> Re: [Repeater-Builder] MSR 2000 R1 Audio Squelch
Normal operation of the MSR-2000 Squelch circuits in repeater
operation works as follows.
The R1-Audio Module Squelch gates the receiver voice audio path
and provides a squelched or un-squelched logic source out to the
backplane for use by other modules and external functions.
The Squelch Gate Module "squelch circuit" provides valid repeater
transmitter ptt (transmit enable) logic if the on-card jumper
selected conditions are properly met (ctcss yes-no).
Transmit repeat audio is routed through and gated/enabled in the
Squelch Gate Module and controlled (enabled) by a logic line
coming in on Pin 5 from the R1-Audio Module.
****
So a quick summary says... the R1-Audio Module gates the audio
while the Squelch Gate module provides the repeater ptt function
when all the proper conditions are met.
****
If you open the R1-Audio Module Squelch the Repeater will still
function 100% but for the short time repeater is on without a
signal in the receiver (often called the repeater tail time) you
will hear white/squelch noise through the repeater. Most of you
call that noise squelch crash... some repeater controllers use
an audio delay to remove the crash noise so sometimes repeater
owners and operators will never know/understand what's really
going on at an external repeater controller input. Not a big deal
really but some repeater controllers have DTMF and CTCSS decoders
spending time hunting through the un-squelched receiver audio for
valid signals. In some multi port controllers these on-board
decoders have to "time-out" on one port before moving to the next
port, which many times means missed signaling (decoding) of a
desired signal. All this depends on your specific external repeater
controller hardware and software. In the case of a stone stock
MSR-2000 we only hear the short squelch noise in the the repeater
tail time... aka squelch crash.
****
So the R1-Audio Module Squelch Pot is set to open at a desired
value, which I directly relate to usable voice audio on/via a
Sinad type meter. In my head I have some relative signal value
picked that I/we feel contains the min usable/required voice/signal
value/level. Signals below that received value are so far into
the noise I/we consider them unusable.
*****
The Squelch Gate Module Squelch Key pot is most often set to
enable the transmitter at a valid signal level slightly below
the R1-Audio Squelch value. So the repeater transmitter is on
the air and ready to allow the tx repeat audio line to open
when the R1-Audio Module squelch logic says valid signal
present. The converse function goes on in the repeater un-key
event.
****
If properly adjusted the MSR-2000 dual (combination) squelch
provides both fast ptt and gated repeat audio. One should not
hear any squelch crash noise under normal conditions. Remember
I have the MSR-2000 coffee mug and tee shirt, which means I've
done about everything there is to do with these units as both
base and repeater stations.
****
If the R1-Audio Module squelch function is set to open at any
usable signal above x-value, you should only hear tx repeat
audio above that signal level. Users can and do dial the R1-Audio
Module squelch to open at x-value and owners who normally don't
like to hear very marginal signals can and do set the pot to
open above those values.
As an example the R1-Audio Module Squelch Pot/Control is set to
open at a semi noisy .15uV (micro-volts) signal versus a much
better .4uV signal. Your specific squelch set-point is a season
to taste selection.
When properly set... squelch crash noise is pretty much a
non-event/issue. The MSR-2000 ptt logic is even more than fast
enough to run Trunking and other similar signaling formats. So
both tx ptt and audio enable lines happen when they should.
The "dead-band" signal level/value where the repeater tx keys and
the audio is enabled is totally adjustable, meaning they can and
are often/normally right next to each other (with the Squelch Gate
Module set to open with signal levels slightly below the R1-Audio
Squelch value) or any practical owner selected distance.
Please don't compare the MSR to the Micro squelch functions. They
are different but they both work very well for what they are and
both should provide nearly crash-free audio gating and cor/cos
logic outputs.
Any port in a storm just as long as you get there...
cheers,
skipp
skipp025 at yahoo.com
www.radiowrench.com/sonic
> "Jesse Lloyd" <[EMAIL PROTECTED]> wrote:
>
> So after reading the writeup about how the R1 audio squelch works I
> discovered that it, like the micor, adjusts the COR dropout time
depending
> on the received signal strength... I think I read that it adds 150
ms for
> weak signals. I don't have any good documentation (other than
schematics)
> on how the squelch gate card works... does it too do this?
>
