VLF'S are IB'S which cause a frequency shift in the TX winding when a target is hit and the change is detected in the RX winding.With the scanning fre

[vlad]

n/t

 

[Fishers Ghost]

The Phase Shift (Not Frequency Shift) of the received signal in an IB VLF is caused by differing minerals and metals and the phase shift is used as a means of discriminating between metals and in the GB ccts.
The phase shifted rx sig is not frequency altered by the phase shift.

I think that it may be a bit early for anybody outside of Garrett to know much about how the ATX does what it does other than being a PI metal detector.

 

[vlad]

The PPD1 built in the 1980's by Eric Foster, when the switch was flipped to on, would discriminate, go silent on pulltabs, using a mono coil. Is this a phase angle?

 

[Fishers Ghost]

Sorry sport. I do not know that detector so cannot say.

 

[FrankMD]

My understanding of a PI detector is that when the receive circuit is turned on between transmit pulses, the circuit measures how long it takes the receive signal to decay. More to it than that of course.