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R C wrote:
Dana Myers K6JQ wrote in message ws.com... It may be worth adding the HDLC/ax.25; initial basestation will likely be a laptop running soundmodem. In which case, AX.25 isn't that hard at all to implement, HDLC is fairly trivial, and the checksum code can be found pretty readily (I have a Java port of something I sponged out of an old RFC if you're looking for sample code). You'll likely need it all for soundmodem recognize your frames, but you don't need to do full-on connected-mode AX.25, UI datagrams are likely enough. Also - I'd avoid the use of transcendental functions (sin()) in the synthesizer loop ; I'd create a lookup table and index it via an integer phase accumulator. Off the top of my head, I'd guess a 16-bit phase accumulator and a 256-element sine array would be plenty. You'd need to precalculate the phase increments for 1200 and 2200 Hz, likely as constants. That is step 2 The target CPU will most likely be a Mega8535 AVR, so conversion to integer is definately indicated. Heh. You're tempting to cobble up the DDS code for giggles and flash it into an atMega16 I have sitting here ;-) Dana |
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