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R&S®NRQ6
Fast Pulse Power Measurement
Application Sheet
(;ÜàZ2)
1178824202
Version 02
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R&S®NRQ6
1 Your Task
This application sheet is related to various pulse measurement tasks with the frequency selective RF power sensor R&S NRQ6. All described scenarios can be summarized under the "Don’t miss a pulse" slogan. You want to:
●
Measure the pulse power of a well-known number of RF pulses.
●
Determine the energy content of a well-known number of RF pulses.
●
Count a random/unknown number of RF pulses without missing a single pulse over
a long period of time.
2 Possible Solution
The R&S NRQ6 frequency selective power sensor is designed to measure RF power in
a wide dynamic range. With its high acquisition speed, large internal memory and
sophisticated internal trigger, the R&S NRQ6 is qualified for reliably measure the power
of every single pulse of a random pulse train. As long as certain key data is observed,
the R&S NRQ6 is an ideal solution to measure pulse power over a relatively long
period. The "Don’t miss a pulse" target is met when the parameters of a pulse
sequence meet the following conditions:
Your Task
Pulse period ≥ 2 µs
Number of pulses < 128000
Pulse width ≥ 300 ns
RF level ≥ -68 dBm
These values are chosen to measure the roof power of every pulse with an uncertainty
of < 1 dB. Chapter 4, "Possible Extensions", on page 6 describes measurement setups where the main attention does not lie on a highly accurate pulse power measurement but (only) on the recognition of pulses. In such cases, the above specifications for
the pulse width can be much lower, for example, down to 70 ns.
3 How to Configure the R&S NRQ6
Prerequisites
We assume that the R&S NRQ6 has been connected to an appropriate PoE+ Ethernet
switch and the network parameters are successfully configured.
The communication between a controlling host and the sensor can take place in any
high-level language. For the sake of convenience, this application sheet only shows
the transmitted SCPI commands.
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R&S®NRQ6
How to Configure the R&S NRQ6
There is a suite of sample programs which go along with this application sheet. The
programming examples come with full source code and are implemented both in
Python and C/C++. On an MS Windows system, see the subfolders of
C:\ProgramData\Rohde-Schwarz\NRP-Toolkit-SDK\NRQ\ for the
DontMissAPulse examples.
Scenario 1
Measurement of settled pulse roof power. The parameters are chosen for acquiring 1
or more samples in the roof of a pulse. For this pulse power measurement, the 25 MHz
NORMAL or 40 MHz FLAT resolution bandwidth filter is selected. Trigger is internal on
the rising edge, selected trigger level approx. 2 dB to 3 dB below the expected pulse
power. Not to include (parts of) the rising edge in the measurement, a 150 ns delay is
chosen after the trigger condition. With a pulse width of approx. 400 ns, an aperture
time of 120 ns to 150 ns is reasonable to exclude any parts of the falling edge of the
pulse.
Given that our pulses are at an RF of 2.4 GHz, the R&S NRQ6 is prepared with the
following commands:
*RST # Reset the power sensor
*CLS # Clear Status subsystem
*IDN? # Query device identification (optional)
SENS:FUNC "POW:AVG" # Select power average measurement mode
SENS:FREQ 2.4e9 # RF = 2.4 GHz
SENS:BAND:RES:TYPE:AUTO OFF # Configuring resolution bandwidth filter
SENS:BAND:RES:TYPE NORMAL # Manual selection for 25 MHz NORMAL filter
SENS:BAND:RES 25.0e6 # ::
SENS:INP:ATT:AUTO OFF # De-activation of input attenuation
SENS:INP:ATT 0 # ::
TRIG:SOUR INT # Internal trigger
TRIG:LEV -68 DBM # @ -68 dBm
TRIG:DEL 150.0e-9 # Mask rising edge & possible overshoot
SENS:POW:AVG:APER 120.0e-9 # Measurement window length 120 ns
BUFF:STAT ON # We expect 95000 pulses...
