Multifrequency waveforms

[Carl]

Finally got around to looking at the TX waveforms for the DFX, Explorer, and CZ7. Below are pics of the DFX & Explorer, I did not bother shooting the CZ7 'cause it's just a 5kHz square wave.

Fisher uses the fundamental and the third harmonic (15kHz) as its two frequencies. TX amplitude was 9.8vpp. The DFX uses 3kHz and 15kHz for its frequencies; waveform has an amplitude of 7.3vpp and a total period of 335us, which is right on the nose for 3kHz. The Explorer claims to use 28 frequencies but I think it really only uses 3. Total period is 620us (1.6kHz) and amplitude is 10vpp.

The oscope photos show roughly a period-and-a-half. The times marked are individual pulse widths, waveforms are fully symmetric.

[Robert Hoolko]

Re: Multifrequency waveforms

Carl

Just as the Fisher transmits one pulse width but demodulates 2 frequencies, the Explorer could demodulate more frequencies than the number of pulse widths it is transmitting. Though 21 sounds awfully high. Some of the odd harmonics would have to be really weak.

Robert

[Carl]

Re: Multifrequency waveforms

My understanding is that the Explorer only demodulates 3 frequencies. I'm going to create an FFT of the waveform, soon as I get a chance.

- Carl

[Sean Goddard]

Re: Multifrequency waveforms

As I understand it, the Explorer demods 3 frequencies at ANY ONE TIME.

It automatically chooses the three best frequencies to use with respect to the soil conditions prevailing.

[Rick, N. Mich]

The advertising says the Explorer uses up to 28 frequencies. Thanks for the post. Very interesting. n/t

sd