[TenTec] DSP in CW transmit?

[Ken Brown]

Tom,

I agree with you on a lot of the points you have made. I am sure you 
will get a lot of responses from people calling you "backward" or saying 
that if we all had your attitude we would be still be using spark. 
Anyway I agree that a lot of the "enhancements" using digital techniques 
are not providing real performance improvents so much as they are 
creating bells and whistles that sell to many who don't really use the 
real performance capabilities of a high end rig.

Building a simple sine wave generator may not be quite as simple as you 
think. When it needs to be keyed at various rates, have the proper rise 
and decay times, have a stable frequency and a low harmonic content (a 
sine way and not a raspy square wave) it really does get to be more than 
trivial. It might be something you could acheive using hand selected 
components, but on a production line to get every one to come out right, 
it might require a more complicated design.

These difficulties with analog designs are part of the driving force 
that makes digital techniques attractive. Even before radios started 
using DSP, there were digital techniques creeping into the design to 
help get better consistancy without having to use more expensive 
selected parts. That is why radios from the eighties and nineties have 
DIP switch selectable BFO fine adustment. Instead of having every SSB tx 
IF filter exactly identical, which would be very expensive, the carrier 
frequencies are fine tuned to match the filter, and then corrections are 
made in the other oscillator frequencies to make the frequency 
calibration work out correctly. You can only do this with a fairly 
complex PLL system. You end up with more phase noise. And you can turn 
out a bunch of radios from a production line cheaper than if you had to 
throw away out of spec filters. Tradeoffs are made.

DE N6KB

> Guess they didn't know
>how to build a simple sine wave generator? Or was  it cheaper to just use
>DSP and let CW performance drop?
>
>Tom - W4BQF
>
>
>----- Original Message -----
>From: <K4IA at aol.com>
>To: <tentec at contesting.com>
>Sent: Friday, August 13, 2004 8:09 AM
>Subject: Re: [TenTec] DSP in CW transmit?
>
>
>  
>
>>I don't understand what DSP has to do with transmitting a CW signal.   I
>>    
>>
>am
>  
>
>>not arguing "it ain't so" but could someone explain what is happening
>>    
>>
>here?
>  
>
>>k4ia
>>Craig  "Buck"
>>Fredericksburg, Virginia USA
>>
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>>
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