Hi,

I've cooking up an idea for some time now but need some ideas on how to make a start on it.

I need a to generate a serial data stream of 10-bit characters as a frequency-shift key audio pattern, and then modulate them throgh a radio transmitter.

Assuming the data is sent out as marks 'n spaces, the frequency shift needs to be between 1300Hz and 2100Hz.

I have successful been able to generate these tones using the FREQOUT command and listen to them using a small speaker.

It appears that the minimum length of each mark and space is only 1ms.

The baud rate of the data stream needs to be 1200Bd which is a mark and space length of around 0.833ms.

Is there a better way of generating these tones so that the baud rate can be fatser?? Maybe using PWM?? I'm using a 20MHz xtal.