Digital detection criteria control device for video mapping, detection parameter control, optimum radar receiver selection and rejection of non-moving targets

• US 3,940,762 A
• Filed: 09/09/1965
• Issued: 02/24/1976
• Est. Priority Date: 09/09/1965
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Wilmot, Richard D., Ethington, David A., Yamashiro, Herbert Y.
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US04/486,047
• Time in Patent Office: 3,820 Days
• Field of Search: 343/5 DP, 343/17.1
• US Class Current: 342/90
• CPC Class Codes: G01S 13/538 eliminating objects that have not moved between successive antenna scans, e.g. area MTi
• CPC Class Codes: G01S 7/2923 based on data belonging to a number of consecutive radar periods
• CPC Class Codes: G01S 7/2927 by deriving and controlling a threshold value

Abstract

A digital detection criteria control device for use in a radar tracking system incorporating a memory that is electronically synchronized to a surveillance radar in a manner to perform video mapping and control functions. This memory is organized so that each small quantum area of the radar'"'"'s surveillance area has code bits which are controlled primarily by inputs from valid and invalid video return detectors. These detectors examine quantized video returns from the radar for certain bit densities and bit patterns to determine whether the video returns are valid or invalid targets. The code bits provide a history of the type of video return for each quantum area thereby making a more accurate indication of the nature of the video return possible.

Claims

1. A digital detection criteria control device for operation in conjunction with a radar transmitter-receiver apparatus having range count and azimuth position signals and capable of generating a quantized video signal, said digital detection criteria control device comprising a memory having a predetermined number of words, each of said words having a plurality of sets of first, second and third bits, corresponding sets of said first, second and third bits within each word corresponding to quantum areas within one of a plurality of sectors constituting the surveillance area of said radar transmitter-receiver;

means responsive to said range count and azimuth position signals for sensing successive bits of said memory at the same rate as and in synchronism with the bits of said quantized video signal;

target detection apparatus responsive to said quantized video signal for determining whether target indications from said quantized video signal are valid or invalid;

means for periodically generating code bits and writing said code bits in said memory in response to said target indications for each quantum area of said surveillance area;

means for reading said code bits out from said memory in synchronism with coverage of said surveillance area by said radar transmitter-receiver; and

means responsive to said code bits read out from said memory for providing control indications for successive corresponding quantum areas of said surveillance area and to switch to preselected types of receivers of said radar transmitter-receiver apparatus for said successive corresponding quantum areas.

2. The digital detection criteria control device as defined in claim 1 wherein said code bits generated and written into said memory increase one in numerical value each scan said valid and invalid target indications are both type.

3. The digital detection criteria control device as defined in claim 1 wherein said code bits generated and written into said memory decrease one in numerical value each scan said valid and invalid target indications are both false.

4. The digital detection criteria control device as defined in claim 1 wherein said code bits generated and written into said memory increase by one every predetermined plurality of scans in response to said valid target indication being true and said invalid targe indication being false.

5. A digital detection criteria control device for operation in conjunction with a surveillance radar transmitter-receiver apparatus having range count and azimuth position signals and capable of generating a quantized video signal, said digital detection criteria control device comprising a memory having a predetermined number of groups of words, each word having a plurality of sets of first, second, third and fourth bits for each of a corresponding plurality of equiangular radial segments constituting the surveillance area of said radar apparatus, the number of said groups of words being equal to the number of quantum sectors in one of said equiangular radial sectors and the number of words in each group being equal to the number of quantum areas in one quantum sector;

means including a target detector memory for providing valid and invalid target threshold indications serially by range;

means responsive to said range count and azimuth position signals for repeatedly recirculating digital signals derived from corresponding sets of said first, second, third and fourth bits from words of successive groups thereof for a number of times equal to the number of azimuth sweeps in one quantum sector;

means once each scan for increasing the count of said digital signals in response to corresponding valid and invalid target threshold indications being true and for decreasing the count of said digital signals in response to corresponding valid and invalid target threshold indications being false;

means once every predetermined plurality of scans no less than four for increasing the count of said digital signals in response to a corresponding valid target threshold indication being true together with a corresponding invalid target threshold indication being false; and

means responsive to said recirculating digital signals for generating signals to control the receiving characteristics of said radar transmitter-receiver for corresponding quantum areas of said surveillance area.

6. The digital detection criteria control device for operation in conjunction with a surveillance radar transmitter-receiver as defined in claim 5 additionally including a track position correlator for generating a false target alarm rate too high signal in response to a number of targets that do not correlate in position exceeding no less than five per second;

and means responsive to the occurrence of a false target alarm rate too high signal for increasing the count of said digital signals.