Posted by
Jim Brown-10 on
Oct 05, 2010; 5:11pm
URL: http://elecraft.85.s1.nabble.com/SSB-transmit-audio-Where-s-the-punch-tp5600109p5604028.html
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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