Meinberg GPS163TDHS User Manual
FUNKUHREN
Technical Information
Operating Instructions
GPS163TDHS
Incl. Windows Software
GPSMON32
Impressum
Werner Meinberg
Auf der Landwehr 22
D-31812 Bad Pyrmont
Telefon: ++49 (0) 52 81 / 9309-0
Telefax: ++49 (0) 52 81 / 9309-30
Internet: http://www.meinberg.de
Email: info@meinberg.de
October 28, 2004
Table of contents
Impressum............................................................................................ 2
General information............................................................................. 5
Block diagram GPS163TDHS....................................................6
Features of GPS163TDHS ................................................................... 7
Time zone and daylight saving .................................................. 7
Pulse outputs .............................................................................. 8
DCF77 emulation ....................................................................... 9
Asynchronous serial ports........................................................10
IRIG-outputs............................................................................. 10
Introduction..................................................................... 10
Available time codes ...................................................... 11
Code generation .............................................................. 11
IRIG standard format......................................................12
AFNOR time code format............................................... 13
Assignment of CF Segment in IEEE1344 mode ............ 14
Installation ......................................................................................... 15
Power supply ............................................................................ 15
Mounting the antenna............................................................... 15
Powering up the system ........................................................... 16
The front panel layout ........................................................................ 17
FAIL LED.................................................................................17
LOCK LED ............................................................................... 17
OCx LEDs................................................................................. 17
BNC connector DCF Out.......................................................... 17
BNC connector GPS Ant .......................................................... 17
Connectors Time code Out....................................................... 17
BSL Key ................................................................................... 18
Assignment of the terminal block............................................ 18
Assignment of the DSUB connectors ...................................... 19
Replacing the lithium battery ............................................................ 19
CE label.............................................................................................. 19
Technical specifications GPS163TDHS............................................ 20
Technical specifications of antenna ......................................... 23
Assembly with CN-UB/E (CN-UB-280DC) ............................ 24
Format of the Meinberg standard time string.......................... 25
Format of the SAT time string................................................. 26
Format of the NMEA (RMC) string ........................................ 27
Format of the time string Uni Erlangen (NTP) ....................... 28
Diskette with Windows Software GPSMON32................................. 31
The program GPSMON32 ................................................................. 32
Online Help .............................................................................. 33
4
General information
The satellite receiver clock GPS163TDHS has been designed to provide an extremly
precise time reference for the generation of programmable pulses and IRIG/AFNORcodes.
The clock has been developed for applications where conventional radio controlled
clocks can´t meet the growing requirements in precision. High precision available 24
hours a day around the whole world is the main feature of the system which receives its
information from the satellites of the Global Positioning System.
The Global Positioning System (GPS) is a satellite-based radio-positioning, navigation, and time-transfer system. It was installed by the United States Departement of
Defense and provides two levels of accuracy: The Standard Positioning Service (SPS)
and the Precise Positioning Service (PPS). While PPS is encrypted and only available for
authorized (military) users, SPS has been made available to the general public.
GPS is based on accurately measuring the propagation time of signals transmitted
from satellites to the user´s receiver. A nominal constellation of 21 satellites together with
3 active spares in six orbital planes 20000 km over ground provides a minimum of four
satellites to be in view 24 hours a day at every point of the globe. Four satellites need to
be received simultaneously if both receiver position (x, y, z) and receiver clock offset
from GPS system time must be computed. All the satellites are monitored by control
stations which determine the exact orbit parameters as well as the clock offset of the
satellites´ on-board atomic clocks. These parameters are uploaded to the satellites and
become part of a navigation message which is retransmitted by the satellites in order to
pass that information to the user´s receiver.
The high precision orbit parameters of a satellite are called ephemeris parameters
whereas a reduced precision subset of the ephemeris parameters is called a satellite´s
almanac. While ephemeris parameters must be evaluated to compute the receiver´s
position and clock offset, almanac parameters are used to check which satellites are in
view from a given receiver position at a given time. Each satellite transmits its own set of
ephemeris parameters and almanac parameters of all existing satellites.
