholders.

Writing when the FIFO is full can be particularly useful if the new command is a RESET which
calls for clearing of the output FIFO. When the RESET is processed, all past and present output
data are discarded, leaving the RVP8 output section completely empty. This is useful whenever
the processor has pending output data which the user wants to truly throw away.

6.1 No-Operation (NOP)

This single-word instruction is simply ignored by the the Signal Processor. The NOP is useful
when a number of words are to be flushed through the RVP8 with no side effects.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 0 0 | Command
|___________________________________________|___________________|

6.2 Load Range Mask (LRMSK)

This command informs the signal processor of the ranges at which data are to be collected. An
arbitrary set of range bins are selected via an 8192-bit mask. The Nth bit in the mask determines
whether data are acquired and processed at a range equal to RES x (N-1). The Range resolution
is specified by a TTY setup question (see section 3.2.5), in the range 25 through 1000 meters.
Any collection of ranges may be chosen from integer multiples of that distance. The example
below is given for the default resolution of 125 meters. The range mask is passed to the RVP8
packed into 512 16-bit words. The least significant bit of each packed word represents the
nearest range, and the most significant bit represents the furthest range in each group of 16.

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According to the range bins that are selected in the mask, the signal processor computes and
stores internally a range normalization table which is later used to convert receiver intensity
levels into reflectivity levels in dBZ. Note that the LRMSK command implicitly specifies the
number of bins to be processed and output. The maximum bin count is 3072, though depending
on the computational intensity of the configuration, the RVP8 may be able to compute fewer
bins. If the number of bins selected in the bit mask exceeds this maximum, the trailing bins are
truncated. If the new mask does not specify any active bins, then a single bin at range zero is
forced on. The default power-up mask selects 256 bins equally spaced by 1.0km starting from
zero range.

Range averaging is also determined by LRMSK. The upper byte of the command controls how
many consecutive bins are grouped together. A value of zero means no averaging; one means
that pairs of samples are averaged; 255 means that 256 terms are summed, etc. The individual
samples that go into each average are still taken according to the bits that are set in the mask,
except that they are now grouped together so that only one net bin results from the several data
samples. Note that the limitation of 3072 sampled ranges applies to the bin count prior to
averaging.

For example, suppose 100 bits are selected in the range mask and no averaging is elected. Then
parameters are computed at those 100 ranges, and 100 bins of data are output. If the averaging
were set to one, rather than zero, samples would still be taken at the same ranges, but pairs of
bins would be averaged together and only 50 ranges would result. Note that the parameters are
averaged by summing the autocorrelations for each bin. The range normalization value
associated with the averaged bin is computed according to the midpoint of the first and last
sample.

Incompletely averaged bins are discarded by the LRMSK command. In the above example, if
the averaging were set to two so that triples of samples were summed, then only 33 bins would
be output. This is because the 100-bit mask left a dangling 100th sample. In the extreme case
where there are not enough mask bits to result in even one complete bin, the RVP8 forces the
averaging to zero and turns on a single bin at zero range.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Range Avg. (See Text) | | 0 0 0 0 1 | Command
|_______________________________|_______|___|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Bits for ranges 0.000km to 1.875km | Input 1
|_______________________________________________________________|
\_1.875 . \_0.000
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Bits for ranges 1022.000 km to 1023.875 km | Input 512
|_______________________________________________________________|
\_1023.875 \_1022.000

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6.3 Setup Operating Parameters (SOPRM)

This command is used to configure the Signal Processor. The command should be issued
whenever any of the parameters in the list change. The default parameter list consists of twenty
16-bit input words. These can be followed by optional XARG parameters as needed.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |NTh| | 0 0 0 1 0 | Command
|___________________________|___|___________|___________________|

NTh If 1, then no threshold values are set. This means ignore input words 4, 5, 6, 7,

11, 12, 13, 14, and 18. This is usually used in conjunction with the THRESH
command (see section 6.29), when setting individual thresholds.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Sample Size | Input 1
|_______________________________________________________________|

The sample size is continually adjustable from 1 to 256 pulses. However, during the alternating
polarization mode, the sample size must be even. If an odd value is entered it is rounded up by
one in that case.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Polar |NHD|ASZ|16B|CMS| R2| |3x3| | |Lsr|Dsr|Rnv| Input 2
|_______|_______|___|___|___|___|___|___|___|___|___|___|___|___|

Each of the single-bit fields selects whether the given processing or threshold option is enabled
(1) or disabled (0).

Polar Configures transmit polarization and Zdr processing:

00 – Fixed polarization, Horizontal
01 – Fixed polarization, Vertical
10 – Alternating polarization pulse-to-pulse
11 – Dual simultaneous transmission

NHD Disables inclusion of header words in the processed data that are output by the

PROC command (See also, CFGHDR command).

ASZ The “Any Spectrum Size” bit requests that DFT processing algorithms, clutter fil-

ters, spectral output, etc. all operate on spectra whose size exactly matches the
number of available pulses (rather than rounding the spectrum size down to the
next lower power-of-two).

16B Configures for 16-bit (rather than 8-bit) data output from the PROC command.

This bit affects the single-parameter versions of Reflectivity, Velocity, Width, and
Zdr data. However, the PROC command’s archive format always holds 8-bit data,
regardless of the setting of 16B. This gives the option of extracting both 8-bit and
16-bit data simultaneously from each ray.

CMS Enables Clutter Microsuppression, in which individual range bins are rejected

(based on excessive clutter) prior to being averaged together in range.

R2 Use three lag (R0/R1/R2) algorithms for width, signal power, and clutter correc-

tion.

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3x3 Switches on the 3x3 output filter (See Section 5.3.3). The RVP8 automatically

handles all of the pipelining overhead associated with running the 3x3 filter, i.e.,
valid output data are always obtained in response to every PROC command.

Lsr Reflectivity speckle remover. When set, range speckles in the corrected and un-

corrected reflectivity data are removed.

Dsr Doppler speckle remover. When set, range speckles in the velocity and width data

are removed.

Rnv Range normalization of reflectivity data. This bit also enables intervening gas at-

tenuation correction.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Log Slope 65536 * dB / (LSB) | Input 3
|_______________________________________________________________|

This number defines the multiplicative constant that converts the signal power in dB to the units
of the 12–bit “Log of power in sample” time series outputs. One fourth of this slope is used to
generate the “Log of Measured Noise Level” output from GPARM (word 6). The recommended
value to use here is 0.03 (1966). This gives a dynamic range of 122 dB in 12 bits.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| LOG Threshold in 1/16 of dB | Input 4
|_______________________________________________________________|

Reflectivity values below this level can result in thresholding of data, if the threshold control
flags (see below) include LOG Noise bits. The threshold value is always non-negative, and the
comparison test is described in Section 5.3.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Clutter Correction (CCOR) Threshold in 1/16 of dB | Input 5
|_______________________________________________________________|

The clutter correction threshold is a bound on the computed log receiver adjustment for clutter.
These corrections (in dB) are always negative. Any clutter correction which is more negative
than the above value can result in thresholding of data.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | SQI Threshold | Input 6
|_______________________________|_______________________________|

The Signal Quality Index (SQI) threshold is an unsigned binary fraction in the range 0 to
255/256. When the SQI for a range bin falls below the stated value it may result in thresholding
of data.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Weather Signal Power Threshold in 1/16 of dB | Input 7
|_______________________________________________________________|

Weather Signal Power (SIG) is an estimate of the SNR of the weather component of the received
signal. When the SIG (see Section 5.2.12) falls below this comparison value it may result in
thresholding of data.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Calibration Reflectivity in 1/16 of dB | Input 8
|_______________________________________________________________|

Host Computer Commands

The calibration reflectivity is referenced to 1.0 kilometers.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | TopMode | | Input 9
|_______________|_______________|_______________________________|

The TopMode bits select the overall data acquisition and processing mode for the RVP8.
Although the processing algorithms that are used in each top level mode are quite different, the
RVP8 command set works in a uniform way in all modes.

0000 Pulse Pair Processing Mode. Doppler clutter filters are 4th-order IIR high pass;

data are processed one pulse at a time as each pulse arrives (see Section 5.2.3).

0001 FFT Processing Mode. Doppler clutter filters use nonlinear frequency-domain

approach; data are processed in batches of pulses (see Section 5.2.2).

0010 Random Phase Processing Mode. Data from first and second trips are dealiased in

range based on knowledge of the radar transmitter phase (see Section 5.7).

0100 DPRT-1 Processing Mode. The trigger generator produces alternate short and long

pulses, and Doppler autocorrelations are computed using only the short pairs (see
Section 5.5).

0101 DPRT-2 Processing Mode. The trigger generator produces alternate short and long

pulses, and Doppler autocorrelations are computed using both pairs (see Section

5.5).

11XX Four codes reserved for custom user modes.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |UVD|PCT| Window |ZER| Filter Stabilization Delay | Input 10
|_______|___|___|___________|___|_______________________________|

The RVP8 clutter filters are controlled by this word.

Delay This delay is introduced prior to processing the next ray of data whenever Dual-

PRF velocity unfolding is enabled or the RVP8 has been reconfigured by user
commands. The delay permits the clutter filter transients to settle down following
PRF and gain switches. The value is specified as the number of pulses, and hence,
the number of filter iterations, to wait.

ZER If set, then the clutter filter’s internal state variables are zeroed prior to waiting the

delay time. For some signal conditions, this may give better results than allowing
the filter to naturally flow into the new data.

Window Selects the type of window that is applied to time series data prior to computing

power spectra via a DFT. Choices are: 0:Rectangular, 1:Hamming, 2:Blackman,
3:Exact Blackman, 4:VonHann.

PCT If set, the RVP8 will attempt to run its standard processing algorithms even when a

custom trigger pattern has been selected via the SETPWF command.

UVD Unfold velocities using a simple (V

high

– V

) algorithm, rather than the standard

low

algorithm described in Section 5.6.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Control Flags for UnCorrected Reflectivity | Input 11
|_______________________________________________________________|

Host Computer Commands

These flags select which threshold comparisons result in unCorrected reflectivity being accepted
or rejected at each bin. There are four test comparisons that are made at each range, as described
above for input words 4, 5, 6, and 7. Each test either passes and produces a code of 1, 2, 4, and
8 respectively, or fails and produces a code of zero. The sum of the codes for each of the four
tests is a number between 0 and 15, which can also be interpreted as the following four-bit
binary number:

3 2 1 0
| | | | |
| 8 | 4 | 2 | 1 |
|___|___|___|___|
\ \ \ \___ LOG Threshold Passes
\ \ \______ CCOR Threshold Passes
\ \_________ SQI Threshold Passes
\____________ SIG Threshold Passes

The individual bits of the Threshold Control Flag word each specify whether data are to be
accepted (1) or rejected (0) in each of the sixteen possible combinations of threshold outcomes.
Thus, the pattern of bits in the flag word actually represents a truth table for a given logical
function of the four threshold outcomes.

The following examples show actual values of the Flag word for the stated combinations of
acceptance criteria:

Value Criteria

FFFF All Pass (Thresholds disabled)
0000 All Fail (No data are passed)
AAAA LOG
8888 LOG and CSR
A0A0 LOG and SQI
8080 LOG and CSR and SQI
F0F0 SQI
FAFA SQI or LOG
C0C0 SQI and CSR
F000 SQI and SIG
C000 SQI and SIG and CSR
FFF0 SQI or SIG
CCC0 (SQI or SIG) and CSR

A simple way to generate these values is to imagine four 16-bit quantities having the following
names and values: LOG=AAAA, CSR=CCCC, SQI=F0F0, SIG=FF00. The flag value needed
to represent a given logical combination of threshold outcomes is obtained as the result when
that same logical combination is applied to these special numbers.

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For example:

(SQI or SIG) and CSR = (F0F0 or FF00 ) and CCCC
= (FFF0) and CCCC
= CCC0

which corresponds with one of the examples given above.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Control Flags for Corrected Reflectivity | Input 12
|_______________________________________________________________|

See Description for Input #11.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Control Flags for Velocity | Input 13
|_______________________________________________________________|

See Description for Input #11.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Control Flags for Width | Input 14
|_______________________________________________________________|

See Description for Input #11.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Additive Offset for Measured AZ Angles (Binary Angle) | Input 15
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Additive Offset for Measured EL Angles (Binary Angle) | Input 16
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Intervening Gas Attenuation Correction (dB/km) | Input 17
|_______________________________________________________________|

Gas attenuation correction attempts to compensate for overall (two-way) beam losses due to
absorption by atmospheric gasses. The correction is linear with range, and is added to the data
along with range normalization. Therefore, clearing the RNV bit in Word #2 above disables the
correction. Of course, gas attenuation compensation can still be turned off even when RNV is
on, simply by setting a slope of 0.0 dB/km.

