SECTION б - INSTALLATION
TONE REMOTE CONTROL PROTOCOL
The Model 16 uses a burst tone protocol to key remote transmitters. There
are 3 basic types of signals used in the protocol as implemented in the
Model 16:
1.
MODEM - The modem uses the Bell 202 standard FSK tone set for sending
the digital paging information. The baseband digital information
cannot be transmitted on standard audio paths so the modem is used to
modulate an audio carrier that can be transmitted over a common audio
path. The modulated audio carrier results in a tone set of 1200 Hz
and 2200 Hz tones.
2.
HLGT - The High Level Guard Tone is 2175 Hz sent out at about +5 dB
above the level of the modem tones. This tone is an attention tone
used to key link transmitters and repeaters. The length of the tone
required at the transmitter site is 120 ms. A longer tone should be
sent if the link transmitter keys via HLGT or if repeaters are used
since they will not key up immediately.
3.
FCN - The function tone is 1950 Hz sent out at the same level as the
modem tones. This tone is the actual tone that causes keying of the
transmitter.
The tone keying sequence is as shown in the following diagram:
Audio Input
Duration programmable (120 ms, 420 ms, 720 ms, etc.)
I
Depending on number of link repeaters used
End of
Transmission
HLGT
FNC
150 ms gap
Bell 202
40 ms
Modem Tones
6-9
