Direction finding techniques employing electronic phase modulation

Claim 1

A method of determining a bearing signal of an electromagnetic energy wavefront relative to two receiving antennas, comprising the steps of: modulating an electrical signal from one of said antennas with a modulating signal of constant frequency in order to generate a pair of sidebands with carrier suppressed, adding the modulated signal to an electrical signal from the other of said antennas to form a composite signal, and generating an error signal proportional to the degree of phase or amplitude modulation of said composite signal and thereby also proportional to the bearing angle of said electromagnetic energy wavefront, said error signal generation including the steps of: applying the composite signal to an antenna input of a frequency modulation responsive radio receiver, thereby detecting the degree of phase modulation of said composite signal, and utilizing an audio output of said receiver for indicating the bearing angle.

Claim 2

A method of determining a bearing signal of an electromagnetic energy wavefront relative to two receiving antennas, comprising the steps of: modulating an electrical signal from one of said antennas with a modulating signal of constant frequency in order to generate a pair of sidebands with carrier suppressed, adding the modulated signal to an electrical signal from the other of said antennas to form a composite signal, and generating an error signal proportional to the degree of phase or amplitude modulation of said composite signal and thereby also proportional to the bearing angle of said electromagnetic energy wavefront, said error signal generation including the steps of: applying the composite signal to an antenna input of a frequency modulation responsive radio receiver, thereby detecting the degree of phase modulation of said composite signal, and utilizing an audio output of said receiver for indicating the bearing angle.

Claim 3

A method of determining a bearing signal of an electromagnetic energy wavefront relative to two receiving antennas, comprising the steps of: modulating an electrical signal from one of said antennas with a modulating signal of constant frequency in order to generate a pair of sidebands with carrier suppressed, adding the modulated signal to an electrical signal from the other of said antennas to form a composite signal, generating an error signal proportional to the degree of phase or amplitude modulation of said composite signal And thereby also proportional to the bearing angle of said electromagnetic energy wavefront, and utilizing said error signal to automatically adjust in response to the error signal relative time delays in the paths of the electrical signals from the two antennas which minimizes siad error signal and thus which minimized the degree of phase modulation of the composite signal, whereby the difference in time delay interposed in the paths of the electrical signals from the two antennas is equal to a desired difference in time of arrival of the electromagnetic energy wavefront at said two antennas.

Claim 4

A method of determining a bearing signal of an electromagnetic energy wavefront relative to two receiving antennas, comprising the steps of: modulating an electrical signal from one of said antennas with a modulating signal of constant frequency in order to generate a pair of sidebands with carrier suppressed, adding the modulated signal to an electrical signal from the other of said antennas to form a composite signal, generating an error signal proportional to the degree of phase or amplitude modulation of said composite signal And thereby also proportional to the bearing angle of said electromagnetic energy wavefront, and utilizing said error signal to automatically adjust in response to the error signal relative time delays in the paths of the electrical signals from the two antennas which minimizes siad error signal and thus which minimized the degree of phase modulation of the composite signal, whereby the difference in time delay interposed in the paths of the electrical signals from the two antennas is equal to a desired difference in time of arrival of the electromagnetic energy wavefront at said two antennas.

Claim 5

A system of developing a signal proportional to the phase difference between first and second electrical signals developed by two antennas that are positioned a fixed distance apart, comprising: means receiving said first signal for amplifying said first signal, a constant frequency oscillator within the audio range, modulating means receiving said second signal and an output of said constant frequency oscillator for developing a double sideband suppressed carrier signal at an output, means for adding the amplified first signal and the modulating means output signal to form a composite signal that may be applied to a radio receiver antenna terminal, and means adapted to receive an audio output of the radio receiver for developing an error signal whose magnitude is proportional to the phase difference between said first and second electrical signals.

Claim 6

A system of developing a signal proportional to the phase difference between first and second electrical signals developed by two antennas that are positioned a fixed distance apart, comprising: means receiving said first signal for amplifying said first signal, a constant frequency oscillator within the audio range, modulating means receiving said second signal and an output of said constant frequency oscillator for developing a double sideband suppressed carrier signal at an output, means for adding the amplified first signal and the modulating means output signal to form a composite signal that may be applied to a radio receiver antenna terminal, and means adapted to receive an audio output of the radio receiver for developing an error signal whose magnitude is proportional to the phase difference between said first and second electrical signals.

