Minelab BBS TX signal

[Cossaro]

Have someone analized the coil TX signal on a Minelab Sovereign Elite with an Ocilloscope or a Spectrum Analizer?

The BBS is more like a "white noise" signal or it seem to be like a frequency-stepped "crescendo"?

[Unregistered]

The TX signal is a retangular wave consisting of one large and one small pulse. As you know the retangular wave is composed of a specific number of frequencies. In this case it is 17 and for the FBS 28. This as you know is not the same as a frequency domain design. You really are only going to see a retangular wave with an oscilloscope so would need to be able to have fourier to extract the individual frequencies. They are from 1.5KHZ for FBS to 100KHZ. One of 11 sets of 28 are selected to compensate for ground noise and EMI. A similar method is used for the FBS spectrum. It is in the ID of the targets and the microprocessor that the frequency domain really comes into play. The Explorer and Sovereigh is a sub-class of a PI detector using time domain.

[Carl-NC]

BBS & FBS use exactly the same transmit signal.

- Carl

[Cossaro]

Ok, this is the TX image for a Sovereign Elite and similar MD by Minelab.
It's composed by a large pulse and a sequence of many small pulse, each
one have the same time period. I'm not shure but it seem to be a train of
17 pulse (and this is the number of freq. from 1.5 to 25KHz inside-analizer).

In this MD the power is from one battery-pack of 12V but the pulse go from
-10 to +10V (my image have an error...), this is obtained by a bridge over
the TX coil. On each pulse my Tecktronics show a pure-ring with
exponentiation decay, like a PulseInduction Coil signal without the dumping
resistor.

I've found some schematics of the input-stage that show a multiplexer for
many OP-Amp and (I suspect) each one followed by a band-filter.

Someone have more details to describe the next stage of this MD?