04030026 is referenced by 47 patents and cites 11 patents.

A sampling type of metal detector is described in which an oscillator transmits an oscillator signal current through the transmit coil of the detector to produce an electromagnetic field in the region of a search head. A received signal is induced in the receive coil of the detector when a metal object is present within that portion of the electromagnetic field which is external to the search head. A sampling pulse generator produces sampling pulses, at a time related to the output signal of the oscillator, which are transmitted to a sampling circuit for sampling the received signal. In the preferred embodiment, the received signal is sampled at a time controlled by a phase shift adjustment means to produce an output sample voltage such that any indication due to mineral soils or other background conditions is excluded from the sample.

Title
Sampling metal detector
Application Number
5/526678
Publication Number
4030026
Application Date
November 25, 1974
Publication Date
June 14, 1977
Inventor
George Calvin Payne
Tempe
AZ, US
Agent
Klarquist Sparkman Campbell Leigh Hall & Whinston
Assignee
White s Electronics
OR, US
IPC
G01R 33/02
G01V 3/10
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