Meinberg GPS167 User manual

GPS167
Technical Information
Operating Instructions

Impressum
Meinberg Funkuhren GmbH & Co. KG
Auf der Landwehr 22
D-31812 Bad Pyrmont
Phone: [phone] / 9309-0
Fax: [phone] / 9309-30
Internet: http://www.meinberg.de
Email: [email protected]
April 25, 2006

Table of Contents
Impressum ............................................................................................ 2
General Information ............................................................................. 6
GPS167 Features .................................................................................. 7
Time Zone and Daylight Saving................................................. 8
Pulse and Frequency Outputs ..................................................... 8
Time Capture Inputs ................................................................... 9
Asynchronous Serial Ports (optional 4x COM).......................... 9
DCF77 Emulation ..................................................................... 10
Programmable pulse (optional) ................................................ 11
Timecode outputs (optional)..................................................... 11
Abstract ........................................................................... 11
Installation .......................................................................................... 12
Power Supply ............................................................................ 12
Mounting the Antenna .............................................................. 12
Antenna Short-Circuit .............................................................. 13
Assembly with CN-UB/E (optional) ........................................ 14
Powering Up the System .......................................................... 15
The Front Panel Layout ..................................................................... 16
FAIL LED ................................................................................ 16
LOCK LED .............................................................................. 16
LC Display ................................................................................ 16
MENU Key ............................................................................... 16
CLR/ACK Key ......................................................................... 16
NEXT Key ................................................................................ 17
INC Key .................................................................................... 17

The Menus in Detail ........................................................................... 17
Root Menu ................................................................................ 17
Menu RECEIVER POS. ........................................................... 19
Menu SV CONSTELLATION ................................................. 19
Menu SV POSITION ............................................................... 20
Menu USER CAPTURE .......................................................... 20
Menu SETUP............................................................................ 20
SETUP FREQUENCY OUTPUT................................... 21
SETUP ENABLE OUTPUTS ........................................ 21
SETUP TIME ZONE ...................................................... 22
SETUP DAYLIGHT SAV ON/OFF .............................. 22
SETUP SERIAL PORT PARM ...................................... 23
SETUP SERIAL STRING TYPE ................................... 24
SETUP SERIAL STRING MODE ................................. 24
SETUP POUT X (optional) ............................................ 25
Mode ...................................................................... 25
Timer mode ............................................................ 25
Single Pulse ........................................................... 26
Cyclic mode ........................................................... 26
PPS, PPM, PPH Modes ......................................... 26
Menu Quick Reference for progr. Pulse ................ 27
SETUP IRIG SETTINGS (optional) .............................. 28
SETUP INITIAL POSITION ......................................... 28
SETUP INITIAL TIME .................................................. 29
INIT USER PARMS ....................................................... 29
INIT GPS PARMS .......................................................... 29
FORCE BOOT MODE ................................................... 30
ANTENNA CABLE ....................................................... 30
Resetting Factory Defaults ................................................................. 31

Firmware Updates .............................................................................. 31
Skilled/Service-Personnel only: Replacing the Lithium Battery ....... 32
CE Label ............................................................................................ 32
Technical Specifications GPS167 ...................................................... 33
Oscillator specifications............................................................ 35
Technical Specifications GPS167 Antenna .............................. 36
Time Strings ............................................................................. 37
Format of the Meinberg Standard Time String ............... 37
Format of the Meinberg Capture String .......................... 38
Format of the SAT Time String ...................................... 39
Format of the Uni Erlangen String (NTP) ...................... 40
Format of the NMEA 0183 String (RMC) ...................... 42
Format of the ABB SPA Time String ............................. 43
Format of the Computime Time String........................... 44
Timecode (optional) ................................................................. 45
Principle of Operation ..................................................... 45
Block Diagram Timecode ............................................... 45
IRIG Standard Format ..................................................... 46
AFNOR Standard Format ............................................... 47
Assignment of CF Segment in IEEE1344 mode............. 48
Generated Timecodes ...................................................... 49
Selection of Generated Time Code ........................ 50
Outputs ............................................................................ 50
AM Sine Wave Output ........................................... 50
PWM DC Outputs .................................................. 50
Technical Data ................................................................ 51
Signal Description GPS167 V7.x ............................................. 52
Rear Connector Pin Assignments GPS167 V7.x ...................... 53
Menu Quick Reference ...................................................................... 55

6
General Information
The satellite receiver clock GPS167 has been designed to provide extremly precise
time to its user. 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
new system which receives its information from the satellites of the Global Posi-
tioning System.
The Global Positioning System (GPS) is a satellite-based radio-positioning, naviga-
tion, 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 several 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 retrans-
mitted 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.
6

