Three dimensional, azimuth-correcting mapping radar

• US 4,321,601 A
• Filed: 04/23/1971
• Issued: 03/23/1982
• Est. Priority Date: 04/23/1971
• Status: Expired due to Term

• Current Assignee: Siemens Rail Automation Ltd. (Siemens AG)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Richman, Donald
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US05/136,677
• Time in Patent Office: 3,987 Days
• Field of Search: 343/5 CM
• US Class Current: 342/25.00C
• CPC Class Codes: G01S 13/9041 Squint mode
• CPC Class Codes: G01S 13/9092 combined with monopulse techniques

Abstract

A terrain mapping radar utilizes two sets of separately processed radar signals, each provided by a coherent pulse doppler synthetic aperture signal processing channel connected to and for processing the signals received from a selected one of a pair of vertically displaced antennas of the type utilized in phase interferometer radars. The invention provides depression angle, and therefore elevation information from the processed signals on a cell by cell basis, uniquely, for each range/doppler cell of each of the processing channels. The invention eliminates azimuthal errors which result from the ambiguity of the range/doppler annulus, and provides a useful map metric: elevation.

Claims

1. A signal processing radar comprising:

coherent pulsed radar transmitting and receiving means for illuminating targets with radiation at a determinable wavelength, including a plurality of radar antenna elements and a pair of receiver means, each of said receiver means receiving radar return signals from related ones of said antenna elements;

coherent pulse doppler synthetic aperture radar signal processing means responsive to said receiver means, said processing means including range gating and doppler filtering to allocate each return signal to a corresponding range/doppler cell, said processing means providing, for each range/doppler cell, a related set of processed signals, the relative information content of which is dependent upon the relative phase angle of arrival of the respective return signals at said radar antenna elements from which the processed signals have been derived;

means responsive to said processed signals from said processing means for generating a signal manifestation of the depression angle at which the return signals related to said processed signals were received by said antenna elements as a function of the difference in said angle of arrival between said return signals relating to a given range/doppler cell, of said determinable wavelength, and of the parameters of said antenna elements; and

means for generating, for each range/doppler cell, in response to the range and doppler identification of that cell and the depression angle signal manifestation relating to that cell, a pair of signal manifestations identifying orthogonal coordinates in a map of a corresponding map point location relating to said range doppler cell in accordance with the following relationships, ##EQU14## where R equals the slant range of the range/doppler cell, θ

equals the cone angle of the doppler frequency of the range/doppler cell, and β

equals the depression angle to the target for that range/doppler cell.

2. A signal processing radar according to claim 1 wherein said last named means additionally comprises means for generating, for each map point location, a manifestation, Z, of map point elevation from the relationship

3. A signal processing radar comprising:

coherent pulsed radar transmitting and receiving means for illuminating targets with radiation at a determinable wavelength, including a plurality of radar antenna elements and a pair of receiver means, each of said receiver means receiving radar return signals from related ones of said antenna elements;

a pair of coherent pulse doppler synthetic aperture radar signal processing channel means, each responsive to a related one of said receiver means, each of said processing channel means including range gating and doppler filtering to allocate each return signal from the related receiver means to a corresponding range/doppler cell, each of said processing means providing, for each range/doppler cell, processed signal manifestations including elements magnitude and phase angle, the phase angle being dependent upon the relative phase angle of arrival of the respective return signals at said radar antenna elements from which the processed signals have been derived;

means responsive to said processed signals from both of said processing channel means for generating a signal manifestation of the depression angle at which the return signals related to said processed signals were received by said antenna elements as a function of;

the difference in electrical phase between the processed signal manifestations from one of said processing channel means relating to a given range/doppler cell and the processed signal manifestations from the other of said processing channel means for the same given range/doppler cell;

said determinable wavelength; and

the parameters of said antenna elements; and

means for generating, for each range/doppler cell, in response to the range and doppler identification of that cell and the depression angle signal manifestation relating to that cell, a pair of signal manifestations identifying orthogonal coordinates in a map of a corresponding map point location relating to said range doppler cell in accordance with the following relationships,

space="preserve" listing-type="equation">X=R cos θ

##EQU15## where R equals the slant range of the range/doppler cell, θ

equals the cone angle of the doppler frequency of the range/doppler cell, and β

equals the depression angle to the target for that range/doppler cell.

4. A signal processing radar according to claim 3 wherein said last named means additionally comprises means for generating, for each map point location, a manifestation, Z, of map point elevation from the relationship