Meinberg GPS169PCI User Manual

Technical Information

Operating Instructions

GPS169PCI

with IRIG-Generator

Impressum

Meinberg Funkuhren GmbH & Co. KG
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: [e-mail]

February 20, 2006

Table of Contents

Impressum ............................................................................................ 2

Driver Diskette ..................................................................................... 4

Content of the diskette .......................................................................... 5

General information .............................................................................. 6

Block diagram GPS169PCI .................................................................. 7

GPS169PCI features ............................................................................. 8

Time zone and daylight saving .................................................... 8

Asynchronous serial ports ........................................................... 9

Time capture inputs ..................................................................... 9

Pulse and frequency outputs ........................................................ 9

DCF77 emulation ...................................................................... 10

Connectors and LEDs in the rear slot cover ....................................... 11

Installing the radio clock ..................................................................... 12

Configuring the 9 pin connector ................................................ 12

Mounting the board ................................................................... 12

Mounting the antenna ................................................................ 13

Powering up the system............................................................. 13

Firmware updates ............................................................................... 14

Replacing the lithium battery .............................................................. 15

CE label .............................................................................................. 15

Timecodes .......................................................................................... 16

The timecode generator ............................................................. 16

IRIG standard format................................................................. 17

AFNOR-standard format........................................................... 18

Assignment of CF Segment in IEEE1344 mode ....................... 19

Generated timecodes ................................................................. 20

Selection of timecode ....................................................... 20

Table of Contents (continued)

Technical Specifications GPS169PCI ................................................ 21

Assignment of the 5 pin jumper block ....................................... 23

Technical specifications of antenna ........................................... 24

Assembly with CN-UB/E (CN-UB-280DC) ............................ 25

Time strings ............................................................................... 26

Format of the Meinberg Standard time string ................... 26

Format of the Meinberg Capture String ........................... 27

Format of the SAT-time string ......................................... 28

Format of the NMEA 0183 string (RMC) ....................... 29

Format of the Uni Erlangen string (NTP) ........................ 30

Format of the ABB SPA time string ................................ 32

Driver Diskette

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Content of the diskette

The diskette contains a driver program that keeps the computer´s system time synchro­nous to the board time. If the present delivered diskette doesn’t include a driver
program for the operating system used, it can be downloaded from:

http://www.meinberg.de/english/sw/

On the diskette there is a file called „readme.txt“, which helps installing the driver
correctly. The content of this file is as follows:

Installation Instructions

-------------------------

Execute Setup.exe and choose the installation directory.
By default, the installation directory is:
C:\Program Files\Meinberg\MbgMon

Then shut down the computer, install the Meinberg radio
clock plug-in board into a free slot and reboot.

Now you are asked to install a driver. The driver file
MEINBERG.INF can be found in the subdirectory Driver\PnP
of the installation directory.

After the installation is complete, start the monitor
program MbgMon. Start the time service, control the state
of the reference clock and configure the device(s).

Copyright (C) Meinberg Funkuhren, Bad Pyrmont, Germany

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General information

The satellite clocks made by Meinberg have been designed to provide extremly
precise time to their users. The clocks have been developed for applications where
conventional radio 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 24 satellites together
with some 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.

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Block diagram GPS169PCI

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GPS169PCI features

The satellite controlled clock GPS169PCI is a plug-in board designed for computers
with 3.3V or 5V PCI bus running with clock frequencies of 33MHz or 66 MHz. The
rear slot cover integrates the antenna connector, the modulated timecode, two status
LEDs, and a 9 pin sub-D male connector.

The antenna/converter unit is connected to the receiver by a 50 Ω coaxial cable with
length up to 250m. Power is supplied to the unit DC insulated across the antenna cable.
Optionally, an overvoltage protection and an antenna distributor are available. The
antenna distributor can be used to operate up to 4 Meinberg GPS receivers using a
single antenna/converter unit.

