Navigational and collision avoidance apparatus

Claim 2

Target evaluation apparatus for use with marine surface radar processing equipment providing digitized target range pulses at a plurality of ranges said target evaluation apparatus comprising target leading edge signal means providing a target leading edge signal pulse at each of successive azimuths target trailing edge signal means providing a target trailing edge signal pulse at each of successive azimuths and initially separated in range from said target leading edge signal pulse the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse providing a target envelope end recognition signal and discriminating means responsive to a maximum number of said target leading edge signal pulses, said maximum number decreasing at successively increasing ranges, for discriminating between landmass targets of greater than a predetermined actual length in azimuth representing a maximum ship length and possible ship targets of less than said predetermined length, providing a discriminated targer output signal responsive to said possible ship targets.

Claim 3

Target evaluation apparatus as claimed in claim 1 wherein said discriminating means provides a landmass output signal responsive to targets of greater than said predetermined length representing a major portion of the leading edge in azimuth of landmass targets.

Claim 4

Target evaluation apparatus for use with marine surface radar processing equipment providing target range pulses at a plurality of ranges and digitized to have one of two values, said target evaluation apparatus comprising target leading edge signal means responsive to the first value of said digitized target range pulses providing a target leading edge signal pulse, target trailing edge signal means responsive to the second value of said digitized target pulses providing a target trailing edge signal pulse at the same azimuth and initially separated in range from said target leading edge signal pulse, azimuth propagation means for propagating said edge signals at successive azimuth intervals to define a target envelope, range stepping means for altering the range position of a said propagated edge signal responsive to the range positions of said digitized target range pulses to define a target envelope range, target end recognition means responsive to a predetermined number of target range pulses having said second value at successive azimuth intervals and at said target envelope range and to the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse for providing a target end recognition signal, and discriminating means responsive to the propagation of a said leading edge signal pulse through a maximum number of azimuth intervals, said maximum number decreasing at successively increasing target envelope ranges, for discriminating between landmass targets of greater than a predetermined actual length in azimuth representing a maximum ship length and possible ship targets of less than said predetermined length, providing a discriminated target output signal responsive to said possible ship targets.

Claim 5

Target evaluation apparatus for use with marine surface radar processing equipment providing target range pulses at a plurality of ranges and digitized to have one of two values, said target evaluation apparatus comprising target leading edge signal means responsive to the first value of said digitized target range pulses providing a target leading edge signal pulse, target trailing edge signal means responsive to the second value of said digitized target pulses providing a target trailing edge signal pulse at the same azimuth and initially separated in range from said target leading edge signal pulse, azimuth propagation means for propagating said edge signals at successive azimuth intervals to define a target envelope, range stepping means for altering the range position of a said propagated edge signal responsive to the range positions of said digitized target range pulses to define a target envelope range, target end recognition means responsive to a predetermined number of target range pulses having said second value at successive azimuth intervals and at said target envelope range and to the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse for providing a target end recognition signal, and discriminating means responsive to the propagation of a said leading edge signal pulse through a maximum number of azimuth intervals, said maximum number decreasing at successively increasing target envelope ranges, for discriminating between landmass targets of greater than a predetermined actual length in azimuth representing a maximum ship length and possible ship targets of less than said predetermined length, providing a discriminated target output signal responsive to said possible ship targets.

Claim 6

Target evaluation apparatus for use with marine surface radar processing equipment providing digitized target range pulses at a plurality of ranges, said target evaluation apparatus comprising target leading edge signal means providing a target leading edge signal pulse at successive azimuths, and target trailing edge signal means providing a target trailing edge signal pulse at successive azimuths and initially separated in range from said target leading edge signal pulse, the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse providing a target envelope end recognition signal.

Claim 7

Target evaluation apparatus for use with marine surface radar processing equipment providing digitized target range pulses at a plurality of ranges, said target evaluation apparatus comprising target leading edge signal means providing a target leading edge signal pulse at successive azimuths, and target trailing edge signal means providing a target trailing edge signal pulse at successive azimuths and initially separated in range from said target leading edge signal pulse, the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse providing a target envelope end recognition signal.

