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Message-ID: <3.0.1.16.20010316165423.21c7d01a@mail.cc.kuleuven.ac.be>
Date: Fri, 16 Mar 2001 16:54:23
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
Subject: Re: LF: "Wolf" BPSK tests anyone?
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Hello Jim,

I just downloaded the WOLF software. I'll try to get it running during the
weekend, I will let you know when I can receive WOLF.
You're 599+ with 1 Watt ERP so I'd prefer something in the mW range.

73, Rik  ON7YD

At 13:31 16/03/01 +0000, you wrote:
>Dear LF Group,
>
>Since transatlantic QRSS activity seems to have ceased for the 
>time being, I thought I would give KK7KA's "Wolf" a try. This is 
>essentially BPSK, but the encoding and decoding scheme is 
>designed so that a weak signal can be effectively integrated over a 
>long period. The current version of the software operates with a 
>fixed-length 15 character message; with good SNR, this will 
>decode in 24 seconds, but with a weak signal, the software will 
>operate on up to about 25 minutes of received signal, hopefully 
>leading to a significant improvement in performance. The US 
>Lowfers seem to have been doing quite well with it. There is quite 
>a bit of info on http://www.scgroup.com/ham/wolf.html, and also 
>http://www.highnoonfilm.com/xmgr/updates/wolf.htm .
>
>I have now tested my Decca TX with a specially built BPSK keyer 
>which has the accurate timing required by Wolf. I am able to 
>receive my own signals, and decode them successfully, so I know 
>it works! Both the carrier frequency, and the timing of the data 
>should be within 1 part in 10^7, which seems to be more than 
>adequate.
>
>The requirements for receiving this mode are basically just 
>receiver plus soundcard/PC, but great care is needed in initially 
>calibrating both the system frequency offsets, and the errors in the 
>soundcard sampling rate, in order to successfully decode weak 
>signals. This is critical for successful operation. The software 
>includes some utilities to help do this. The signal processing is "off 
>line"; first you record a period of received signal at 8k samples/sec 
>using the software of you choice (I used DL4YHF's Spectrum Lab, 
>which conveniently allows you to display a spectrogram at the 
>same time). Then, you run the recorded .wav file through the Wolf 
>program, together with the appropriate calibration factors. The 
>program prints the decoded message. This can be repeated if 
>neccessary, until you are happy with the results.
>
>I gather VA3LK is also nearly ready to start trials using this mode, 
>so if anyone is interested in trying some tests, I would be happy to 
>oblige. The most important thing seems to be which frequency to 
>use; from this end, the obvious choice seems to be either in the 
>135.9 - 136.0kHz, or 137.4 - 137.6kHz ranges. I can vary ERP 
>from about 1W down to 1mW, or less if you like, and set frequency 
>in 0.1Hz steps.  Let me know what signal would best suit your 
>needs. I should be able to be QRV most evenings over the next 
>couple of weeks. 
>
>Cheers, Jim Moritz
>73 de M0BMU
>
>