An attenuation of G db/km is encoded into the unsigned 16-bit word N as follows:

0  N  10000 G = N / 100000

else G = 0.1 + (N – 10000)/10000
This format is backward compatible with the previous linear format for all values between 0.0
and 0.1dB/km; but it extends the upper range of values from 0.65535 up to 5.6535. These larger
attenuation corrections are needed for very short wavelength radars.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Control Flags for Differential Reflectivity (Zdr) | Input 18
|_______________________________________________________________|

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See Description for Input #11.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed Zdr Calibration Offset in 1/16 dB (GDR) | Input 19
|_______________________________________________________________|

When differential reflectivity is computed there is a possibility that radar asymmetries will
introduce a bias in the Zdr values, i.e., that Zdr will be non-zero even when observing purely
spherical targets. This calibration offset permits nulling out this effect. The GDR offset
accounts for the overall Tx/Rx gain imbalance between the two channels of the radar.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Radar Wavelength in Thousandths of Centimeters | Input 20
|_______________________________________________________________|

The radar wavelength is used in the calculation of 16-bit velocity and width data, to convert
from Nyquist units to absolute physical units.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed LDR Calibration Offset in 1/100 dB (XDR) | XARG 1
|_______________________________________________________________|

The XDR offset is used in the Linear Depolarization Ratio equations, and is the differential
receiver gain between the two channels. Note that unlike the GDR offset (used for ZDR), the
gain difference does not depend on differential transmit power.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Range smoothing (0:None, 1:pairs, etc) | XARG 2
|_______________________________________________________________|

Range smoothing can be performed on raw moment data prior to the computation of scientific
parameters. The number of bins to sum together is given here. This should generally be an odd
integer so that no range bias is introduced by the smoothing operation.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
|Ena| | Point Clutter Thresh | Side Skip | XARG 3
|___|_______________________|_______________________|___________|

Point clutter detection is configured with this word. A bin will be flagged as containing clutter
if it’s power exceeds that of its two neighboring bins by more than the detection threshold (in
deciBels). Up to seven bins may optionally be skipped on each side of the central bin prior to
making these two comparisons.

Ena This bit is set to enable point clutter detection. Flag bits will then be reported in

the “Flg” output data type of the PROC command.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
|Ena|All| | XARG 4
|___|___|_______________________________________________________|

Point clutter censoring is configured with this word.

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Ena This is set to enable point clutter censoring. Raw moment data containing point

clutter will be interpolated from valid signal levels on either side.

All Optionally expand the reported detection flags to show the entire replaced interval,

not just the original detected bins. This gives a more honest view of the data bins
that have been altered.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Bit mask of TS playback mismatch conditions to ignore | XARG 5
|_______________________________________________________________|

This word is a combination of MMTS_xxx bits specifying what types of mismatches are okay
(do not cause an all-zero ray to be produced) during PROC command processing of timeseries
data that are played back from an external source into the RVP8.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Flag bits related to timeseries (playback) | XARG 6
|_______________________________________________________________|

Combination of OPTS_xxx bits which modify details of timeseries behavior.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 | Offset in deciBels | Slope as 100 * dB/dB | XARGs 7&8
|___|___________________________|_______________________________|

These two words allow you to set the breakpoints and slopes that modify the LOG threshold
according to the Clutter-to-Noise ratio of the target. This makes the LOG threshold behave
properly even as the noise floor becomes elevated due to very strong clutter targets. A value of
zero will restore the RVP8 defaults from the Mf menu.

The default (power-up) values for the above parameters are listed below. Both the scientific
units and the integer-input required by the command to set up that value are given. Most of
these defaults will likely be reasonable for a wide variety of radars.

Table 6–1:Default Values For Operating Parameters

Parameter

Sample Size 25 pulses 25
Flag Word 0007 Hex
Log Slope 0.03 dB/LSB 1966
LOG Threshold 0.5 dB 8
CCOR Threshold –25.0 dB –400
Signal Quality Index Threshold 0.5 (dimensionless) 128
SIG Threshold 10.0 dB 160
Calibration Reflectivity –22.0 dBZ –352

Scientific Units Input

Gas Attenuation 0.016 dB/km 1600
Zdr Offset (GDR) 0.0 dB 0

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Table 6–1:Default Values For Operating Parameters (cont.)

Parameter InputScientific Units

LDR Offset (XDR) 0.0 dB 0
AGC Integration Period 8 pulses 8
Radar Wavelength 5.3 cm. 5300
Dual PRF Filter Stabilization 10 pulses 10
UnCor Refl. Thresh. Control Flag LOG AAAA Hex
Cor Refl. Thresh. Control Flag LOG & CSR 8888 Hex
Velocity Thresh. Control Flag SQI & CSR C0C0 Hex
Width Thresh. Control Flag SQI & CSR & SIG C000 Hex
Zdr Refl. Thresh. Control Flag LOG AAAA Hex
AZ/EL Angle Offsets

0 degrees 0000 Hex

6.4 Interface Input/Output Test (IOTEST)

This command is used to test both the input and output data busses of the signal processor
interface. When issued, the command causes sixteen words to be read from the host controller,
after which those same sixteen words are written back out. Typically, the controller supplies a
“barber pole” input sequence consisting, for example, of successive powers of two. If all of the
output words are correct, one may conclude that there are no malfunctioning bits in the interface
hardware.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 1 1 | Command
|___________________________________________|___________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Arbitrary Data Word #1 Supplied by Host Controller | Input 1
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Arbitrary Data Word #16 Supplied by Host Controller | Input 16
|_______________________________________________________________|

Host Computer Commands

Note: The IOTEST command can also process and echo up to 128 additional

XARGS data words (See Section 6.20).

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Copy of Data Word #1 as supplied by Host Controller | Output 1
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Copy of Data Word #16 as supplied by Host Controller | Output 16
|_______________________________________________________________|

6.5 Interface Output Test (OTEST)

This command is used to test the integrity of the data being output by the signal processor. The
command causes sixteen words to be output consisting of successive powers of two starting from
one. By verifying whether each output word is correct, malfunctioning bits in the interface data
bus can easily be isolated. This test is less stringent than the input/output test IOTEST, since the
input data paths to the processor are not being checked. Typically, the OTEST is performed only
when the IOTEST fails, and then to determine whether the fault was on input or output.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 1 0 0 | Command
|___________________________________________|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 | Output 1
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | Output 16
|_______________________________________________________________|

6.6 Sample Noise Level (SNOISE)

This command is used to estimate the current noise level from the receiver, so that the noise can
be subtracted from subsequent measurements. Data are sampled for 256 pulses at 256 bins,
beginning at a selectable range and spaced by the range resolution at that pulse width. The

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internal trigger generator is temporarily set to a special noise rate (usually much lower than the
operating rate) during the process. It is ultimately the user’s responsibility to insure that no
returned power is present within the approximately 32km sampling interval. In some cases it
may be necessary to raise the antenna during the noise measurement to avoid thermal noise
pickup from the ground, or from weather targets.

SNOISE has the option of setting up a new sampling range and trigger generator rate each time
it is called. Two bits in the command word determine which (if any) of the new values overrides
the current values stored in the RVP8. The power-up sampling range is 250km (input value of

250), and the power-up trigger rate is 200Hz (input value of 30000). These initial values persist
until such time as they are altered here. Note that both input words must always be supplied
after the command, even if the command calls for ignoring one or both of them. The range is
supplied directly in kilometers up to a maximum of 992km. The trigger rate resulting from a
given input is 6MHz divided by the input value, i.e. the input value is the trigger period in

0.1667 microsecond increments. Keep in mind that the given rate is bounded against the
minimum PRT allowed for the current radar pulse width.

The SNOISE command bounds the requested starting range of the noise sampling interval. This
is to insure that the noise samples will fit within the specified PRT, and within the range mask
hardware RAM. The RVP8 sets an error bit when an improper range is requested.

The SNOISE command should be re-issued now and then to compensate for drift in the RF and
A/D systems. However, because DC offsets do not propagate into the “I” and “Q” values,
reissuing the command is much less critical than with the RVP6. The noise levels must be
measured for the RVP8 to properly process data. This can be done by issuing the SNOISE at
least once after power-up, or by setting the correct values for the powerup noise levels with the
“mt” setup command, see section 3.2.5. The RVP8 does not automatically take a noise sample
as part of its initialization procedure.

The measured offsets are stored internally for all subsequent uses inside the RVP8. The offset
values may be inspected via the GPARM command, as may the current range and rate values
themselves. Of course, whenever the range or rate are changed the user must ensure that the
new trigger rate allows at least 32km following the new noise range. If this requirement is not
met, or if other failures are detected during the noise measurement, appropriate bits are set in the
GPARM latched status word. This word should generally be checked after SNOISE to make
sure that everything worked properly.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |Action |Rat|Rng| | 0 0 1 0 1 | Command
|_______________|_______|___|___|___________|___________________|

Rng If 1, then the range in input word 1 is taken as the starting noise range for this and

all subsequent SNOISE calls.

Rat If 1, then the trigger rate in input word 2 is taken as the noise rate for this and all

subsequent SNOISE calls.
Action Specifies what action is carried out by the command.
0 Compute a new noise sample based on the present IFD input signals.
1 Do not compute a noise sample, but rather, read new noise values from the host

computer and use them for subsequent processing. Four additional input words

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supply the noise information, and GPARM words 6, 9, and 44-50 will be changed

to reflect the new noise settings.
2 Do not compute a noise sample, but rather, restore the powerup noise defaults.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Starting Range in km (Max 992km) of 32km Sampling Interval | Input 1
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Internal Trigger Rate (6Mhz/N) to use During Noise Sampling | Input 2
|_______________________________________________________________|

The following input words are optional, only if Action=1.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 0 0 | (MSB) Log of Measured Noise Level (LSB) | Input 3
|_______|_______________________________________________________|

The is the same number as GPARM output 6. See the discussion in Sections 6.7 and 6.9.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Noise Level Standard Deviation (in 1/100 of a dB) | Input 4
|_______________________________________________________________|

This is the same number as the GPARM output 49.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Ratio of Horizontal/Vertical Noise Power in Hundredths of dB | Input 5
|_______________________________________________________________|

This is the same number as the GPARM output 50.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| <Spare> |Err|Ttf|Ntg| Input 6
|___________________________________________________|___|___|___|

These fault bits will then be output in the latched status GPARM word 9 .

Ntg No Trigger during noise measurement.
Ttf Trigger too fast during noise measurement, i.e., some of the noise sample bins

were positioned past the trigger range.
Err Error detected during the SNOISE command.

6.7 Initiate Processing (PROC)

The PROC command controls the actual processing and output of radar data. The operating
modes and types of data available from the RVP8 are described in detail in Chapter 1. That
section also describes the proper use and application of the RVP8 to different radar
environments.

PROC is a single-word command that specifies the type of processing to be performed, and the
type of output to be generated. The two mode bits in the command word select either

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Host Computer Commands

 Synchronous mode — The processor acquires, processes, and outputs one ray in

response to each PROC command. Processing is begun only after each command is
actually received.

 Free running mode — A single PROC command is issued and rays are continually output

as fast as they can be produced and consumed. This continues until any other command
is written, e.g., a NOP could be used to terminate the free running mode with no other
consequences.

 Time Series mode — Always produced in a synchronous manner, this mode require a

new PROC command to initiate each new set of samples. Data are output as 8-bit time
series, 16-bit time series, or 16-bit power spectra.

Optional Dual-PRF velocity unfolding is chosen by command bits eight and nine. For Doppler
data either a 2:3, 3:4, or 4:5 PRF unfolding ratio may be selected. The RVP8 carries out all of
the unfolding steps internally, so that mean velocity is now output with respect to the larger
unambiguous interval. There is no additional velocity processing needed by the user, except of
course, to change the velocity scale on any displays being generated. Furthermore, spectral
widths are scaled consistently with respect to the higher PRF, and require no user modification
before being plotted.

When unfolding is selected, the internal trigger generator automatically switches rates on
alternate rays. The switch over occurs immediately after the last pulse of the current ray has
been acquired; thus overlapping the internal post-processing and output time, with transmitter
stabilization and data acquisition at the new rate.

Output data are selected by the upper six bits of the PROC command. Packed archive output is
selected by setting the ARC bit. Individual byte or word display output is selected by setting any
or all of the Z, T, V, W, Zdr, and KDP command word bits. When more than one of these bits is
set, the output array consists of all of the bins for the leftmost selected parameter, followed by all
of the bins for the next selected parameter, etc. Bits selected in XARG #1 behave the same way,
except that the output order is right-to-left. Both archive and display formats can be selected
simultaneously, in which case the archive format is output first, followed by whichever
individual display format values were also selected. The archive format is not recommended for
use with new drivers because it can only handle four of the many possible output parameter
types.

When time series mode is selected there are three output data formats available. For backwards
compatibility, there is an 8-bit integer format in which the eight most significant bits from the I,
Q, and LOG signals are represented in a byte. This format is not recommended because it will
generally miss weak signals. We recommend the floating-point format that uses 16-bits per A/D
sample. There is also a 16-bit power spectrum output that is accurate to 0.01dB. (See also
GPARM output word #10).

In addition to the above output data, the first words of each ray optionally contain additional
information about the ray itself. These header words are configured by the CFGHDR opcode,
and are included only if the NHD (No-Headers) bit in SOPRM Input #2 is clear. For example, if
TAG angle headers are requested, if the ARC, Z and V bits are all set, and if there are 100 bins
selected in the current range mask, then each RVP8 output ray consists of the following:

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1] TAG15 – TAG0 \ From Start of Acquisition
2] TAG31 – TAG16 / Interval
3] TAG15 – TAG0 \ From End of Acquisition
4] TAG31 – TAG16 / Interval
* 200 words of packed archive data,
* 100 words of Corrected Reflectivity data in low byte only.
* 100 words of Velocity data in low byte only,

Host Computer Commands

The Command word format for Synchronous Doppler Mode is:

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
|ARC| Z | T | V | W |ZDR|Unfold |KDP| 0 1 | 0 0 1 1 0 | Command
|___|___|___|___|___|___|_______|___|_______|___________________|

The Command word format for Free Running Doppler Mode is:

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
|ARC| Z | T | V | W |ZDR|Unfold |KDP| 1 0 | 0 0 1 1 0 | Command
|___|___|___|___|___|___|_______|___|_______|___________________|

Either of these may be augmented by an optional XARG word (See Section 6.20)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | (Tx Vert) | (Tx Horz) | | | |
| |Flg|Phi Rho Ldr|Phi Rho Ldr|SQI|RHV|PDP| XARG 1
|_______________________|___|___|___|___|___|___|___|___|___|___|

Unfold Selects Dual–PRF unfolding scheme:

00 : No Unfolding 01 : Ratio of 2:3

10 : Ratio of 3:4 11 : Ratio of 4:5
ARC Selects archive output format in which four data bytes (see 8-Bit descriptions be-

low) are packed into two output words per bin as follows:

High Byte Low Byte
| | |
| V | Z | First Word
|___________|___________|
_______________________
| | |
| W | T | Second Word
|___________|___________|

The remaining data parameters are available in both 8-Bit and 16-bit formats, according to
SOPRM Command input word #2 (See Section 6.3). The same SOPRM word configures the
RVP8 for Single or Dual polarization. The later is required for KDP, PDP, and RHV to be
computed properly.