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R&S®NRQ6
How to Configure the R&S NRQ6
BUFF:SIZE 95000 # configuring buffer size and
TRIG:COUN 95000 # trigger count for that number of pulses
CAL:ZERO:AUTO ONCE;*OPC? # Zero calibration. Especially important for
# RBW filter >= 50 MHz. In the present case
# this is optional
INIT:IMM;*OPC? # Starting measurement. This will be ready
# after the occurance of 95000 pulses
# (as configured before)
FORM:DATA REAL,64 # We want binary results...
FETCH? # Reading the results (95000 ‘double’ values)
Scenario 2
This measurement is similar to scenario 1. However, instead of pulse roof power, we
are interested in the overall energy content of every pulse (Energy = AveragePower *
Time). Different to scenario 1, we need the average power of the whole pulse, including rising and falling edge portions. Hence, we work with a small negative trigger delay
and also select an aperture time long enough to contain the whole pulse and a bit
beyond.
The selection of negative trigger delay and aperture time depends on the pulse form.
Ideally, we can acquire at least 25 ns before the rising edge and up to 100 ns beyond
the falling edge of the pulse.
For the correct signal evaluation, we chose the NORMAL filter characteristic for a
100 MHz resolution bandwidth filter. Note: For resolution bandwidths ≥ 50 MHz and
very low signal levels of < -55 dBm, it is essential to execute always a zero calibration
directly before starting a measurement. A zero calibration compensates any DC offset
of the output of the zero IF mixer.
The parameters for this scenario are chosen for acquiring the average power of pulses
which are 200 ns in length. Acquisition starts 50 ns before the rising edge and ends
50 ns after the falling edge, resulting in an aperture of 300 ns in total. RF is set to
2.4 GHz.
*RST # Reset the power sensor
*CLS # Clear Status subsystem
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R&S®NRQ6
How to Configure the R&S NRQ6
*IDN? # Query device identification (optional)
SENS:FUNC "POW:AVG" # Select power average measurement mode
SENS:FREQ 2.4e9 # RF = 2.4 GHz
SENS:BAND:RES:TYPE:AUTO OFF # Configuring resolution bandwidth filter
SENS:BAND:RES:TYPE NORMAL # Manual selection for 100 MHz NORMAL filter
SENS:BAND 100.0e6 # ::
SENS:INP:ATT:AUTO OFF # De-activation of input attenuation
SENS:INP:ATT 0 # ::
TRIG:SOUR INT # Internal trigger
TRIG:LEV -66 DBM # @ -66 dBm
TRIG:DEL -50.0e-9 # Pre-trigger delay to get full pulse
SENS:POW:AVG:APER 300.0e-9 # Measurement window length 300 ns, means
# 50 ns + 200 ns + 50 ns
# = pre-trigger + pulse width + settle time
BUFF:STAT ON # We expect 100000 pulses...
BUFF:SIZE 100000 # configuring buffer size and
TRIG:COUN 100000 # trigger count for that number of pulses
{switch OFF the RF signal before executing Zero Calibration}
CAL:ZERO:AUTO ONCE;*OPC? # Zero calibration. Especially important for
# RBW filter >= 50 MHz
{switch ON the RF signal again}
INIT:IMM;*OPC? # Starting measurement. This will be ready
# after the occurance of 100000 pulses
# (as configured before)
FORM:DATA REAL,64 # We want binary results...
FETCH? # Reading the results (100000 ‘double’ values)
The corresponding sample program has to multiply every resulting average power
value with the aperture time to get the final energy content of every measured pulse.
Scenario 3
In this measurement scenario, we are interested in counting the number of pulses
which occur. Our main interest is not the evaluation of the absolute power of every single pulse. Since the primary goal is not the absolute pulse power measurement, we
can cope with much shorter pulses. Since rise & fall times and overshoots are not relevant, pulse widths can be as short as 25 ns.
