Gated range search radar

Claim 3

An electronic process for deriving equivalent radio detection and ranging information for distant objects at reduced transmission output power, comprising the steps of: repetitively transmitting discrete pulses of signal energy at a selected frequency along a predetermined propagation path; receiving said signal energy reflected from said distant objects and generating an electrical signal; generating a coherent signal at said selected frequency which is in phase with said transmitted signal energy; mixing said received energy electrical signal with said coherent signal to remove all signal content at said selected frequency thereby to derive returned signals having frequencies other than said selected frequency; dividing said returned signals into plural, different resolution time zone signals, said time zones being disposed successively relative to the travel time of said transmitted signal energy, and each having a discrete time width; separately filtering each of said time zone signals to limit the frequency passband of each to a predetermined value and to generate a plurality of filtered output signals; and displaying said filtered output signals as separate indications each coordinated with its respective disposition relative to said travel time.

Claim 4

An electronic process for deriving equivalent radio detection and ranging information for distant objects at reduced transmission output power, comprising the steps of: repetitively transmitting discrete pulses of signal energy at a selected frequency along a predetermined propagation path; receiving said signal energy reflected from said distant objects and generating an electrical signal; generating a coherent signal at said selected frequency which is in phase with said transmitted signal energy; mixing said received energy electrical signal with said coherent signal to remove all signal content at said selected frequency thereby to derive returned signals having frequencies other than said selected frequency; dividing said returned signals into plural, different resolution time zone signals, said time zones being disposed successively relative to the travel time of said transmitted signal energy, and each having a discrete time width; separately filtering each of said time zone signals to limit the frequency passband of each to a predetermined value and to generate a plurality of filtered output signals; and displaying said filtered output signals as separate indications each coordinated with its respective disposition relative to said travel time.

Claim 5

A radar device for detection of distant objects, comprising: antenna means; transmitter means connected to said antenna means to generate a pulsed transmission signal at a selected output frequency; receiver means receiving transmission signal energy from said objects and generating an output signal at a second selected frequency modulated with doppler frequency variations; signal generating means for producing a coherent signal in phase with said second selected frequency output signal from the receiver means; mixer means receiving as input said receiver means output signal and said signal generating means coherent signal to produce an output signal consisting of said doppler frequency variations; switching means for time gating said doppler frequency variations into a series of separate, time-displaced signal portions having finite time width; plural filtering means each receiving a selected one of said time-displaced signal portions, to provide a low frequency passband output signal indication; and display means receiving said output signal indications to provide display which is range coordinated with said time-gating.

Claim 6

A radar device for detection of distant objects, comprising: antenna means; transmitter means connected to said antenna means to generate a pulsed transmission signal at a selected output frequency; receiver means receiving transmission signal energy from said objects and generating an output signal at a second selected frequency modulated with doppler frequency variations; signal generating means for producing a coherent signal in phase with said second selected frequency output signal from the receiver means; mixer means receiving as input said receiver means output signal and said signal generating means coherent signal to produce an output signal consisting of said doppler frequency variations; switching means for time gating said doppler frequency variations into a series of separate, time-displaced signal portions having finite time width; plural filtering means each receiving a selected one of said time-displaced signal portions, to provide a low frequency passband output signal indication; and display means receiving said output signal indications to provide display which is range coordinated with said time-gating.

Claim 7

A radar device as set forth in claim 3 wherein said signal generating means comprises: circulator means receiving a portion of said transmitter output signal to generate an output comparison signal which is coherent with the transmission signal; and second mixer means receiving as input said comparison signal to provide an output coherent signal at said second selected frequency.

Claim 8

A radar device as set forth in claim 4 wherein said receiver means includes: third mixer means receiving said received transmission signal energy and providing said receiver means output signal; local oscillator means providing a heterodyning output signal both to said third mixer means and to said second mixer means.

Claim 9

A radar device as set forth in claim 3 wherein said display means is a plasma display.

Claim 10

A radar device as set forth in claim 3 which is further characterized to include: antenna control means connected to control beam energy propagation direction from said antenna means while providing representative electrical control indications to said display means.

Claim 11

A radar device as set forth in claim 7 wherein said antenna control means directs said propagated beam energy through continuous angular sweeps scanning a predetermined arc.

Claim 12

A radar device as set forth in claim 7 wherein: said antenna means is a phased array; and said antenna control means generates antenna phase control signals for controlling said beam energy propagation in two coordinates.

Claim 13

A radar device as set forth in claim 3 wherein said switching means comprises: diode matrix means receiving said mixer means output signal, to generate a plurality of outputs each conducting a separate one of said time-displaced signal portions, said signal portions constituting a time-length signal which is approximately the time per resolution cell of said radar device.

Claim 14

A radar device as set forth in claim 3 wherein said plural filtering means comprise: plural active filters including operational amplifiers and which filters have a passband from zero frequency to the highest doppler frequency to be received by the radar device.