Radar seismograph improvement

Claim 3

The method of claim 1 wherein the step of transmitting electromagnetic waves includes transmitting said waves in a pattern which progressively scans said earth's surface.

Claim 4

The method of claim 1 wherein the step of receiving reflecting electromagnetic waves includes transmitting and receiving said waves in a pattern which progressively scans said earth's surface.

Claim 5

The method of claim 1 wherein said steps are carried out from an aircraft positioned above said earth surface.

Claim 6

The method of claim 1 wherein said elastic waves are generated by means under the control of apparatus in an aircraft.

Claim 7

The method of claim 1 wherein said elastic waves are generated by means dropped from an aircraft.

Claim 8

The method of claim 3 wherein said scanning pattern is continuously repeated, with a specific time period between repeated positions, so that individual sectors of the earth's surface are repeatedly examined at selected time intervals.

Claim 9

The method of claim 1 wherein step (4) includes converting said received electromagnetic waves into electrical currents and processing said electrical currents to enhance differences of electromagnetic reflection in response to differences in the electrical conductivity of the earth's surface as produced by differences in the strength of said elastic waves.

Claim 10

The method of claim 8 wherein said electric currents are divided into two transmission paths, one of which has a substantially longer time of transmission than the other; and combining said divided electric currents in a subtracting device to enhance differences of detected electromagnetic reflection to minimize the effects of electromagnetic wave reflection having no relationship with said elastic waves, and thereby to derive from received electromagnetic waves indications of the structure of the earth's subsurface formations in the earth wherein elastic waves are generated and transmitted.

Claim 11

The method of claim 9 wherein said selected time period is equal to said longer time of transmission.

Claim 12

The method of claim 9 wherein said scanning pattern is synchronized with said longer time of transmission.

Claim 15

A system for geophysical exploration according to claim 12 wherein said electromagnetic waves are used as a modulated carrier of elastic wave information and wherein said means of transmitting and said means of receiving electromagnetic waves comprises: antennae means which project electromagnetic waves from a radio-frequency power source against said area of the earth and which receives electromagnetic waves reflected and scattered back from said earth surface; means associated with said antennae and said transmitting equipment for forming said electromagnetic waves into a beam and steering said beam in a pattern over said earth's surface; said means of receiving said reflected electromagnetic waves including selection, transduction, demodulation and amplification associated with said antennae and said means for forming and steering said beam of electromagnetic waves to produce electrical signal currents representative of said elastic wave information; means for nulling said electrical signal currents before said means of generating elastic waves has been activated; and means to time, measure, correlate, display and record seismic information represented by said electrical signal currents after said source of elastic waves has been activated.

Claim 16

A system for geophysical exploration as in claim 13 wherein said means for nulling said electrical signal currents comprising a phase and amplitude network, with adjustable phase and amplitude controls, the input of said network being connected to said radio-frequency power source, the output of said network being connected to said receiving means, and means of adjusting said phase and amplitude controls until a null is obtained in said equipment to time and measure said electrical currents before said source of elastic waves has been activated.

Claim 17

A system for geophysical exploration as in claim 13, wherein said means for nulling said electrical signal currents comprises: means for separating said electrical signal currents into two transmission paths, one of which includes time-delay means, to produce two signal portions, one of which is delayed in time with respect to the other; and recombination means for comparing said signal portions and producing a resultant signal that is the difference between the two signal portions.

Claim 18

A system for geophysical exploration as in claim 15 wherein said time-delay means comprising an acoustic delay line.

Claim 19

A system for geophysical exploration as in claim 16 wherein said delay line is used conjointly by a phase-shift oscillator to determine the frequency of said oscillator, said oscillator controlling said means for steering said beam of electromagnetic waves over the earth's surface to synchronize the movement of said beam with said delay time to said electronic signal portion.

Claim 20

A system for geophysical exploration as in claim 15 in which both of said paths of transmission have time delay means, one of which provides a greater delay than the other.

Claim 21

A system for geophysical exploration as in claim 18, in which both time delay means comprise acoustic delay lines which are identical in all structures except length.

Claim 22

A system for geophysical exploration as in claim 17 in which said phase-shift oscillator employs said delay line as a half-wave-length feedback device, and the path connecting said oscillator and said means for steering said beam of electromagnetic waves including a harmonic amplifier.