V Selects radial velocity data.

8-Bit Velocity Format

— Mean velocity, expressed as a fraction of the unambig-

uous velocity interval, is computed from the unsigned byte N as:

V

m/sec =VNyquist

x (N–128) / 127.5

0 : Indicates velocity data is not available at this range
1 : Maximum velocity towards the radar

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When velocity unfolding is selected, the output is still interpreted as above, ex­cept that the unambiguous interval is increased by factors of 2, 3, and 4 for for
2:3, 3:4, and 4:5 unfolding.

Host Computer Commands

128 : Zero velocity
255 : Maximum velocity away from the radar

16-Bit Velocity Format

— Mean velocity in meters/second is computed from the

unsigned word N as:

V

m/sec

The overall range is from –327.67m/sec to +327.66m/sec in one centimeter/sec­ond steps as follows:

0 : Indicates velocity data is not available at this range

1 : –327.67 m/sec (towards the radar)
32768 : 0.00 m/sec
65534 : +327.66 m/sec (away from the radar)
65535 : Reserved Code

W Selects spectral width data.

8-Bit Width Format

—Spectral width is computed from the unsigned byte N as:

W

The overall range is a fraction between 1/256 to 255/256 of the unambiguous in­terval. The code of zero indicates that width data was not available at this range.

16-Bit Width Format

— Spectral width in meters/second is computed from the

unsigned word N as:

W

The overall range is from 0.01m/sec to 655.34m/sec in one centimeter/second
steps as follows:

0 : Indicates width data is not available at this range

1 : 0.01 m/sec
65534 : 655.34 m/sec
65535 : Reserved Code

= (N–32768) / 100

m/sec

= N / 256

= N / 100

Nyquist

Z Selects clutter corrected reflectivity data.

8-Bit deciBel Format

— The level in decibels is computed from the unsigned

byte N as:

dBZ = (N–64)/2.

The overall range is therefore from –31.5 dBZ to +95.5 dBZ in half-dB steps as
follows:

0 : Indicates no reflectivity data available at this range

1 : –31.5 dBZ

64 : 0.0 dBZ

128 : 32.0 dBZ

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Host Computer Commands

255 : +95.5 dBZ

16-Bit deciBel Format

— The level in decibels is computed from the unsigned

word N as:

dBZ = (N–32768) / 100

The overall range is from –327.67dB to +327.66dB in 1/100dB steps as follows:

0 : Indicates no reflectivity data available at this range

1 : –327.67 dBZ
32768 : 0.00 dBZ
65534 : +327.66 dBZ
65535 : Reserved Code

T Selects total reflectivity. Same 8-bit and 16-bit coding formats as for clutter cor-

rected reflectivity above.

ZDR Selects differential reflectivity data.

8-Bit ZDR Format

— The level in decibels is computed from the unsigned byte

N as:

dB = (N–128) / 16

The overall range is from –7.935dB to +7.935dB in one-sixteenth dB steps as fol­lows:

0 : Indicates no reflectivity data available at this range

1 : –7.9375 dB

128 : 0.0000 dB
255 : +7.9375 dB

16-Bit ZDR Format

— Same as 16-bit deciBel format.

KDP Selects dual polarization specific differential phase data.

8-Bit KDP Format

— Values are coded into an unsigned byte using a logarith­mic scale. The KDP angles are multiplied by the wavelength in cm. (to reduce
dynamic range) and then converted to a log scale separately for both signs. The
minimum value is 0.25 deg*cm/km, and the maximum value is 150.0 deg*cm/
km. A code of zero represents no data, and a code of 128 represents 0 deg*cm/
km. The conversion equation for positive values (codes from 129 to 255) is:

N*129

ƪ

ƫ

KDP l + 0.25 600

126

The conversion equation for negative values (codes from 1 to 127) is:

127*N

ƪ

ƫ

KDP l + –0.25 600

126

16-Bit KDP Format — Same as 16-bit deciBel format, except that the units are
hundredths of degrees per kilometer. No weighting by wavelength is introduced.

F

PDP Selects dual polarization differential phase

6–18

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8-Bit FDP Format — The phase angle in degrees is computed on a 180-degree
interval from the unsigned byte N as:

16-Bit

interval from the unsigned word N as:

F

Ă(modĂ180) = 180 (N – 1) / 254

DP

0 : Indicates no

F

DP

1 : 0.00 deg
254 : 179.29 deg
255 : Reserved Code

F

Format — The phase angle in degrees is computed on a 360-degree

DP

F

Ă(modĂ360) = 360 (N – 1) / 65534

DP

0 : Indicates no

F

DP

1 : 0.000 deg

65534 : 359.995 deg
65535 : Reserved Code

Host Computer Commands

data available at this range

data available at this range

RHV Selects dual polarization correlation coefficient

ò

8-Bit

Format — The correlation coefficient is computed on the interval 0.0

HV

ò

data.

HV

to 1.0 using a square root weighting of the unsigned byte N as:

òHVĄ +Ą

Ǹ

(

N * 1

253

)

0 : Indicates no òHV data available at this range

1 : 0.0000 (dimensionless)

2 : 0.0629
253 : 0.9980
254 : 1.0000
255 : Reserved Code

16-Bit

ò

Format — The correlation coefficient is computed on the interval 0.0

HV

to 1.0 linearly from the unsigned word N as:

ò

= (N – 1) / 65533

HV

ò

0 : Indicates no

data available at this range

HV

1 : 0.0 (dimensionless)

65534 : 1.0
65535 : Reserved Code

SQI Selects Signal Quality Index data. This dimensionless parameter uses the same

8-bit and 16-bit data formats as RHV (ò

HV

).

LDR Selects Linear Depolarization Ratio, measured either on the horizontal receive

channel while transmitting vertically, or on the vertical receive channel while
transmitting horizontally.

8-Bit LDR Format

— The level in decibels is computed from the unsigned byte

N as:

dB = –45.0 + (N–1) / 5

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This spans an asymmetric interval around zero decibels, and allows for cross
channel isolation as large as 45dB. The overall range is from –45.0dB to +5.6dB
in 0.2dB steps as follows:

Host Computer Commands

0 : Indicates no LDR data available at this range

1 : –45.0 dB
226 : 0.0 dB
254 : +5.6 dB
255 : Reserved Code

16-Bit LDR Format

— Same as 16-bit deciBel format.

RHO Selects the cross channel correlation coefficient. This dimensionless parameter

ò

uses the same 8-bit and 16-bit data formats as RHV (

HV

).

PHI Selects the cross channel differential phase. This parameter uses the same 8-bit

and 16-bit angular data formats as PDP (F

DP

).

Flg Selects flag word output, bits defined as follows:

0 Reflectivity obscured at this bin
1 Velocity obscured at this bin
2 Width obscured at this bin
3 Point clutter detected at this bin

The Command word format for Time Series Mode is:

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| TSOUT | Spec Type |Unfold | | 1 1 | 0 0 1 1 0 | Command
|_______|_______________|_______|___|_______|___________________|

TSOUT Selects type of data to be output.

00 : 8-bit Time Series 01 : Power Spectrum
10 : 16-bit Time Series 11 : Unused

When the TSOUT bits select “Power Spectrum” then, depending on the current major mode, a
further choice may be needed to select one of several spectral view points. For the Random
Phase major mode the possible values of “Spec Type” are:

0: Raw First Trip 4: Raw Second Trip
1: Whitened First Trip 5: Whitened Second Trip
2: Cleaned First Trip 6: Cleaned Second Trip
3: Final First Trip 7: Final Second Trip

When time series output is selected the output data consist either of (3xBxN) or (2xBxN) words,
depending on the output format, where B is the number of bins in the current range mask, and N
is the number of pulses per ray. Data samples for each bin of pulse #1 are output first, followed
by those for each bin of pulse #2, etc. up to pulse #N. In other words, the data are output in the
same time-order that they were acquired.

In the floating point format, three words are used for each bin:

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Exponent | S | Mantissa | (I)
|___________________|___|_______________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Exponent | S | Mantissa | (Q)
|___________________|___|_______________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 0 0 0 0 | Log of Power in Sample | (LOG)
|_______________|_______________________________________________|

Host Computer Commands

To convert these “legacy format” floating I and Q samples to voltages: First create a 12-bit
signed integer in which bits zero through nine are copied from the Mantissa field, and bits ten
and eleven are either 01 or 10 depending on whether S is 0 or 1. Then, multiply this number by
2**(exponent–40), where the exponent field is interpreted as an unsigned 5-bit integer. Finally
multiply by the maximum voltage. The resulting value has 12-bits of precision and a dynamic
range of approximately 190dB. The large dynamic range is necessary to cover the full range of
data. In summary:

Voltage + V

(Sign, Mantissa) 2

MAX

Note that the resulting voltage span is actually " 4 V

ƪ

Exponent*40

. The extra factor of four is built into

MAX

ƫ

the format so that transient excursions above the full scale input voltage can still be encoded
properly. These may arise for time series data that have been processed by an IIR clutter filter.

An improved “High-SNR” packed floating format is also available that offers nearly the same
dynamic range but provides a 6dB improvement in SNR, i.e., a commensurate improvement in
sub-clutter visibility of –78dB versus –72dB.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Exponent | S | Mantissa | High–SNR
|_______________|___|___________________________________________|

The High-SNR packed format is similar to the legacy packed format except that it uses one extra
mantissa bit and one fewer exponent bit. The dynamic range lost in the exponent is recovered
through a formatting trick known as “soft underflow”, i.e., the mantissa is allowed to become
unnormalized when the exponent is zero.

To decode this format when the exponent is non-zero, first create a 13-bit signed integer in
which bits zero through ten are copied from the Mantissa field, and bits eleven and twelve are
either 01 or 10 depending on whether S is 0 or 1. Then, multiply this by 2**(exponent–25),
where the exponent field is interpreted as an unsigned 4-bit integer.

To decode the High-SNR format when the exponent is zero simply interpret the mantissa as a
12-bit signed integer and multiply by 2**-24.

A complete analysis of the noise properties of the floating point codes would be fairly tricky.
For the High-SNR format, the 12-bit mantissa with hidden normalization bit will vary from 2048
to 4095. The SNR will therefore vary from 66dB to 72dB and we can assign a mean value of
69dB. Another 9dB of useful range is contained within the code as follows:

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Host Computer Commands

 In a floating point encoding format, the notion of fixed additive quantization noise is not

really correct. For a signal having a given power, the additive noise within each
instantaneous sample will scale down according to the magnitude of that sample. The
ensemble of noise terms thus contributes an RMS power that is smaller than the
Peak–to–Noise ratio would imply. In the case of a sinusoidal input, this gives a 3dB
boost in effective SNR.

 The format, of course, also represents negative amplitudes with the same relative

precision as positive values. In a fixed–point format this would add 6dB (one more bit)
to the overall dynamic range and large–signal SNR. In the floating format we really only
gain 3dB (half a bit) because the RMS noises add independently on the positive and
negative excursions.

 The packed format is used to encode timeseries (I,Q) pairs, and it’s the SNR properties of

these pairs that we’re really concerned about. To a first approximation, having a pair of
values roughly doubles the information content and adds another 3dB to the SNR.

The last of the three timeseries output words, the “Log of Power in Sample”, is provided mainly
for backwards compatibility. It can be calculated from the I and Q numbers. To convert to dBm
it requires a slope and offset as follows:

dBm + P

) Slope [Value * 3584

MAX

]

Where:

P

= +4.5dBm for 12-bit IFD, +6.0dBm for 14-bit IFD

MAX

V

= 0.5309 Volts for 12-bit IFD, 0.6310 Volts for 14-bit IFD

MAX

Slope = “Log Power Slope” word 3 of SOPRM command. 0.03 recommended.

For backwards compatibility the RVP8 produces a 8-bit fixed point time series format. Because
of the limited dynamic range available, this will only show strong signals, and is not
recommended for use. The I, Q, and Log power triplets are packed into two 16-bit output words
as follows:

High Byte Low Byte
| | |
| Q Sample | I Sample | First Word
|___________|___________|

| | |
| Zero | Log Power | Second Word
|___________|___________|

The “Log Power” value is the upper 8 bits of the long format. The other numbers are produced
by the equation:

Sample

Voltage + V

MAX

ƪ

128

ƫ

When Power Spectrum output is selected, the spectrum size is chosen as the largest power of two
(N2) that is less than or equal to the current sample size (N). When the sample size is not a
power of two, a smaller spectrum is computed that by averaging the spectra from the first N2

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Host Computer Commands

and the last N2 points. The data format is one word/bin/pulse, in the same order as for time
series output. Each word gives the spectral power in hundredths of dB, with zero representing
the level that would result from the strongest possible input signal (

P

). Thus, the spectral

MAX

output terms are almost always negative.
The time series that are output by the RVP8 are the filtered versions of the raw data, when

available. If a non-zero time-domain clutter filter is selected at a bin, then the I and Q data for
that bin show the effects of the filter. Whenever you need to observe the raw samples, make sure
that no clutter filters are being applied.

