Radar method and apparatus

Claim 1

A directional radar apparatus for detecting objects in a detection cone and rejecting carrier waves reflected by objects located outside the detection cone, comprising: means for radiating carrier waves from a radiating position; means for receiving, at a receiving position, carrier waves returned by reflection from at least one object within the broadcast range of the radiating means; means for repetitively moving one of the radiating or receiving positions on a line which lies on the extended axis of the detection cone to induce directionally dependent frequency modulation in the carrier waves due to the Doppler effect; and means for selecting carrier waves reflected by objects inside the detection cone, including filter means for blocking received carrier waves having an induced frequency modulation less than a predetermined value.

Claim 9

An apparatus for determining the distance of an object comprising the steps of: means for broadcasting a periodic rectangular-wave frequency-shift modulated carrier wave, said carrier wave having alternating higher and lower frequency portions; means for receiving the frequency modulated phase-shifted carrier wave reflected from the object; means for mixing the higher frequency portions of the received carrier wave with portions of the broadcast carrier wave to produce an IF signal having a frequency within a predetermined range; means for separately mixing the lower frequency portions of the received carrier wave with other portions of the broadcast carrier wave to produce an IF signal having a frequency within the predetermined range; and means for producing a signal related in value to the distance of the object responsive to the difference between the average phases, over a predetermined time interval, of the IF signals.

Claim 10

An apparatus for determining the distance of an object comprising the steps of: means for broadcasting a periodic rectangular-wave frequency-shift modulated carrier wave, said carrier wave having alternating higher and lower frequency portions; means for receiving the frequency modulated phase-shifted carrier wave reflected from the object; means for mixing the higher frequency portions of the received carrier wave with portions of the broadcast carrier wave to produce an IF signal having a frequency within a predetermined range; means for separately mixing the lower frequency portions of the received carrier wave with other portions of the broadcast carrier wave to produce an IF signal having a frequency within the predetermined range; and means for producing a signal related in value to the distance of the object responsive to the difference between the average phases, over a predetermined time interval, of the IF signals.

Claim 11

A method for detecting objects in the path of a moving vehicle comprising the steps of: radiating carrier waves from a radiating position carried by the vehicle; receiving at a receiving position carried by the vehicle carrier waves returned to the vehicle by reflection from objects in proximity to the vehicle; repetitively moving one of the radiating and receiving positions with respect to the vehicle at a uniform velocity along a line of motion having a predetermined orientation with respect to the vehicle; and detecting carrier waves reflected by an object in the path of the vehicle by filtering the returned carrier waves to select carrier waves having the frequency characteristics of carrier waves radiated in directions deviating from the direction of motion of the vehicle by less than a preselected angle determined by the band width of the filtering.

Claim 12

A method for detecting objects in the path of a moving vehicle comprising the steps of: radiating carrier waves from a radiating position carried by the vehicle; receiving at a receiving position carried by the vehicle carrier waves returned to the vehicle by reflection from objects in proximity to the vehicle; repetitively moving one of the radiating and receiving positions with respect to the vehicle at a uniform velocity along a line of motion having a predetermined orientation with respect to the vehicle; and detecting carrier waves reflected by an object in the path of the vehicle by filtering the returned carrier waves to select carrier waves having the frequency characteristics of carrier waves radiated in directions deviating from the direction of motion of the vehicle by less than a preselected angle determined by the band width of the filtering.

Claim 14

A method of inhibiting collision between a moving vehicle and an object in the path of the vehicle comprising the steps of: radiating carrier waves from a radiating position carried by the vehicle; receiving at a receiving position, carried by the vehicle, carrier waves returned to the vehicle by reflection from objects in proximity to the vehicle; repetitively moving one of the radiating and receiving positions with respect to the vehicle at a uniform velocity along a line of motion having a predetermined orientation with respect to the vehicle, to induce, by the Doppler effect, higher frequency and lower frequency portions in the received signal; detecting carrier waves reflected by an object in the path of the vehicle by frequency-shifting separately down the same intermediate frequency the higher frequency and the lower frequency portions of the returned carrier waves and filtering to select carrier waves having the frequency characteristics of carrier waves radiated in directions deviating from the direction of motion of the vehicle by less than a preselected angle determined by the bandwidth of the filtering; measuring the phase difference between the selected carrier waves; determining the range of the object responsive to said measured phase difference; measuring the Doppler shift of a signal, returned by the object, due to relative motion between the vehicle and the object; determining the range rate of the object responsive to said measured Doppler shift; and controlling the motion of the vehicle responsive to the occurance of predetermined combinations of range and range rate of the object.

