[amsat-bb] Re: SSTV Algorithms?

Curt Nixon cptcurt at flash.net
Fri Oct 17 06:43:47 PDT 2008

Nope...you got it just right!

As Simon pointed out, its all about knowing what information you want to 
get from the "re-constructed" wave.  If you want all the detail, you 
have to sample at least 2f of the highest harmonic content.  Square 
waves with fast rising leading edges are a real mutha!!  Its why we sold 
alot of multi-gig one-shot samplers!
For repetitive waveforms, averaging with a sample rate much slower and 
randomly distributed across the signal results in  good reconstruction 
but is not "realtime" or one-shot capable.


Nigel Gunn G8IFF/W8IFF wrote:
> According to Mr Nyquist (I think that's who it was) you only need to sample at twice the highest frequency contained in the sampled waveform but 
> remember that here we are talking about twice the frequency of the highest harmonic contained in the waveform so 8KHz wouldn't be sufficient for 
> a 4KHz square wave but would be sufficient to reconstruct a 4KHz sine wave.....  or is my theory screwed up as well?
> Gordon JC Pearce MM3YEQ wrote:
>> Hmm.  That's not quite true. 
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