This scenario uses the buffered mode of the power average measurement like in the
previously mentioned measurements. However, we merely use the R&S NRQ6 as an
RF trigger source and/or RF pulse counter. The R&S NRQ6 is configured as shown
here:
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R&S®NRQ6
Possible Extensions
*RST # Reset the power sensor
*CLS # Clear Status subsystem
*IDN? # Query device identification (optional
SENS:FUNC "POW:AVG" # Select power average measurement mode
SENS:FREQ 2.4e9 # RF = 2.4 GHz
SENS:BAND:RES:TYPE:AUTO OFF # Configuring resolution bandwidth filter
SENS:BAND:RES:TYPE NORMAL # Manual selection for 25 MHz NORMAL filter
SENS:BAND:RES 40.0e6 # ::
SENS:INP:ATT:AUTO OFF # De-activation of input attenuation
SENS:INP:ATT 0 # ::
TRIG:SOUR INT # Internal trigger
TRIG:LEV -66 DBM # @ -66 dBm
SENS:POW:AVG:APER 50.0e-9 # Measurement window length 50 ns
BUFF:STAT ON # Configure max. buffer size...
BUFF:SIZE 128000 # Later the buffer will be emptied
TRIG:COUN 128000 # continuously and the number of contained
# results will be counted
CAL:ZERO:AUTO ONCE;*OPC? # Zero calibration. Especially important for
# RBW filter >= 50 MHz. In the present case
# this is optional
FORM:DATA REAL,64 # We want to read out the results in binary
INIT:CONT ON # Starting continuous measurement mode.
# From here we continuously check whether
# the buffer contains any measurements at all,
# and read-out and count the results...
{loop}
SENS:POW:AVG:BUFF:COUN? # Any measurements?
SENS:POW:AVG:BUFF:DATA? # If yes, read results and count them...
{endloop}
INIT:CONT OFF # Finally, stop the continuous measurement mode.
4 Possible Extensions
The configuration of scenario 3 could be enhanced with the corresponding trigger
delays and appropriate aperture time as used in scenario 1. In this case, we not only
count the number of RF pulses, but we also measure the roof power of every pulse:
::
TRIG:DEL 100.0e-9 # Mask rising edge & possible overshoot.
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R&S®NRQ6
Learn More about the R&S NRQ6
# Values depend on the pulse characteristics
SENS:POW:AVG:APER 50.0e-9 # Select appropriate measurement window length
::
Another extension of scenario 3 could be to use the sensor as a high-speed trigger
source on the RF pulses. We can configure the SMA type external trigger connector on
the back of the R&S NRQ6 as an output for the trigger condition. Thus, the R&S NRQ6
internally triggers on the RF pulse and outputs the trigger on the corresponding connector.
::
TRIG:SOUR INT # Sensor will trigger on the RF signal
TRIG:LEV 1.0e-8 # @ -50 dBm
::
TRIG:SEND:PORT EXT2 # Output a trigger pulse on ext. connector
TRIG:SEND:STAT ON # whenever an internal signal trigger occurs.
# Trigger pulse has a length of 100 ns
::
5 Learn More about the R&S NRQ6
For a detailed description of the capabilities of the R&S NRQ6, read its user manual.
The user manual also explains all aspects of remote control features in details.
Also, you can always install our basic driver and tools package called R&S NRP Toolkit. Among various tools, this package supplies an optional SDK (Software Development Kit), which contains many sample programs with full commented source code in
various programming languages. On an MS Windows PC, you find the SDK after
installation under:
C:\ProgramData\Rohde-Schwarz\NRP-Toolkit-SDK\
The examples especially for the R&S NRQ6 are under:
C:\ProgramData\Rohde-Schwarz\NRP-Toolkit-SDK\NRQ\
Download the latest version of the R&S NRP Toolkit at:
www.rohde-schwarz.com/software/nrp_s_sn/
7Application Sheet 1178.8242.02 ─ 02
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