In pulse pair time series mode with dual receivers, selecting (H+V) will produce data in one of
two formats according to the “Sum H+V Time Series” question in the Mp setup section:

 Answering “Yes” will result in summed time series from both channels, but spectra from

the DSP will be the averaged spectra from each channel individually. This allows the
IRIS ascope utility to display either the spectrum-of-sum or sum-of-spectra according to
whether the “Spectra from DSP” button is pressed in the Processing/Gen-Setup window.

 Answering “No” will still produce the usual (BxN) time series output samples, except

that the first half of these samples will be the first half of the “H” data in their normal
order. This will be followed by a zero sample if (BxN) is odd; followed by the first half
of the “V” data, also in their normal order.

 In other words, only the first halves of the individual “H” and “V” sample arrays are

output by the RVP8. As an example, if you select 25 bins and 100 pulses, then the output
data will consist of 1250 “H” samples (from all bins in the first 50 pulses), followed by
1250 “V” samples from the exact same set of bins and pulses. This is the more useful
option when custom algorithms are being run on the data from the two separate receivers.

When the number of output words is large there is a possibility that the internal buffering within
the RVP8 may overflow and data may be lost. Due to internal memory limitations, the product
(BxN) must be less than 12000. A bit in the latched status word (See GPARM) indicates when
time series overflows occur. In such cases, the correct number of words are still output, but they
are all zero after the point at which overflow was detected.

6.8 Load Clutter Filter Flags (LFILT)

A special feature of the RVP8 processor is that any of the available clutter filters may be chosen
independently at each selected range. This range-dependent clutter removal is useful when the
clutter characteristics vary with increasing range. Typically, clutter interference is most severe in
the immediate vicinity of the radar. Thus, a highly rejective filter might be chosen for near
ranges, and a less rejective or perhaps no filter could be used at far ranges.

Legacy Version

In the legacy version of LFILT, the input words following the command specify the choice of
filter to be applied at each of the selected range bins. A fixed size filter table is always loaded,
regardless of whether the range mask (See LRMSK) is using the full number of bins. In such
cases, the later filter codes are simply ignored for the current range mask. However, if a longer

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Host Computer Commands

range mask is loaded in the future, then those later codes would apply to the correspondingly
numbered bins. Put another way, each filter code is associated with a particular bin number, not
with a particular range. The correspondence between bin numbers and actual ranges is made
only through the range mask.

Only the low three bits are used in each word to specify the filter number. If the ALL bit is set
in the Command, then 3072 words are loaded, corresponding to the maximum number of range
bins that are allowed. Otherwise only 512 words are loaded, and the 512th filter choice is
replicated for all bins further in range.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |ALL| 0 1 0 0 0 | Command
|_______________________________________|___|___________________| (Legacy)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Filter #1 | Input 1
|___________________________________________________|___________|
.
.
Either 512 or 3072 Words Loaded

Enhanced Version

The RVP8 supports an enhanced version of the LFILT command that provides “Clutter Maps”,
i.e., much greater flexibility by allowing filter choices to depend on antenna angle as well as
range. This lets you specify a 2D or even 3D table of clutter filter selections that are
dynamically selected during live data processing.

The RVP8 maintains an internal array of up to 1024 different filter-versus-range tables, each of
which is keyed to a particular solid angle AZ/EL sector. Each enhanced LFILT command fills in
one of these slots with a filter selection table similar to that of the legacy command, except that
the number of range bins is specified explicitly and eight bits are used for filter selection rather
than three. Then, for each live ray being processed, the RVP8 applies clutter filters according to
the filter slot whose solid sector includes the midpoint AZ/EL of the ray. If the antenna angle of
the ray does not fall within any of the defined filter sectors, then the all-pass filter (#0) will be
used at all ranges.

The low and high angle limits in each filter slot are inclusive; hence, the pair (0x000, 0xFFFF)
would span the full 360-degree circle with no gaps. Also, the filter array can be sparse (not all
slots filled in), and have overlapping sectors (in which case the highest numbered slot that spans
a ray’s AZ/EL midpoint will be used). Choosing the highest numbered encompassing slot is a
subtle but important detail that allows complex regions to be defined as a layered hierarchy of
overlapping sectors. For example Slot-0 might define a default 360-degree filter-versus-range
table, while Slot-1 defines special filtering within 0-90 degrees that is further modified by Slot-2
filters in a 40-50 degree span. A 45-degree ray would then be filtered according to Slot-2, a
60-degree ray would use Slot-1, and a 100-degree ray would use Slot-0.

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Host Computer Commands

If the CLR bit is set in the opcode, then no additional arguments follow and the entire internal
filter array (all slots) will be invalidated. The result is that no clutter filter will be applied to any
of the processed data, regardless of Range, AZ, or EL. Moreover, loading a given slot with a
table consisting of zero bins of filter data will invalidate just that one slot. This allows some
data to be removed from the table without having to resort to a complete CLR operation.

The legacy LFILT command is equivalent to calling the enhanced command first with the CLR
bit set, followed by a second call that writes the legacy filter choices into slot #0 using AZ/EL
limits that cover all of space. Thus, the legacy behavior is obtained as a special case of the
enhanced mechanism.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 1 |CLR| 0 1 0 0 0 | Command
|___________________________________|___|___|___________________| (Enhanced)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Internal Slot for This Filter Ray Specification (0–1023) | XARG 1
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Bins of Filter Selections to Load (0–3072) | XARG 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Lower AZ (Binary angle) | XARG 3
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Upper AZ (Binary angle) | XARG 4
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Lower EL (Binary angle) | XARG 5
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Upper EL (Binary angle) | XARG 6
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Filter for Range Bin #2 | Filter for Range Bin #1 | Input 1
|_______________________________|_______________________________|
.
.
Total of Ceil(NBins/2) Words Loaded

6.9 Get Processor Parameters (GPARM)

This command is used to access status information from the RVP8 processor. Sixty-four words
are always transferred, some later words are reserved for future compatibility and are read as
zeros. For convenience, a shorthand table of the output words is given in Table 6–2.

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Table 6–2: RVP8 Status Output Words

Host Computer Commands

Word

Description Word Description

1 Revision / Serial number 33 LOG Threshold
2 Number of Range Bins 34 CCOR Threshold
3 Current trigger period 35 SQI threshold
4 Current TAG00 – TAG15 36 SIG Threshold for Width
5 Current TAG16 – TAG31 37 Calibration Reflectivity
6 Log of Measured Noise Level 38 — Reserved —
7 “I” Channel DC Offset 39 — Reserved —
8 “Q” Channel DC Offset 40 Range Averaging Choice

9 Latched Processor Status 41 — Reserved —
10 Immediate Status Word #1 42 — Reserved —
11 Diagnostic Register A 43 Header configuration of PROC data
12 Diagnostic Register B 44 I-Squared Noise (Low 16-bits)
13 Number of Pulses / Ray 45 I-Squared Noise (High 16-bits)
14 Trigger count (Low 16-bits) 46 Q-Squared Noise (Low 16-bits)
15 Trigger Count (High 8-bits) 47 Q-Squared Noise (High 16-bits)
16 No. of Properly Acquired Bins 48 Log of Measured Noise Level
17 No. of Properly Processed Bins 49 LOG Noise Standard Deviation
18 Immediate Status Word #2 50 Horizontal/Vertical Noise Ratio
19 Noise Range in Km 51 AFC/MFC Control Value
20 Noise Trigger Period 52 Interference Filter Select
21 Pulse Width 0 min. Trig. Period 53 Interference Filter C1 Constant
22 Pulse Width 1 min. Trig. Period 54 Interference Filter C2 Constant
23 Pulse Width 2 min. Trig. Period 55 Immediate Status Word #3
24 Pulse Width 3 min. Trig. Period 56 Burst Tracking Slew
25 Pulse Width Bit Patterns 57 Polarization Algorithm Choices
26 Current /Pulse Width 58 Range Mask Spacing
27 Current Trigger Gen. Period 59 Immediate Status Word #4
28 Desired Trigger Gen. Period 60 — Reserved —
29 PRT at Start of Last Ray 61 — Reserved —
30 PRT at End of Last Ray 62 — Reserved —
31 Processing/Threshold Flags 63 — Reserved —
32

Log Slope 64 — Reserved —

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 1 0 0 1 | Command
|___________________________________________|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Rev Bits 3–0 | Rev 6–4 | Serial Number | Output 1
|_______________|___________|___________________________________|

Host Computer Commands

The revision and serial numbers of the particular RVP8 board are accessible here. This
information is useful when computer software is being designed to handle a variety of signal
processor revisions. The revision number is seven bits total; four of which are still in the high
four bits of the word for compatibility with an older format.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Bins Currently Selected in Range Mask | Output 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| TRIGIN Current Trigger Period in 1/8km (0.83333 usec) Steps | Output 3
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Current Sample of TAG bits 15–0 | Output 4
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Current Sample of TAG bits 31–16 | Output 5
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 0 0 | (MSB) Log of Measured Noise Level (LSB) | Output 6
|_______|_______________________________________________________|

This value is scaled 4 times higher than the time series LOG format (see the discussion in
Section 6.7). To convert to dBm, use the equation:

dBm + P

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| ”I” Channel Measured DC Offset | Output 7
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| ”Q” Channel Measured DC Offset | Output 8
|_______________________________________________________________|

) Slope ƪ(Valueń4) * 3584

MAX

ƫ

These two words convey the measured “I” and “Q” DC offsets from the last noise sample. The
output format is either signed 16-bit values in which 32767 represent 1.0 (legacy format), or

packed timeseries values using the High-SNR encoding format. Bit-9 of GPARM Word-59 tells
which format to use.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Latched Status Word (Bits Cleared After Each Access) | Output 9
|_______________________________________________________________|

Host Computer Commands

Bit 0 No Trigger during noise measurement.
Bit 1 Trigger too fast during noise measurement, i.e., some of the noise sample bins

were positioned past the trigger range.
Bit 2 No trigger during PROC command.
Bit 3 PRT varied by more than 10 microseconds within portions of a processing interval

that should have been at a fixed rate.
Bit 4 Error in polarization control and/or polarization status readback
Bit 5 FIFO overflow during last PROC command.
Bit 6 Command received while waiting for output FIFO space. The command was pro-

cessed but some output data has been lost (zeroed).
Bit 7 Error detected during last SNOISE command.
Bit 9 Error in last Load Range Mask (LRMSK) Command. This generally means that

too many range bins were selected.
Bit 10 Error in LSIMUL command protocol.
Bit 11 Measured phase sequence is incorrect.
Bit 15 Invalid processor configuration. This bit is set if the last PROC command called

for an illegal combination of parameters. The possible causes are:

 Spectrum size greater than 128 or less than 4

 More than 342 bins/slave in FFT modes

 (bins/slave) x (4 + sample size) exceeds 26200 in FFT modes

 (bins/slave) x (sample size) exceeds 3000 for Time Series or Spectra output

 Odd number of bins selected during fast polarization switching

 Bad combination of polarization parameters

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Immediate Status Word #1 (Current State of Affairs) | Output 10
|_______________________________________________________________|

Bit 0 No trigger, or, more than 50ms. since last trigger.
Bit 1 Error in loading trigger angle table (See LSYNC Command).
Bit 2 PWINFO command is disabled.
Bit 3 Angle sync input is BCD (Else binary angle).
Bit 4 Angle sync is on elevation axis (Else azimuth axis).
Bit 5 Angle sync is enabled.
Bit 6 Angle sync is not interruptible.
Bit 7 Angle sync is dynamic (else rays begin on sync angles).
Bit 8 DSP has full IAGC hardware and firmware configuration.
Bit 9 DSP supports 16-bit floating time series.
Bits 11,10 Current unfolding mode.
Bits 13,12 Number of RVP8/PROC compute processes minus one

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Bit 14 DSP supports Power Spectrum output

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Diagnostic Result Register A | Output 11
|_______________________________________________________________|

Bit 0 RVP8/Rx card #1 failure
Bit 1 RVP8/Rx card #2 failure
Bit 2 RVP8/Tx card #1 failure
Bit 3 RVP8/Tx card #2 failure
Bit 4 IO62 card #1 failure
Bit 5 IO62 card #2 failure
Bit 6 Error loading config/setup files
Bit 7 Error attaching to antenna library
Bit 8 Problem when forking compute processes
Bit 9 Error(s) in softplane configuration
Bit 10 Signals raised during startup
Bit 11 RVP8 running without ’root’ privileges
Bit 12 Problem creating daemon process
Bit 13 Inconsistent setup values detected

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Diagnostic Result Register B | Output 12
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Pulses Being Integrated | Output 13
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Trigger Count (Low 16-bits) | Output 14
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Trigger Count (high 8-bits) | Output 15
|_______________________________|_______________________________|

The trigger count is a running tally of the number of triggers received by the RVP8 on the
TRIGIN line. It is a full 24-bit counter.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Properly Acquired Bins for Current Range Mask & PRT | Output 16
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| No. of Valid Bins in Initial Part of Ray From Last PROC Cmd | Output 17
|_______________________________________________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Immediate Status Word #2 (Current State of Affairs) | Output 18
|_______________________________________________________________|

Host Computer Commands

Bit 0 Processor supports FFT algorithms
Bit 1 Processor supports Random Phase algorithms
Bit 2 Reserved (zero)
Bit 3 Processor supports DPRT-1 (Dual-PRT) algorithms
On dual IFD systems: Bits 4,5,7, and 11 are set if either IFD fails:
Bit 4 Problem in UpLink cable from RVP8/Rx ––> IFD
Bit 5 Problem in DownLink cable from IFD ––> RVP8/Rx
Bit 7 IFD PLL is not locked to external user-supplied clock reference
Bits 8–10 Status of burst pulse and AFC feedback

1: AFC Disabled 2: Manual Frequency Control

3: No burst pulse detected 4: AFC is waiting for warm-up

5: AFC is locked 6: AFC is tracking
Bit 11 IFD test switches are not in their normal operating position
Bit 12 Set according to whether the RVP8 is performing trigger blanking. This allows

the host computer to decide whether to interpret the End-TAG-0 bit in the output

ray header as a blanking flag, or as a normal TAG line.
Bit 13 Missing signal at IFD #1 Burst Input
Bit 14 Reserved (zero)
Bit 15 Set when valid burst power is detected but the center-of-mass lies outside of the

aperture sub-window that defines the portion of the pulse used for AFC analysis.

