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Digital modes for the visually disabled

October 26, 2008

N1SZH QSL card showing Zody his service dog

N1SZH QSL card showing Zody his service dog

For amateurs with hearing disabilities digital modes can be extremely helpful to keep one going effectively in the hobby.  However, because of the visual nature of the digital modes on HF, like PSK31 or MFSK16, one would expect the visually impaired operators to not use these modes.  Not so for Brian, N1SZH, who I had an excellent contact with last week on 80m.  I replied to Brian’s call and was rewarded with being his first MFSK16 contact.  I was then surprised to read during our QSO that he was a blind amateur and using two computers to make the contact.  We had a great chat and he directed me to his website where I could download a QSL card (see the above image). On reading his website Brian has added some great content on how to set up a station for digimodes for the visually impaired, with contributions from Bill, N8BA.  Shows you cannot stop an amateur from innovating and making things work.

Brian is an accomplished amateur, take a look here to see places he has contacted on HF.  His MFSK signal was 599 for me in Eastern Ontario with Brian located in Milford, MA. My QRP signal was 59 from Brian and he kindly made a note on his digimodes page of our conversation.

This contact reminded me of a tip for digimode operation, which new users may not be aware of.  When I first replied to Brian’s call he told me he was trying to lock onto my signal, on his first reply (MFSK can be a little more sensitive to tuning than PSK31).  At that point I switched off the digimode software’s automatic frequency control (AFC).  Although a helpful tool, the AFC can cause signals to wander about on the waterfall as on each over each station tries to lock onto the other when receiving, but may not be exactly on the trace.  Over time, this can look like drift in a transceiver, but it is most likely the AFC algorithm in both stations causing the movement of a few Hz on each over.  If one operator switches off their AFC, the cycle of trying to lock onto a moving trace is broken and the other station has a better chance of locking on.  In the case of this QSO, once we were locked the copy was 100% each time.

Thanks for the QSO Brian and hope to CUL on the waterfall.

Finally, for amateurs with disabilities check out

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