4.8
ASP Card Operation
M805-00
30/09/96
Copyright TEL
4.3.1.1
Local Mode
In this mode the AIM has two states of operation: pass and inversion.
(a)
Pass Mode
In this mode the AIM is completely transparent. Any audio or signalling (e.g.
FSK) input in the 67-2850Hz frequency range is passed straight through to the
appropriate output.
(b)
Inversion Mode
This is the normal operating mode and is invoked by the user activating the AIM's
ICCS input or adding a 2970Hz tone to the speech audio. The speech audio,
CTCSS and any signalling tones are shifted from the 67-2550Hz band to a 350-
2833Hz band by being mixed with an internally generated 2900Hz carrier (base-
band shifting). This allows the equalised audio signal, which includes CTCSS, to
be sent along a land line. It also offers immunity to total audio cancellation due to
line reversals.
The baseband shifted audio/CTCSS signal and 2900Hz carrier are transmitted
down the link to be processed by the ARM.
Figure 4.4 Example Of Signals Fed Into An AIM
Figure 4.5 Example Of Inverted Signals Output From An AIM
4.3.1.2
Remote Mode
In this mode the AIM is in the inversion mode all the time.
Amplitude
Audio +
CTCSS
67
2550
2970 Frequency (Hz)
350
2833
2900
Amplitude
Inverted audio
+ CTCSS
Frequency (Hz)
1
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 ...