This error bit effectively flags when the burst pulse has drifted out of its optimal

placement within the sampling window.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Starting Range in Km at Which Noise Sample Data are Taken | Output 19
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Trigger Period (0.16667usec Increments) During Noise Sampling | Output 20
|_______________________________________________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 0 | Output 21
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 1 | Output 22
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 2 | Output 23
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 3 | Output 24
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Four 4-bit Control Bit Patterns for Each Pulse Width | Output 25
|_______________________________________________________________|

Host Computer Commands

See PWINFO command, input word #1, for definition of these bits.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Window | TopMode | | P.W. | Output 26
|___________________|___________|_______________|_______|_______|

P.W. Currently selected radar pulse width
TopMode Major Mode (See SOPRM Input #9)
Window Spectral Window Choice (See SOPRM Input #10)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Current Trigger Generator Period (0.16667usec Increments) | Output 27
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Desired Trigger Generator Period (0.16667usec Increments) | Output 28
|_______________________________________________________________|

The desired trigger generator rate is that which was selected in the most recently issued
SETPWF command (or power-up rate if SETPWF was never issued). The current rate may be
different from the desired rate due to bounding against limits for the current pulse width, or
being in an odd ray cycle during dual-PRT processing. The measured PRT’s are forced to
0xFFFF (the maximum unsigned value) whenever the external trigger is expected but missing.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| TRIGIN Period at Start of Last PROC Acquisition Time | Output 29
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| TRIGIN Period at End of Last PROC Acquisition Time | Output 30
|_______________________________________________________________|

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Host Computer Commands

The PRTs from the start and end of the last ray are the actual measured values whenever
possible, i.e., when non-simulated data are being processed, and we either have an external
trigger, or an internal trigger that is not in any of the Dual-PRT modes. The units are the same
as for the measured current trigger period in Output #3.

Outputs 31 through 37 are the current processing and threshold parameters set by SOPRM. See
Section 6.3 for additional notes on each of these parameters. Since the threshold levels for each
data parameter can be different (See THRESH command, Section 6.29), words 33-36 are taken
from the velocity parameter.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Polar |NHD|ASZ|16B|CMS| R2| |3x3| | |Lsr|Dsr|Rnv| Output 31
|_______|_______|___|___|___|___|___|___|___|___|___|___|___|___|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Log Slope 65536 * dB / LSB | Output 32
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| LOG Noise Threshold in 1/16 of dB | Output 33
|_______________________________________________________________| (From V)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Clutter Correction (CCOR) Threshold in 1/16 of dB | Output 34
|_______________________________________________________________| (From V)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | SQI Threshold | Output 35
|_______________________________|_______________________________| (From V)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| SIG Threshold in 1/16 of dB | Output 36
|_______________________________________________________________| (From V)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Calibration Reflectivity in 1/16 of dB | Output 37
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved (Zero) | Output 38
|_______________________________|_______________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved (Zero) | Output 39
|_______________________________|_______________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Range Avg (From LRMSK Command)| Output 40
|_______________________________|_______________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved (Zero) | Output 41
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved (Zero) | Output 42
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Header Config of PROC data (CFGHDR Input #1, Section 6.22) | Output 43
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Noise Sum of I Squared MSB=2**–16 LSB=2**–31 | Output 44
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Noise Sum of I Squared MSB=1 LSB=2**–15 | Output 45
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Noise Sum of Q Squared MSB=2**–16 LSB=2**–31 | Output 46
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Noise Sum of Q Squared MSB=1 LSB=2**–15 | Output 47
|_______________________________________________________________|

Host Computer Commands

To compute the noise power in dBm from Words 44-47, first calculate:

NI+ (Word 45) 2
NQ+ (Word 47) 2

*15

) (Word 44) 2

*15

) (Word 46) 2

*31
*31

From which we obtain:

dBm + P

MAX

) 10 log

10

ǒ

NI) N

Ǔ

Q

* 3dB

Note that the four integer values become rather small and severely quantized when the noise
power drops to low values. Historically, these four words were used to balance the individual
gain of the “I” and “Q” channels in the RVP6 in the presence of a strong test signal. Since “I”
and “Q” are inherently balanced in the RVP8, these output words are no longer of much value.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Log of Measured Noise Level (same as word 6) | Output 48
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Vert Noise Stdev in dB*10 | Horiz Noise Stdev in dB*10 | Output 49
|_______________________________|_______________________________|

The noise standard deviations for each receive channel are normalized to the mean power. The
values reported here will therefore hover around 0dB for ordinary exponentially distributed
noise in which the standard deviation scales directly with the mean.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Ratio of Horizontal/Vertical Noise Power in Hundredths of dB | Output 50
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 16–Bit AFC/MFC Value (–32768 through +32767) | Output 51
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| PhaseSeq | IFD Sat.Power | MinRev | Inter.F | Output 52
|_______________|_______________|_______________|_______________|

Host Computer Commands

Inter.F Specifies which interference filter is running. Zero means “none”; see Section

5.1.5 for a description of the interference filter algorithms.

MinRev Minor revision level of the RVP8 code that is currently running.

P

IFD Sat.Power (

MAX

)
Input power required to saturate the IF-Input A/D converter for the RVP8/IFD re­ceiver that is currently attached.

0: +4.5dBm 1: +6.0dBm

PhaseSeq Tx Phase modulation sequence (See Section 6.27)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Interference Filter Parameter “C1” in Hundredths of deciBels | Output 53
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Interference Filter Parameter “C2” in Hundredths of deciBels | Output 54
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Immediate Status Word #3 (Current State of Affairs) | Output 55
|_______________________________________________________________|

Bit 0 Burst pulse timing adjustments can be made
Bit 1 Burst pulse frequency adjustments can be made
Bit 2 Burst pulse hunting is enabled
Bit 3 Burst pulse hunt is running right now
Bit 4 Last burst pulse hunt was unsuccessful
Bit 5 Processor supports DPRT-2 (Dual-PRT) algorithms
Bit 6 Could not generate the requested phase sequence
Bit 7 Problem with digital transmitter clock
Bits 8-11 User-defined Major Modes 1-4 are supported

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed trigger slew in hundredths of microseconds | Output 56
|_______________________________________________________________|

This is the same format that is used by the SETSLEW command to set the current trigger slew
(See Section 6.25)

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Polarization Algorithm Choices | Output 57
|_______________________________________________________________|

Host Computer Commands

Bit 0 Use H transmissions for (T,Z,V,W)
Bit 1 Use V transmissions for (T,Z,V,W)
Bit 2 Use Co–Pol reception for (T,Z,V,W)
Bit 3 Use Cross–Pol reception for (T,Z,V,W)
Bit 4 Correct all polar Parameters for noise
Bit 5 Use filtered data for all polar Parameters
Bit 6 Sign convention for PHIdp

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Range mask spacing for current pulsewidth (centimeters) | Output 58
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Immediate Status Word #4 (Current State of Affairs) | Output 59
|_______________________________________________________________|

Bit 0 Internal power spectra size matches sample size (else power-of-2)
Bit 1 PROC command output spectra match sample size (else power-of-2)
Bit 2 Trigger pattern has been altered to fit within the desired PRT
Bit 3 PRT has been altered to preserve the desired trigger pattern
Bit 4 Using High–SNR packed (I,Q) format
Bit 5 Trigger sequence truncated due to insufficient pattern memory
Bit 6 TimeSeries data source is external to the RVP8
Bit 7 WSR88D “Batch” mode is supported
Bit 8 Major mode refuses to use external trigger
Bit 9 GPARM outputs #7 and #8 use Hi-SNR format, else linear
Bit 10 Receiver protection fault
Bit 11 IFD dual-channel inconsistency (e.g., power and/or phase out of bounds for ratio

of HiGain-to-LoGain channels)

Bit 12 GPS 1-pulse-per-second input clock error

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved (Zero) | Output 60
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved (Zero) | Output 64
|_______________________________________________________________|

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Host Computer Commands

6.10 Load Simulated Time Series Data (LSIMUL)

This command is provided as a diagnostic for proper functioning of the RVP8 algorithms. It
permits arbitrary simulated data samples to be input to the processing routines, rather than
sampled data from the A/D converters as is ordinarily the case. Since the properties of the
simulated data are known exactly, it is possible to verify that the calculations within the RVP8
are proceeding correctly.

The LSIMUL command (with operation=1) should be issued prior to the PROC command which
is being tested. This enables the simulated data mode. The next PROC command will then wait
for N (N = sample size) LSIMUL commands (with operation=2) prior to outputting each ray.
The arrival of any other command during that time will cause the simulated data mode to be
exited, and error bit #10 will be set in the GPARM latched status word. The error bit is also set
if an LSIMUL command with operation=2 is received while simulated data mode is disabled.

You may specify a single simulated data sample for every range bin, or a pattern or simulated
samples to be replicated over the range of bins. Most RVP8 algorithms are independent of
range, and can be tested with identical data at every bin. Notable exceptions, however, are the
“pop” clutter filter, and range bin averaging procedures. In its full generality, the LSIMUL
command permits independent I and Q samples to be simulated at every bin of every pulse. If
this results in more host computer I/O than is practical, then specify fewer simulated bins and
allow the RVP8 to replicate them internally.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Operation | | 0 1 0 1 0 | Command
|___________________|___________|___________|___________________|

The available operations are:

0 Disable the use of simulated data. RVP8 returns to acquisition and processing of

live data from the A/D converters.

1 Enable processing of simulated data. Subsequent PROC commands will use the

data supplied in the next N (N = sample size) LSIMUL commands with Opera­tion=2.

The receiver noise and offset levels which are internally maintained by the RVP8
are set to their special simulated values (from the M+ setup menu) by this com­mand. This is because the measured offsets are not relevant to the simulated data,
and must not be used in the subsequent computations. Thus, it is important to is­sue the SNOISE command before resuming the acquisition and processing of live
radar data.

2 or 3 Load one pulse of data samples beginning with the following 4-word header, and

continuing with an array of items each representing a single instantaneous sample
of (I,Q) data. You may specify one or more bins to be loaded, and the RVP8 will
replicate these data as necessary in order to fill out the entire count of acquired
bins. If the number of bins is zero, then a zero-valued sample is applied for all
channels.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Bins of Simulated Data Which Follow | Input 1
|_______________________________________________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Transmit Phase of This Pulse (16-bit Binary Angle) | Input 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Transmit Power in Hundredths of dB (Zero dB Nominal) | Input 3
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved | Input 4
|_______________________________________________________________|

Host Computer Commands

In the legacy Format #2 (RVP5-RVP8) each bin within the pulse is represented by
four 16-bit fixed point words. Thus, the total number of words loaded is (4+4B),
where B is the bin count specified in Word #1. This takes account of the four
“header” words, plus four words for every bin being defined.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved | Input 5
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed “I” A/D Sample (F16.12 Format) | Input 6
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed “Q” A/D Sample (F16.12 Format) | Input 7
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Reserved | Input 8
|_______________________________________________________________|

.
.
.

In Format #3 (new in the RVP8) each bin within the pulse is represented by two
16-bit floating point words having the exact same format as the packed (I,Q) time­series data that are output by the PROC command (See Section 6.7). Compared to
the legacy 4-word format, this 2-word format uses half the I/O bandwidth, has su­perior dynamic range, and allows data to be fed back into the signal processor in
their native packed format. The total number of words loaded (including the ini­tial header section) is (4+2B), where B is the bin count specified in Word #1.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Exponent | S | Mantissa | Input 5 (I)
|___________________|___|_______________________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Exponent | S | Mantissa | Input 6 (Q)
|___________________|___|_______________________________________|

.
.
.

Host Computer Commands

6.11 Reset (RESET)

The RESET command permits resetting either the entire RVP8 processor, or selected portions
thereof. Flags within the command word determine the action to be taken.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |Nv |Nse|Fif|Nv |Nv | 0 1 1 0 0 | Command
|_______________________|___|___|___|___|___|___________________|

Nv Reloads configuration from the saved nonvolatile settings. For compatibility with

RPV6 and RVP7, any of 3 bits will trigger this response.

Nse Reset the receiver noise levels to the power-up default value for all pulsewidths as

defined in the Mt setup questions (See Section 3.2.5).