Claim 15

A method of determining a bearing signal of an electromagnetic energy wavefront relative to two receiving antennas, comprising the steps of: modulating an electrical signal from one of said antennas with a modulating signal of constant frequency in order to generate a pair of sidebands with carrier suppressed, adding the modulated signal to an electrical signal from the other of said antennas to form a composite signal, and generating an error signal proportional to the degree of phase or amplitude modulation of said composite signal and thereby also proportional to the bearing angle of said electromagnetic energy wavefront, said error signal generaTion including the steps of: applying the composite signal of an antenna input of an amplitude modulation responsive radio receiver, thereby detecting the degree of amplitude modulation of said composite signal, and utilizing an audio output of said receiver for indicating the bearing angle.

Claim 16

A method of determining a bearing signal of an electromagnetic energy wavefront relative to two receiving antennas, comprising the steps of: modulating an electrical signal from one of said antennas with a modulating signal of constant frequency in order to generate a pair of sidebands with carrier suppressed, adding the modulated signal to an electrical signal from the other of said antennas to form a composite signal, and generating an error signal proportional to the degree of phase or amplitude modulation of said composite signal and thereby also proportional to the bearing angle of said electromagnetic energy wavefront, said error signal generaTion including the steps of: applying the composite signal of an antenna input of an amplitude modulation responsive radio receiver, thereby detecting the degree of amplitude modulation of said composite signal, and utilizing an audio output of said receiver for indicating the bearing angle.

Claim 17

A system for determining a bearing angle of an electromagnetic wavefront relative to two antennas, comprising: means including a beam forming network for receiving signals from said two antennas and for producing first and second output signals that are different combinations of the signals from both of said two antennas, an oscillator, a modulating means receiving said first network output signal and an output of said oscillator for developing a double sideband suppressed carrier signal at an output, means receiving said modulating means output and said second network output signal for summing into a composite signal, whereby said composite signal is both phase and amplitude modulated in degrees proportional to said wavefront bearing angle to be determined.

Claim 18

A system for determining a bearing angle of an electromagnetic wavefront relative to two antennas, comprising: means including a beam forming network for receiving signals from said two antennas and for producing first and second output signals that are different combinations of the signals from both of said two antennas, an oscillator, a modulating means receiving said first network output signal and an output of said oscillator for developing a double sideband suppressed carrier signal at an output, means receiving said modulating means output and said second network output signal for summing into a composite signal, whereby said composite signal is both phase and amplitude modulated in degrees proportional to said wavefront bearing angle to be determined.

Claim 20

A system for determining a bearing angle of an electromagnetic wavefront relative to an observer, comprising: first and second antennas, an audio frequency oscillator, modulating means receiving a signal from one of said antennas and an output of said audio frequency oscillator for developing a double sideband suppressed carrier signal at an output thereof, means receiving the modulating means output and a signal derived from the other of said antennas for summing the received signals together to form a composite signal, whereby said composite signal is both phase and amplitude modulated to a degree proportional to said wavefront bearing angle to be determined, an amplitude modulation responsive receiver having an antenna terminal connected to receive said composite signal, whereby an audio output of said receiver contains a signal proportional to the bearing angle of interest, and a phase shifting network disposed between said modulating means output and said summing means for shifting the phase of said modulating means output signal substantially ninety degrees before it is applied to said summing means.

Claim 21

A system for determining a bearing angle of an electromagnetic wavefront relative to an observer, comprising: first and second antennas, an audio frequency oscillator, modulating means receiving a signal from one of said antennas and an output of said audio frequency oscillator for developing a double sideband suppressed carrier signal at an output thereof, means receiving the modulating means output and a signal derived from the other of said antennas for summing the received signals together to form a composite signal, whereby said composite signal is both phase and amplitude modulated to a degree proportional to said wavefront bearing angle to be determined, an amplitude modulation responsive receiver having an antenna terminal connected to receive said composite signal, whereby an audio output of said receiver contains a signal proportional to the bearing angle of interest, and a phase shifting network disposed between said modulating means output and said summing means for shifting the phase of said modulating means output signal substantially ninety degrees before it is applied to said summing means.

