AUTOMATIC RADAR TARGET DETECTION AND SCAN CONVERSION SYSTEM

• US 3,797,014 A
• Filed: 09/21/1970
• Issued: 03/12/1974
• Est. Priority Date: 09/21/1970
• Status: Expired due to Term

• Current Assignee: Birnam R. Tompkins, John K. Smith
• Original Assignee: Birnam R. Tompkins, John K. Smith
• Inventors: Tompkins, Birnam R., Smith, John K.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Montone, G. E.
• Application Number:
  US05/074,097
• Time in Patent Office: 1,268 Days
• Field of Search: 343/5DP,17.1,5SC,112CA,8
• US Class Current: 342/90
• CPC Class Codes: G01S 7/2923 based on data belonging to a number of consecutive radar periods

Abstract

The specification discloses an automatic detection system for use with, for example, an airborne radar system. Automatic gain control circuitry is responsive to a predetermined false alarm rate for varying the amplitude of radar video signals derived from the airborne radar system. Threshold circuitry is connected to the output of the automatic gain control circuitry for passing only the radar video signals above a selected threshold. A pulseto-pulse processor operates upon the output signals from the threshold circuitry to generate signals representative of the existence of a valid target return only if the target return occurs for a predetermined consecutive number of radar returns. A scan-to-scan processor is responsive to the output of the pulseto-pulse processor for generating a valid target signal only when a predetermined number of target returns occur during a selected number of radar antenna scans. A final processor processes the output of the scan-to-scan processor longer than a lifetime of clutter spikes in order to generate an output signal representative of valid target returns. A range stabilization system stabilizes the pulse-to-pulse processor, scan-to-scan processor, and final processor with respect to range in dependence upon the aircraft velocity. A north stabilization circuit stabilizes the scan-to-scan processor and final processor with respect to a predetermined azimuth to enable operation of the system during an aircraft turn. A digital scan converter system is responsive to the output of the final processor for operating a multi-mode display.

Claims

1. An automatic target detection and scan conversion system for use with radar systems comprising:

circuit means for receiving a radar video signal, threshold circuitry for passing only portions of said video signals above a threshold to indicate target reflections, a preprocessor means responsive to the output of said threshold circuitry to generate an output signal when a predetermined number of target reflections occur during selected number of radar antenna scan;

a final processor means for discriminating between valid target reflections and false alarms for generating an output video signal of the valid target reflections for display, said final processor means including A register means, means for adding a value to said register means upon the occurrence of an output signal from said preprocessor means, means for subtracting a value from said register means if an output signal is not generated from said preprocessor means, and means for sensing when the stored value in said register means exceed a predetermined valve.

2. An automatic detection system according to claim 1 further comprising:

means for range stabilizing said pulse-to-pulse processor circuitry, said scan-to-scan processor circuitry and said final processor means in dependence upon the velocity of the radar carrier.

3. An automatic detection system according to claim 1 further comprising:

self-regulating means for stabilizing said scan-to-scan processor circuitry and said final processor means with respect to a predetermined azimuth direction to enable automatic detection of a target reflection during a turn of the radar carrier.

4. An automatic detection system according to claim 1 further comprising:

automatic gain control circuitry for varying the input false alarm rate of said system on a scan-to-scan basis with varying clutter density.

5. The automatic detection system according to claim 1 further including a digital scan converter means operatively responsive to the output of the final processor for converting the processed video signals for display at a flicker free rate, said digital scan converter means including a display for displaying the video signals at the flicker free rate.

6. An automatic detection system according to claim 1 further comprising:

digital scan converter means including a memory for storing the output of said final processor means, and display means operable in response to said digital scan converter means for displaying valid target reflections at a flicker-free rate.

7. An automatic radar detection system comprising:

a radar system for generating radar video signals, automatic gain control circuitry responsive to a predetermined false alarm rate for varying the amplitude of said radar video signals, threshold circuitry for passing only reflected radar video signals above a selected threshold, a pulse-to-pulse processor connected to the output of said threshold circuitry for generating a signal representative of the existence of a valid target return only if said target return occurs for a predetermined consecutive number of radar returns, means for stabilizing said pulse-to-pulse processor with respect to range in dependence upon the velocity of the radar carrier, a scan-to-scan processor connected to the output of said pulse-to-pulse processor for generating a valid target signal only when a predetermined number of target returns occur during a selected number of radar antenna scans, means for stabilizing said scan-to-scan processor with respect to range in dependence upon the velocity of the radar carrier, means for stabilizing said scan-to-scan processor with respect to a predetermined azimuth, a final processor for processing the output from said scan-to-scan processor longer than the lifetime of clutter spikes to generate an output signal representative of valid target returns, means for stabilizing said final processor with respect to range in dependence upon the radar carrier velocity, means for stabilizing said final processor with respect to a predetermined azimuth, a scan converter means coupled to the radar system and final processor for producing display control signals at a flicker-free rate, and display means for displaying the control signals at a continuous flicker-free rate.

8. An automatic radar detection system according to claim 7 further comprising:

a memory arranged in a matrix according to azimuth and range for storing representations of target returns to enable the operation of said scan-to-scan processor and said final processor.

9. An automatic radar detection system according to claim 8 wherein saId scan conversion means utilizes said memory to control the operation of a multi-mode display.

10. A method of automatic target detection and scan conversion comprising:

scanning an area of space with pulses of electro-magnetic energy;

detecting reflected pulses of the electro-magnetic energy;

processing said reflected pulses in a pulse-to-pulse processor to produce a signal representative of a plurality of consecutive target indicating pulse returns within a selected number of pulses;

processing any pulse-to-pulse processor signals in a scan-to-scan processor to produce a signal representative of the receipt of a desired plurality of pulse-to-pulse processor signals within a selected number of radar scans;

processing the scan-to-scan processor signal output to discriminate between targets and false alarms by processing said scan-to-scan output signals for a period sufficient to distinguish target indicating signals from false alarm signals;

processing the detected target output signals and electromagnetic energy signals through a digital scan converter including storing the video display control signals, and reading out the stored video display control signals to provide a circular raster scan for a display means at a flicker free rate.