FSK support

Val

I've searched the forum a bit and the programming guides and haven't found any support for this so I thought I'd ask.

We're using a STAMP controller to send acoustic signals underwater. However the STAMP seems limited to the freqout command for sending signals. We've tried to work around this as best we can. For example, to send a chirp signal, we rapidly send small steps of constant frequency tones in increasing frequency.

However we can see many applications in which a true FSK (frequency shift key) sequence would be very handy. These would allow sending of signals from multiple units that are more readily distinguishable from each other. (orthogonal in a correlation for the mathematically inclined).

So my questions are: 1) Does anyone know a way to send an FSK signal from a stamp, 2) if not, would the gods who write the programming language for the stamp please consider a command to send an FSK signal.

Thanks,

Val

Phil Pilgrim (PhiPi)

Val,

FSK and "chirp" are two very distinct concepts. In frequency shift keying (FSK) only two frequencies are typcially used, swithcing back and forth between them for "mark" (1) and "space" (0). Is this what you really intend? If so, what baudrate do you require for communication?

-Phil

Mike Green

1) You've already found the main way to send low frequency signals with just the Stamp
2) Sorry, it won't happen. The interpreter doesn't really have the means to do FSK other than by using FREQOUT

3) There are many ways to do FSK with simple external circuitry. Here's one from EDN magazine:

Mike Green

The Propeller can produce complex waveforms throughout the audio spectrum including a chirp where the frequency is swept through a portion of the audio spectrum. It's even cheaper than the Stamps when you use the Protoboard.