US4100482A — Method and apparatus for measuring ellipse parame…

Claim 1

Independent Claim 274 words

A method of geophysical exploration and detection and geophysical anomalies which manifest themselves by production of a secondary alternating electromagnetic field in the presence of a primary alternating electromagnetic field, where the resultant secondary field is elliptically polarized and the ellipse of polarization is tilted at any location where the presence of said secondary field is being tested for, by measuring the ellipse parameters of polarization of said resultant secondary electromagnetic field, where said method comprises the steps of: (a) placing a transmitter in a first specific orientation at a transmission location and placing a receiver having a pair of crossed coils therein in a second specific orientation at a testing location remote from said transmission location, so that said specific orientations of said transmitter and receiver coils are maintained at any transmission location and testing location, respectively, during execution of the following steps; (b) when said transmitter and receiver are each set up in a transmission and testing location, respectively, such that said receiver is within range of said transmitter, transmitting a primary electromagnetic field at at least one known frequency from said transmitter; (c) when an output signal is detected from both of said crossed coils of said receiver, examining said output signals to determine the phase difference quantity φ between said detected signals and the magnitude ratio quantity r of said signals at said known transmitted frequency of said primary EM field; and (d) where the quantities φ and r are determined, mathematically analyzing and processing said quantities to obtain such ellipse parameters of polarization of the resultant secondary electromagnetic field as the tilt angle, ellipticity angle and ellipticity ratio thereof.

Claim 2

Independent Claim 274 words

A method of geophysical exploration and detection and geophysical anomalies which manifest themselves by production of a secondary alternating electromagnetic field in the presence of a primary alternating electromagnetic field, where the resultant secondary field is elliptically polarized and the ellipse of polarization is tilted at any location where the presence of said secondary field is being tested for, by measuring the ellipse parameters of polarization of said resultant secondary electromagnetic field, where said method comprises the steps of: (a) placing a transmitter in a first specific orientation at a transmission location and placing a receiver having a pair of crossed coils therein in a second specific orientation at a testing location remote from said transmission location, so that said specific orientations of said transmitter and receiver coils are maintained at any transmission location and testing location, respectively, during execution of the following steps; (b) when said transmitter and receiver are each set up in a transmission and testing location, respectively, such that said receiver is within range of said transmitter, transmitting a primary electromagnetic field at at least one known frequency from said transmitter; (c) when an output signal is detected from both of said crossed coils of said receiver, examining said output signals to determine the phase difference quantity φ between said detected signals and the magnitude ratio quantity r of said signals at said known transmitted frequency of said primary EM field; and (d) where the quantities φ and r are determined, mathematically analyzing and processing said quantities to obtain such ellipse parameters of polarization of the resultant secondary electromagnetic field as the tilt angle, ellipticity angle and ellipticity ratio thereof.

Claim 3

Dependent Claim 21 words

The method of claim 1 where said pair of crossed coils in said receiver are fixed perpendicularly one to the other.

Claim 4

Dependent Claim 59 words

The method of claim 2 where the frequency of transmission of said primary alternating electromagnetic field is controlled by a first stable oscillator and frequency divider, and where the signal processing and conditioning circuits of said receiver are controlled by a second stable oscillator and frequency divider which are substantially identical to said first stable oscillator and frequency divider.

Claim 5

Dependent Claim 86 words

The method of claim 3 including the further step of arithmetically adding the signal levels of succeeding signals from both coils of said receiver in first and second signal level stacking circuits, each of which is controlled by said second stable oscillator and freqency divider, until the level in one of said signal level stacking circuits reaches a predetermined level, whereupon an output from each of said signal level stacking circuits is gated to signal divider means whereby the magnitude ratio quantity r can be determined.

Claim 6

Dependent Claim 104 words

The method of claim 3 where said quantities φ and r are mathematically analyzed according to the following rules: (i) magnitude of the signal detected from a first coil of said receiver X = |X| exp(jφ.sub.1) (ii) magnitude of the signal detected from the other coil is Y = |Y| exp(jφ.sub.2) (iii) quantity φ = φ 2 - φ 1 (iv) quantity r = |Y|/|X| = tan γ (v) tilt angle β = 1/2 tan -1 (tan 2 γ cosφ) (vi) ellipticity angle α = 1/2 sin -1 (sin 2 γ sinφ) (vii) ellipticity ratio e = tanα = tan[1/2sin -1 (sin γ2 sinφ)]

Claim 7

Dependent Claim 16 words

The method of claim 5 where the quantities β and α are also expressed as: ##EQU3##

Claim 8

Dependent Claim 30 words

The method of claim 5 where said quantities φ and r are fed to a suitably programmed calculating mens for determination therein of said further quantities β, α and e.

