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Old 12th January 2011, 07:58 PM   #1
AuroraB is offline AuroraB  Norway
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Question Noise gate circuit

Not sure if this is the right corner here, but anyway.....

I'm operating a fairly large ClearCom partyline intercom circuit, with some extension spurs that us IP codecs. As the ClearCom type cct's don't have a key line, I'm left with the codec's "Send on Level" function, which for some reason does not seem to be optimal, as outgoing messages end up being somewhat broken up. I'm pretty sure this is not a network related problem, as incoming messages that are sent by "Talk key trigger", as crystal clear and stable.

To solve this, I'm looking for a noise gate cct- or unit- that can give me a reliable audio activated trigger line, preferrably a commercial unit, but home built is also OK. There are lots of commercial noise gates, but I need the trigger line . not a gated audio line.

If anybody have any pointers, I'd really appreciate it!
( Google have sofar not found what I need..... )
While the Lie leapt from Bagdad to Constantinopel, the Truth was still looking for it's sandals!
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Old 12th January 2011, 09:09 PM   #2
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Have you spoken with ClearCom about your issue?
Your problem may be that the station(s) is dropping out of the transmit mode between words. The solution may be nothing more than adding a capacitor to the gating circuit(s) to hold the station(s) in the transmit mode a little longer after the audio goes away.
RDL makes some VOX modules which provide a dry contact closure in the presence of audio but I'm not sure how well they would interface with your ClearCom system.
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Old 12th January 2011, 09:18 PM   #3
AuroraB is offline AuroraB  Norway
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Hi - thnks for your reply...

As far as I know, ClearCom does not have a cct to solve this problem, - the codecs I use are from Barix in Switzerland - interfaced via 2/4 wire hybrids.
I could have used ClearCom's digital series for the IP part, but this was a cost issue...CC digital would have cost alost 10 times more, and the far end is a lot simpler with the Barix units - just the codec, a mic and a little PSU ( the codecs have small built-in amp, - just add a mini speaker....) and works really well.... lunchbox IP intercom.. :-)

EDIT: ( Should have been at the top )
It seems quite possible that it's the level triggering that drops out in short pauses, but the codecs have settings for both pre-and post-trigger transmit, but beyond that there's no variables.
Using the external trig line, though, gives a very consistent result.
While the Lie leapt from Bagdad to Constantinopel, the Truth was still looking for it's sandals!

Last edited by AuroraB; 12th January 2011 at 09:36 PM.
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