Raspberry Pi Autofox?

I stumbled into a wiki on Turning the Raspberry Pi Into an FM Transmitter.

The code uses the hardware on the raspberry pi that is actually meant to generate spread-spectrum clock signals on the GPIO pins to output FM Radio energy.  Just add a quarter wave length of wire to GPIO 4 to act as an antenna.



root@raspberrypi:~# ./pifm
Usage:   program wavfile.wav [freq] [sample rate]




Looking at the source, it seems simple enough to narrow it a bit: 
In pifm.c look for:


float dval = sample*15.0;  // actual transmitted sample.  15 is bandwith (about 75 kHz)

Obviously this isn't a clean transmitter implementation, so don't expect much more than an autofox.

For a low power foxhunt it might amusing to wire a motion sensor to the other GPIO to adjust your transmit and announce timing cycle, when folks are getting close.


{Update 3/13}
Apparently some people think like me:
https://github.com/DanAnkers/WsprryPi

https://github.com/threeme3/WsprryPi

Plenty of folks using the basis of this for Weak Signal Propagation Reporting

And:

http://www.instructables.com/id/Raspberry-Pi-security-Slow-Scan-Television-Camera/?ALLSTEPS

It would also be interesting to use it as a Part 15 FM transmitter with modified code to allow a GPS for transmitter phase locking.

{Update 8/14}
Alessandro, IK1PLD released a binary to the Yahoo Raspberry_Pi_4-Ham_RADIO group:

Narrow Band FM transmitter derived from pifm. It is able to transmit FM from VLF to UHF with a settable deviation and pre-emphasys, frequency correction and subtones. It runs under debian distr.   In a SSH session type ./nbfm.out for help.