On Fri, Oct 23, 2009 at 9:21 AM, Kevin Custer wrote:
> n...@no6b.com wrote:
>> At 10/22/2009 19:15, you wrote:
>>
>>
>>
>>> I disagree that an audio delay board negates the positive effect of
>>> a MICOR squelch.
>>>
>>
>> ...and let's not forget that many simply don't like ADMs. Ever try
>> to operate full-duplex with a quarter second delay on the repeat
>> audio? Also if the squelch chops the signal at all, an ADM set to a
>> long delay can turn those muted valleys into muted peaks, creating a
>> problem with the squelch where none existed before.
>>
>> Bob NO6B
>
> This is where the MICOR squelch shines. If you ever heard a UHF
> repeater with a poor carrier squelch (kendecom comes to mind), no
> matter how loose the squelch is set, mobiles in deep flutter chop up
> the audio. The human brain is not as good at putting broken words
> together where the break is a total dead absence. On the contrary, if
> the broken word is bridged with noise, the brain can fill in the
> blanks, and a severely broken sentence can make sense. While this
> problem is worse on UHF where close spaced deep nulls can occur more
> frequently, the situation exists on VHF as well. Motorola did a lot or
> research on this subject during the Space Program of the late 1960's.
> The result is the MICOR squelch many try to replicate. If anyone that
> is interested in this subject would like to learn more about the what
> the Motorola engineers take on it was, I suggest you get a copy of a
> MICOR manual and read the theory.
>
> Kevin Custer
Kevin,
Thanks for that explanation... you're spot-on with your observation
about how difficult it is to understand spoken-word chopped up Kendecom
style! My system is on VHF, but exhibits exactly the behavior you
describe and it's very difficult if not impossible to make any sense out
of what is being said. Before you explanation, I could not rationalize
why, but it makes good sense now.
Eventually I'll try putting a Micor squelch into it. I'm sure I can
find the proper place to tap/interrupt the existing squelch circuit with
a bit of detective work/trial and error.
73,
Mike
WM4B
