Video extractor

A video extractor for use in a pulse radar apparatus, comprising:

• A. a shift-register memory, which is capable of storing a number of words corresponding with the number of range quants dividing the range interval to be covered by the pulse radar apparatus, said words containing information describing the number of hits received in a range quant, the number of misses established in a range quant, the initial and the final azimuth values of a target, the number of range quants in which the hits contributing to the buildup of a target have been recorded, the initial range of a target, and the status of various control bits for each range quant, said control bits including:
• a. a recording bit (R bit), indicating that a new echo is applied to the video extractor in a certain range quant;
• b. a detection bit (D bit), indicating that in a certain range quant a minimum number of hits have been recorded;
• c. an identification bit (H bit), indicating the word in which the data to be determined is concentrated;
• d. a miss bit (M bit), indicating that in a certain range quant no hits have been recorded;
• and
• e. a readout bit (U bit), indicating that the word associated with a certain range quant can be read out;
• B. a range counter whose counting rate is equal to the rate at which said words are shifted in the memory;
• C. an arithmetic unit, comprising:
• a. a hit counter for recording the number of hits received in a range quant;
• b. a miss counter for recording the number of misses established in a range quant;
• c. a circuit for determining the initial and the final azimuth values of a target;
• d. a range interval counting unit for determining the number of range quants in which the hits contributing to the buildup of a target have been recorded;
• e. a circuit for determining the initial range of a target;
• f. control bit recording means for recording the status of the various control bits for each range quant;
• said arithmetic unit receiving the words shifted out of memory and, in response to video and angular data received from the pulse radar apparatus and to range data provided by the range counter, updating information contained in said words during successive range sweeps and effecting concentration of information referring to each target in a single word by transferring the updated information to following or preceding words fetched from memory;
• D. a central control unit generating control signals which together with the control bits controls the counters and circuits of the arithmetic unit;
• and
• E. a readout circuit adapted to read out target position, size and range information from the words and to read out target range information from the range counter.