From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Naylor Subject: Re: [Moon-Net] JT44 on Linux Date: Tue, 20 Aug 2002 23:06:37 +0200 Sender: linux-hams-owner@vger.kernel.org Message-ID: <02082023063710.00798@g4klx> References: <0208152233020B.00798@g4klx> Reply-To: g4klx@qsl.net Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <0208152233020B.00798@g4klx> List-Id: Content-Type: text/plain; charset="us-ascii" To: moon-net@nlsa.com Cc: linux-hams Hi All A little status report on the progress of JT44 for Linux. What does it do now: Transmits JT44 and FSK441 (WSJT decode is perfect) Has timing control for both modes Can use soundcards in 16-bit or 8-bit mode Can read/write WAV files in 16-bit or 8-bit formats Can use the serial, parallel or no ports for TX switching What doesn't it do at the moment: No receive capability for either mode No GUI (will probably use KDE/Qt) The development is being done slowly as I am learning at the same time. The receive side is much more complex that the transmit side since (at least for JT44) you have time and frequency correlation which is not trivial, I am hoping Bob K1JT can provide pointers to how he did it in his WSJT program. I had to change my tone generation from an IFFT to a Numerically Controlled Oscillator because the symbol length is not a power of 2. However the NCO is probably more efficient in terms of CPU and is performing well. I have started on the JT44 receive, I have a sliding FFT which is producing lots of data and its quite interesting to see the symbols appearing in the "bins". My plan is to have two programs, one for JT44 and one for FSK441, with priority being given to JT44. In the GUI I will probably not include the information about Sun and Moon positions as there are other programs which do that better. I am going to follow the UNIX principle of one program for one task, even if I have to write the adjunct programs. My plans are intitally to have a simple text based user interface until such time as I am happy with the operation of the underlying signal processing. The GUI will probably be written in KDE/Qt as that has native C++ bindings. The whole thing is written in C++ and I am taking time to provide a good framework for doing further development of new weak signal protocols. A case that comes to mind is a protocol that is more suitable for EME on frequencies higher than 1296 MHz where the scintillation causes frequency spreading which can make the JT44 signal spread over more than one receiving bin. Something more akin to slowed down FSK441 with fewer tones and greater spacing is possibly more suited to that task. The test of the framework was that I was able to implement FSK441 transmit about one hour after I had JT44 transmit working. This is a lot of fun to work on, and a learning experience. I hope that the lack of replies about JT44 on Linux is more to do with their having been an EME conference this weekend rather than no-one being interested. As previously stated all of my work is under the GPL and is free to have and to modify. If anyone is interested in having it, drop me a line. In theory you could use Linux JT44 transmit and Windows receive, I can't wait to hear of the first QSO off the moon with it ! My priority is to work on JT44 and then FSK441 later. After listening to the monkey house on 144.370 MHz during the Persieds, I am not sure we need more operators on FSK441 in Europe, but as a technical challenge it is very interesting. 73 to all Jonathan HB9DRD/G4KLX