AUTOMATIC DETECTION CRITERIA CONTROL UNIT FOR PENCIL BEAM RADARS

• US 3,680,095 A
• Filed: 04/17/1967
• Issued: 07/25/1972
• Est. Priority Date: 04/17/1967
• Status: Expired due to Term

• Current Assignee: Norol T. Evans
• Original Assignee: Norol T. Evans
• Inventors: Evans, Norol T.
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US04/631,307
• Time in Patent Office: 1,926 Days
• Field of Search: 343/5DP,7A
• 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

Abstract

An automatic detection criteria control system for pencil beam radar in which video returns are coded and correlated to provide target reports. The amplitude of the coded returns from each range bin is subject to modification as a function of the history of target detection in an incremental volume of space which includes the particular range bin. The system includes a memory in which a target-detection-history indicating code is stored for each incremental volume. The code is read out, in real time, with the video returns from all range bins of a given incremental volume. The codes are updated during a sequence of update cycles to indicate the latest history of target detection in each incremental volume.

Claims

1. An automatic target detection criteria control system for use in a radar receiving system of the type including a radar receiver for receiving with a surveillance antenna return signals from a plurality of range bins in the surveillance volume as said antenna is rotated in azimuth and directed in a plurality of different elevations at each azimuth position, said radar receiving system further including quantizing means responsive to said return signals to produce quantized video returns from each of said range bins and means for processing said quantized video returns to produce target-detection-indicating signals suppliable to target-detection utilization means, said radar receiving system further includIng means providing a range signal indicative in real time of the range of the range bin from which return signals are received and azimuth and elevation signals indicative of the azimuth and elevation positions of said antenna, said automatic target-detection criteria control system comprising:

first means responsive to range, azimuth and elevation signals from said radar receiving system for generating address signals defining incremental volumes in the radar surveillance volume surveyed by said antenna, each volume being of a selected range, which includes the range of an integral number of range bins, each volume having a width of a preselected azimuth segment and a height of a selected number of elevations, said first means providing the addressing signals defining an incremental volume as said antenna is in the azimuth segment and elevation of the incremental volume and the return signals received by said radar receiving means are from the particular range included in the incremental volume;

memory means including means for storing a multibit code for each of said incremental volumes, said memory means further including a read register and an address register responsive to said address signals for reading into said read register the multibit code of the incremental volume defined by said address signals;

logic means responsive to the code in said read register for selectively controlling the amplitudes of quantized video returns supplied to said means for processing as a function of the code value from said memory means.

2. An automatic target detection criteria control system as recited in claim 1 further including gating means for inhibiting the supply of target detection indicating signals from said means for processing to said target-detection utilization means when the code from said memory means has a predetermined value.

3. An automatic target detection criteria control system as recited in claim 1 further including means defining a sequence of code update cycles and means for supplying said target-detection indicating signals from said means for processing to said logic means, said logic means including gating means for updating during each update cycle the code in said read register as a function of the code characteristics and a target-detection indicating signal from said means for processing, whereby the code associated with each incremental volume which is read out between update cycles is a function of the history of target-detection in range bins in the incremental volume, said memory means including a write register responsive to signals from said logic means for storing the updated code in said means for storing.

4. An automatic target detection criteria control system as recited in claim 3 wherein said means defining a sequence of update cycles includes a multibit counter which is incremented at preselected intervals, and means coupling said logic means to said counter to provide said logic means with update cycle-defining signals when the count in said counter is of predetermined values.

5. An automatic target detection criteria control system as recited in claim 3 wherein said means defining a sequence of update cycles includes a resettable multibit counter with a selected maximum count;

means providing said counter with input signals at a contrOlled rate, which substantially equals the rate of rotation of said antenna, the time required for said counter to reach its maximum count defining a period between successive update cycles, and means coupling said logic means to said counter to provide said logic means with three successive signals defining three successive phases of each update cycle when the count in said counter is of three successive values.

6. An automatic target detection criteria control system as recited in claim 3, said system further including means for defining a sequence of phases within each update cycle, said logic means including means responsive during each phase to the code read ouT from said read register for selectively modifying the amplitudes of the quantized video returns supplied to said means for processing as a function of the value of the code and the phase within the update cycle, said gating means of said logic means restoring at the end of each phase a code in said means for storing.

7. An automatic target detection criteria control system as recited in claim 6 wherein the gating means of said logic means includes first means to develop selected values of the code storable at the end of each update cycle include, in which a first code value is indicative of the absence of a target-detection-indicating signal from said means for processing during the last update cycle.

8. An automatic target detection criteria control system as recited in claim 7 wherein said gating means of said logic means includes second means to develop said selected code values to include a second code value indicative of a target-detection-indicating signal during an update cycle preceding the last cycle and a target-detection-indicating signal during the last cycle in spite of a modification of the amplitude of the quantized video returns supplied to said means for processing, a third code value indicative of target-detection-indicating signals during three successive update cycles, a fourth code value indicative of target-detection-indicating signals during three successive update cycles and a fifth code value indicative of target-detection-indicating signals during four successive update cycles.