5
Block diagram GPS163TDHS
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synchronization
3
GPS163TDHS
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clock
driver
RS232
(RS485)
program
memory
Flash EPROM
dual T x/Rx
program m able pu lses
enerator
timecode
Tx
PPS
data
addr/data
reference clock
microcontrollercorrelator
clock
addr/data
D/A-converter
clock
control
voltage
master
oscillator
sample
clock
data
clock
IF-circuit
SRAM
EEPROM
data memories
addr/data
real time clock
DCF-pulses
7
F
7
C
-
u
D
o
t
p
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DCF77
simulation
C
antenna power
internal power
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GPS-signal (IF)
LO-frequency
tional
htnin
rotector
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li
without additional amplifier
RG58-cable up to 250 met ers
unit
antenna/
converter
66
Features of GPS163TDHS
The GPS163TDHS is designed for mounting on a DIN rail. The front panel integrates
five LED indicators, a hidden push button, an eight-pole terminal block, three female DSUB-9- and three BNC-connectors. The receiver is connected to the antenna/converter
unit by a 50 Ω-coaxial cable with length up to 250 m (if using RG58-cable). It is possible
to connect up to four receivers to one antenna by using an optional antenna diplexer.
The navigation message coming from the satellites is decoded by GPS163´s microprocessor in order to track the GPS system time with an accuracy of better than ±1 µsec.
Compensation of the RF signal´s propagation delay is done by automatical determination
of the receiver´s position on the globe. A correction value computed from the satellites´
navigation messages increases the accuracy of the onboard TCXO to ±5.10
-9
and
automatically compensates the oscillators aging. The last recent value is restored from the
battery-backed memory at power-up.
Time zone and daylight saving
GPS system time differs from the universal time scale (UTC) by the number of leap
seconds which have been inserted into the UTC time scale after GPS has been initiated in
1980. The current number of leap seconds is part of the navigation message supplied by
the satellites, so GPS163´s internal real time is based on UTC.
Conversion to local time including handling of daylight saving year by year can be
done by the receiver´s microprocessor if the corresponding parameters are set up with the
help of the software GPSMON32 (included Windows software).
7
Pulse outputs
The pulse generator of the satellite controlled clock GPS163TDHS containes three
independant channels and is able to generate a multitude of different pulses, which are
configured with the software GPSMON32.
The active state of each channel is invertible, the pulse duration settable between
10 msec and 10 sec in steps of 10 msec.
In the default mode of operation the pulse outputs are disabled until the receiver
has synchronized after power-up. However, the system can be configured to enable
those outputs immediately after power-up.
The pulse outputs are electrically insulated by optocouplers (option: PhotoMOS
relays) and are available at the terminal block.
The following modes can be configured for each channel independently:
Timer mode: Three on- and off-times per day per channel programmable
Cyclic mode: Generation of periodically repeated pulses.
A cycle time of two seconds would generate a pulse at
0:00:00, 0:00:02, 0:00:04 etc.
DCF77-Simulation
mode: The corresponding output simulates the DCF77 time telegram.
The time marks are representing the local time as configured by the user.
Single Shot Mode: A single pulse of programmable length is generated once a day at a
programmable point of time
Per Sec.
Per Min.
Per Hr. modes: Pulses each second, minute or hour
Status: One of three status messages can be emitted:
‘position OK’: The output is switched on if the receiver was able to
compute its position
‘time sync’: The output is switched on if the internal timing is
synchronous to the GPS-system
‘all sync’: Logical AND of the above status messages.
The output is active if position is calculated AND the
timing is synchronized
Idle-mode: The output is inactive
8
DCF77 emulation
The GPS163TDHS satellite controlled clock generates time marks which are compatible with the time marks spread by the German long wave transmitter DCF77. If
configured in GPSMON32, these time marks are available as pulse outputs. In
addition, an AM-modulated carrier frequency of 77.5kHz is available at a BNCconnector in the front panel. This signal can be used as a replacement for a DCF77antenna.
