Technical Fact
    File: 1

    
 

    
TETRA

    
TErrestrial Trunked
    RAdio

    
 

    
Many existing
    security systems, car key and alarm control fobs operate between
    433.92 MHz and 418.00 MHz.These radio frequencies are currently
    being encroached upon by a system called TETRA.

    
The TETRA system
    is similar to cell phone technology and is intended to be a nationwide
    method of contact for police, fire, ambulance and similar organisations.
    By 2005 all police forces in the UK will be connected to this
    system via a country wide network of transmitters. The standard
    is approved by the European Telecommunications Standards Institute
    (ETSI) and is an integral part of European public safety organisations.

    
The TETRA system
    uses many, high powered radio transmitters (around 25W) which
    will interfere with radio receivers operating on the 418.00 MHz
    frequency, causing them to be blocked or to malfunction.

    
This is now a
    serious problem for older car fobs and alarms (and other devices
    such as automatic garage doors). In many locations around the
    UK they no longer operate correctly.

    
The ArtGuard
    Alarm System operates on a specific, safer MHz area within the
    band of authorised frequencies. ArtGuard has been designed with
    the associated problems of TETRA in mind and will reject interference
    from TETRA except in extreme conditions.