Frequency offset vs depth

[Picketwire]

Some time ago on the NASA engineer's forum, he said that before he detects, he checks the depth of each frequency with a dime and that one or two is usually deeper than the rest. He said that it was not always the same frequency even in the same place at different times. He called it the result of silent EMI which caused quite a ruckus.

I decided to experiment to see if this had some validity. I set my Deus on a bench, turned it on, turned the sensitivity down so that the detector was quiet and switched offset frequencies to see if I could tell the difference in depth. There was a definite difference between the ones I tried. There was also a difference in the sound of the tones at the same depth. Some sounded sharp and some were scratchy and warbled a bit. All I changed was the offset of the lowest frequency on the HF round 9" coil. I am going to check it out more and do the same with the Legend. Some people say there is no difference in interference no matter the offset. That might be true for the sound of the interference but the difference in depth seems to me to be there.

Has anyone else tried this and if so, what were your results?

 

[Odanscoils]

Interesting. Like to see your results.
Especially on the Legend.

 

[Steve O]

I always carry a coin to check for silent EMI, also to make sure my hunting partner's unit isn't killing my depth without me knowing. Usually I can hear if another unit is scrambling my detector.
With some modern units they have this noise cancel .. I like that feature.
That NASA fellow has been at it for many years . . .gets into the nitty-gritty with detectors . . .he's a bit above my pay grade.

 

[vito]

Some time ago on the NASA engineer's forum, he said that before he detects, he checks the depth of each frequency with a dime and that one or two is usually deeper than the rest. He said that it was not always the same frequency even in the same place at different times. He called it the result of silent EMI which caused quite a ruckus.

I decided to experiment to see if this had some validity. I set my Deus on a bench, turned it on, turned the sensitivity down so that the detector was quiet and switched offset frequencies to see if I could tell the difference in depth. There was a definite difference between the ones I tried. There was also a difference in the sound of the tones at the same depth. Some sounded sharp and some were scratchy and warbled a bit. All I changed was the offset of the lowest frequency on the HF round 9" coil. I am going to check it out more and do the same with the Legend. Some people say there is no difference in interference no matter the offset. That might be true for the sound of the interference but the difference in depth seems to me to be there.

Has anyone else tried this and if so, what were your results?

Been there, done that. And it is as you described, using the same settings but different frequencies will cause a coin is detected at different depth. And, the coil style (DD / con) also takes effect to freq./coin depth, but here in I think ground balance has it's place, too.
Never thought having fun will be that complicated.