Good feedback from Ironpatch and Captn_Se...Thanks guys
Here is my (limited) understanding of how this kind of works...
When performing noise cancel, you remain perfectly still and make sure the coil is not directly over any targets holding coil 12" above the ground. If you noise cancel over a metal object, detector may confuse signal as EMI and attempt to find a channel that does not receive the signal as strongly. Resulting in the wrong channel being selected and causing sens to operate lower or cause "falsing" in a higher manual setting.
I've found that if I go into quickmask (all metal) and manual sens at max, then find a spot where I can do a 2 to 3 foot sweep while still getting a threshold (not easy) before I noise cancel, my sensitivity will run higher in auto and in manual without too much falsing. (dependent on site conditions from day to day)
Noise cancelling this way, insures 1: you are not picking up readings from an object under the coil while scanning channels to be selected and 2: receiving maximum EMI in the atmosphere and from surrounding ground so the quietest channel is selected.
When I first get to a site and power up, my sens may only be at 20 (auto) for example, and after noise cancel it may jump to 27 or to 16, so I know noise cancel helps determine what sens the electronics recommend. Also, sens will adjust as I go along possibly due to erratic iron everywhere or EMI. Trashy sites seem to drive the sens down while on a "cleaner" site, sens will run higher.
Also, if having trouble with falsing and a low auto sens, try lowering gain a little
before lowering sens. Lower sens will reduce detection depth as we all know, but a lower gain will only cause deeper targets to sound fainter
and lowering gain
first helps reduce falsing (which pushes sens lower). Also, a lower gain will
reduce co-mingling of targets in the trash and increase ID accuracy. Experiment with gain to see where you can still get an audible signal on a deepie.
On a cleaner site where deep keepers are expected, try running gain a little higher if it does not affect sensitivity overly much
Dan, I didn't think of it at the time to select channel 9 and see how my sensitivity responded. I will keep this in mind next time.
IP, We were both in auto mode at the time of the observation. You can't see selected sens on explorers? Auto mode is represented by a small icon above the two sensitivity bars (suggested and actual) Manual mode the icon is absent...I too thought about my machine
being "quirked"