Fif Remove any data currently in the output FIFO’s. This permits flushing output

data that was left from a previous command, so that new output can be read from
scratch. See notes in the Introduction to this chapter concerning actions taken by
the RVP8 when the output FIFO becomes full.

6.12 Define Trigger Generator Waveforms (TRIGWF)

Note: This opcode is obsolete, and is included only for backward compatibility
with the RVP6. The opcode is disabled by default (See Section 3.2.1), because
the interactive trigger setup procedure described in Section 4.3 is the preferred
method of defining all RVP8 triggers and timing. TRIGWF should not be used
in any new code applications that drive the RVP8.

The RVP8 has a built-in trigger generator that can synthesize six independent digital output
waveforms, each having arbitrary shape and being active anywhere in a window centered around
zero-range. The six trigger outputs can be defined by a 2048-word by 6-bit table which is
loaded from the user computer. The patterns are automatically read from the table and output to
the six trigger lines during each radar pulse. The six outputs can be used for transmitter triggers,
scope triggers, range strobes, PLL gates, etc. The writable waveform table makes the RVP8
unique, in that the detailed timing of trigger and related control signals can be easily adjusted in
software, without having to resort to reprogramming PROMs. This makes it possible for user
software to edit the trigger timing in a convenient interactive manner.

Trigger waveforms are loaded using the TRIGWF command. Four bits in the command word
(PW0 through PW3) select which pulsewidths will receive the new waveforms. On power-up,
all four pulsewidths are initialized to user-selected waveforms.

The first word following the TRIGWF command specifies the transition point of the POLAR0
polarization control signal. This control signal is either held low or high for the cases of fixed
horizontal or vertical polarization, or it alternates from pulse to pulse for fast-switching

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Host Computer Commands

polarization measurements such as Zdr. The transition point is specified as a value between 0
and 2047, where 1024 represents range zero. These units are the same as the time units for the
waveforms which follow, i.e., a 2048-word array holding 6-bit trigger patterns. Bit 0 in each of
these words affects the TGEN0 digital output line, bit 1 affects TGEN1, etc. The bits are output
at a 7.195MHz rate, and the beginning of the 1024th array word (1025th word following the
command) corresponds exactly to the instant at which data at range zero are sampled by the
RVP8. Note that the output rate can also be interpreted as a new bit coming every 1/48 km. In
some cases this is a more useful view.

As an example, suppose we wish to make the TGEN0 output be a 0.42 microsecond pretrigger
pulse, with a rising edge exactly five microseconds prior to range zero. This would be done by
setting bit 0 in input words 988, 989, and 990 following the TRIGWF command, and leaving all
other bit 0’s clear. Further, if TGEN1 was to be a 0.14 microsecond marker strobe at 20km, we
would simply set bit 1 of input word 1984.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |PW3|PW2|PW1|PW0| | 0 1 1 0 1 | Command
|_______________|___|___|___|___|___________|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| H | | Transition Point of POLAR0 Control Line | Input 1
|___|_______________|___________________________________________|

H This bit defines the sense of the control line when horizontal polarization is se-

lected.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Bits for –142.22 usec | Input 2
|_______________________________________|___|___|___|___|___|___|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Bits for zero range | Input 1025
|_______________________________________|___|___|___|___|___|___|

.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Bits for +142.08 usec | Input 2049
|_______________________________________|___|___|___|___|___|___|

6.13 Define Pulse Width Control and PRT Limits (PWINFO)

The RVP8 is equipped to control the radar transmitter’s pulse width and corresponding receiver
bandwidth. There are four pulse/bandwidth codes, numbered simply 0 through 3. The
association between codes and pulse widths is completely determined by the needs and
capabilities of the particular radar on hand. In some cases, the zero code might represent 0.25
microsecond pulse width, and in other cases it may represent 2.0 microseconds. Likewise, some

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radars may use all four codes, whereas others have fewer options from which to choose. The
PWINFO command defines what happens for each of the four possible codes, but does not
actually select which code is being used. The later function is performed by SETPWF.

The RVP8 drives four TTL output lines (PWBW0 – 3) which are intended to control the radar
pulse/bandwidth hardware. Typically this control is via relays or solid-state switches in the
transmitter and receiver. The user decides what state the four lines assume for each pulse width
code. This is done using word #1 following the command, which contains four codes packed
into one 16-bit word. The power-up default is to drive output line N low for a code of N,
keeping all other lines high (Input of 7BDE Hex). The flexibility in defining the output bits
usually makes the radar hardware connections very simple. For example, if pulsewidth selection
relied on choosing one of four relays, then each PWBWn line could serve directly as a relay
driver using the default pattern.

For each pulse width there is a corresponding minimum trigger PRT permitted. This bound is
intended to limit the transmitter duty cycle to a safe value under all conditions. PWINFO sets up
these minimum PRT’s using words 2 through 5 following the command. The maximum
frequency of the internal trigger generator is then constrained at each pulse width to the
indicated rate. This protection applies at all times, i.e., during noise sampling, during ray
processing, and during the standby time between rays. The default PRT bounds are 2000, 1000,
750, and 500 Hertz (Inputs of 3000, 6000, 8000, and 12000). If your radar does not use all four
pulse width codes, it is still a good idea to set the unused PRT limits to reasonable values. This
way protection is still provided in the event that SETPWF accidently selects one of the unused
states. If the internal trigger generator is not being used, then the PRT limits no longer affect the
actual trigger rate and transmitter protection becomes the responsibility of the the user hardware.
Finally, note that the entire pulse/bandwidth mechanism can be effectively turned off by setting
the four bit patterns and the four PRT limits all to the same value.

The PWINFO command can be disabled (for transmitter safety), so that PRT limits cannot
accidently be changed by the host computer. When this is done the RVP8 still reads the five
input words, but no changes are made to the pulse width and PRT information. Thus, the
command I/O behaves the same way, whether enabled or disabled.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |UpperPW| | 0 1 1 1 1 | Command
|_______________________|_______|___________|___________________|

UpperPW Upper two bits of the four 4-bit pulsewidths being defined.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Bits for PW 3 | Bits for PW 2 | Bits for PW 1 | Bits for PW 0 | Input 1
|_______________|_______________|_______________|_______________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 0 | Input 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 1 | Input 3
|_______________________________________________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 2 | Input 4
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Min Trig Period (0.16667usec Increments) for Pulse Width 3 | Input 5
|_______________________________________________________________|

Host Computer Commands

6.14 Set Pulse Width and PRF (SETPWF)

This command selects the pulsewidth and trigger rate. A 2-bit pulse width code is passed in bits
8 and 9 of the command word, and selects one of four pulse widths as described under PWINFO.
The new radar PRT is passed in word #1. For all processing modes that use a fixed trigger rate,
this value defines the trigger period that is output at all times except during noise measurements.
For Dual-PRF applications, this word defines the short period (high PRF) rate. The long period
is internally computed as either 3/2, 4/3, or 5/4 the short period, and the trigger generator
alternates between the short and long rates on each successive ray.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |UpperPW| (Rsv) |LowerPW| | 1 0 0 0 0 | Command
|_______|_______|_______|_______|___________|___________________|

UpperPW Upper two bits of overall 4-bit pulsewidth selection
LowerPW Lower two bits of overall 4-bit pulsewidth selection

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Desired Trigger Generator Period (0.16667usec Increments) | Input 1
|_______________________________________________________________|

When Input #1 is zero, then the arguments take on an alternate form that allows an array of N
(up to 64) trigger periods to be specified, and also gives much finer time resolution in the choice
of each period. The XARGS command is first used to load an array of N 32-bit words that
define the trigger period(s) in nanoseconds. The RVP8 will then generate triggers whose shapes
(relative starts and widths) are identical for each pulse, but whose periods follow the selected
sequence. Trigger patterns such as these are intended to support research customers who use the
real–time (I,Q) data stream directly.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Lower 16–Bits of 32–Bit Trigger Period in Nanoseconds | XARG 1
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Upper 16–Bits of 32–Bit Trigger Period in Nanoseconds | XARG 2
|_______________________________________________________________|
.
.

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Host Computer Commands

6.15 Load Antenna Synchronization Table (LSYNC)

The RVP8 can operate in a mode wherein radar data are acquired in synchronization with the
antenna motion along either the azimuth or elevation axis. This special feature frees the user
computer from having to separately monitor the antenna angles and request each data ray
individually. To use this mode, it is assumed that TAG0-15 are wired to receive azimuth angles,
and that TAG15-31 are wired to receive elevation. Angle input may be in the form of either
16-bit binary angles, or four-digit BCD. This synchronization mode is the only one which
ascribes any meaning to the TAG inputs; ordinarily they are merely passed on to the user
computer as ancillary information.

Antenna synchronization is accomplished by way of a table of trigger angles. This table, which
contains between three and 1024 angles, is used to define the angle boundaries for each
processed ray. The trigger angles need not be uniformly spaced, nor must they span the full
360-degrees of rotation. This gives considerable flexibility in the choice of angles. For
example, if local obstructions cause shadows in the radar image, then those regions can be
skipped merely by omitting table entries in their vicinity. Likewise, as the antenna rotates data
can be acquired within one or more sectors by simply specifying the appropriate sets of
contiguous bearings at whatever angular resolution is desired. Note that on power-up the angle
table is initialized to 360 values corresponding to integer-valued degrees from zero to 359.

The synchronization algorithm works automatically with either clockwise or counterclockwise
antenna rotation, and can tolerate any sequence of changes in direction, e.g., if the antenna itself
is scanning a sector, or if it is turning erratically. Moreover, the trigger angles do not have to be
hit exactly in order to start each new ray — the antenna need only move across them. This
minimizes the possibility of losing data due to missing codes in the angle encoders. The RVP8
will automatically produce an output ray after one second of waiting, even if no trigger angles
have been crossed. This is to avoid timeouts with the host computer when the antenna is not
moving at all.

To use the synchronization mode, the trigger angle table is first loaded using the LSYNC
command. The user chooses the number of table entries and then writes the required number of
words to the RVP8. The angles must be supplied in a clockwise strictly increasing order, and
they must neither reach nor pass zero degrees by the table’s end. The first value, however, may
be zero. Binary angle representation is used wherein Bit 15 represents 180 degrees, Bit 14
represents 90 degrees, etc. The Ld bit must be set in the command word to indicate that a new
table size and set of angles are being loaded. A flag bit is to be set (See GPARM) if errors are
detected when loading the table of angles.

To actually enable synchronized operation the Ena command bit must eventually be set, and EL
and BCD should be either set or cleared according to the user’s needs. These bits may be used
independent of reloading the actual table values. Thus, antenna synchronization may be turned
on and off without having to reload the table each time. However, if there were errors when the
table was last loaded, the processor ignores the Ena bit and synchronization is forced off. Once
enabled, PROC commands are then issued in the usual manner to acquire and process the radar
data. Either the single-cycle or free-run PROC mode may be used. Data collection proceeds as
usual, except that the rays are now automatically aligned with the trigger angles.

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The angle sync algorithm is dynamic and works as follows. Each ray begins immediately upon
the user’s request, or upon completion of the previous ray when in continuous processing mode.
At the start of the ray, the RVP8 finds the pair of sync angles that enclose the previous trigger
angle. The current ray then runs until the antenna passes outside of either limit, at which point
processing for that ray is terminated. Once this happens, a new trigger angle is assigned based
on which limit was crossed.

The maximum number of pulses that will be present in each ray during angle syncing is still
given the by the Sample Size field of the SOPRM command. The actual number of pulses will
be less only if a trigger angle is crossed before the full pulse count is reached. In general, you
should set the Sample Size somewhat larger than the expected pulse count so that the trigger
angle crossings make the best use of every available pulse when the antenna is scanning at the
expected rate.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |NoI|Ena|El |BCD|Ld | | 1 0 0 0 1 | Command
|___________|___|___|___|___|___|___________|___________________|

NoI Ordinarily, the potentially lengthy sync wait loop is terminated if the user writes

additional words to the RVP8. Setting this bit prevents such interrupts. Beware
that the processor loop can not be broken in this case except by moving the anten­na across a trigger angle, or cycling the RESET_ line.

Ena Enables antenna synchronization.
El Synchronization is based on TAG15–31 (Elevation) inputs, else TAG0–15 (Azi-

muth) is used.

BCD Specifies that TAG angle input is in the form of 4-digit Binary Coded Decimal;

otherwise, a 16-bit binary angle is assumed.

Ld Indicates that a new table size and array of values follow the command. If Ld = 0,

then LSYNC is a one-word command only.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Trigger Angles that Follow (3 – 1024) | Input 1
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| (Ignored) | Input 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| First Trigger Angle (16-Bit Binary Angle) | Input 3
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Last Trigger Angle (16-Bit Binary Angle) |
|_______________________________________________________________|

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6.16 Set/Clear User LED (SLED)

This command simply turns the red user LED on and off under program control. The LED is on
during the initial running of internal diagnostics, and then remains off unless changed by this
command. Note that the red LED can be configured to serve as an internal activity indicator
(see TTY setups), in which case this command has no effect.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |LED| | 1 0 0 1 0 | Command
|___________________________|___|___________|___________________|

6.17 TTY Operation (TTYOP)

This command controls the TTY “chat mode” interface to the host computer. The command can
simulate the typing of characters on the RVP8’s setup TTY. Characters entered in this manner
are indistinguishable from those typed on the actual TTY; hence, whatever one can do via the
TTY, one can also do via this command. The RVP8 sends all TTY output to whichever stream
(TTY, or host computer) provided the most recent input character. This command is also used to
monitor the graphical data from the special scope plotting modes.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Operation | 1 0 0 1 1 | Command
|_______________________________|___________|___________________|

The operation codes are as follows:

0 Sends the ASCII character in the upper byte of the word to the RVP8 as if it had

been typed on the setup TTY’s keyboard.

