COORDINATE STORE DIGITAL SCAN CONVERTER
First Claim
1. In a radar system wherein it is desired to employ a scan converter for the purpose of improving the display of the targets detected by said radar system, and wherein said radar system provides digital data indicative of the coordinates of each target hit, the improvement in said scan converter comprising:
- cyclic memory means for storing the digital data coordinates for a plurality of target hits received from said radar system, said cyclic memory means including age code memory means for storing a code for each target hit digital data entered in said memory indicative that it is newly entered, and means for decrementing said age code for each target hit digital data each time it is cycled through said memory, means for comparing the coordinates of each new target hit digital data with the target hit digital data in said memory to determine if correlation exists and to provide a correlation signal indicative thereof, meaNs responsive to said correlation signal to prevent the storage of said new target hit digital coordinates in said memory, and means responsive to the absence of a correlation signal for storing said new target hit digital coordinates in said memory.
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Abstract
A radar processor encodes the data associated with target hits. This digital data is entered into a small circulating memory together with an age code. The age code is decremented at a predetermined rate. The digital data while being transferred between the output and the input of the memory is also applied to a suitable display system. The age code determines the brightness of the display. When the age code has decreased below a predetermined level, this is sensed and new target hit data is entered into the location occupied by the target hit data associated with the minimum age code. To minimize the size of the memory required, new target hit data either from the same radar processor or another source, if desired, is compared with all of the target hit data in the memory, and if correlation is established, then the new target hit data is not entered into memory, but the old target hit data has its age updated and a record of correlation is made.
10 Citations
7 Claims
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1. In a radar system wherein it is desired to employ a scan converter for the purpose of improving the display of the targets detected by said radar system, and wherein said radar system provides digital data indicative of the coordinates of each target hit, the improvement in said scan converter comprising:
- cyclic memory means for storing the digital data coordinates for a plurality of target hits received from said radar system, said cyclic memory means including age code memory means for storing a code for each target hit digital data entered in said memory indicative that it is newly entered, and means for decrementing said age code for each target hit digital data each time it is cycled through said memory, means for comparing the coordinates of each new target hit digital data with the target hit digital data in said memory to determine if correlation exists and to provide a correlation signal indicative thereof, meaNs responsive to said correlation signal to prevent the storage of said new target hit digital coordinates in said memory, and means responsive to the absence of a correlation signal for storing said new target hit digital coordinates in said memory.
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2. means for comparing the coordinates of each new target hit digital data with the target hit digital data in said memory to determine if correlation exists and to provide a correlation signal indicative thereof, and including:
- 2a. means for establishing a predetermined range of target hit digital coordinates for target hit digital coordinates in memory which is to be compared with said new target hit digital coordinates, said means for establishing a predetermined range of target hit digital coordinates including;
2a1. means for establishing incremental target hit digital azimuth, range and elevation coordinates, 2a2. means for combining said incremental target hit digital azimuth, range and elevation coordinates with corresponding target hit digital azimuth, range and elevation coordinates derived from said memory to produce incremented target hit digital azimuth, range and elevation coordinates, 2a3. first comparator means to which said new target hit digital azimuth, range and elevation coordinates and said incremented target hit digital azimuth, range and elevation coordinates are applied to produce a first output when said incremented target hit digital azimuth, range and elevation coordinates are all less than said corresponding new target hit digital azimuth, range and elevation coordinates, 2a4. second comparator means to which said new target hit digital azimuth, range and elevation coordinates and said target hit digital azimuth, range and elevation coordinates derived from said memory produce a second output indicative that said target hit digital azimuth, range and elevation coordinates derived from memory are all greater than said new target hit digital data, and 2a5. means responsive to said first and second outputs to produce said correlation signal, and
- 2a. means for establishing a predetermined range of target hit digital coordinates for target hit digital coordinates in memory which is to be compared with said new target hit digital coordinates, said means for establishing a predetermined range of target hit digital coordinates including;
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3. means for comparing said range of target hit digital coordinates with said new target hit digital coordinates and producing said correlation signal whenever said new target hit digital coordinates falls within said range,
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4. In an aircraft radar system wherein it is desired to employ a scan converter for the purpose of improving the display of the targets detected by said radar system and wherein said radar system provides digital position coordinates indicative of each target hit, the improvement in said scan converter comprising:
- cyclic memory means including means for storiNg the digital position coordinates for a plurality of target hits received from said radar system, means for generating an age code for each new target hit to be stored in said cyclic memory means, means for entering an age code into said cyclic memory means together with each new target hit being stored, means to periodically update said age code for each target hit stored in memory, means in said display responsive to said age code for establishing the brightness of the target hit displayed in accordance with its age code, a source of new target hit position coordinates, means for comparing new target hit position coordinates with all of the target hit position coordinates in said cyclic memory means for determining whether or not correlation exists and producing a correlation signal when it is established, means responsive to said correlation signal for storing an indication of correlation in said cyclic memory means for identifying the target hit for which correlation has been established, means for indicating when all of the target hit position coordinates in said cyclic memory means has been compared for correlation and producing a correlation completed signal indicative thereof, and means responsive to a correlation signal and a correlation completed signal for calling for new target hit position coordinates to be compared with the position coordinates in said memory.
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5. means responsive to the absence of a correlation signal for storing said new target hit digital coordinates in said memory.
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6. In an aircraft radar system as recited in claim 4 wherein said source of new target hit position coordinates is an IFF system.
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7. In an aircraft radar system as recited in claim 4 wherein said means for comparing includes means for establishing whether or not correlation exists over a predetermined range of target hit digital position coordinates values.
Specification