M805-00
ASP Card Operation
4.9
Copyright TEL
30/09/96
4.3.2
T805-01 Audio Recovery Module (ARM)
Figure 4.6 ARM Block Diagram
As with the AIM, the ARM operates in either the local or remote mode, although in
most applications it operates in the remote mode (remotely located from the TSGM(s),
LEMs and system controller).
4.3.2.1
Remote Mode
In this mode the ARM has two states of operation: pass and recovery.
(a)
Pass Mode
As for the AIM, in this mode the ARM is completely transparent to any audio in
the 67-2850Hz range. Any audio input is passed straight through to the appropri-
ate output.
(b)
Recovery Mode
The presence of a 2900Hz key tone at the input places the ARM in the recovery
mode and it uses this 2900Hz carrier to recover the original audio by demodula-
tion. The inverted CTCSS (and signalling if used) is shifted down to the
nominal bands of 67-300Hz for CTCSS and 300-2550Hz for the speech/ signalling.
DIP switches D5 and D6 are used to configure the outputs. D5 determines
whether or not a 2970Hz key tone is present in the speech audio output, and D6
determines if the CTCSS is present in the speech audio or has its own separate
output.
A/D
Audio
amps
Audio
buffer
Audio
buffer
Audio
amps
A/D
Audio
buffer
Audio
buffer
Audio
amps
DSP
processor
D/A
D/A
Audio
amp
Audio
amp
Electronic
relay
Electronic
relay
1
3
4
2
1
2
N/C
N/C
N/C
(Inverted)
HF/LF audio
HF audio
to transmitter
LF audio to
transmitter
DIGOUT
Transmitter
control
Summary of Contents for T805
Page 16: ...4 2 ASP Card Operation M805 00 30 04 95 Copyright TEL ...
Page 44: ...7 18 Initial Programming Adjustment M805 00 30 09 96 Copyright TEL ...
Page 70: ...14 1 2 PCB Information M805 00 30 04 95 Copyright TEL ...
Page 89: ...Copyright TEL 30 09 96 M805 00 T805 Front Panel PCB Information 14 5 3 ...