1 Allow scope plotting data to be output whenever a plot is being drawn. All rele-

vant status and data words are output once upon each receipt of this command.
Subsequently, status and data will be output only when a change has taken place.

2 Disable the scope plotting output data.

Any of the following types of data may be output by the RVP8 while the TTY monitor is
running. The order of arrival of each data type is indeterminate, but all multi-word sequences
will always be output as contiguous words.

Individual “TTY” characters generated by the RVP8 are output in the low byte of the word, with
the upper byte set to zeros.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 0 0 0 0 0 0 0 0 | ASCII Character | TTY Char
|_______________________________|_______________________________|

The status of the plotting modes is given in the following word.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 0 0 | |PLT| Status
|_______________|___________________________________________|___|

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Host Computer Commands

PLT Indicates that a scope plot is being drawn now.

The 2-bit intensities of each of 16 possible strokes of data is given in the following 4-word
sequence. An intensity of zero represents “OFF”; one, two and three are successively brighter.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 0 1 | 0 0 0 0 | Int 3 | Int 2 | Int 1 | Int 0 |
|_______________|_______________|_______|_______|_______|_______|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 0 1 | 0 0 0 1 | Int 7 | Int 6 | Int 5 | Int 4 |
|_______________|_______________|_______|_______|_______|_______|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 0 1 | 0 0 1 0 | Int 11| Int 10| Int 9 | Int 8 |
|_______________|_______________|_______|_______|_______|_______|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 0 1 | 0 0 1 1 | Int 15| Int14 | Int 13| Int 12|
|_______________|_______________|_______|_______|_______|_______|

The data for each stroke of the plot is given by the following sequence of 501 words.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 1 0 | | Stroke Number | Plot Data
|_______________|_______________________________|_______________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 1 1 | Value to Plot (0 – 4095) | Word #1
|_______________|_______________________________________________|

.

.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 1 0 1 1 | Value to Plot (0 – 4095) | Word #500
|_______________|_______________________________________________|

6.18 Load Custom Range Normalization (LDRNV)

Reflectivities computed by the RVP8 are ordinarily corrected for range effects by adding an
offset in deciBels equal to 20 log(R / 1km), where R is the range in kilometers. This correction
is based on a simple filled beam geometry, and is sufficiently accurate for most meteorological
observations. The LDRNV command is provided for applications in which an alternate custom
range correction is required, for example, if the radar receiver’s LNA were to be driven by an
external user-supplied STC waveform.

LDRNV loads a 251-word custom correction table holding values in hundredths of deciBels over
five decades of log(range) from 0.01km to 1000km. There are 50 table entries per decade of

N*1

ƪ

ƫ

*2

50

range. Thus, the range in kilometers corresponding to an input word #N is
default correction table (automatically used on power-up) is simply

6–45

40(N * 101) . The table

10

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Host Computer Commands

values are stored and interpolated whenever the RVP8 loads a new range mask (See LRMSK), at
which point custom values for the actual user ranges are computed. The LDRNV command
need be issued only once, but it must be done prior to choosing the working set of range bins.

The linear intervening gas attenuation correction (See SOPRM) is always added to the
reflectivity data, regardless of whether default or custom range normalization is in effect. If this
is undesirable, the intervening gas slope should be set to zero.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 1 0 1 0 1 | Command
|___________________________________________|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed Hundredths dB of Range Normalization for Range 0.01 km | Input 1
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed Hundredths dB of Range Normalization for Range 1000 km | Input 251
|_______________________________________________________________|

6.19 Read Back Internal Tables and Parameters (RBACK)

This command permits some of the RVP8 internal tables to be read back for confirmation and
diagnostic purposes. This command would not generally be used during normal data acquisition
and processing.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Data to Show | | 1 0 1 1 0 | Command
|_______________________________|___________|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of words to output | Input 1
|_______________________________________________________________|

The data that can be returned are:

0 Full operational parameter table from last SOPRM command.
1 Ray history array consisting of six words per ray for the last 40 rays (in reverse

time order) that were processed. Each six-word group holds

a. Actual number of samples that went into the ray
b. Time since the last ray (in tenths of ms)
c. Ending azimuth TAG bits
d. Ending elevation TAG bits
e. Starting azimuth TAG bits
f. Starting elevation TAG bits

2 Angle sync table from last LDSYNC command.

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Host Computer Commands

3 Reserved (was AGC table)
4 Filter selection array from the last LFILT command. This returns the filter selec-

tion codes, one per word, for all range bins described by filter slot #0.
5 Reserved (was STC table)
6 Custom range normalization from last LDRNV command.
7 Samples of the TAG input lines at 4ms intervals. The sampling begins at the mo-

ment the RBACK command is received, and continues until the output count is

reached. Each 32-bit sample is output as a pair of 16-bit words:

a. Azimuth (TAG bits 0 – 15)

b. Elevation (TAG bits 16 – 31)
8 Doppler clutter filter coefficients (Same format as for LFCOEFS command)
9 Reserved (was LOG clutter filter coefficients)
10 Range mask spacing in cm for each pulsewidth
11 Current value of UIQ bits from Set/Clr all prior operations
12 Individual threshold configuration for each data type. This allows read back of the

threshold table set with the THRESH command (section 6.29). Outputs 7 words

per data type. Datatypes in the order specified in the selection mask.
13 Extended parameter information defined in struct dspExParmIO .
14 Minimum and Maximum values of the optional I/O-62 A/D converter, sampled

over at least one complete pulse period. Sixteen bit signed outputs represent the

full range of the A/D converter. When the RVP88D backpanel is connected, the

first Min/Max pair samples the LOGVideo input, the second pair samples the Ca-

thodePulse input, and the third and fourth pairs sample internal levels.
15 Returns an array of struct rvp8SpecFiltIO structures for each of the non-zero

clutter filter definitions, beginning with #1. This is the same format used by the

LFSPECS command to define each individual clutter filter. The order is as de-

fined in the PPRMS_N_* #defines in rvp8.h.

6.20 Pass Auxiliary Arguments to Opcodes (XARGS)

This command provides a backward compatible mechanism for supplying additional (optional)
arguments to other opcodes. The command may be used freely in the RVP8’s instruction stream,
even if the opcode being modified does not expect any optional arguments. XARGS will be a
NOP in that case.

To supply optional arguments to another opcode “OP”, the XARGS command is first executed
with the additional argument count encoded in its upper 11-bits. This is followed by the array of
between 0 and 2047 additional arguments. At this point the XARGS command is finished and
the “OP” command is fetched as the next instruction. “OP” will execute normally, except that
the additional arguments from XARGS can be picked up after its own input list has been read to
completion.

XARGS affects only the opcode that immediately follows it. The entire list of optional
arguments is discarded after “OP” executes, even if “OP” did not use some or all of the list.
However, if “OP” is yet another XARGS command, then the additional arguments that it
supplies will be appended to the first set. In this way, XARGS can supply an arbitrarily large
number of additional arguments.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Number of Additional Arguments N | 1 1 0 0 0 | Command
|___________________________________________|___________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| First Additional Argument | Input 1
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Last Additional Argument | Input N
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| “OP” Command that accepts optional arguments | Command
|_______________________________________________________________|
.
.

Host Computer Commands

6.21 Load Clutter Filter Specifications (LFSPECS)

The RVP8 allows seven different clutter filters (plus the fixed all-pass filter) to be resident at
once, so that an appropriate filter can be selected and applied to each processed ray based on
Range, Azimuth, and/or Elevation. The LFSPECS command allows this suite of filters to be
redefined on the fly.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 0 0 0 0 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Filter # | Input 1
|___________________________________________________|___________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Filter Type | XARG 1
|_______________________________________________________________|
.
.
Variable number of XARGS depending on Filter Type

The “Filter Number” tells which filter definition slot is being modified, and the “Filter Type”
conveys the type of clutter filter to construct. The command is then followed by additional
XARGs that give the specific filter parameters. Beginning with the Filter Type, the complete
XARG list is a struct rvp8SpecFiltIO ( Please see include/rvp8.h ) for each of the following
filter types.

Type:0 SPFILT_FIXED Fixed Width Spectral Filter

Legacy clutter filter inherited from the RVP6/7, specified by a width parameter

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telling how many points to remove (center zero velocity point, plus one side), plus

an “Edge Points” parameter telling how many points to minimize on each side of

the gap to compute the end points of a linear interpolation to fill the gap.
Type:1 SPFILT_VARIABLE Variable Width Spectral Filter

Similar to the fixed width filter except that the width parameter is interpreted as a

minimum width, and a third parameter indicates the maximum width. The actual

clutter gap width will be dynamically determined at each bin based on the slopes

of the spectral terms. Linear interpolation of the gap (based on “Edge Points”) is

the same as above.
Type:2 SPFILT_VARLSQ Variable Width / Quadratic interpolation

Similar to the variable width filter except that quadratic gap interpolation is used.

This filter is experimental and should not be used.
Type:3 SPFILT_GMAP Gaussian Model Adaptive Processing Spectral Filter

This is the RVP8’s most advanced clutter filter, combining the best techniques for

determining the clutter gap width and restoring whatever low-velocity spectral

points are removed. This filter is characterized by a single parameter, which is the

assumed clutter width expressed as a physical velocity.

Host Computer Commands

6.22 Configure Ray Header Words (CFGHDR)

The processed data that are output by the PROC command may contain optional header words
that give additional information about each ray. This command configures the set of words that
makeup each header. There are (up to) thirty two different choices of words or groups of words
to include, as indicated by the bit mask following the command. Setting a bit requests that those
words be included in the header, and be placed in the order implied by the sequence of the bits.
Leaving all bits clear will suppress the header entirely; though this can also be done without
changing the configuration via the NHD (No-Headers) bit in SOPRM Input #2.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 0 0 1 0 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |TID|PBN|SYT|MMT|UTC|Flg|Gpm|Tim|Pul|PRT|Tag| Input 1
|___________________|___|___|___|___|___|___|___|___|___|___|___|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Input 2
|_______________________________________________________________|

Tag Four words containing two 32-Bit TAG samples, one from the beginning and one

from the end of the ray:

Word #1 TAG15–0 Start of Ray

Word #2 TAG31–16 Start of Ray

Word #3 TAG15–0 End of Ray

Word #4 TAG31–16 End of Ray

 When the RVP8 is operating in dual PRF mode, bit zero of the “start” TAG word is

replaced with a flag indicating that the ray’s PRF was low (0) or high (1).

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 When trigger blanking is enabled, bit zero of the “end” TAG word is replaced with a flag

indicating that the trigger was blanked (0) or normal (1). Note that the data within a ray
are considered to be invalid if any of the pulses that were used to compute the ray were
blanked. Also, the RVP8 will output all zeroed data whenever a ray contains any blanked
pulses.

PRT PRT (Pulse Repetition Time) measured at the end of the ray. Same format as

GPARM Word #30. The measured PRT’s are forced to 0xFFFF (the maximum

unsigned value) whenever the external trigger is expected but missing.
Pul Number of pulses that were used to compute the ray.
Tim Milliseconds universal time (0–999), sampled at the end of the ray.
Gpm GPARM. Sends a copy of the 64-word GPARM output with each ray.
Flg Ray Flag word:

Bit 0: Dual PRF is in the low PRF state

Bit 1: Trigger is blanked for this ray

Bit 2: This ray is from one of the PRFSECT special sectors

Bits4–6: Tells which PRFSECT when Bit-2 is set
UTC 3-word universal time, sampled at the beginning of the ray

Word 1: Milliseconds (0–999)

Word 2: Low 16-bits of 32-bit UTC time

Word 3: High 16-bits of 32-bit UTC time
MMT MisMatched Timeseries bits (playback versus RVP8 configuration). See the

MMTS_* flags in dsp.h.
SYT IFD system clock time at the beginning of the ray

Word 1: Low 16-bits of 32-bit clock counter

Word 2: High 16-bits of 32-bit clock counter
PBN Timeseries playback version number
TID Task ID encoded as struct rvp8TaskID_IO (14 words total)

6.23 Configure Interference Filter (CFGINTF)

The RVP8 can optionally apply an interference filter to its incoming (I,Q) data stream, with the
goal of rejecting occasional and sparse interference from other (usually man-made) signal
sources. The CFGINTF command is used to choose which filtering algorithm will be applied,
and to configure its operation via additional XARGS parameters (See Section 6.20).

If the XARGS are not supplied, then the filter parameters will simply retain their previous
values. Thus, CFGINTF with no XARGS can be used to turn the interference filters On/Off
without making any other changes to their threshold constants. Likewise, if only XARG 1 is
supplied, then that single threshold value will be used for both C1 and C2.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Filter | 0 0 0 0 0 1 1 1 1 1 1 1 | Command
|_______________|_______________________________________________|

Filter Chooses which interference algorithm should be run. See Section 5.1.5 for a de-

scription of the available algorithms.