7
GPS167 Features
The hardware of GPS167 is a 100mm x 160mm microprocessor board. The 105mm
wide front panel integrates a 4 x 16 character LC display, two LED indicators and 4
push buttons. The receiver is connected to the antenna/converter unit by a 50 ohm
coaxial cable (refer to "Mounting the Antenna"). Feeding the antenna/converter oc-
curs DC insulated via the antenna cable. Optional an antenna splitter for up to four
receivers connected to one antenna is available.
GPS167 is using the "Standard Positioning Service" SPS. The navigation message
coming in from the satellites is decoded by GPS167´s microprocessor in order to track
the GPS system time. 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
board´s oven controlled master oscillator (OCXO) and automatically compensates the
OCXO´s aging. The last recent value is restored from the battery buffered memory at
power-up.
The GPS167 provides different optional outputs, i.e. three progammable pulse
outputs, modulated/unmodulated timecode output, and up to a total of four RS232
COM ports. Additionally, you can order the GPS167 with different OCXOs (e.g.
OCXO-LQ / MQ / HQ or an external Rubidium) to match the required accuracy.
The hard- and software configuration of the clock is dis-
played if the NEXT key is pressed two times from the root
menu.

8
Time Zone and Daylight Saving
GPS system time differs from the universal time scale UTC (Universal Time Coordi-
nated) 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 GPS167´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 by the user.
Pulse and Frequency Outputs
The pulse generator of GPS167 generates pulses once per second (P_SEC) and once
per minute (P_MIN). Additionally, master frequencies of 10 MHz, 1 MHz and 100
kHz are derived from the OCXO. All the pulses are available with TTL level at the
rear connector. The included synthesizer generates a frequency from 1/8 Hz up to 10
MHz synchronous to the internal timing frame. The phase of this output can be shifted
from -360° to +360° for frequencies less than 10 kHz. Both frequency and phase can
be setup from the front panel or using the serial port COM0. Synthesizer output is
available at the rear connector as sine-wave output (F_SYNTH_SIN), with TTL level
(F_SYNTH) and via an open drain output (F_SYNTH_OD). The open drain output
can be used to drive an optocoupler when a low frequency is generated.
In the default mode of operation, pulse outputs and the synthesizer output are
disabled until the receiver has synchronized after power-up. However, the system can
be configured to enable those outputs immediately after power-up. An additional TTL
output (TIME_SYN) reflects the state of synchronization. This output switches to
TTL HIGH level when synchronization has been achieved and returns to TTL LOW
level if not a single satellite can be received or the receiver is forced to another mode
of operation by the user.

9
Time Capture Inputs
Two time capture inputs called User Capture 0 and 1 are provided at the rear connector
(CAP0 and CAP1) to measure asynchronous time events. A falling TTL slope at one
of these inputs lets the microprocessor save the current real time in its capture buffer.
From the buffer, capture events are transmitted via COM0 or COM1 and displayed on
LCD. The capture buffer can hold more than 500 events, so either a burst of events
with intervals down to less than 1.5 msec can be recorded or a continuous stream of
events at a lower rate depending on the transmission speed of COM0 or COM1 can be
measured. The format of the output string is ASCII, see the technical specifications at
the end of this document for details. If the capture buffer is full a message "** capture
buffer full" is transmitted, if the interval between two captures is too short the warning
"** capture overrun" is being sent.
Asynchronous Serial Ports (optional 4x COM)
Four asynchronous serial RS232 interfaces (COM0 ... COM3) 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 mode
of operation can be configured separately using the setup menu. COM0 is compatible
with other radio remote clocks made by Meinberg. It sends the time string either once
per second, once per minute or on request with ASCII ´?´ only. Also the interfaces can
be configured to transmit capture data either automatically when available or on
request. The format of the output strings is ASCII, see the technical specifications at
the end of this document for details. A separate document with programming instruc-
tions can be requested defining a binary data format which can be used to exchange
parameters with GPS167 via COM0.

10
DCF77 Emulation
The GPS167 satellite controlled clock generates TTL level time marks (active HIGH)
which are compatible with the time marks spread by the German long wave transmit-
ter DCF77. This 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, GPS167 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:
M Start of Minute (0.1 s)
R RFTransmission via secondary antenna
A1 Announcement of a change in daylight saving
Z1, Z2 Time zone identification
Z1, Z2 = 0, 1: Daylight saving disabled
Z1, Z2 = 1, 0: Daylight saving enabled
A2 Announcement of a leap second
S Start oftime code information
P1, P2, P3 Even parity bits
0
10
20
30
40
50
R
M
1
4
2
1
20
10
8
4
2
1
P2
20
10
8
4
2
1
2
4
8
10
1
2
4
8
10
20
40
80
P3
A1
Z1
Z2
A2
S
1
2
4
8
10
20
40
P1
Minute
(reserved)
Hour
Day of Month
Day of Week
Year of the Century
Month of Year
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. The DCF
emulation output is enabled immediately after power-up.