Method and apparatus for determining target elevation angle, altitude and range and the like in a monopulse radar system with reduced multipath errors
First Claim
1. A method for determining at least one of target elevation angle and altitude in a monopulse radar system based on first and second antenna beams, the first and second antenna beams defining an axis location which is aligned substantially on a horizon, comprising the steps of:
- a) receiving a sum signal and a difference signal caused by an echo from the first and second antenna beams;
b) determining a first peak value based on the sum signal in a first fading cycle of the sum signal;
c) determining a second peak value based on the difference signal in a second fading cycle of the difference signal; and
d) determining at least one of the target elevation angle and altitude based on the first peak value and the second peak value.
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Abstract
The present invention relates to a method and system for determining target elevation angle, altitude and range and the like in a monopulse radar system with reduced multipath errors. A transmitter/receiver unit receives monopulse sum and difference signals caused by echoes from targets. The sum and difference signals are then logarithmically-amplified in a logarithmic amplifier unit. A selector selects one of the sum and difference signals having the largest amplitude, and generates a selection signal indicating which of the sum and difference signals has the largest amplitude. The selection signal is provided to a search radar target tracking unit which determines whether a target at a given range interval and azimuth interval, for example, has been selected for tracking by an operator. The search radar target tracking unit then controls a gate unit to selectively provide either the logarithmically-amplified sum signal or the logarithmically-amplified difference signal to a peak detection unit based on the selection signal, and based on whether a particular target has been selected for tracking. The peak detection unit determines peak value(s) in the logarithmically-amplified sum and difference signals provided by the gate unit. A target elevation angle/altitude calculation unit uses the peak value(s) to determine target elevation angle or altitude values, or average target elevation angle or altitude values. Such values may be displayed on a CRT for in correspondence with the selected target(s).
46 Citations
23 Claims
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1. A method for determining at least one of target elevation angle and altitude in a monopulse radar system based on first and second antenna beams, the first and second antenna beams defining an axis location which is aligned substantially on a horizon, comprising the steps of:
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a) receiving a sum signal and a difference signal caused by an echo from the first and second antenna beams; b) determining a first peak value based on the sum signal in a first fading cycle of the sum signal; c) determining a second peak value based on the difference signal in a second fading cycle of the difference signal; and d) determining at least one of the target elevation angle and altitude based on the first peak value and the second peak value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for determining at least one of target elevation angle and altitude of a target in a monopulse radar system based on an echo from the target caused by first and second antenna beams, the first and second antenna beams defining an axis location which is aligned substantially on a horizon, comprising:
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a transmitter/receiver unit for generating the first and second antenna beams, and for receiving a sum signal and a difference signal caused by the echo from the first and second antenna beams; a peak detection unit, coupled to said transmitter/receiver unit, for determining a first peak value based on the sum signal in a first fading cycle of the sum signal, the first fading cycle being caused by movement of the target relative to said transmitter receiver unit, and for determining a second peak value based on the difference signal in a second fading cycle of the difference signal, the second fading cycle being caused by the movement of the target relative to said transmitter/receiver unit; and a target elevation angle/altitude calculation unit, coupled to said peak detection unit, for determining at least one of target elevation angle and altitude based on the first peak value and the second peak value. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A system for determining at least one of target elevation angle and altitude of a target in a monopulse radar system based on an echo from the target caused by first and second antenna beams, the first and second antenna beams defining an axis location, comprising:
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means for receiving a sum signal and a difference signal caused by the echo from the first and second antenna beams; and means for determining a first peak value based on the sum signal in a first fading cycle of the sum signal, the first fading cycle being caused by movement of the target relative to said means for receiving, for determining a second peak value based on the difference signal in a second fading cycle of the difference signal, the second fading cycle being caused by the movement of the target relative to said means for receiving, and for determining at least one of the target elevation angle and altitude based on the first peak value and the second peak value. - View Dependent Claims (18, 19, 20, 23)
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21. A method for determining at least one of target elevation angle and altitude in a monopulse radar system, based on first and second antenna beams, comprising the steps of:
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a) receiving a sum signal and a difference signal caused by an echo from the first and second antenna beams; b) determining peak values of the sum and difference signals; c) determining at least one of the target elevation angle and altitude, based on the peak values. - View Dependent Claims (22)
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Specification