White’s Electronics Spectra V3 - Manual (Page 38)

38 Complete Owner’s Guide - Spectra
®
• Higher number settings allow greater differences between a target at the
different frequencies and still be considered a good or valued target
signal.
• Lower number settings dictate less difference between the target at the
different frequencies is require to be considered a good or valued target
as opposed to a trash metal.
• Ideal span limit varies with the ground and target corrosion conditions.
Typically a lesser span limit is better suited to lower ground
mineralization and/or lesser target corrosion factors. A higher span limit
is better suited to higher ground mineralization and higher target corrosion
factors.
• Primarily developed for rejecting difficult iron, Correlate has an advantage
over Best Data in difficult ground and target corrosion applications.
• Wrap Limit – When searching in the difficult ground and target corrosion
conditions Correlate was developed to address, it is typical for high range
target signals (Quarter through Silver Dollar) to exceed the top end of the
scale (+95) at one or more of the primary operating frequencies. VDI range
from -95-+95 is circular (phase) so targets that exceed +95 re-appear at the
<-> end of the scale -90s.
• Correlate normally perceives -90s indications combined with +90s indications as hugely
uncorrelated (span the entire scale) so dictates such a target as a trash metal.
• Wrap limit allows correlate to disregard normal correlation methods (sequential or linear) and
consider any -90s range signals that also have one or more +90s range target measurements,
as within reasonable correlate parameters. In other words a +95 combined with a -95 =
one digit off (close correlation) rather than when Wrap is OFF = full scale (no reasonable
correlation).
• By adjusting Wrap Limit, Correlate becomes more effective, indicating difficult targets in
difficult ground as good or valued target signals as opposed to immediately dictating such
signals as trash metal. Because in difficult ground and corrosion conditions the target
signal at one or more frequency often wraps around to the <-> end of the scale, wrap limit
effectively captures these target signals as worthy of interest.
• OFF eliminates (rejects) all target signals that wrap around to the -90s.
• Adjustments from -95 through -90 increases the acceptable range a difficult target can wrap
around to the -90s and still be considered near to (correlate with) the +90s.
• Salt Compensate – provides a special frequency subtraction technique to compensate for wet conductive
salt conditions (ocean beaches).
• VDI Best Data – Applies the Best Data multi frequency technique to Salt Compensate.
• Correlate – Applies the Correlate multi frequency technique to Salt Compensate.
• Span Limit - Adjust how different target signals can be at the different frequencies and
still be considered a likely valued target signal or rejected as a trash metal.
• Wrap Limit - Wrap limit allows correlate to disregard normal correlation method and consider
-90s range signals that also have one or more +90s range target measurements, as within
reasonable correlate parameters. In other words a +95 combined with a -95 = one digit off
(close correlation) rather than when Wrap is OFF = full scale (no reasonable correlation).