[hpsdr] eSSB for SDR's

[Jonathan Naylor]

I think that eSSB is missing a 
trick here. Instead of increasing the bandwidth, and 2.5-3 kHz is plenty for spoken word, development should be channelled into making better 
use of what we already have. As an aside, I have heard recording from 
the 1950s of 20m AM operation, and the audio sounded lovely, it wasn't 
because the audio bandwidth was high, it wasn't, but because the signal, and hence the audio, was properly tuned due to it having its carrier.


Many years ago, not far from where I live, GB3SF an SSB repeater was built 
and operated. This was not a simple linear transponder, but made use of 
1750 Hz tonebursts like a typical UK FM repeater and had the concept of a squelch. All this was achieved by insisting that users leak a little of their carrier into their transmission. The repeater phase locked onto 
this carrier and provided synchronous demodulation. When listening on 
the receiver at the repeater site, incoming transmissions sounded superb as they were properly tuned and didn't sound like SSB at all. This 
repeater closed down over ten years ago now, but with SDR techniques it 
would be very easy to investigate this idea further than was possible 
then. The point being that bandwidth is not the answer, more intelligent use of what we already have is.


Jonathan  G4KLX
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