9. An automatic target detection criteria control system as recited in claim 8 wherein said logic means includes means responsive to said code values for controlling the amplitudes of the quantized video returns supplied to said means for processing as a function of said code values.

10. An automatic target detection criteria control system as recited in claim 9 wherein said logic means in response to said third and fourth code values reduces the amplitude of the quantized video returns by a first and second magnitude respectively, and further including gating means for inhibiting the supply of target-detection-indicating signals from said means for processing to said target-detection utilization means, said logic means controlling said inhibiting gating means to inhibit the supply of target detection indicating signals to said utilization means when the code from said means for storing is of said fifth value.

11. An automatic target detection criteria control system as recited in claim 1 further including counting means responsive to the target detection indicating signals for providing a count indicative of the rate at which said means for processing provide said target-detection-indicating signals;

and means responsive to said counting means for selectively controlling the amplitude of the quantized video returns supplied to said means for processing as a function of said count.

12. An automatic target detection criteria control system as recited in claim 1 further including means including counting means responsive to the quantized video returns from said quantizing means for providing a count indicative of the rate at which quantized video returns exceeding a selected amplitude are supplied by said quantizing means.

13. An automatic target detection criteria control system as recited in claim 12 further including target-rate counting means responsive to the target-detection-indicating signals from said means for processing for providing a count which is indicative of the rate of target detection, and means responsive to said count indicative of target detection rate and the count from said counting means which is indicative of the rate at which quantized video returns exceeding a selected amplitude are supplied by said quantizing means, to control the amplitude of the quantized video returns supplied to said means for processing.

14. A detection criteria control system for operation in conjunction with a surveillance raDar receiving system, including a surveillance radar antenna rotated in azimuth and controlled to successively receive signals at a plurality of elevations at each of a plurality of azimuth positions said antenna being rotated to complete one revolution defining a radar scan in a selected interval, said radar receiving system including a source of range bin defining signals, a receiver and quantizing means for providing quantized video returns from the signals received by said antenna from each range bin, and means for processing the quantized video returns to provide a target report signal from a range bin to target report utilization means only when the amplitude of the quantized video returns from the range bin and from range bins related in azimuth and elevations are of preselected amplitudes, said detection criteria control system comprising:

first means responsive to said range bin defining signals and signals indicative of the azimuth and elevation of the radar antenna for generating, in real time, sets of addressing signals, each set defining an incremental volume of the volume surveyed by said antenna being generated as said receiving system produces quantized video returns for range bins included in the incremental volume;

memory means for storing a code for each incremental volume of the radar surveillance volume;

a read register;

an address register responsive to a set of addressing signals from said first means for controlling said memory means to read the code of the incremental volume defined by the set of addressing signals into said read register; and

means including logic means responsive to at least the code in said read register for controlling the amplitudes of the quantized video returns from all the range bins included in the incremental volume associated with the read out code as a function of the code characteristics.

15. In a radar receiving system of the type including means developing quantized video returns for signals returned from each range bin of the radar surveillance volume and means for correlating the quantized video returns to provide target reports, the improvement comprising:

means for storing a target-detection-history indicating code for each multirange bin incremental volume of said surveillance radar;

means for utilizing each code to control the quantized video returns from the range bins of the incremental volume associated with said code; and

means for updating during each of a sequence of update cycles the code of each incremental volume as a function of the code characteristics and a target report from said correlating means provided during the update cycle for any of the range bins in the incremental volume.

16. In the radar receiving system as recited in claim 15 wherein said means for storing includes means to provide the code at the beginning of an update cycle to be representative of the history of detection of targets in any of the range bins of an incremental volume associated with said code during preceding update cycles in said sequence.

17. In the radar receiving system as recited in claim 16 wherein the quantized video returns from each range bin are represented by a multibit number whose numerical value is indicative of the peak of the video returns with respect to a preselected threshold level, said utilizing means subtracting a first numerical quantity from the quantized video returns of all range bins in an incremental volume when the code represents target detection in two successive update cycles and a second numerical quantity larger than said first, when the code represents target detection in three successive update cycles.

18. In the radar receiving system as recited in claim 17 further including means for blanking the supply of target reports from said receiving system from range bins in a given incremental volume when the code associated with said volume is indicative of target detection in a preselected number of successive update cycles.

19. In the radar receiving system as recited in claim 15 further including means for modifying the quantized video returns as a function of the rate of target reports from said correlating means.

20. In the radar receiving system as recited in claim 15 further including means for modifying the quantized video returns supplied to said correlating means as a function of the rate at which quantized video returns above a selected value are developed.