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Re: LF: Re: Old "Coherent" mode

To: [email protected]
Subject: Re: LF: Re: Old "Coherent" mode
From: Andy Talbot <[email protected]>
Date: Wed, 2 Mar 2016 11:22:35 +0000
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Interesting

Looking back in my PIC code archives, the listing labelled "VE2IQIF.ASM" is dated October 2000 and is a 7200Hz version of the original 10kHz sampling one I used for DSP back then.   Do recall studying the VE2IQ "official" interface circuitry and suddenly realising it was a straightforward A/D plus RS232 formatter combined into a set of logic chips.   So the PIC sampler just needed a sampling rate change.

Back then we had to use expensive UV erasable chips for code development, then cheaper One Time Programmable ones for final versions.   So for code development I used to have three windowed chips on the go at any time, one in the eraser, one running and one waiting the next set of changes.  
It was possible to reuse OTP chips by starting way down in memory, then working back for each version and overwriting an initial GOTO statement with a NOP - very tedious

How technology has changed is less than two decades.

Andy  G4JNT

On 2 March 2016 at 11:02, Alan Melia <[email protected]> wrote:
Hi Andy Bill moved west but did appear on one of the groups a few months back I think. I seem to remember Toronto being mentioned.
 
The progress was COHERENT>> AFRICA >> AFRICAM. I think, Wolf appeared later from a different source as a sound card application. (somewhere I have a print of the original web posting for it) All Bill's software was operated via his sigma-delta ADC with RS-232 comms to the PC.......I have a nice boxed one here acquired from Dave Bowman.
 
One other system that was quite popular was Jason from Alberto, as a keyboard QSO data mode.
 
Alan
G3NYK
 
----- Original Message -----
Sent: Wednesday, March 02, 2016 7:59 AM
Subject: LF: Old "Coherent" mode

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

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