How to measure crosstalk

I can't stress Doug's suggestion enough (even Fremer left this out in his instructions) - if you measure without a bandpass at 1kHz, your azimuth measurements will be close to meaningless.

Alternatively you could use an oscilloscope or spectrum analyzer, but a 1KHz bandpass filter with a multimeter will do.

Pryso: Doug and I meant the same thing, but notch filter is wrong and does actually the opposite. The correct one needed here is a bandpass that passes only frequencies in a narrow band around 1KHz.

Here is a link to some info about bandpass filters:
Band-pass filters
Band-pass filter on Wikipedia

I hope this clarifies things.

Rene