Jim,
> This only works with full bandwidth audio (that is, 20-20,000 Hz);
> the bandwidth we transmit would fit into one of those individually
> processed bands.
Wes Stewart, N7WS had a very successful split band approach for amateur
use years ago ... it was butchered by Alpha (the Vomax) but three bands
(300 - 600 Hz, 1200 - 2000 Hz and 2000 - 3500 Hz) is a very good choice
for "communications/talk." By keeping each band less than one octave
in width, IMD and harmonic products from clipping can be minimized even
with analog techniques.
With modern DSP technology one can add phase scrambling (rotation),
per band noise gating, pre- and post-clipping equalization and use
half octave bands with minimal hardware cost to achieve very clean
compression/clipping with very tight dynamic range even in noisy
environments.
73,
... Joe, W4TV
On 10/5/2010 1:11 PM, Jim Brown wrote:
> On 10/4/2010 11:13 AM, Rob May wrote:
>> I'll turn the compression up to 25.
>
> That is the WRONG WAY to set compression. Rather, compression should be
> set using the COMPRESSION section of the K3's meter (the one that's to
> the left of the ALC indicator.
>
> Grant said:
>
>> Just guessing here, but 65 watts of "average" power out with 100 watts
>> peak must sound pretty awful ..
>
> You're absolutely right, Grant. Any good audio (or broadcast) engineer
> knows that speech has a peak-to-average ratio on the order of 24dB. That
> ratio can be reduced (using peak limiting and compression) by 10-14dB
> before it starts sounding bad. Broadcasters use VERY sophisticated signal
> processing systems to reduce that ratio by another 3-4 dB. Many years ago,
> I sold some of this gear to broadcasters. Cost was in the $5K range in the
> early80s. One of the common techniques is to split the spectruminto
> multiple frequency bands and process each band separately, then combine
> them. This only works with full bandwidth audio (that is, 20-20,000 Hz);
> the bandwidth we transmit would fit into one of those individually
> processed bands.
>
> 73, Jim Brown K9YC
>
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