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The CHTX/DDA System is designed to comply with the recommendations detailed in BS5839-1: 2002 for alerting the hearing impaired to the activation of a Fire Alarm System.

The system can also be used in conjunction with a security alarm panel to alert guards who might be located remotely from the main premises.

Main users include factories, offices, universities, schools, hospitals, hotels and public buildings.



  • UHF radio link for maximum licensable protection
  • Unique coding avoids neighbouring system clashes
  • Self-monitoring of system health
  • Rugged steel enclosure to IP65
  • Backlit 2 line Text Display continuously reports system status
  • Additional Visible and Audible status indicators
  • Prioritised Fire Alarm inputs and Fault inputs
  • Automated test calls alert pagers to loss of radio signal
  • Fault notification to the host Control Equipment via monitored link
  • Key locked ‘System Test' facility for routine confidence checking
  • Over 90 hour's backup operation with internally fitted battery


Good practice dictates that unique coding is also vital to prevent false triggering of pagers from neighbouring systems,especially where more than one transmitteris installed on the same site (e.g. a universitycampus). This too, is acknowledged in Section 27.2 of BS 5839-1: 2002. All Channel systems use coding which provides a minimum of 2 million differs; this can be further increased to 16 million using the inherent features of Channel pagers.


As any professional radio designer and manufacturer will confirm, radio is not perfect. You cannot guarantee 100% coverage 100% of the time, nor can you neatly limit its coverage to the shape of a building (despite what some ‘radio sculptors' might claim!) Even when a manual frequency co-ordinated license is used, this will deter but not prevent illegal interference, nor will it stop a metalclad building being erected where there was previously excellent signal propagation.

Channel recognises these facts and has designed extra safeguards to alert the system user to any loss of radio signal. In addition to the system's self-diagnostics which will recognise a transmitter fault or antenna mismatch, if any Channel pager goes out of coverage, within two minutes the pager will vibrate until acknowledged by the user, and will display a ‘No Service' message. The message will remain on screen until the pager is back in the service area. A reminder vibrate alert will also activate every 15 minutes until the pager is back in the coverage area.

B.S.5839-1 Pager Transmitter
Portable Receiver (pocket datapager)
12v 7ah battery
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