Meinberg IMS-GPS180 Скачать руководство пользователя страница 16

4 GPS Clock

Extended Options

The Trusted Source (TRS) feature is a powerful tool to protect the GNSS

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receiver from spoofing attacks. For

the moment, the Trusted Source feature is supported only in combination with a Meinberg GPS or GNSS
receiver and a Meinberg XHE external Rubidium holdover unit.

To activate this feature, select "Use Trusted Source" check box for the GPS reference signal. It means that
GPS reference will be checked for consistency by another reference source which is acknowledged as a Trusted
Source. In our case the trusted source is a Rubidium atomic clock. It is denoted as ext.Osc. (external oscillator)
in the table of Extended Options. Therefore select this check box "Is Trusted Source".

The external Rubidium acts as an external oscillator that is synchronized by the GPS or GNSS Master as
long as the master is available and its precision is better than the precision of the XHE. If the Master fails
or for some reason uses corrupted or manipulated data the TRS will detect this as an offset limit violation.
Consequently, the reference selection algorithm will discard the current master and the XHE Rubidium source
will become the new master for synchronization.

Both GNSS and Rubidium reference signals need to be configured first in the Source Priority list, GPS or
GNSS as "Source 1" and external Oscillator as "Source 2". All other positions should be left empty (see chapter
MRS Source Priority).

Second, the IRSA Reference algorithm should be activated with corresponding precisions (see chapter IRSA -
Intelligent Reference Selection Algorithm).

The precision for GPS or GNSS is at same time also the TRS limit, that the reference should comply with. If the
TRS limit is violated the reference selection algorithm discards the current master and switches automatically to
the Trusted Source - XHE Rubidium. For the GPS or GNSS precision value we take 250ns which is maximum
time deviation allowed for the receiver.

Finally, the GPS or GNSS source should have enabled "Time of Day Source" and "Phase Source", which
means that the receiver is a source for both Time of Day and Phase. At the XHE Rubidium only the Phase
Source should be enabled, since the atomic clock alone does not deliver the ToD information (see chapter MRS
Features).

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GPS / GNSS: The Trusted Source (TRS) feature will only work with GPS180 and GNS181 receivers.

IMS-GPS180 Setup Guide

Date: 10th January 2018

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Содержание IMS-GPS180

Страница 1: ...MANUAL IMS GPS180 Setup Guide Hot Plug Module 10th January 2018 Meinberg Radio Clocks GmbH Co KG...

Страница 2: ......

Страница 3: ...g 4 3 Replacement or Installation of a Hot pluggable IMS Module 5 4 GPS Clock 6 4 1 Configuration of IMS Modules via Web Interface 8 4 1 1 Clock 8 4 2 Meinberg GPS Antenna Converter 25 4 2 1 Introduct...

Страница 4: ...g Funkuhren GmbH Co KG Lange Wand 9 31812 Bad Pyrmont Germany Phone 49 0 52 81 93 09 0 Fax 49 0 52 81 93 09 30 Internet http www meinberg de Mail info meinberg de Date 2017 05 31 IMS GPS180 Setup Guid...

Страница 5: ...to the manufacturer for maintenance Exchange of hot swap components Ensure that components which will be replaced during operation always be treated with the utmost care Avoid contact with live compo...

Страница 6: ...n of high voltage devices 2 2 Supply Voltage WARNING This device is powered by a dangerous voltage Nonobservance of the safety instructions of this manual may lead to serious damage to persons and pro...

Страница 7: ...work done the connectors particularly when connectors are opened may never be carried out when the installation is energized All connectors must be covered to prevent from accidental contact to life...

Страница 8: ...nchored in the connector block of the housing You need a certain amount of force to release the module from this link Once the connection to the connector block of the system s backplane is loosened t...

Страница 9: ...1 First IF Frequency 35 4 MHz 1 1 these frequencys are transfered via the antenna cable Power Requirements 15 V 100 mA via antenna cable Figure right GPS Receiver and GPS with XHE SPI Connector option...