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Host Computer Commands

0: None (Interference filtering is disabled)

1: Alg.1 (Traditional JMA Algorithm)

2: Alg.2 (Alg.1 optimized for additive interference)

3: Alg.3 (Alg.2 with better statistics)

We recommend that you choose Alg.3 for general operational use. The other algo-

rithms are included mostly for historical reasons.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Parameter “C1” in Hundredths of deciBels | XARG 1
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Parameter “C2” in Hundredths of deciBels | XARG 2
|_______________________________________________________________|

6.24 Set AFC level (SETAFC)

This command sets the AFC level to a given value. The signed 16-bit span is identical to
GPARM Output #51 which shows the present AFC level, i.e., corresponding to the –100% to
+100% AFC range that is defined in the Mb menu. The RVP8 will automatically convert the
new level into whatever analog or digital AFC output format has been configured. The only
exception is for the Motor/Integrator type of AFC loop, in which case this command does
nothing.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 0 1 0 1 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 16–Bit AFC/MFC Value (–32768 through +32767) | Input 1
|_______________________________________________________________|

6.25 Set Trigger Timing Slew (SETSLEW)

The Mt menu allows you to select a subset of triggers that can be slewed “left” and “right” in
order to place the burst pulse accurately at range zero. This command allows you to manually
set the present amount of slew. The input argument is in hundredths of microseconds, i.e.,
ranging from –327.68msec to +327.67msec. The actual span permitted by the RVP8 is +
This is the same format used in GPARM Output #56 which shows the present slew value.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 0 1 1 0 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed trigger slew in hundredths of microseconds | Input 1
|_______________________________________________________________|

20msec.

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Host Computer Commands

6.26 Hunt for Burst Pulse (BPHUNT)

This command starts up the internal procedure to hunt for a missing burst pulse when we are
uncertain of both its time and frequency. Depending on how the hunting process has been
configured in the Mb menu, the whole procedure may take several seconds to complete. The
RVP8’s host computer interface remains completely functional during this time, but any acquired
data would certainly be questionable. GPARM status bits in word #55 indicate when the hunt
procedure is running, and whether it has completed successfully.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |Now| 0 0 0 0 1 1 1 1 1 1 1 1 | Command
|___________|___|_______________________________________________|

Now Forces the hunt procedure to be started even if the burst pulse is already present.

Normally the procedure will only be started when the burst pulse is missing at the

time BPHUNT is given.

6.27 Configure Phase Modulation (CFGPHZ)

This command configures the RVP8 phase control output lines, which determine the relative
phase of each transmitted pulse. In some cases the phase sequence that is chosen will also have
side effects elsewhere in the processor, e.g., different algorithms may be used in Random Phase
mode according to the transmit sequence that is requested.

Some of the phase sequences chosen by CFGPHZ also expect additional arguments to have been
supplied by the XARGS command. Phase sequences are expressed as a list of N 16-bit binary
angles representing the desired phase sequence. The sequence is assumed to be periodic with
period N. The Mz command defines the correspondence between phase codes and phase angles,
and is described in Section 3.2.8.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | PhSeq | 0 0 0 1 0 0 0 1 1 1 1 1 | Command
|___|___________|_______________________________________________|

PhSeq=0 Selects No Modulation. The RVP8 outputs a constant default phase request as

defined in the Mz menu.
PhSeq=1 Selects a Random Phase sequence. This is also the default phase modulation that

will be output following power-up. From the set of valid phase codes that are de-

fined in the Mz setup section, a random code is automatically chosen for each

pulse. Each code has an equal probability of being chosen each time, and the

choice is independent of any previous state. No XARG words accompany this

command.
PhSeq=2 Selects a User Defined sequence. If no XARGS have been supplied, then the

RVP8 outputs the default idle phase that is defined in Mz. If XARGS are sup-

plied, then they are interpreted as a sequence of 16-bit binary angles. The RVP8

will make the best match between each desired angle and the closest realizable

angle that the phase modulation hardware can produce. The maximum length of

the sequence is 1024 pulses.

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PhSeq=3 Selects the SZ(8/64) sequence. This is a systematic code due to Sachidananda and

Zrnic, which does a nice job separating and recovering first and second trip echoes

in “Random Phase” mode. It will usually perform better than a truly random

transmit sequence, especially when the processing interval is fairly short (as little

as 32-pulses). With no XARGS, the RVP8 automatically generates the phase se-

quence using the closest realizable angles that the phase modulation hardware can

produce. This is the recommended way to invoke SZ(8/64) coding. However,

you may also supply your own 32-pulse angle sequence.

6.28 Set User IQ Bits (UIQBITS)

Load user-specified bits that will be included with the pulse headers in the RVP8 TimeSeries
API data stream. The permanent Set/Clr bits are updated in the signal processor and retain their
value from the last time they were defined. These bits are then repeated into all pulse headers.
The ONCE bits, however, are transitory and will appear in only one pulse header each time they
are set.

A FIFO history of the permanent bits is maintained so that the bits can be associated with the
data being acquired right now as the UIQBITS opcode is executed. Each 16-bit command arg
specifies bits to Set/Clr in successive bytes of the structure. This allows user code to safely
change some bits without affecting others.

The user bits from separate calls will never be collapsed into a single pulse header, even if the
header and bit times indicate that they could. This means that each UIQBITS opcode will
always result in at least one pulse header being tagged with exactly those data. This is generally
what you want, since no other exact outcome could be guaranteed based on time-of-arrival
alone.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 1 0 0 1 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 64 Permanent User Bits to SET | Inputs 1–4
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 64 Permanent User Bits to CLEAR | Inputs 5–8
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| 64 User Bits to Apply ONCE | Inputs 9–12
|_______________________________________________________________|

6.29 Set Individual Thresholds (THRESH)

The SOPRM command in section 6.3 allows you to configure four threshold numbers used by
all data types, and to select the threshold control flags for five of the data types. See that section
for detailed documentation on how the thresholds work. Use the THRESH command if you

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wish to apply different threshold numbers to different data types. Using this command you can
individually set the thresholds and mask used for each data type, or for groups of data types.
Note that the GPARM command will read out the threshold numbers set for velocity. To read
back the numbers for each data type use the RBACK command (section 6.19).

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 1 0 1 0 1 1 1 1 1 | Command
|_______________|_______________________________________________|

The first three words supply a mask that indicates which data types are being set:

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Z | T | V | W |ZDR| |KDP| | Input 1
|___|___|___|___|___|___|_______|___|___________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | (Tx Vert) | (Tx Horz) | | | |
| |Flg|Phi Rho Ldr|Phi Rho Ldr|SQI|RHV|PDP| Input 2
|_______________________|___|___|___|___|___|___|___|___|___|___|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| <all spares> | Input 3
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| LOG Threshold in 1/16 of dB (SOPRM Input 4) | Input 4
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| CCOR Threshold in 1/16 of dB (SOPRM Input 5) | Input 5
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | SQI Threshold (SOPRM Input 6) | Input 6
|_______________________________|_______________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Weather Signal Power Threshold in 1/16 of dB (SOPRM Input 7) | Input 7
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Threshold Control Flags (SOPRM Input 11,12,13,14,19) | Input 8
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| <spare> | Input 9
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| <spare> | Input 10
|_______________________________________________________________|

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6.30 Set Task Identification Information (TASKID)

This command allows the user to “name” the (I,Q) data that are currently being acquired by the
RVP8. This naming information then becomes associated with these data, and is available in the
pulse information structures (struct rvp8PulseInfo) that are read from the Timeseries API. The
iAqMode field of the pulse headers (struct rvp8PulseHdr) will be incremented each time a
TASKID opcode is received, but the continuous flow of (I,Q) data from the RVP8/Rx card(s)
will not be disturbed in any way.

The TASKID command defines a 16-character Null-terminated name, along with a 16-bit sweep
number and 16-bit auxiliary (user defined) number. You may use all sixteen characters of the
name, as it is stored internally in seventeen slots. The “Sweep Number” and “Scan Geometry”
(one of SCAN_xxx parameters) should be filled in with values best approximating those notions.
“Auxiliary Number” may be filled in with any value that you find meaningful.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 1 0 1 1 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Sweep Number | Input 1
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Auxiliary (User Defied) Number | Input 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Name Byte–2 | Name Byte–1 | Input 3
|_______________________________|_______________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Name Byte–16 | Name Byte–15 | Input 10
|_______________________________|_______________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Scan Geometry | XARG 1
|_______________________________|_______________________________|

6.31 Define PRF “Pie Slices” (PRFSECT)

This command supplements the SETPWF command (Section 6.14) and allows an alternate
trigger PRF to be generated within prescribed AZ/EL sectors. As many as eight different trigger
sectors can be defined by invoking PRFSECT for each separate region. The trigger pattern will
then automatically change whenever the antenna enters any of these regions, but the timeseries
data will remain continuous and uninterrupted throughout each change. The motivation behind
PRFSECT is that it allows a complete volume scan to run with PRFs that have been optimized to
the radar echoes in all directions. Some caveats should be observed:

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 Dual-PRF unfolding can not possibly work properly at PRF sector boundaries, so we

recommend not using Dual-PRF and PRFSECT at the same time.

 When PRF sectors are used in conjunction with angle sync’ing, it is best to set the PRF

sector boundaries at the midpoint between individual sync angles. This will prevent the
PRF seam from bobbling between two adjacent sync angles.

The SETPWF opcode completely erases any alternate sectors that have been setup so far. Thus,
the PRFSECT command can only be used after SETPWF has established the pulsewidth and
default trigger rate for the entire AZ/EL scan volume.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 1 1 0 0 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Sector | Input 1
|___________________________________________________|___________|

Sector Selects which sector number is being defined to have an alternate trigger pattern.

This is simply an arbitrary index from 0-7.

The following four arguments define a solid sector in azimuth and elevation within which the
alternate trigger pattern will be used in preference to the default (SETPWF) pattern. When the
current AZ/EL angle pair is contained in more than one defined sector, then the trigger pattern
from the lower numbered sector will be used. Note that the sector bounds are inclusive, i.e.,
they include the Upper/Lower AZ/EL boundaries themselves. This convention makes it simpler
to define several contiguous regions without generating slivers in between.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Lower AZ (Binary angle) | Input 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Upper AZ (Binary angle) | Input 3
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Lower EL (Binary angle) | Input 4
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Upper EL (Binary angle) | Input 5
|_______________________________________________________________|

The following two arguments specify a trigger period in the same manner as the optional form of
the SETPWF command.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Lower 16–Bits of 32–Bit Trigger Period in Nanoseconds | Input 6
|_______________________________________________________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Upper 16–Bits of 32–Bit Trigger Period in Nanoseconds | Input 7
|_______________________________________________________________|
.
.

Host Computer Commands

6.32 Configure Target Simulator (TARGSIM)

The RVP8 contains a built-in target simulator tool that can test and debug processing algorithms
that work with multiple trip returns. Several real physical targets can be simulated, each having
a range span measured in kilometers, a Doppler shift in Hertz, and an echo power relative to the
saturation level of the receiver. The echoes are placed in range exactly according to how they
have been illuminated by whatever sequence of pulses have been transmitted so far. Multiple
trip returns and range folding are all modeled correctly.

The target simulator can be used with both live and simulated (I,Q) data (See LSIMUL opcode
in Section 6.10). In the former case, it allows you to overlay simulated physical targets on top of
real physical targets from the radar receiver.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Oper | 0 0 0 1 1 0 1 1 1 1 1 1 | Command
|_______|_______|_______________________________________________|

Oper=0 Disable all target simulation activity (no additional args)
Oper=1 Enable simulation of all defined targets (no additional args)
Oper=2 Define a new simulated target (arg list follows)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | Co| Cx| | Targ | Input 1
|_______________________________|___|___|_______________|_______|

Targ Which target is being defined
Co/Cx Place simulated target in Co-Pol and/or Cross-Pol Rx channels

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Target Starting Range in Tenths of Kilometers | Input 2
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Target Length in Tenths of Kilometers | Input 3
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Target Power in Tenths of dB Relative to Saturation (signed) | Input 4
|_______________________________________________________________|

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Target Power Delta over Range Span in Tenths of dB (signed) | Input 5
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Target Doppler Shift in Hertz (signed) | Input 6
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Target Doppler Delta over Range Span in Hertz (signed) | Input 7
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Four Spare Words | Inputs 8–11
|_______________________________________________________________|

Host Computer Commands

6.33 Set Burst Pulse Processing Options (BPOPTS)

Some burst pulse processing options can be set by this command.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 0 0 0 1 1 1 0 1 1 1 1 1 | Command
|_______________|_______________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| |ACY|ACN|PLY|PLN| Input 1
|_______________________________________________|___|___|___|___|

PLY/N These bits affect whether the RVP8 will phase lock its (I,Q) data to the measured

burst pulse. The “PLY” and “PLN” bits force “Yes” and “No” responses. If both

bits are clear or both bits are set, then no change will be made.
ACY/N These bits affect whether the RVP8 applies pulse-to-pulse amplitude correction to

its (I,Q) data. The Yes/No bits behave the same as PLY/PLN.

6.34 Custom User Opcode (USRINTR and USRCONT)

These opcodes are part of the open software extensions to the RVP8, which allow custom
opcodes to be defined for each major mode of operation. Arguments may be passed into a
custom opcode handler as an XARG list. Likewise, an optional array of words returned from
that handler will appear after the command executes.

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| User Bits | 1 1 1 1 1 0 |CON| 1 1 1 1 1 | Command
|_______________|_______________________|___|___________________|

UserBits Four additional bits defined by the user to help subdivide the opcode functions if

desired.
CON If set, then the RVP8’s IQ data acquisition thread proceeds continuously while the

opcode is executed. If clear, then the IQ stream is interrupted prior to handling the

call.

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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Optional Input Words | XARG List
|_______________________________________________________________|

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Optional Output Words | User Output
|_______________________________________________________________|

6–59