Claim 15

A method of inhibiting collision between a moving vehicle and an object in the path of the vehicle comprising the steps of: radiating carrier waves from a radiating position carried by the vehicle; receiving at a receiving position, carried by the vehicle, carrier waves returned to the vehicle by reflection from objects in proximity to the vehicle; repetitively moving one of the radiating and receiving positions with respect to the vehicle at a uniform velocity along a line of motion having a predetermined orientation with respect to the vehicle, to induce, by the Doppler effect, higher frequency and lower frequency portions in the received signal; detecting carrier waves reflected by an object in the path of the vehicle by frequency-shifting separately down the same intermediate frequency the higher frequency and the lower frequency portions of the returned carrier waves and filtering to select carrier waves having the frequency characteristics of carrier waves radiated in directions deviating from the direction of motion of the vehicle by less than a preselected angle determined by the bandwidth of the filtering; measuring the phase difference between the selected carrier waves; determining the range of the object responsive to said measured phase difference; measuring the Doppler shift of a signal, returned by the object, due to relative motion between the vehicle and the object; determining the range rate of the object responsive to said measured Doppler shift; and controlling the motion of the vehicle responsive to the occurance of predetermined combinations of range and range rate of the object.

Claim 21

A method for identifying objects in a detection cone having a vertex angle φ, comprising the steps of: generating a carrier wave having a radio frequency f o ; generating a rectangular wave of repetitive frequency f m , lower than f o ; radiating the carrier wave from a radiating position moved repetitively responsive to the rectangular wave at a uniform velocity back and forth along a straight line of motion lying along the extended axis of the detection cone, to induce a directionally dependent Doppler shift in the radiating carrier wave such that carrier waves radiated on the detection cone axis alternately shift in frequency between a higher frequency, f o +Δf, and a lower frequency f o -Δf, Δf being the Doppler induced frequency shift; locally providing a periodic rectangular-wave frequency-shift modulated wave responsive to said generated rectangular wave, shifted between a higher frequency, f o -f if +Δf, and a lower frequency f o -f if =Δf, where f if is an intermediate frequency greater than f m ; receiving the radiated carrier waves reflected by objects within the broadcast range of the carrier waves; mixing the higher frequency portions of the received carrier waves with lower frequency portions of the locally provided wave to produce a first IF signal; and filtering the first IF signal by means of a filter having a bandwidth, B f , centered at f if , the bandwidth B f being selected to reject IF signals having a frequency lower than f if -B f /2, corresonding to the reduction in the Doppler shift of the carrier waves at the angle φ from the cone axis; whereby the filtered IF signal provides an indication that an object is located in the detection cone.

Claim 22

A method for identifying objects in a detection cone having a vertex angle φ, comprising the steps of: generating a carrier wave having a radio frequency f o ; generating a rectangular wave of repetitive frequency f m , lower than f o ; radiating the carrier wave from a radiating position moved repetitively responsive to the rectangular wave at a uniform velocity back and forth along a straight line of motion lying along the extended axis of the detection cone, to induce a directionally dependent Doppler shift in the radiating carrier wave such that carrier waves radiated on the detection cone axis alternately shift in frequency between a higher frequency, f o +Δf, and a lower frequency f o -Δf, Δf being the Doppler induced frequency shift; locally providing a periodic rectangular-wave frequency-shift modulated wave responsive to said generated rectangular wave, shifted between a higher frequency, f o -f if +Δf, and a lower frequency f o -f if =Δf, where f if is an intermediate frequency greater than f m ; receiving the radiated carrier waves reflected by objects within the broadcast range of the carrier waves; mixing the higher frequency portions of the received carrier waves with lower frequency portions of the locally provided wave to produce a first IF signal; and filtering the first IF signal by means of a filter having a bandwidth, B f , centered at f if , the bandwidth B f being selected to reject IF signals having a frequency lower than f if -B f /2, corresonding to the reduction in the Doppler shift of the carrier waves at the angle φ from the cone axis; whereby the filtered IF signal provides an indication that an object is located in the detection cone.

Claim 24

A method for determining the distance to an object comprising the steps of: broadcasting a carrier wave having abrupt frequency shifts; receiving the carrier wave returned by reflection from the object; frequency converting a higher frequency portion of the received carrier wave to produce a first signal within a predetermined frequency range; separately frequency converting a lower frequency portion of the received carrier wave to produce a second signal within the same predetermined frequency range; and producing a signal related in value to the distance of the object responsive to the phase difference between the first and second signals.

Claim 25

A method for determining the distance to an object comprising the steps of: broadcasting a carrier wave having abrupt frequency shifts; receiving the carrier wave returned by reflection from the object; frequency converting a higher frequency portion of the received carrier wave to produce a first signal within a predetermined frequency range; separately frequency converting a lower frequency portion of the received carrier wave to produce a second signal within the same predetermined frequency range; and producing a signal related in value to the distance of the object responsive to the phase difference between the first and second signals.