[TenTec] Type of Speech Processing in Jupiter/Pegasus?

[Tom Rauch]

I haven't been following this closely, so forgive me if I repeat 
something that has already been said but......

> The r-f clipping and filtering approach which prevents the distortion
> products from appearing in the output passband is still regarded by
> most folks as the most effective process to both increase average
> power and increase articulation.

The most effective processor is a split-band audio processor, 
assuming you can keep the phase constant between channels. It 
is much better than RF processing, which eliminates harmonic 
distortion but not the in-band odd-order IM distortion associated 
with mixing of inband signals with harmonics and harmonics with 
harmonics.

Is that what the Jupiter does???

The 1870's vintage VOMAX was a somewhat frail attempt at this, 
and it would be much better to do it with DSP now. I was actually 
working on a DSP processor which was the equivalent of gain 
compression (AGC), splitting audio into multiple channels with 
individual level controls, "clipping" them with  adjustable clipping for 
each channel, converting the clipped waveforms back to sinewaves 
(low pass filtering), and putting them back in phase with adjustable 
levels. But I don't care about SSB enough to finish the work I guess.

If you bandpass-split audio into multiple channels, preventing 
clipping harmonics from falling inside cutoff of each clipper's low-
pass output filter, you wind up without clipping-generated IMD or 
harmonic distortion no matter how much clipping you use.


73, Tom W8JI
W8JI@contesting.com