ASL INTERCOM VAR8 Operation And Maintenance Manual page 40

VAR8 and Variants Operation, Commissioning, Fault Finding, and Maintenance Guide
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ASL Microphones produce this surveillance tone as standard and typically this feature
would be enabled (set to 'LF') if any ASL proprietary microphone is used, in order to
provide monitoring of the audio cabling.
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The surveillance tone level adjustment is described in the following guideline. Note that
after each setting the SELECT key should be pressed to save the new configuration.
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When the Router input is connected to an audio source other than an ASL microphone,
this feature should be disabled (set to 'Off') in order to prevent faults from being raised,
e.g., background music, PC/DVA system, non-ASL microphones, etc.
To Adjust the Surveillance Tone Level on ASL Microphones:
a. Set 'Mode=LF' and 'Level (dB)=–40'.
b. Clear any existing faults by pressing the FAULT CLEAR button on the system front panel.
c. Any fault reported by the microphone at this stage should be cleared.
d. Raise the surveillance tone level slowly (1dB step) from –40dB until the "IPXX AUDIO INPUT" fault is
reported. Where XX is the Mic/Line input to which the microphone is connected.
e. Set the surveillance tone level to 4dB below the level that caused the fault to be reported.
E.g. if a –18dB level causes the fault, then set the surveillance tone level to –22dB.
f. Make sure that no fault is reported for the microphone.
9. Define the relative gain for each frequency band (low, mid, and high frequencies) of the 3-band
equaliser.
A switchable High Pass filter is also configurable. This would typically be used on microphone inputs to
prevent excessive 'pop' noise.
Menu: Configuration System Router Inputs Mic/Line I/P #<nn> <mic type> Audio EQ
10. Define the time over which this audio channel is faded up/down when audio sources change.
Menu: Configuration System Router Inputs Mic/Line I/P #<nn> <mic type> Audio Fade
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The time is given in tenths of a second, so divide by ten for the time in seconds.
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It is important for Fire Microphones to be able to override other sources quickly;
therefore Fire Microphones are set-up for a short Fade Down time.
The Fade Down time is:
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The time it takes for the signal to fade down when turned off (un-routed);
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The time it takes for the signal to fade down before an overriding broadcast is made in its place
The Fade Up time is the time the signal takes to fade up when:
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Turned on (routed);
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Override removed.
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Is sue: 02 complete, approved
Page 40 of 166