Return-Path: Received: (qmail 34264 invoked from network); 12 Dec 2004 21:34:36 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore01.plus.net with SMTP; 12 Dec 2004 21:34:36 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CdbhE-000CUZ-5u for dave@picks.force9.co.uk; Sun, 12 Dec 2004 21:56:04 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CdbhE-000CUW-39 for dave@picks.force9.co.uk; Sun, 12 Dec 2004 21:56:04 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1CdbMR-000Bdm-Rb for dave@picks.force9.co.uk; Sun, 12 Dec 2004 21:34:35 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CdbLo-0006M0-Ke for rs_out_1@blacksheep.org; Sun, 12 Dec 2004 21:33:56 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CdbLo-0006Lr-7u for rsgb_lf_group@blacksheep.org; Sun, 12 Dec 2004 21:33:56 +0000 Received: from mail.nrtco.net ([216.168.96.52]) by relay.thorcom.net with esmtp (Exim 4.41) id 1CdbLk-00064V-B9 for rsgb_lf_group@blacksheep.org; Sun, 12 Dec 2004 21:33:56 +0000 Received: from nocturna-y1zrar (nrtcorback-216-168-120-162.nrtco.net [216.168.120.162]) by mail.nrtco.net (8.12.10/8.12.1) with SMTP id iBCLdfHC023794 for ; Sun, 12 Dec 2004 16:39:42 -0500 Message-Id: <3.0.6.32.20041212163345.00c63b18@magma.ca> X-Sender: ve2iq@magma.ca X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.6 (32) Date: Sun, 12 Dec 2004 16:33:45 -0500 To: rsgb_lf_group@blacksheep.org From: Bill de Carle In-Reply-To: <41BC4158.9080808@freenet.de> References: <82.1d33c60e.2eec2207@aol.com> <82.1d33c60e.2eec2207@aol.com> Mime-Version: 1.0 X-SPF-Result: relay.thorcom.net: 216.168.96.52 is neither permitted nor denied by domain of magma.ca X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=no, Subject: LF: Generate MSK .WAV files Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit At 02:02 PM 12/12/2004 +0100, WOLF wrote: [..] >Talking about "digimode" beacons... Do you use a DDS for the frequency >generation, and -if so- does the DDS have TWO frequency registers which >can be toggled via control pin (some chips have this option) ? If so, it >would be great to have a low-symbol-rate MSK test signal on air... Another way to do this is to use a linear Tx and an audio beacon message generated by a sound card. I just put up on my website a simple-minded program which lets you type in a short message to be sent out as MSK. The program can generate 16-bit audio files (preferably at 8200 or 8000 samples per second) in either the usual format I use around here (.AUD), or the more standard .WAV format. These files can be looped using COOL EDIT or some other program. When played back in loop mode, the resulting MSK waveform is phase-continuous. I have MSK sorta working now in AFRICAM 5.0 - still need to clean up a few details. Although it works with GPS-disciplined bit and frame sync, I have to add a way to track the bit edges without GPS. The already existing frame sync in AFRICAM works well with MSK because I basically use ET1 coding (16-bit frames) in the non-differential PSKL format. I'll put AFRICAM 5.0 up on my website after we have finished testing it. AFRICAM has an output (RTS) pin which can be used to generate MSK messages if you have one of those DDS synthesizers with two frequency registers. You can also use the AD9851 (only 1 phase increment register but it has a separate input reg) if you pre-load the next frequency (anticipating that the next frequency to be generated will be the "other" MSK frequency, not the one that is currently being transmitted) - then carefully synchronize the loading of the input register into the phase increment register once RTS toggles. At low clock rates, you have tons of time to do it cleanly - one way is to generate the rising edge needed (FQ_UP) on a *falling* edge of SYSCLK, then clear it on the next rising edge of SYSCLK. To be compatible with AFRICAM, transmit the higher of the two MSK frequencies when RTS is asserted (positive), the lower signal otherwise. The RTS output from AFRICAM is not perfectly synchronized with the clock on your DDS board, so the MSK signal won't be suitable for coherent demodulation, but AFRICAM will be able to decode it as FSK. Performance not great, but bandwidth much less than BPSK. I'll see about doing a coherent demodulation of MSK in a later version. You can get the MSKGEN program from my website at: http://www.magma.ca/~ve2iq/bbs.htm Unzip it and see the READ.MSK file for more info. Bill VE2IQ