On Wed, 04 Jul 2007 16:49:13 -0700, Telspam Electronics
wrote in
. com:

On Jul 4, 10:37 am, Frank Gilliland
wrote:
No, I don't. That's why I want to run it through the bench. The only
thing I'm sure that works is the noise gate, but I still don't see the
point since all it does is shut off the audio when you're not talking
to eliminate ambient noise. And it's that ambient noise that let's the
other guy know that you're still keyed up. A noise gate would make
your radio sound like a cheap speaker phone, or that crappy digital
voice from Comcast. Hey, here's an idea -- when you're done talking,
why not just unkey the mic?

Well... I still don't know why you would want to bench test something
that you have said doesn't work from day one. But that aside... let's
talk about the significance of the noise gate. Your understanding of
the way the noise gate works is correct.


I know it's correct, Brian. I've been working with them for longer
than you've been living with your parents.


When the audio falls below a
user-defined threshold... the audio mutes. If you stop to think that
the VoiceMax has very high gain in the AGC... you realize that any low-
level background sound will be greatly amplified... up to around
+60dB. Without the noise gate... the hissing and wind noise in the
background between words would be extremely distracting. The
background noise detracts intelligibility from the voice signal. This
blocking of background noise between words helps the vocal clarity of
the transmission. It's really quite effective .. and the audio quality
is excellent.


No, it isn't. What you are doing is muting the ambient noise only when
the voice is loud enough to trigger the gate. Once the gate is open,
both voice -AND- noise are passed. What it sounds like to the human
ear is distorted audio because the audio "processor" in your brain
hears the noise only with the voice and associates the two as one.

Noise gates have their place, such as stage audio applications where
ambient noise is perceived as distorting the -desired- sounds. That's
what it was designed to do. Your processor does exactly the opposite
by making the noise audible with, and -only- with, the desired sounds.


It certainly doesn't sound like a cheap speakerphone.
The speakerphone is quite different as the the person is quite a
distance from the mic in that application. This does present a big
problem... since the S/N ratio in that appliaction is very poor.


Say what?


That's why speakerphones sound hollow... due to room acoustics... and
many times are choppy on transmit/receive... because of the poor S/N
ratio... and therefore very critical threshold setting.


Not even close. Speakerphones sound choppy (like the noise gate in
your "processor") because they are voice-operated half-duplex. They
sound "hollow" because of the filtering needed to prevent the thing
from triggering it's own VOX.


So far there
are eight pre-production units in the field right now. I haven't had
one complaint or problem.


That's because nobody can hear you. Not suprising when your antenna's
ground plane is only 9 square feet.....


I have two installed in both my Cobra19 and
Cobra25 using the stock mic on one... and the Astatic 636L on the
other. They both work like a million bucks. I have the audio of a
power mic... without all the background noise. In my book... that's
the best of both worlds. My on-air experiences so far in the past few
months have substantiated my beliefs that the clarity is enhanced. I
came to that conclusion knowing how much less I've had to repeat
transmissions.


How about a testimonial from some of the people on the other end?


Oh, and where's that schematic, Brian?