RRM02 - Product Manual
Issue: 02 complete, approved
Page 38 of 68
6.1.4.2 Microphone
Surveillance Tone Detection
Menu:
Configuration
Æ
System
Æ
Router
Æ
Inputs
Æ
Mic/Line
Æ
<I/P #
nn
–
input name
>
Æ
Single Button Microphone
Æ
Audio
Æ
Surv
Possible values:
–40dB to 0dB (1dB steps)
System default configuration: ‘–40dB’
If this surveillance is enabled, then in the absence of a surveillance tone, an Input Audio fault will be raised
and logged. This would indicate that the microphone audio connection is broken, or is a poor connection.
L
On VAR4/12/20 the microphone input gain affects the surveillance tone, therefore the
surveillance tone detection should only be set after configuring the microphone input gain; see
Section “
6.1.4.1 Microphone Input Gain
” (page
37
).
The detection threshold level is adjustable as follows.
1.
Configure
Mode=LF
and
Level (dB)=
–
40
, enabling the Router to detect the presence of the low
frequency surveillance tone that is generated by ASL microphones.
2.
Clear any existing faults by pressing the FAULT CLEAR button on the system front panel.
3.
Make sure that no fault is reported for the RRM02. Any fault reported by the RRM02 at this stage
should be cleared; see Section “
7 Fault Finding
” (page
52
).
4.
Raise the surveillance tone level slowly (1 dB step) from –40 dB until the “IPXX AUDIO INPUT” fault is
reported. Where XX is the Mic/Line input to which the RRM02 is connected.
5.
Set the surveillance tone level to 4 dB below the level that caused the fault to be reported.
E.g. if a –18 dB level causes the fault, then set the surveillance tone level to –22 dB.
6.
Make sure that no fault is reported for the RRM02.