The long wave transmitter installed in Mainflingen near Frankfurt/Germany transmits the reference time of the Federal Republic of Germany: time of day, date of
month and day of week in BCD coded second pulses. Once every minute the complete
time information is transmitted. However, GPS163TDHS generates time marks
representing its local time as configured by the user, including announcement of
changes in daylight saving and announcement of leap seconds. The coding sheme is
given below:
P
8
3
M
4
Year of the Century
Month of Year
Day of Week
Day of Month
0
0
2
0
1
0
8
4
2
1
1
0
50
8
4
2
1
4
2
1
40
0
2
0
1
8
4
2
0
30
1
2
0
P
2
0
1
Hour
P
8
1
1
4
2
(reserved)
10
R
A
1
Z
1
Z
2
20
A
2
S
1
2
4
8
1
2
0
4
0
Minute
0
M Start of Minute (0.1 s)
R RF T ransmission via secondary ante nna
A1 Announcement of a ch ange in dayligh t saving
Z1, Z2 Time zone identification
Z1, Z2 = 0, 1: Daylight saving d isabled
Z1, Z2 = 1, 0: Daylight saving enabled
A2 Announcement of a lea p second
S Start of time code inf ormation
P1, P2, P3 Even parity bits
Time marks start at the beginning of new second. If a binary "0" is to be transmitted, the length of the corresponding time mark is 100 msec, if a binary "1" is
transmitted, the time mark has a length of 200 msec. The information on the current
date and time as well as some parity and status bits can be decoded from the time
marks of the 15th up to the 58th second every minute. The absence of any time mark
at the 59th second of a minute signals that a new minute will begin with the next time
mark.
9
Asynchronous serial ports
Two asynchronous serial interfaces (RS-232) called COM0 and COM1 are available
to the user. In the default mode of operation, the serial outputs are disabled until the
receiver has synchronized after power-up. However, the system can be configured to
enable those outputs immediately after power-up. Transmission speeds, framings
and the kind of the time string can be configured separately. The serial ports are
sending a time string either once per second, once per minute or on request with
ASCII ´?´ only. The format of the output strings is ASCII, see the technical specifications for details. The corresponding parameters can be set up by GPSMON32 using
serial port COM0.
As an option the serial port COM1 is available as a RS485 interface.
IRIG-outputs
Introduction
The transmission of coded timing signals began to take on widespread importance
in the early 1950´s. Especially the US missile and space programs were the forces
behind the development of these time codes, which were used for the correlation of
data. The definition of time code formats was completely arbitrary and left to the
individual ideas of each design engineer. Hundreds of different time codes were
formed, some of which were standardized by the "Inter Range Instrumantation
Group" (IRIG) in the early 60´s. Detailed information about IRIG and other time
codes can be found in the "Handbook of Time Code Formats", by Datum Inc., 1363
South State College Boulevard, Anaheim, California 92806-5790.
Except these time codes other formats, like NASA36, XR3 or 2137, are still in use.
The module GPS163TDHS however generates IRIG-B or AFNOR NFS-500 only.
The selection of the generated timecode is done by the software GPSMON32.
10
Av aila ble time codes
The timecode generator of the module GPS163TDHS is able to generate the timecodes shown below. The modulated codes (IRIG B122/B123, AFNOR, IEEE1344)
are available via the BNC-connector, the unmodulated codes (IRIG B002/B003 and
IEEE1344) via a DSUB connector in the front panel. The unmodulated codes are
available as a transistor output with internal pull up (1 kΩ to +5V), with TTL-level
into 50 Ω and with RS422 level.
B002: 100pps, DC Level Shift pulse width coded, no carrier
BCD time of year
B122: 100pps, amplitude modulated sine wave signal, 1 kHz carrier frequency
BCD time of year
B003: 100pps,DC Level Shift pulse width coded, no carrier
BCD time of year, SBS time of day
B123: 100pps, amplitude modulated sine wave signal, 1 kHz carrier frequency
BCD time of year, SBS time of day
AFNOR: 100pps, amplitude modulated sine wave signal, 1 kHz carrier frequency
BCD time of year, complete date, SBS time of day
output level adapted
IEEE1344: Code according to IEEE1344-1995
100pps, AM-Sine wave signal, 1kHz carrier frequency,
BCD-time of year, SBS time of day
IEEE1344 extensions for:
date, timezone, daylight-saving and leap second
in control functions ( CF ) segment.
also see table ‘Assignment of CF segment in IEEE1344 mode’
Code generation
The IRIG-code is available after the code-generation-unit of GPS163 has been
synchronized by a pulse per second and a serial time telegram. In the default mode of
operation the pulse outputs and the serial ports are disabled until the GPS-receiver
has been synchronized after power-up. The generation of the IRIG-code only starts
after synchronization therefore.
If the code must be available immediately after power-up, the software GPSMON32 can be used to enable the pulse outputs and the serial ports without synchronization of the GPS-receiver. In this mode of operation the IRIG-code is not locked to
UTC-second until synchronization.
11
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