Claim 22

A system for determining a bearing angle of an electromagnetic wavefront relative to an observer, comprising: first and second antennas, an audio frequency oscillator, modulating means receiving a signal from one of said antennas and an output of said audio frequency oscillator for developing a double sideband suppressed carrier signal at an output thereof, means receiving the modulating means output and a signal derived from the other of said antennas for summing the received signals together to form a composite signal, whereby said composite signal is both phase and amplitude modulated to a degree proportional to said wavefront bearing angle to be determined, and a frequency modulation responsive receiver with an antenna terminal connected to receive said composite signal, whereby an audio output of said receiver contains a signal proportional to the bearing angle of interest.

Claim 23

A system for determining a bearing angle of an electromagnetic wavefront relative to an observer, comprising: first and second antennas, an audio frequency oscillator, modulating means receiving a signal from one of said antennas and an output of said audio frequency oscillator for developing a double sideband suppressed carrier signal at an output thereof, means receiving the modulating means output and a signal derived from the other of said antennas for summing the received signals together to form a composite signal, whereby said composite signal is both phase and amplitude modulated to a degree proportional to said wavefront bearing angle to be determined, and a frequency modulation responsive receiver with an antenna terminal connected to receive said composite signal, whereby an audio output of said receiver contains a signal proportional to the bearing angle of interest.

Claim 25

A system for determining a bearing angle of an electromagnetic wavefront relative to an observer, comprising: first and second antennas, an audio frequency oscillator, modulating means receiving a signal from one of said antennas and an output of said audio frequency oscillator for developing a double sideband suppressed carrier signal at an output thereof, means receiving the modulating means output and a signal derived from the other of said antennas for summing the received signals together to form a composite signal, whereby said composIte signal is both phase and amplitude modulated to a degree proportional to said wavefront bearing angle to be determined, a radio receiver having an antenna terminal that is connected to receive said composite signal, and a demodulator connected to an audio output of said receiver, said demodulator being driven from said audio frequency oscillator, whereby said demodulator forms a direct current output level proportional to the wavefront bearing angle of interest.

Claim 26

A system for determining a bearing angle of an electromagnetic wavefront relative to an observer, comprising: first and second antennas, an audio frequency oscillator, modulating means receiving a signal from one of said antennas and an output of said audio frequency oscillator for developing a double sideband suppressed carrier signal at an output thereof, means receiving the modulating means output and a signal derived from the other of said antennas for summing the received signals together to form a composite signal, whereby said composIte signal is both phase and amplitude modulated to a degree proportional to said wavefront bearing angle to be determined, a radio receiver having an antenna terminal that is connected to receive said composite signal, and a demodulator connected to an audio output of said receiver, said demodulator being driven from said audio frequency oscillator, whereby said demodulator forms a direct current output level proportional to the wavefront bearing angle of interest.

Claim 28

A system for determining a bearing angle of an electromagnetic energy wavefront relative to an observer, comprising: first and second antennas positioned a fixed distance apart, said antennas being responsive to said electromagnetic radiation to form electrical signals proportional thereto at their outputs, a beam forming network receiving the signals from said first and second antennas, said beam forming network being characterized by having first and second output signals that are different combinations of the signals from both of said first and second antennas, a modulator circuit receiving directly said first network output signal, said modulator characterized by developing at an output thereof a double sideband suppressed carrier signal, means receiving said modulator output without any significant phase shift and receiving said second network output signal for summing into a composite signal, and means receiving said composite signal for generating a signal proportional in level to the amount of phase modulation present in said composite signal, whereby said signal level is proportional to the bearing angle of an electromagnetic wavefront relative to said first and second antennas.

Claim 29

A system for determining a bearing angle of an electromagnetic energy wavefront relative to an observer, comprising: first and second antennas positioned a fixed distance apart, said antennas being responsive to said electromagnetic radiation to form electrical signals proportional thereto at their outputs, a beam forming network receiving the signals from said first and second antennas, said beam forming network being characterized by having first and second output signals that are different combinations of the signals from both of said first and second antennas, a modulator circuit receiving directly said first network output signal, said modulator characterized by developing at an output thereof a double sideband suppressed carrier signal, means receiving said modulator output without any significant phase shift and receiving said second network output signal for summing into a composite signal, and means receiving said composite signal for generating a signal proportional in level to the amount of phase modulation present in said composite signal, whereby said signal level is proportional to the bearing angle of an electromagnetic wavefront relative to said first and second antennas.