White’s Electronics Classic 1 SL - Manual (Page 11)

White’s Pulsescan TDI Field Manual
More On Tones -
It seems we will be able to get more information from the TDI responses if we listen to not only the tones produced,
but also the way the actual signal starts and stops.
Iron signals tend to ‘draw out’ more than non-ferrous responses. In other words, the less iron a target has in it,
the sharper the response will be. Na ils and other long iron objects often give a double low “blip” in one sweep
direction and a single, much weaker single high tone in the other direction.
For non-ferrous targets we are looking for a “CRISP” edge to the signal as the coil approaches and leaves the
target.
Pulse Delay Facts -
Be sure to set your Pulse Delay prior to Ground Balancing.
Lower delay settings are more sensitive on small targets. Set delay as low as possible. For relic hunting this control
should not be set over 17.5 uS. If a balance can’t be achieved, say at 10uS, then increase the delay slightly until it
can be achieved.
Keep in mind that adjusting the delay will have a direct effect on how the GEB control operates. In general, when
the Pulse Delay is advanced, the GEB control will have to be reduced. Example: A nail may be ignored at 5 with
the delay at minimum, but may be ignored at 3 or less with the pulse delay advanced to 17.5 uS.
Expected Pulse Delay/Ground Balance Relationships -
Pulse Delay = 10 uS Ground Balance = 8-9
Pulse Delay = 17.5 uS Ground Balance = 6
Pulse Delay = 25 uS Ground Balance = 3
NOTE: Depth will be lost at the low 1.5 GB setting, but it has the advantage of rejecting nearly all iron junk.
Ground Balance Procedure -
When finding the ground balance point the TDI will always signal a high tone when the ground balance setting is
insufficient.
This high tone will gradually reduce in strength as the GB control is rotated clockwise, until a point is reached where
there is little or no change in audio. As the GB control is further rotated, the signal will emerge again, but with a low
tone, which indicates that now too much GB has been applied.
At this point turn the GB control back into the Null zone.
Always bob the coil when adjusting the ground balance, otherwise the SAT auto-tune will cancel the signal and
result in a false setting.