White’s Electronics Spectra VX3 - Manual (Page 69)

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Spectra VX 3 User’s Guide
“residual” signal is being seen. Ideally, if you hold the loop in
the air away from metal targets, this number should be zero.
However, it is impossible to make a perfect loop null so this
number is usually at least a few percent. Ground mineralization
also creates a residual signal, so as you lower the loop to the
ground you may see an increase in the Signal percentage.
In most cases you should adjust the Rx Gain to maintain a
residual Signal of no more than 30-40%. VX 3 will overload at
60%, so it’s still possible that large shallow targets will cause an
overload.
The Noise number represents the amount of spurious noise;
that is, noise that comes and goes, as opposed to the residual
signal which is continuous. This is the noise that is often audi-
ble, especially in Pinpoint mode, as chatter. A high noise level
(more than a few percent) should persuade you to consider a
different frequency offset, or to try the 5Hz Bandpass filter.
Ground Probe
If you select Tracking from the Live Control Bar and press
VIEW , you will see the Tracking menu:
Tip: An overload signal is a long, loud grunt. If you are get-
ting a lot of overloading, drop the Rx Gain.