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Appendix A: Alarms Transmission
System
This appendix documents the manufacturer’s information requirements of EN 50136-2.
Overview
The control units incorporate an Alarms System (AS) and an integral Supervised Premises
Transceiver (SPT). The SPT can be configured to use:
PSTN or GSM, via an optional COM-SD-PSTN or COM-SD-GSM module.
Note:
Please refer to the important note on page 15 regarding the use of GSM for ARC
communications
Internet protocols, via the built-in Ethernet capability or an optional COM-DATA-4G
plug-on module (which is also cabable of switching to 2G).
GSM and PSTN transmissions
Mode of operation
Alarms from the AS are transmitted, via the SPT, in a pass-through mode of operation by
forwarding them directly to the alarm receiving centre via its Receiving Centre Transceiver
(RCT). If an alarm transmission is unsuccessful, the following event is logged:
“PSTN Alarm Fail" – for PSTN communications.
“GSM Alarm Fail"– for GSM communications.
The SPT attempts to send unsuccessful alarm transmissions until the retry sequence has
expired, and if still unsuccessful, the alarm transmissions are tagged for repeat
transmission with the next alarm.
Acknowledgments of successful alarm transmissions received from the RCT are forwarded
to the AS via the SPT.
Transmission monitoring
The Primary ATP can be either the PSTN or the GSM connection. Monitoring the integrity
of the transmission system is performed in two stages:
1.
The transmission network interface is monitored as follows:
PSTN
– the local connection from the SPT to the PSTN network is verified by
monitoring the line voltage.
GSM
– the local connection from the SPT to the GSM network is verified by
periodically checking the signal strength and registration to a service provider.
Note:
the SPT does not check the credit on PAYG SIMs, or the provider's
contract validity.