Claim 8

Target evaluation apparatus as claimed in claim 4, further including means for altering the range position of a said edge signal responsive to the range position of said digitized target range pulses.

Claim 9

Target evaluation apparatus for use with marine surface radar processing equipment providing digitized target range signal pulses at a plurality of ranges said apparatus comprising discriminating means responsive to said signal pulses for discriminating against at least a major portion of landmass targets of greater than a predetermined length in azimuth while providing output signals responsive to targets of less than said predetermined length representing possible ship targets, said discriminating means being responsive to a maximum number of successive azimuthal target pulses, said maximum number decreasing at successively increasing ranges, for discriminating against landmass targets of greater than a predetermined actual length in azimuth representing maximum ship length.

Claim 10

Target evaluation apparatus for use with marine surface radar processing equipment providing digitized target range signal pulses at a plurality of ranges said apparatus comprising discriminating means responsive to said signal pulses for discriminating against at least a major portion of landmass targets of greater than a predetermined length in azimuth while providing output signals responsive to targets of less than said predetermined length representing possible ship targets, said discriminating means being responsive to a maximum number of successive azimuthal target pulses, said maximum number decreasing at successively increasing ranges, for discriminating against landmass targets of greater than a predetermined actual length in azimuth representing maximum ship length.

Claim 11

Apparatus as claimed in claim 6, wherein said discriminating means provides discriminated output signals selectively responsive to targets of less than said predetermined length representing possible ship targets and to targets of greater than said predetermined length representing a major portion of the leading edge in azimuth of landmass targets.

Claim 12

Marine surface radar processing equipment for use with marine surface radar providing target range pulses at a plurality of ranges to provide digitized target range pulses at one of two values, comprising target evaluation apparatus including target leading edge signal means responsive to the first value of said digitized target range pulses providing a target leading edge signal pulse, target trailing edge signal means responsive to the second value of said digitized target range pulses providing a target trailing edge signal pulse at the same azimuth and initially separated in range from said target leading edge signal pulse, azimuth propagation means for propagating said edge signals at successive azimuth intervals to define a target envelope, range stepping means for altering the range position of a said propagated edge signal responsive to the range positions of said digitized target range pulses to define a target envelope range, and target end recognition means responsive to a predetermined number of target range pulses having said second value at successive azimuth intervals and at said target envelope range and to the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse for providing a target end recognition signal.

Claim 13

Marine surface radar processing equipment for use with marine surface radar providing target range pulses at a plurality of ranges to provide digitized target range pulses at one of two values, comprising target evaluation apparatus including target leading edge signal means responsive to the first value of said digitized target range pulses providing a target leading edge signal pulse, target trailing edge signal means responsive to the second value of said digitized target range pulses providing a target trailing edge signal pulse at the same azimuth and initially separated in range from said target leading edge signal pulse, azimuth propagation means for propagating said edge signals at successive azimuth intervals to define a target envelope, range stepping means for altering the range position of a said propagated edge signal responsive to the range positions of said digitized target range pulses to define a target envelope range, and target end recognition means responsive to a predetermined number of target range pulses having said second value at successive azimuth intervals and at said target envelope range and to the coincidence in range of a leading edge signal pulse and a trailing edge signal pulse for providing a target end recognition signal.

Claim 14

Equipment as claimed in claim 8 further including discriminating means responsive to the propagation of a said leading edge signal pulse through a maximum number of azimuth intervals, said maximum number decreasing at successively increasing target envelope ranges, for discriminating between landmass targets of greater than a predetermined actual length in azimuth representing a maximum ship length and possible ship targets of less than said predetermined length, providing a discriminated target output signal responsive to said possible ship targets.

Claim 15

Equipment as claimed in claim 9 wherein said discriminating means also provides a discriminated landmass output signal responsive to said landmass targets.