I operate PSK 31 and RTTY almost exclusively. Just a tiny bit of SSB, no CW
any more. But I'd like to try digital voice. Is anyone using it ?
Comments ? Hardware ? How's it work with Ten Tec radios ?
----- Original Message -----
From: "Martin AA6E" <aa6e@ewing.homedns.org>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Friday, October 27, 2006 3:41 PM
Subject: Re: [TenTec] speech processing idea
> Dr. Gerald N. Johnson wrote:
> > On Fri, 2006-10-27 at 00:30 -0400, Gary Hoffman wrote:
> >> They had pc's in 1958 ? Interesting. I was still using mainframes and
> >> terminals in 72....shows how much I missed.
> >>
> >>
> > Not really PCs. Tended to take up a whole room or building, and tended
> > to have lots of noise from the card readers. I don't know of any
> > analogue inputs in real time.
> >
> > But speech clippers were tried and they caused much splatter on SSB.
> > Even when filtered. The only effective clipping was RF clipping that was
> > reformed by running the clipped IF signal through another mechanical or
> > crystal filter. But fast acting ALC sometimes does as much. Though one
> > rig's popular mod was to add 10 MFD to the ALC line for more punch. But
> > then the PA was driven to clipping for a long time before the ALC could
> > do anything. A case of slow AGC.
> >
> > The tests on punch power that I've done hint that the relative phase
> > responses of the microphone, audio stages, and SSB filter have a great
> > effect on the average power. I've only gone through trying several
> > microphones. I have a Turner made for shipboard steam boiler room
> > service that weighs a ton (and its a hand microphone) that in one of my
> > VHF rigs gives great punch. It may be that its a bit bassy and so keeps
> > down the higher frequency parts of my voice to cut back on the peaks
> > that can be inherent when mixing multiple tons of similar amplitudes.
> > The peak to average power of a multiple channel cell phone amplifier
> > goes down with each additional signal. RF clipping only raises the
> > intermod and interference between those signals so the PA has to get
> > along with the condition. That could well be a fundamental problem in
> > SSB that average power is always going to be significantly lower than
> > peak power and there is no solution that doesn't introduce excessive
> > intermod which is usually detected as splatter.
>
> Hey, the "solution" to equalize peak-to-average is to use CW, PSK31,
> RTTY, or if you must, digital voice! I suppose you could also use NBFM
> if you want to keep your linear busy.
>
> Seriously, the Orion v1 software has "real" RF signal compression
> (increased average talk power w/o much distortion), while v2 "SP" seems
> to be more like an audio compressor that does not change the fast peak
> to average ratio much. It's easy to verify this by watching an output
> power meter. That's one important reason I'm still on v1.
>
> 73 Martin AA6E
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>
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