Страница 10: ...he optional XHE SPI Connectors A1 PPS In A2 PPS Out Pin 1 SCL_Out SPI Clock Pin 2 CS Chip Select Pin 3 MOSI Master Out Slave In Pin 4 MISO Master In Slave Out Pin 5 GND Attention Use this plug only to...

Страница 11: ...m which means whether it is a single reference clock or a system with two installed remote clocks and a changeover card the web interface builds up accordingly This also applies to the type of referen...

Страница 12: ...he system Is locked the system synchronizes itself to the reference source Is accurate Basic accuracy of synchronization reached Offset Time difference of the reference clock to the specified time sou...

Страница 13: ...switching will follow in case that a master reference becomes unavailable The selection of signals in the list is automatically generated by the LANTIME according to the hardware configuration The pr...

Страница 14: ...re that IRSA is working properly follow these steps 1 Configure a priority list of available reference signals in descending order from the superior to inferior one in the MRS Settings menu see chapte...

Страница 15: ...rmation for example GPS NTP PTP PPS plus string If you use the mixed mode the reference clock will be steered first by a reference signal which includes the ToD The oscillator will be roughly adjusted...

Страница 16: ...the current master and the XHE Rubidium source will become the new master for synchronization Both GNSS and Rubidium reference signals need to be configured first in the Source Priority list GPS or GN...

Страница 17: ...digit year the offset to the UTC time the current daylight saving time status and announcements from the start and the end of the summer time as well as information about an upcoming leap second are t...

Страница 18: ...time telegram in response Features MRS PPS Plus String If the system has the MRS PPS plus string option the baudrate and framing for the incoming time string must be configured via this submenu Meinbe...

Страница 19: ...erence clock The data of the time zone are used from the time zone table see chapter System Display Enabling the Outputs Optionally the outputs of the reference clock can be set to always supply a sig...

Страница 20: ...hh mm ss DCF Suspend After min In the DCF77 Marks mode you can configure a shutdown time for the output port so that in the case of an asynchrony of the reference clock no DCF mark is available at the...

Страница 21: ...ge By entering the frequency 0 Hz the synthesizer can be switched off Phase With phase you can enter the phase position of the set frequency in the range 180 to 180 with a resolution of 0 1 When the p...

Страница 22: ...pagation time of the antenna cable can be compensated by this value The received time grid is delayed by approx 5ns m antenna cable This time error is automatically compensated by entering the cable l...

Страница 23: ...ng the simulation mode the corresponding status information for the NTPD is permanently set to SYNC This also makes it possible to transmit other times which have been entered via the menu item Initia...

Страница 24: ...smitter km PZF AM Receivers only In the menu item Distance to the Transmitter you can enter the transmitter distance in km which is used for the delay compensation of the incoming PZF signal The adjus...

Страница 25: ...all GPS system values this means that all stored satellite data will be deleted Please note that the receiver takes about 15 minutes to read in the information of the satellites again to complete the...

Страница 26: ...4 GPS Clock Receiver Information This menu item lists all the important information and options of the reference clock IMS GPS180 Setup Guide Date 10th January 2018 23...

Страница 27: ...system the order of the active and the reserve system is exchanged at every change over For example if the active system switches to the free running mode while the reserve system is operating synchro...

Страница 28: ...ernal power supply is required near the location of the antenna if a coaxial cable is used If more than a single GPS receiver are to be operated then a GPS antenna splitter can be used to distribute t...

Страница 29: ...required then this can be ordered accordingly Surge protectors should be installed indoors directly where the antenna cable comes in The optionally delivered protection kit is not for outdoor usage Th...

Страница 30: ...mal Operation If no valid data can be found in the battery buffered memory e g because the battery has been discon nected or replaced the receiver has to scan for satellites and collect the current al...

Страница 31: ......

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