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EPSILON CLOCK MODEL EC20S Spectracom
User’s Manual
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9.3 EXTERNAL NMEA DATATION SOURCE
An external NMEA datation source can be used in conjunction with the external 1PPS synchronization
source to timestamp the 1PPS.
The external NMEA datation source shall be received on the ‘ NMEA ’ SUBD -9 connector on the rear
panel:
- Connector type : 9-pin female SUB-D
- Port configuration : Asynchronous RS232C, 9600 bauds, 8 bits, 1 stop bit, no parity.
- NMEA messages format : GPRMC from NMEA 0183 V3.01
For detailed information about this output interface, refer to the appendix 19.1 and 19.1.2.
This datation source is defaulted to ‘ Disabled ’ by the factory settings.
NOTA: When this datation source is not used, it is strongly recommended to disable it (this is the
factory setting) . See 13.7.3 NMEA Datation for External 1PPS.
9.4 SYNCHRONIZATION SOURCES MONITORING
The validity of the synchronization sources is monitored :
- by the ‘ SRC ’ LED (see 11.1),
- by the ALARMS signalling (see 11.2.2),
- via the web interface (see 13.3.2.3 and 13.3.2.5),
- via the SNMP service (see 14.1.1, SNMP parameters 14, 16 and 17).
10. OPERATIONAL TASKS
10.1 SELECTION OF THE SYNCHRONIZATION SOURCE
Two synchronization sources can be used to discipline the internal oscillator:
- The integrated multi-GNSS synchronization source (or GNSS source, see 9.1)
- An External 1PPS/NMEA synchronization source (see 9.2 and 9.3).
The GNSS source can be used as the main synchronization source and the External 1PPS/NMEA
synchronization source as a backup synchronization source.