Hi Mike,
If you're still having trouble with Jim's WOLF signal, please
email me a one minute .wav file, and I try to diagnose the
problem. You can convert it to 8-bit samples to save some
space, if you like. My mail server will accept attachments of
up to about 7 MB.
73,
Stewart KK7KA
----- Original Message -----
From: "Mike Dennison" <[email protected]>
To: <[email protected]>
Sent: Tuesday, March 20, 2001 2:24 AM
Subject: WOLF: Success and failure
I tried out WOLF for the first time last night with total success.
Jim was sending GY(^%? JGGF, followed by H(*^RCKO KKl, followed by . . . .
OK, so it wasn't quite as successful as I would have liked.
My first problem was finding the Command Prompt (pseudo DOS) on
Windows ME. After 20 minutes, I located it under Programs, Accessories!!
I then successfully generated a test signal (WAV file) and 'received' it 100%
as per the instructions. So WOLF is easy after all.
Now for the big test - real RF. Jim came up with his test transmission and I
recorded it using Spectrogram but this didn't work. The problem seems to be
that WOLF needs a sample rate of 8kb, and Spectrogram doesn't do this rate.
An hour later, I used Cool Edit (a nice program) to generate a usable WAV
file of Jim's signal.
Several hours later I gave up, having failed to read anything at all from Jim.
Possible causes: Jim's signal is very strong so possible sound card level
problem. Also I may have been a long way off frequency (see below). Will test
further tonight.
Getting the correct audio frequency proved difficult and I only fixed it this
morning after breakfast. I can use BBC 198kHz to calibrate Argo to measure
a 136kHz signal to much better than 1Hz, but could not find an easy way of
measuring 800Hz!! First I believed the Argo readout at 800Hz, but later tests
showed this to be a long way out (this is not a complaint against Argo). I
finally listened to DBF38 on AM and beat my DDS against it, then used the
resultant 800Hz beat note to calibrate Argo. Later I found the offset facility
on
my IC-706. This sets the audio frequency for comfortable CW reception -
normally about 400Hz. Setting this to 800Hz gave me 800Hz audio to within
half a Hertz with the RF dial set to the correct frequency. Now why didn't I
think of that in the first place?
Some thoughts on WOLF:
It looks very useful and I think it may well be the mode for the 2001/2002 DX
season (though I will still run CW and QRSS).
The command line is hard work and needs a lot of interpretation. I am sure
there are programmers out there who could provide an easy display with
'switches' and 'dials', and some automation of the variables to optimise
reception.
Transmit is a bigger problem if you cannot generate high power SSB at
136kHz. Jim has cracked the problem with his Decca (Class D), and I look
forward to him publishing his modulator circuit. His signal is VERY clean with
me only a few km away.
We will need to devise a protocol for QSOs.
We will also need to find a way of having 'random' QSOs. At present the
frequency must be known accurately in advance and monitored for a very
long time. This is not viable if you don't know there is someone transmitting.
I find WOLF fascinating and challenging, whilst - at least on receive - not
needing huge amounts of work to get going.
I hope Jim will continue his test transmissions to get more people set up.
Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net
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