|Original optical beacon|
|Optical beacon capable of continuous subcarrier (choice of freqs) or QRSS/CW|
|SpectrumView in action - it's brilliant|
I also want to optimise the use of the iPod Touch 4g as a handheld audio spectrum analyser. I have used it for this sort of test before using an excellent package available free called SpectrumView (see screenshot) available from Oxford Wave Research. With a laptop PC, running Spectran, the problem is the brightness of the screen which emits an interfering optical signal. With a tiny iPod Touch it is much less bright and can be held in the hand. Unfortunately the bandwidth can't be screwed down as narrow as with Spectran on the PC, so there will be S/N limitations. One test will be to see how far away I can detect my beacon (about 0.5W into the LED) over the horizon using just the optical receiver and the iPod Touch.
The beauty of 481THz (red light) work is the kit is simple: everything that matters is at audio frequencies and can be built and tested with the simplest of test gear.