RTS CS9500, User Manual

Page: 39 / 95

button in) while audio is present on the
INPUT.
Turning
this
trimmer up much past the LED increase
the send level to the phone line due to the digital AGC!
Overdriving the input may result in distortion and very
hybrid performance!
The output level meter is placed
before
the output gain control.
This is
so
that the level may be adjusted to equipment downstream
The Telos' output level meter -LEVEL button out,
button out) shows caller level. Adjust the trimmer marked "OUT"
on the hybrid for a (0 reading on your equipment while
audio is present on the phone line. Dial tone is OK for this, but
keep in mind that dial tone level
is
about
6
dB hotter than voice.
Note:
When the AGC button is switched out, the meter reads the
telco line level and thus may be used to determine if there
is
a
phone line level problem. The meter's indication corresponds
to a phone line level of approximately
-15
3.3
FEEDBACK CONTROL
Sometimes, even with the exceptional trans-hybrid loss produced
by the digital process, trouble with feedback may occur when the
system is being used with an open speaker. Generally, this
happens only with poorer phone lines, or with very weak callers
requiring
lots of gain in the phone-to-speaker path.
Some suggestions for solution of this problem:
1. the Telos
OVERRIDE
function.
When mic processing is being
used,
connect the hybrid input in
such a way that it gets the unprocessed mic signal. The problem
here is that the mic processing combines with the internal Telos
input AGC to increase
gain in the feedback path when no announcer
audio is present. Depending on the mic processor, the feedback
margin
could be reduced by many dB. The Telos intemal AGC has a
smart adaptive gate to prevent inappropriate gain increase, but it
is thwarted by additional processing. If it is not possible to wire
around the processing, try to set the mic processing gate function
that the gain
is
not "sucked-up" during pauses. You might
also
reducing the input level to the hybrid. The send level will still be
OK, since the AGC has considerable range, but the system won't
ONE ONE OPERATION