Meinberg GPS167LCD-MP User Manual
FUNKUHREN
Technical Information
Operating Instructions
GPS167LCD-MP
Impressum
Werner Meinberg
Auf der Landwehr 22
D-31812 Bad Pyrmont
Phone: ++49 52 81 - 9309-0
Fax: ++49 52 81 - 9309-30
Internet: http://www.meinberg.de
Email: info@meinberg.de
September 23, 2004
Table of Contents
Impressum ............................................................................................ 2
General Information.............................................................................7
The Modular System GPS167LCD-MP .............................................. 9
GPS167 Features..................................................................................9
Time Zone and Daylight Saving................................................. 9
Pulse Outputs ............................................................................ 10
Time Capture Inputs ................................................................. 10
Asynchronous Serial Ports........................................................ 10
DCF77 Emulation.....................................................................11
Installation.......................................................................................... 12
Mounting the Antenna .............................................................. 12
Assembly with CN-UB/E .........................................................13
Antenna Short-Circuit .............................................................. 14
Powering Up the System ..........................................................14
The Front Panel Layout ..................................................................... 15
FAIL LED ................................................................................ 15
LOCK LED .............................................................................. 15
LC Display................................................................................ 15
MENU Key...............................................................................15
CLR/ACK Key ......................................................................... 15
NEXT Key................................................................................ 16
INC Key.................................................................................... 16
The Menus in Detail........................................................................... 16
Root Menu ................................................................................16
Menu RECEIVER POS. ........................................................... 17
Menu SV CONSTELLATION.................................................17
Menu SV POSITION ............................................................... 18
Menu GOOD SVS 24HOURSS MIN/MAX ............................ 18
Menu USER CAPTURE .......................................................... 18
Menu SETUP............................................................................ 19
SETUP ENABLE OUTPUTS ........................................ 19
SETUP TIME ZONE......................................................20
SETUP DAYLIGHT SAV ON/OFF .............................. 20
SETUP SERIAL PORT PARM......................................22
SETUP SERIAL STRING TYPE................................... 22
SETUP SERIAL STRING MODE ................................. 23
SETUP INITIAL POSITION .........................................24
SETUP INITIAL TIME.................................................. 24
INIT USER PARMS ....................................................... 24
INIT GPS PARMS..........................................................25
FORCE BOOT MODE ...................................................25
ANTENNA CABLE .......................................................26
Resetting Factory Defaults.................................................................26
Firmware Updates .............................................................................. 27
Skilled/Service-Personnel only: Replacing the Lithium Battery ....... 27
Technical Specifications GPS167LCD-MP.......................................28
Front/Rear Panel Connectors....................................................28
Rear View GPS167LCD-MP.................................................... 29
Pin Assignments of the SUB-D Connectors.............................30
CE Label ................................................................................... 30
Technical Specifications GPS167 (OCXO-LQ) ................................ 31
Technical Specifications GPS167 Antenna..............................34
Time Strings ............................................................................. 35
Format of the Meinberg Standard Time String............... 35
Format of the GPS167 Capture String ............................ 36
Format of the SAT-Time String...................................... 37
Format of the Uni Erlangen String (NTP) ...................... 38
Format of the NMEA 0183 String (RMC)...................... 40
Format of the ABB SPA Time String ............................. 41
Format of the Computime Time String........................... 42
Signal Description GPS167 ...................................................... 44
Rear Connector Pin Assignments GPS167............................... 45
Technical Specifications Power Supply T-60B ................................. 46
Menu Quick Reference GPS167LCD-MP ......................................... 47
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 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 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 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.
789
The Modular System GPS167LCD-MP
GPS167LCD-MP GPS-Receiver is a set of equipment composed of a satellite controlled clock GPS167 (LQ-OCXO) together with a power supply unit Mean Well T-60B,
both installed in a metal desktop case MULTIPAC and ready to operate. The interfaces and input/output signals provided by GPS167 are accessible via connectors in
the rear and the front panel of the case. Details of the components are described below.
GPS167 LCDMP
satellite controlled
LIGHT
GPS167LCD-MP GPS-Receiver in desktop case MULTIPAC (front view)
LOCK
FAIL
MENU
CLR/ACK NEXT INC
GPS167 F eatur es
The front panel integrates a 2 x 40 character LC display, two LED indicators and five
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 occurs 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 altitude with its
variation of ±180m is the most inaccurate component of the position. This inaccuracy
is caused by the operator (United States Departement of Defense) and not by the
GPS167, but it has no influence on the accuracy of the generated time. 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.
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 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.
In the default mode of operation, 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. 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.
Time Captur e 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
Two asynchronous serial interfaces 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 Meinberg´s standard time string either once
per second, once per minute or on request with ASCII ´?´ only. The interfaces can also
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 instructions 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 transmitter 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:
P
8
3
M
4
Year of t he 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
0
2
4
0
Minute
0
M Start of Minute (0.1 s)
R RF Transmission via secondary antenna
A1 Announcement of a change in da ylight savi ng
Z1, Z2 Time zone identification
Z1, Z2 = 0, 1: Daylight sa ving disabled
Z1, Z2 = 1, 0: Daylight sa ving enabled
A2 Announcement of a leap second
S Start of time code information
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. The DCF
emulation output is enabled immediately after power-up.
