This is a system of Selectively Calling a
Specific Radio and having it give an Audible
(Series of pips) & Visual (Flashing led) Response to alert the person Called. The
radio is also configured to respond with a transmitted acknowledgement. This means that
the person who is toning the receiptant can also hear that the receiptant radio is on and
responding even if the receiptant is not available.
The Process used is called 5 Tone EEA. The 5 being for the number of
transmitted And the EEA as the standard. Each tone frequency is assigned to a number
within the standard as also is the duration of it. See Chad at end.
The radios which are being used at present have a 5 tone Identity Number
which is fixed
and is the Decode Number for them. They will commence with the numbers 57---. The last 3
digits will be for that specific radio.
E-g- my base at home is a Motorola with number 57106
The Encode side of the radios only have 3 digits variable, the 57 being pre-set in the
software. So although you may set up on the variable 345 and transmit that, the number
that is sent is 57345.
Thus to call my Base radio you would dial up 106 and press the C (Call)
The radio would transmit the 57106, my radio would recognise it as its call, give an audio
& visual alert and transmit a 5 tone acknowledgement. I would then know someone was
trying to call me and respond.
Typical time format for toning:-
squelch to open, transmitter to key up, and receiptant's radio squelch to open.
EEA Tone Standard:-
Length of individual tones:- 40ms
Tone No. Freq.