ACC RC-96 Owner's Manual page 97

Chapter Seven: Generaf Operation
Touch-Tone Muting
Noise and Kerchunker
Filtering
Touch-Tone commands through the repeater are normally muted
by the controller, both for security and so that users don't have to
listen to the tones. Since about 50 ms are required by the con­
troller to detect that tones are present, a shon "blip" will be heard
on the fIrst and second tones. Following the second tone, the
muting overlaps to subsequent tones so that no further blips are
heard. (The AD-2 Audio Delay board eliminates these Touch­
Tone "blips." See Appendix H for further information.) The
controller inserts a cover tone on the transmitter audio to indicate
to users that someone is entering a Touch-Tone command. The
pitch of the cover tone is programmable.
Users can defeat the controller's Touch-Tone muting to send
tones directly. through toa.1inkedrepeater ofto the telephone line
if necessary.
The Control Op can disabkTouch.".Tone muting so that all tones
pass through the repeater.
The RC-96 controller provides filtering against noise and ker­
chunking on the repeater receiver .. An algorithm fIlters against
spurious noise on the receiver COS logic input, preventing static
crashes and random noise bursts from bringing up the repeater.
Kerchunker filtering prevents shon transmissions from holding
up the repeater transmitter, frustrating the kerchunker into mak­
ing a "real" transmission to see if the repeater is up. The ker­
chunker filter requires that a user key down for more than 750
ms or an instant hang time is generated. The Kerchunker fIlter
can be enabled or disabled with Control Op level commands.
In the Control Op selectable "Zero Hang Time Mode" neither the
noise nor kerchunker fIltering apply.
80
I
I
L -_ _ ----J.
cos
ms
PTT
Figure 7-5. Noise Rejection
<750 ms
I
>750 ms
cos
I
' - - - - - '
o
HANG HOLDS UP TRANSMITTER
TIME
PH ----'
' - - - - - '
Figure 7-6. Kerchunker Filtering
RC-96 REPEATER CONTROLLER OWNER'S MANUAL· 69
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