Digital PCM Radio Transmitter

INTRODUCTION
The PICmicro™ can be used in a pulse coded radio
transmitter. The PICmicro’s crystal oscillator serves as
the RF source. “On” pulses are generated by running in
a timing loop. “Off” pulses can be generated by sleeping
with the WDT running. The WDT prescaler can be
changed dynamically to generate variable width “Off”
pulses.
An I/O pin can turn off an optional final and/or multiplier.
The transmitted code can be fixed or encoded data
from I/O pins.The PICmicro’s oscillator serves to bias the final at
VDD/2. The 120W
resistor then sets the current in the
final. The tank can match the crystal or be an odd multiply.