PI "SAT" adjustable ?

[Anonymous]

Is any one making a PI with an adjustable "SAT" maybe even an adjustment for the "attack" and "decay" of the "SAT".
It would seem a good addition as the sand/soil is different in many locations .
I have used both a surfmaster PI and a baracuda PI and both have a"sat" but are adjusted differently.
Russ
certified detector sales

 

[Anonymous]

Hi Russ,
SAT, or Self Adjusting Tuning, is a bit of a misnomer as far as PI is concerned. There is no actual tuning of any sort in a PI but what it refers to is a circuit that eliminates steady or long period signals and just passes the short period ones. A simple resistor capacitor coupling in the later amplifier stages will do the job. The speed of the SAT , or Auto Zero as I prefer to call it, can be varied by altering the RC values; a smaller C or R will speed things up while larger values will slow it down. However, this arrangement comes after the integrator and it is this that has the major effect on the response speed of the detector. I currently make a detector (Superscan) that has a control to vary the integration time. The Superscan is primarily a large object/large coil detector and you do not need a fast response generally speaking. Large coils tend to pick up more noise and this can be smoothed out by setting a longer integration time. The variable integrator is followed by an RC coupled amplifier that has a longer time constant than the longest integration time so that the response is purely determined by the integrator adjustment.
Eric.