Hi Andy. If you are up to something simple, reliable and useful, I have a proposal for a PSK31 transmitter. With a VFO, fast XOR gate and a CW shaping circuit you may generate a decent PSK31 signal. You just need a cheap controller to control the XOR gate and CW on/off. I developed a simple protocol, where the commands for the XOR gate and CW on/off are modulated synchronously by a sound card and decoded by a simple algorithm on a cheap controller. Any DIP part (Atmel or PIC) would do. I am currently writing an article for QEX, but I can give you more detail if you like the idea. What I am proposing is an offspring of an already proven concept.
http://www.kufr.cz/~ok1iak/HAM/ATS3a-digital/index.php3 http://www.kufr.cz/~ok1iak/HAM/ATS3b/index.php3 http://www.kufr.cz/~ok1iak/HAM/WSPR/index.php3 The "commands over sound card" protocol is supported by PocketDigi http://sourceforge.net/projects/pocketdigi/ http://www.n0hr.com/PocketDigi/PocketDigi_intro.htm The firmware for the MSP430 controller of the ATS-3b is freely available. 73, Vojtech OK1IAK, AB2ZA