Claim 9

Dependent Claim 53 words

The method of claim 3 where, when an output is detected from both coils of said receiver at a first transmitted frequency of said primary alternating electromagnetic field, said primary field is subsequently transmitted at at least another frequency while maintaining said first and second orientations of said transmitter and receiver coils, respectively.

Claim 10

Dependent Claim 50 words

The method of claim 3 including the further step of rotating the transmitter coil on a horizontal axis through 90° to a third specific orientation which differs from said first specific orientation only in respect of the position of said rotated transmitter coil, and repeating said steps (c) and (d).

Claim 11

Dependent Claim 28 words

The method of claim 9 where the axis about which said transmitter coil is rotated extends substantially perpendicularly to the coupling axis between said transmitter and said receiver.

Claim 12

Dependent Claim 275 words

Apparatus for detection of geophysical anomalies which manifest themselves by production of a secondary alternating electromagnetic field in the presence of a primary alternating electromagnetic field, where the resultant field is elliptically polarized and the ellipse of polarization is tilted at any location where the presence of said secondary field is being tested for, comprising: (a) a transmitter capable of transmitting a primary alternating electromagnetic field at at least one frequency, and being capable of being set up and maintained in a first specific orientation at a transmission location during any such transmission procedure; (b) a receiver including a pair of crossed coils, and being capable of being positioned at a testing location remote from said transmitter and of being set up and maintained in a second specific orientation of said crossed coils at any such testing location during any transmission procedure from said transmitter; (c) first and second signal detecting means for detecting the presence of a signal on the one of the other of said crossed coils of said receiver, respectively; (d) phase detector means for detecting and producing a signal which is a functon of the phase difference quantity φ between the signals detected on said crossed coils of said receiver; (e) signal divider means for producing a signal which is a function of the magnitude ratio quantity r of the signals detected on said crossed coils of said receiver; and (f) calculating means for mathematically analyzing and processing said phase differece quantity φ and said magnitude ratio quantity r to obtain such ellipse parameters of polarization of said resultant electromagnetic field as the tilt angle, ellipticity angle and ellipticity ratio thereof.

Claim 13

Dependent Claim 275 words

Apparatus for detection of geophysical anomalies which manifest themselves by production of a secondary alternating electromagnetic field in the presence of a primary alternating electromagnetic field, where the resultant field is elliptically polarized and the ellipse of polarization is tilted at any location where the presence of said secondary field is being tested for, comprising: (a) a transmitter capable of transmitting a primary alternating electromagnetic field at at least one frequency, and being capable of being set up and maintained in a first specific orientation at a transmission location during any such transmission procedure; (b) a receiver including a pair of crossed coils, and being capable of being positioned at a testing location remote from said transmitter and of being set up and maintained in a second specific orientation of said crossed coils at any such testing location during any transmission procedure from said transmitter; (c) first and second signal detecting means for detecting the presence of a signal on the one of the other of said crossed coils of said receiver, respectively; (d) phase detector means for detecting and producing a signal which is a functon of the phase difference quantity φ between the signals detected on said crossed coils of said receiver; (e) signal divider means for producing a signal which is a function of the magnitude ratio quantity r of the signals detected on said crossed coils of said receiver; and (f) calculating means for mathematically analyzing and processing said phase differece quantity φ and said magnitude ratio quantity r to obtain such ellipse parameters of polarization of said resultant electromagnetic field as the tilt angle, ellipticity angle and ellipticity ratio thereof.

Claim 14

Dependent Claim 21 words

The apparatus of claim 11 where said pair of crossed coils in said receiver are fixed perpendicularly one to the other.

Claim 15

Dependent Claim 24 words

The apparatus of claim 12 further comprising first and second substantially identical stable oscillators and frequency dividers in said transmitter and said receiver, respectively.

Claim 16

Dependent Claim 33 words

The apparatus of claim 13, further including first and second signal level stacking circuits interposed between said respective first and second signal detecting means and said phase detector and said signal divider means.

Claim 17

Dependent Claim 26 words

The apparatus of claim 11 where the coil of said transmitter is capable of being rotated 90° about a horizontal axis to a third specific orientation.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1981-07-10	1982-01-09	1982-07-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1985-07-10	1986-01-09	1986-07-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1989-07-10	1990-01-09	1990-07-11	$7700.00	Window Closed / Lapsed

Method and apparatus for measuring ellipse parameters of electromagnetic polarization in geophysical exploration

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