Writing in the Waterfall
There’s something quite fascinating about waterfall display’s. With the advent of Software radio they’ve become common and familiar to many, yet all they usually show is multiple vertical coloured bars that help to locate a transmission or identify a type of modulation. So this is all about my experiments in ‘writing in the waterfall’ and pure frequency domain modulation schemes, otherwise know as fuzzy modes or Multi-Tone Hellschreiber.
Included below are two PIC microcontroller projects of mine for writing text directly on a waterfall display and an interesting ‘music’ program that will create pictures in a waterfall. Both PIC projects generate spectrally clean PP/MT Hell suitable for high power linear transmitters.
SCRIBER uses a low cost 14pin DIL 16F pic and a hand full of components to generate MT Hell audio to drive an SSB transceiver.
HELL’s BELL’s uses a fast dsPIC to generate I/Q SSB and MT Hell text anywhere from 0 to 500KHz.