REJECT control ; What part is this on the Hammerhead circuit

[Anonymous]

REJECT control; What part is this on the Hammerhead or GQ circuit. And there are few controls like second sample
and sample pulse width,I do not understand these features?

 

[Anonymous]

Hi Percy,
The reject control on the GQ has the same function as the delay control on the Hammerhead. It simply changes the delay time before sampling.
As for the second sample control, it is there to allow the operator to adjust just when the second sample is taken. The main purpose of the second sample is to eliminate the signal caused by the Earth's magnetic field as the coil is swept over the ground. Without the second sample signal being subtracted, one woud hear a false signal caused by the magnetic field of the Earth. This Earth field effect signal becomes quite noticeable as the sensitivity of the detector or the coil sweep speed is increased.
The concept of the second sample is to subtract a later sample from the first, which eliminates by subtraction, signals that are very low frequencies, so it will help with noise also.
The sample width simply gives the operator control over the length of the time the received signal is sampled. If this sample time is too long, the effect is much like adjusting the delay, it will reduce the sensitivity. If it is too short, there is insufficient time for the signal to be properly analyzed, so one would see a sensitivity decrease also.
The best way to see what the sample width does to a signal from an object is to experiment with it using various objects as test targets. The type of target does make a difference. If I were experimenting with it, I would start out with a 10 usec to 20 usec sample width and adjust it both ways.
I hope this helps.
Reg