Configuration
Voice Problems
Each installation is unique. There are configurable voice parameters that can be tuned to maximize
the quality of transmitted audio. Remember, most audio configuration values are compromises, so
some experimentation may be required to obtain optimum settings.
P
:
Too much echo.
S:
On any link with delay that gets above 100 ms or so, the 2-wire to 4-wire conversion echo becomes
noticeable. The AVA-E has echo cancellation, but with that much delay, one has to be more picky about
setting the voice transmit and receive levels. "That much delay" is the digitization of the AVA-E plus the
transmission path turn around. The transmission path delay is likely the largest component of the delay.
The same issue comes up with all VOIP applications. One has to work with the levels to get the echo down
to where it is either not heard any more or so low that it is ignored by the caller.
Excessive echo is usually present when audio levels are higher than need be. Lower the levels one step at a
time. Eventually there should be a good talk level found where the echo fades far into the background, but
the talk level is sufficient for normal conversation.
P
:
E&M Interface Control Lead Problems
S:
The "M" lead is the input on pin 7 of the E&M interface. With a -48 VDC in on pin 7, with the + side of
the 48 volts on pin 8, ground of the RJ45 interface, the M lead relay is activated. At the far end AVA-E,
pin 2, the "E" lead relay closes. If testing with a VOM between pin 2, the E lead, and pin 1, ground, it
shows that the circuit between 2 and 1 goes from open to closed. The input side, M lead, is a mechanical
relay. The E lead output is solid state.
The M lead relay is 48 volts. It is activated by a voltage of at least 38 volts. The holding voltage is 4 volts
or more. There are a number of relays available at different voltages available as factory options, such as
24 volts, 12 volts, 9 volts, 6 volts, 5 volts.
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