Back in the last millennium, on 73kHz I remember using a BPSK mode called
"Coherent" by VE1IQ. I do remember generating raw
unfiltered BPSK and casually 'ignoring' its sidebands, and also that the
abrupt phase transition led to audible clicks from my antenna loading
coil
Purely out of interest (and because I thought I'd include it in a talk on
LF operation I'm giving in a couple of weeks) I searched for any details
on t'web. VE2IQ's page still seems to exist, but all references
date back to that era - I didn't try downloading the software.
In those pre-soundcard days we had to use hardware audio digitisers on
receive, and I remember doing a PIC based one to replace the board of TTL
logic otherwise needed. Still have a PCB on a shelf here labelled
"VE2IQ Interface"; it's just an A/D converter and serial interface to a
PC, with 8 bit sampling at 7200Hz.
Did Coherent morph into Wolf? As they both use the
same modulation / baud rate it seems more than coincidence...
Andy G4JNT