The navigation message coming in from the satellites is decoded by satellite clock's
microprocessor in order to track the GPS system time with an accuracy of better than
250nsec. 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 tempera­ture compensated master oscillator (TCXO) to ±5•10
the TCXO´s aging. The last recent value is restored from the non-volatile memory at
power-up. Optionally, the clock is also available with a higher precision time base.

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and automatically compensates

A monitoring software shipped with the board can be used to check the clock's status
and configure some operational parameters.

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 the satellite clock´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. For Germany, the local time zone is UTC + 3600 sec for
standard time and UTC + 7200 sec if daylight saving is in effect.

The clock's microprocessor determines the times for start and end of daylight saving
time by a simple algorithm e. g. for Germany:

Start of DST is on the first Sunday after March, 25th, at 2 o'clock standard time.

End of DST is on the first Sunday after October, 25th, at 3 o'clock daylight time.

The monitoring software shipped with the board can be used to configure the time zone
and daylight savings parameters easily. Switching to daylight saving time is inhibited
if for both start and end of daylight saving the parameters are exactly the same.

The timecode (IRIG, AFNOR, IEEE) generated by GPS169PCI is available with
these settings or with UTC as reference. This can be set by the monitor program.

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Asynchronous serial ports

Two asynchronous serial interfaces (RS232) called COM0 and COM1 are available
to the user. Only COM0 is available at the rear panel slot cover, COM1 must use
another submin-D connector which can optionally be connected to the 5 pin jumper
block on the board. The monitoring program can be used to configure the outputs. In
the default mode of operation, the serial outputs are disabled until the receiver has
synchronized after power-up. However, they can be configured to be enabled imme­diately after power-up. Transmission speed, framing and mode of operation can be
configured individually for each port. Both of the ports can be configured to transmit
either time strings (once per second, once per minute, or on request with ASCII ´?´
only), or to transmit capture strings (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.

Time capture inputs

The board provides two time capture inputs called User Capture 0 and 1 (CAP0 and
CAP1) which can be mapped to pins at the 9 pin connector at the rear panel. These
inputs can be used 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, an ASCII string per capture event can be transmitted via COM1 or
displayed using the monitoring program. 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 COM1 can be measured. The format of the output string is described in the
technical specifications at the end of this document. 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 via COM1.

Pulse and frequency outputs

The satellite clock's pulse generator outputs TTL level pulses once per second
(P_SEC) and once per minute (P_MIN). A DIL switch on the board can be set up to
map one or both of the pulses to pins at the 9-pin connector at the rear slot cover.

A TTL level master frequency of 10 MHz is derived from the TCXO. By default,
this frequency is available only at the 5 pin jumper block on the board.

In the default mode of operation, the pulse outputs are disabled until the receiver has
synchronized after power-up. However, the monitoring program can be used to enable
these outputs immediately after power-up.

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DCF77 emulation

The GPS169PCI satellite 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, the clock 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:

Time marks start at the beginning of a 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.

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Connectors and LEDs in the rear slot cover

The coaxial antenna connector, two status
LEDs and a 9 pin sub D connector can be
found in the rear slot cover. (see figure). The

GPS
antenna

LOCK FAIL

modulated
timecode

BSL key

upper, green LED (LOCK) 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.

The lower, red LED (FAIL) is turned on
after power-up until the receiver has synchro­nized or if a severe error occurs during opera­tion.

RxD
TxD

GND

A DIL switch on the board can be used to wire some TTL inputs
or outputs (0..5V) to some connector pins. In this case, absolute
care must be taken if another device is connected to the port,
because voltage levels of -12V through +12V (as commonly used
with RS-232 ports) at TTL inputs or outputs may damage the
radio clock.

The 9 pin sub D connector is wired to the
GPS169PCI's serial port COM0. Pin assign­ment can be seen from the figure beside. This
port can not be used as serial port for the compu­ter. Instead, it can be uses to send out Meinberg's
standard time string to an external device.

Behind the little hole in the slot cover there is a push button (BSL) which is needed
if the clock's firmware shall be updated. See the chapture about firmware updates for
details.

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