Angle measurement device for amplitude monopulse receivers
First Claim
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1. An angle-measurement device in an amplitude-modulated monopulse radar receiver, comprising:
- two logarithmic amplifiers connected to an antenna system and responsive to two antenna-pattern signals in the form of a sum and of a difference denoted as a sigma signal and a delta signal, respectively, for generating log sigma and log delta signals;
respective hard limiters connected to outputs of said logarithmic amplifiers and having respective outputs representing the phases of said sigma and delta signals;
a 90°
phase shifter connected to an output of one of said hard limiters to effect a 90°
phase shift of the signal outputted thereby;
a phase detector connected to an output of said 90°
phase shifter and the output of the other of said hard limiters for outputting a signal representing the cosine of the phase difference between said sigma and delta signals;
a first analog-to-digital converter connected to an output of said phase detector for digitalizing said cosine;
a subtractor connected to said outputs of said logarithmic amplifiers for outputting a signal representing the logarithm of the quotient of said sigma and delta signals;
a second analog-to-digital converter connected to an output of said subtractor for digitalizing said signal representing the logarithm of said quotient;
a first comparator connected with the output of one of said logarithmic amplifiers for comparing the respective log signal with a detection threshold to provide an enabling signal;
a second comparator connected with the output of said subtractor for comparing the logarithm of the quotient with another threshold to output a signal representing the existence of a predetermined condition; and
a third comparator connected with the output of said phase detector and having a zero input for generating a signal representing the sign of the cosine;
a decoder connected to said first and second analog-to-digital converters and to said first, second and third comparators and enabled by said enabling signal to provide angle measurement output selectively in accordance with the function;
space="preserve" listing-type="equation">θ
=SK.sub.m b.sup.-z (
1),and
space="preserve" listing-type="equation">θ
=CK.sub.m b.sup.-z (
2),whereθ
is the measured azimuth angle,b is the logarithm base,z is the logarithm of the quotient,S is the sign of the cosine,C is the cosine, andKm is a constant system parameter,in accordance with the output of said second comparator.
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Abstract
Device for angle measurement for inclusion within a monopulse amplitude comparison radar receiver for particular application within secondary radars. In essence it consists of a log (Σ) signal comparator (9) against a detection threshold, which is meant to enable further processing; of two-analog-numerical converters (10, 11), a codes (12), receiving outputs Σ and Δ from converters above, which provides the calculation of target azimuth.
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Citations
2 Claims
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1. An angle-measurement device in an amplitude-modulated monopulse radar receiver, comprising:
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two logarithmic amplifiers connected to an antenna system and responsive to two antenna-pattern signals in the form of a sum and of a difference denoted as a sigma signal and a delta signal, respectively, for generating log sigma and log delta signals; respective hard limiters connected to outputs of said logarithmic amplifiers and having respective outputs representing the phases of said sigma and delta signals; a 90°
phase shifter connected to an output of one of said hard limiters to effect a 90°
phase shift of the signal outputted thereby;a phase detector connected to an output of said 90°
phase shifter and the output of the other of said hard limiters for outputting a signal representing the cosine of the phase difference between said sigma and delta signals;a first analog-to-digital converter connected to an output of said phase detector for digitalizing said cosine; a subtractor connected to said outputs of said logarithmic amplifiers for outputting a signal representing the logarithm of the quotient of said sigma and delta signals; a second analog-to-digital converter connected to an output of said subtractor for digitalizing said signal representing the logarithm of said quotient; a first comparator connected with the output of one of said logarithmic amplifiers for comparing the respective log signal with a detection threshold to provide an enabling signal; a second comparator connected with the output of said subtractor for comparing the logarithm of the quotient with another threshold to output a signal representing the existence of a predetermined condition; and a third comparator connected with the output of said phase detector and having a zero input for generating a signal representing the sign of the cosine; a decoder connected to said first and second analog-to-digital converters and to said first, second and third comparators and enabled by said enabling signal to provide angle measurement output selectively in accordance with the function;
space="preserve" listing-type="equation">θ
=SK.sub.m b.sup.-z (
1),and
space="preserve" listing-type="equation">θ
=CK.sub.m b.sup.-z (
2),where θ
is the measured azimuth angle,b is the logarithm base, z is the logarithm of the quotient, S is the sign of the cosine, C is the cosine, and Km is a constant system parameter, in accordance with the output of said second comparator.
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2. An angle-measurement device in an amplitude-modulated monopulse radar receiver, comprising:
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two logarithmic amplifiers connected to an antenna system and responsive to two antenna-pattern signals in the form of a sum and of a difference denoted as a sigma signal and a delta signal, respectively, for generating log sigma and log delta signals; respective hard limiters connected to outputs of said logarithmic amplifiers and having respective outputs representing the phases of said sigma and delta signals; a 90°
phase shifter connected to an output of one of said hard limiters to effect a 90°
phase shift of the signal outputted thereby;a phase detector connected to an output of said 90°
phase shifter and the output of the other of said hard limiters for outputting a signal representing the cosine of the phase difference between said sigma and delta signals;a first analog-to-digital converter connected to an output of said phase detector for digitalizing said cosine; a subtractor connected to said outputs of said logarithmic amplifiers for outputting a signal representing the logarithm of the quotient of said sigma and delta signals; a second analog-to-digital converter connected to an output of said subtractor for digitalizing said signal representing the logarithm of said quotient; a comparator connected with the output of one of said logarithmic amplifiers for comparing the respective log signal with a detection threshold to provide an enabling signal; and a decoder connected to said first and second analog-to-digital converters and to said comparator and enabled by said enabling signal to provide angle measurement output selectively in accordance with the function;
space="preserve" listing-type="equation">θ
=CK.sub.m b.sup.-z,where θ
is the measured azimuth angle,b is the logarithm base, z is the logarithm of the quotient, C is the cosine, and Km is a constant system parameter.
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Specification