Radar cross correlator

Claim 2

Apparatus for correlating radar return signals comprising a memory having time slots for storing radar return signals in digital form according to the range represented by the return, adjacent time slots representing consecutive units of range having boundaries therebetween, means to locate each radar return signal at one of a plurality of time divisions within the time slot according to range, means to define a predetermined ciritical time period within said time slot representing at least one of said time divisions adjacent a boundary, range comparing means for comparing the range of said return signal with the range of a corresponding preceding return signal upon initiation by a return signal being located in said critical time period, and range signal transferring means for transferring the memory location of said return signal to a location representing a range corresponding to that of said preceding return when said preceding return signal is in an adjacent critical time period of the adjacent time slot.

Claim 3

Apparatus as defined in claim 1 wherein said means to locate each radar return signal at one of a plurality of time divisions comprises a plurality of bits accompanying the radar return signal representing the respective time division.

Claim 4

Apparatus as defined in claim 1 and further including a code generating means for generating a code representative of the history of a radar return signal.

Claim 5

Apparatus as defined in claim 3 in which the code generating means generates a code representing at least one of conditions in the group comprising (a) no radar return signal in a critical time period, (b) a radar return signal occurring in a critical time period, (c) no radar return signal occurring in a critical time period in the present scan but a radar return signal occurring in a critical time period in the previous scan, and (d) no radar return signal occurring in a critical time period in the present scan or in the previous scan but a radar return signal occurring in a critical time period in the scan previous to that.

Claim 6

Apparatus for correlating radar return signals in digital form in a radar system where a predetermined number of radar return signals at the same range from successive scans are required to provide a target display, comprising a memory having time slots for storing radar return signals in digital form according to the range represented by the return, adjacent time slots representing consecutive units of range having boundaries therebetween, means providing for each return a signal representing one of a plurality of time divisions within a time slot according to a fine range within said time slot, means defining a critical time period adjacent each boundary of a time slot, each critical time period representing at least one of said time divisions, a temporary storage unit for storing data representing a radar return signal for comparison with data representing a succeeding radar return signal, range data comparing means for comparing data representing successive radar return signals upon initiation by a return signal being located in a critical time period, range signal transferring means for transferring the memory location of a return signal to a location representing a range corresponding to that of a preceding return signal when said preceding return signal is in an adjacent critical time period in the adjacent time slot, and means providing an output from said memory for use in providing a target display.

Claim 7

Apparatus for correlating radar return signals in digital form in a radar system where a predetermined number of radar return signals at the same range from successive scans are required to provide a target display, comprising a memory having time slots for storing radar return signals in digital form according to the range represented by the return, adjacent time slots representing consecutive units of range having boundaries therebetween, means providing for each return a signal representing one of a plurality of time divisions within a time slot according to a fine range within said time slot, means defining a critical time period adjacent each boundary of a time slot, each critical time period representing at least one of said time divisions, a temporary storage unit for storing data representing a radar return signal for comparison with data representing a succeeding radar return signal, range data comparing means for comparing data representing successive radar return signals upon initiation by a return signal being located in a critical time period, range signal transferring means for transferring the memory location of a return signal to a location representing a range corresponding to that of a preceding return signal when said preceding return signal is in an adjacent critical time period in the adjacent time slot, and means providing an output from said memory for use in providing a target display.

Claim 8

Apparatus as defined in claim 5 and further including a code generating means associated with each time slot for generating a code representative of the history of a radar return signal.

Claim 9

Apparatus as defined in claim 6 in which the code generating means generates a code representing at least one of the conditions in the group comprising (a) no radar return signal in a critical time period for at least three scans, (b) a radar return signal in a first critical time period adjacent a first boundary, (c) no radar return signal occurring in said first critical time period in the present scan but a radar return signal in said first critical time period of the previous scan, (d) no radar return signal occurring in said first critical time period in the present scan or in the previous scan but a radar return signal in said first critical time period in the scan previous to that, (e) a radar return signal in a second critical time period adjacent said first boundary, (f) no radar return signal occurring in said second critical time period in the present scan but a radar return signal in said second critical time period of the previous scan, and (g) no radar return signal occurring in said second critical time period in the present scan or in the previous scan but a radar return signal in said second critical time period in the scan previous to that.

Claim 10

Apparatus as defined in claim 7 in which each time slot represents one quarter of a nautical mile and each time division therein represents one thirty second of a nautical mile.