RF-photonic pulse doppler radar

Patent metadata

Field	Value
Publication number	US-10491306-B2
Application number	US-201715451456-A
Country	US
Kind code	B2
Filing date	Mar 7, 2017
Priority date	Mar 7, 2017
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

Systems, methods, architectures, mechanisms or apparatus for receiving and storing electromagnetic pulses using photonics includes a transmission unit transmitting electromagnetic pulses; an antenna receiving electromagnetic pulses reflected from a target; an optical recirculation loop for storing replica received electromagnetic pulses; and a processor for extracting target related phase information from the replica received electromagnetic pulses.

First claim

What is claimed is:

1. A system for detecting a target using a single reflecting electromagnetic pulse transmitted from said system, said system comprising:
a transmission unit for transmitting electromagnetic pulse;
an antenna for receiving electromagnetic pulses reflected from the target;
a main optical recirculation loop for circulating therein an optical pulse replica carrying information of a received electromagnetic pulse;
a coupling device, for tapping a portion of the circulated optical pulse replica in each circulating cycle to produce a plurality of replica pulses carrying thereby phase evolution information of the received electromagnetic pulse;
a photodetector, for converting the plurality of optical replica pulses to a plurality of electromagnetic replica pulses;
a mixer, for generating a beating signal by mixing a local oscillator (LO) signal with said electromagnetic replica pulses; and
a processor for extracting target related frequency and phase information from the beating signal further comprising:
a mixer, for generating an intermediate frequency (IF) signal by mixing a local oscillator (LO) signal associated with said transmitted electronic pulse and a radio frequency (RF) signal in accordance with a pulse replicas train provided by said main optical recirculation loop; and
a channelizing filter configured to filter said IF signal and provide to said processor a lower frequency output signal for passing Doppler frequency information and a higher frequency output signal for passing phase information.

2. The system of claim 1 , further comprising:
a second optical recirculation loop; and
a coupler for coupling to said second optical recirculation loop a portion of replica pulse optical energy circulating in said main optical recirculation loop, and for coupling to main optical recirculation loop a portion of replica pulse optical energy circulating in said second optical recirculation loop;
said main and second optical recirculation loops have associated with them loop delay times of τ1 and τ2, respectively, wherein τ1>τ2.

3. The system of claim 2 , further comprising:
a third optical recirculation loop; and
a coupler for coupling to said third optical recirculation loop a portion of replica pulse optical energy circulating in said main optical recirculation loop, and for coupling to main optical recirculation loop a portion of replica pulse optical energy circulating in said third optical recirculation loop;
said third optical recirculation loop having associated with it a loop delay time of τ3, wherein τ1>τ3.

4. The system of claim 1 , wherein a size of said main optical recirculation loop is selected in accordance with a sufficient processing time delay and a round trip loop travel time exceeding a width of an optical pulse replica.

5. A method of processing returned radio frequency (RF) pulses associated with a pulse radar system, comprising:
modulating a coherent optical signal in accordance with a band limited RF pulse returned within a predefined time range to provide an optical replica of the returned RF pulse;
circulating said optical replica in a main optical recirculation loop;
coupling a portion of optical energy from said main optical recirculation loop to provide thereby an optical pulse replicas train;
processing optical pulse replicas train to extract therefrom target related frequency and phase information from a signal comprising a plurality of replica pulses retrieved from the main optical recirculation loop;
wherein processing said optical pulse replicas train comprises:
converting said optical pulse replicas train to a radio frequency (RF) pulse replicas train;
mixing said RF pulse replicas train and a local oscillator (LO) signal associated with said returned RF pulse to generate an intermediate frequency (IF) signal;
filtering said IF signal to provide a lower frequency output signal for passing Doppler frequency information and a higher frequency output signal for passing phase information; and
extracting target Doppler information from said lower frequency output signal.

6. The method of claim 5 , further comprising:
coupling a portion of replica pulse optical energy circulating in said main optical recirculation loop to a second optical recirculation loop; and
coupling a portion of optical energy from said second optical recirculation loop to said main optical recirculation loop to provide therein a second optical pulse replicas train;
said main and second optical recirculation loops having associated with them loop delay times of τ1 and τ2, respectively, wherein τ1>τ2.

Assignees

• Zhou Weimin
• Us Army

Inventors

• Zhou Weimin

Classifications

• H04B1/03

  Constructional details, e.g. casings, housings · CPC title

• G01S13/581 Primary

  using transmission of interrupted pulse modulated waves and based upon the Doppler effect resulting from movement of targets · CPC title

• G01S7/32

  Shaping echo pulse signals; Deriving non-pulse signals from echo pulse signals · CPC title

• G01S13/34

  using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal · CPC title

• G01S7/032

  Constructional details for solid-state radar subsystems · CPC title