Radar provided with pulse repetition frequency discrimination

Claim 2

A radar including pulse receiving means, means for monitoring the amplitude of pulses derived from said pulse receiving means, means controlled by said monitoring means for attenuating said pulses when the said amplitude exceeds a predetermined value, means for generating a signal representative of the degree of attenuation, means for integrating for a particular integration period those pulses of the said pulses occurring at the pulse repetition frequency of the radar, and means for passing only those integrated pulses which exceed a predetermined threshold level to utilisation means, said utilisation means also receiving the said signals representative of the degree of attenuation for those pulses passed to it.

Claim 3

A radar as claimed in claim 1 wherein the attenuation means is preceded by a moving target indicator.

Claim 4

A radar as claimed in claim 2 wherein the moving target indiCator is preceded by converter means operative to generate digital codes representative of the amplitude of the pulses derived from said pulse receiving means.

Claim 5

A radar as claimed in claim 3 wherein the means for generating a signal representative of the degree of attenuation is operative to append to the digital code representative of the amplitude of the attenuated pulses a further digital code representative of the degree of attenuation.

Claim 6

A radar system comprising, in combination: pulse receiving means for receiving echo pulses which are received from a target as the target is scanned by a radar beam of selected prf and having an output which may include interference pulses; integrating means for integrating successive pulses received thereby at said selected prf for each of a plurality of successive particular integration periods and having an output at the end of each period which is the additive combination of each successive pulses during each such period; attenuator means connecting said output of the pulse receiving means to said integrating means for selectively stepwise attenuating pulses passed to said integrating means; monitoring means connected to the output of said pulse receiving means for monitoring the amplitudes of the pulses at the output of said pulse receiving means and connected to said attenuator means to cause stepwise attenuation thereby in response to pulse output amplitude from said pulse receiving means which exceeds a first predetermined limit; utilization means for displaying information derived from the output of said integrator means; gate means connecting the output of said integrator means to said utilization means for selectively passing the output of said integrator means to said utilization means; and threshold detector means connected to the output of said integrator means and to said gate means for opening said gate means in response to an output of said integrator means which exceeds a second predetermined limit which is greater than said first predetermined limit.

Claim 7

A radar system comprising, in combination: pulse receiving means for receiving echo pulses which are received from a target as the target is scanned by a radar beam of selected prf and having an output which may include interference pulses; integrating means for integrating successive pulses received thereby at said selected prf for each of a plurality of successive particular integration periods and having an output at the end of each period which is the additive combination of each successive pulses during each such period; attenuator means connecting said output of the pulse receiving means to said integrating means for selectively stepwise attenuating pulses passed to said integrating means; monitoring means connected to the output of said pulse receiving means for monitoring the amplitudes of the pulses at the output of said pulse receiving means and connected to said attenuator means to cause stepwise attenuation thereby in response to pulse output amplitude from said pulse receiving means which exceeds a first predetermined limit; utilization means for displaying information derived from the output of said integrator means; gate means connecting the output of said integrator means to said utilization means for selectively passing the output of said integrator means to said utilization means; and threshold detector means connected to the output of said integrator means and to said gate means for opening said gate means in response to an output of said integrator means which exceeds a second predetermined limit which is greater than said first predetermined limit.

Claim 8

A radar system as defined in claim 5 wherein said pulse receiving means includes an analog-to-digital converter which converts amplitudes of said echo pulses to k-bit digital words and wherein said attenuator means produces an n-bit output where n > k and where k of said n bits represent amplitude while remaining bits represent the level of attenuation.

Claim 9

A radar system as defined in claim 6 wherein said pulse receiving means also includes a moving target indicator preceeding said attenuator means.

Claim 10

A radar system as defined in claim 7 wherein said integrating means produces at least two complete integration periods during the time for which the envelope of echo pulses exceeds the level of -3dB from peak amplitude thereof.

Claim 11

A radar system as defined in claim 8 wherein said first predetermined limit to which said monitoring means responds in less than said -3dB level.

Claim 12

A radar system as defined in claim 9 wherein said integration periods each encompass a whole number of echo pulses.

Claim 13

A radar system as defined in claim 7 wherein said integrating means produces at least two complete integration periods during the time for which the envelope of echo pulses exceeds the level of -3dB from peak amplitude thereof.

Claim 14

A radar system as defined in claim 11 wherein said first predetermined limit to which said monitoring means responds is less than said -3dB level.

Claim 15

A radar system as defined in claim 12 wherein said integration periods each encompass a whole number of echo pulses.

Claim 16

A radar system as defined in claim 6 wherein said integrating means produces at least two complete integration periods during the time for which the envelope of echo pulses exceeds the level of -3dB from peak amplitude thereof.

Claim 17

A radar system as defined in claim 14 wherein said first predetermined limit to which said monitoring means Responds is less than said -3dB level.

Claim 18

A radar system as defined in claim 15 wherein said integration periods each encompass a whole number of echo pulses.

Claim 19

A radar system as defined in claim 6 wherein said integration periods each encompass a whole number of echo pulses.

Claim 20

A radar system as defined in claim 5 wherein said integration periods each encompass a whole number of echo pulses.