Using a compressor on your feeds

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kc2rgw

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For anyone who has idle audio gear kicking around, I figured I would mention this.

I have this Joe Meek 3Q compressor kicking around that I play with for various uses. Right now it wasn't in use so I figured I would toss it on the audio line for my PRO-2006 feed. It makes a tremendous difference applied as a leveling device in the audio path.

With the analog feeds I provide there is a massive difference in audio levels from one system to the next. The worst of the signals are the NYC based central dispatch frequencies that overlap since I have no CTCSS decode on this old scanner. They are many db above some of the local systems, with the local Monmouth County EMS dispatch being the worst low level audio 'violator'.

By cranking down the attack to it's fastest level and adjusting the input gain and threshold until the compressor is at the point where it just won't engage on the quietest signals, it clamps down at high ratio on the louder signals limiting their output level. This is basically applying as a peak limiter. Because there is little concern for fidelity with scanner audio, you can use abusive 10:1 or higher compression ratios with very little audible artifacts as a result.

I certainly wouldn't recommend spending this sort of cash for a scanner feed, but if you happen to have any compressors kicking around that aren't being used...give it a go. The results are pretty nice.

Here's my feed link if you want to check it out.

Middletown area Fire, Police, and EMS Live Scanner Audio Feed

The down side is, you can hear every flaw in the systems being monitored. Bad audio levels, emphasis and deviation settings are a lot more obvious now.

The real test will be later to see if this aggravates the RFI intrusion issues I have when operating HF at high power on the low bands. I'm hoping all the isolation and decoupling in the compressor will actually help as it worked perfectly on my transmit audio for the HF station when used for that.

For the guys with stacks of radios on feeds, this comp from Behringer is a huge bargain with 4 channels in a single rack space.

Behringer | MDX4600 MULTICOM PRO-XL 4 Channel Dynamics | MDX4600
 

iMONITOR

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I've used a similar device in the past when I was running two Uniden BC796D's, that had no AGC for P25 mode. Now that I've upgraded my scanners to BCD996XT's, they do a great job themselves and it is no longer required.
 

ka3jjz

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Equipment notes like this are potentially very useful to other feed providers who are using older scanners. We are collecting such notes here (anything in blue is a link)

Connecting Your Equipment - The RadioReference Wiki

Please consider writing this up and putting it in here. It's not hard to edit in the wiki - in fact if you write it up in Word, there is a Macro you can install that will change your writeup to wiki markup language. It's mentioned in our Wiki user's guide (found under Important links on the left when you are in the wiki).

The more detail, the better. 73 Mike
 

kc2rgw

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Yeah I wrote up the darkice Ubuntu article in there.

I'll dress this up and throw it in when I get a chance.
 
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