11
Installation
Mounting the Antenna
The GPS satellites are not stationary but circle round the globe in a period of about 12
hours. They can only be received if no building is in the line-of-sight from the antenna
to the satellite, so the antenna/converter unit must be installed in a location from which
as much of the sky as possible can be seen. The best reception is given when the
antenna has a free view of 8° angular elevation above horizon. If this is not possible
the antenna should be installed with a mostly free view to the equator because of the
satellite courses which are located between latitudes of 55° North and 55° South. If
even this is not possible problems occure especially when at least four sattelites for
positioning have to be found.
The antenna/converter unit can be mounted on a pole with a diameter up to 60 mm
or at a wall. A 50cm plastic tube, two holders for wall-mounting and clamps for polemounting are added to every GPS167. A standard coaxial cable with 50 ohms
impedance should be used to connect the antenna/converter unit to the receiver. The
maximum lenght of cable between antenna and receiver depends on the attenuation
factor of the used coaxial cable.
Example:
Type of cable diameter
Ø [mm]
RG58/CU 5mm 15.9 250
RG213 10.5mm 6.9 500
The values are typically ones; the exact ones are to find out from
the data sheet of the used cable.
1
This specifications are made for antenna/converter units produced
after May, 1999. Older devices amount to 200m resp. 400m.
Attenuation at 100MHz
[dB]/100m
max. lenght
[m]
1
1
Up to four GPS167 receivers can be run with one antenna/converter unit by using the
optional antenna splitter. The total length of one antenna line between antenna, splitter
and receiver must not be longer than the max. lenght shown in the table above. The
position of the splitter in the antenna line does not matter.
12
Assembly with CN-UB/E
FUSE 5V/2A SB
50/60 Hz
100 .. . 240 V AC
ANTENNA
(MTPR_LCD_V1 / 10.05.01)
SWITCHED
10MHz
Rückansicht GPS1 67 mi t LCD im 1HE Multi pac Gehäu s e
2.048MHz
male N-Norm
SWITCHEDPULSE OUTPUT COM1 COM0
TIME CAPTUR E RS-232 RS-232
30m
(Max. total cable l ength: 250m)
CN-UB/E
male type N
20m
GPS
Antenna
male type N
max. 1.5m
13
male type N
Antenna Short-Circuit
In case of an antenna line short-circuit the following message appears in the display:
ANTENN A SHO RT -C IRCUIT
DISCONNECT POWER !!!
If this message appears the clock has to be disconnected from the mains and the defect
is to eliminate. After that the clock can be powered-up again. The antenna supply
voltage must be in a range of 18.5VDC (free) and 17V
(connected GPS antenna).
DC
Powering Up the System
If both the antenna and the power supply have been connected the system is ready to
operate. About 10 seconds after power-up the receiver´s OCXO has warmed up and
operates with the required accuracy. If the receiver finds valid almanac and ephemeris
data in its battery buffered memory and the receiver´s position has not changed
significantly since its last operation the receiver can find out which satellites are in
view now. Only a single satellite needs to be received to synchronize and generate
output pulses, so synchronization can be achieved maximally two minutes after
power-up. After 20 minutes of operation the OCXO is full adjusted and the generated
frequencies are within the spezified tolerances.
If the receiver position has changed by some hundred kilometers since last operation, the satellites´ real elevation and doppler might not match those values expected by
the receiver thus forcing the receiver to start scanning for satellites. This mode is
called Warm Boot because the receiver can obtain ID numbers of existing satellites
from the valid almanac. When the receiver has found four satellites in view it can
update its new position and switch to Normal Operation. If the almanac has been lost
because the battery had been disconnected the receiver has to scan for a satellite and
read in the current almanacs. This mode is called Cold Boot. It takes 12 minutes until
the new almanac is complete and the system switches to Warm Boot mode scanning
for other satellites.
14
The Front Panel Layout
FAIL LED
The FAIL LED is turned on whenever the TIME_SYN output is low (receiver is not
synchronized).
LOCK LED
The LOCK LED is turned on when after power-up the receiver has acquired at least
four satellites and has computed its position. In normal operation the receiver position
is updated continuously as long as at least four satellites can be received. If the
position is known, only one satellite sufficient to hold synchronisation.
LC Display
The 2 x 40 character LC display is used to show the receiver´s status and let the user
edit parameters. The keys described below let the user select the desired menu. The
next chapter lists all available menus in detail. A quick reference of the available
menus and submenus can be found at the end of this document.
MENU Key
This key lets the user step through several display menus showing specific data.
CLR/ACK Key
This key has to be used when parameters are to be modified. When this key is pressed
the parameters that have been edited are saved in the battery buffered memory. If the
menu is left without pressing CLR/ACK all changes are discarded.
15
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