Angular discrimination process and device for radar
AssigneeElectronique Serge Dassault
InventorBernard J. Maitre
Life of this patent
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Abstract
In a process and device for the angular discrimination of targets by airborne radar, the angular position of a point on the ground is ascertained as a function of the Doppler frequency of an echo signal relating to the point under consideration, as determined by passband filtering the echo signals. The Doppler frequencies are selected by a bank of filters and an angular determination is made by analyzing signals including a signal representing the position in the bank of that filter selecting the Doppler frequency of the echo signal, and a reference frequency subject to closed loop control and representing the true Doppler frequency of the ground. Means are provided for maintaining data relating to the position and the range of the target constant during the process of analysis.
Claims25
A process for the angular discrimination, by a coherent pulse radar carried by a flying missile, of close terrestrial points, which comprises the steps of:
- (a) determining Doppler frequency of close terrestrial points to be discriminated between by narrow passband filtering of the frequencies;
- (b) making an angular determination of the points by analysis based on the determined Doppler frequencies during a period of analysis;
- and
- (c) during the period of said analysis, maintaining the Doppler frequency to be determined at its initial value.
A coherent pulse radar device for use in an airborne craft to discriminate the angular positions of close terrestrial points relatively to the velocity vector of the craft, said device comprising passband filtering means for determining the Doppler frequencies associated with pairs formed by the radar antenna and by the points on the ground illuminated by the radar beam, and means for analyzing said Doppler frequencies to determine the angular positions of said points, said passband filtering means comprising a bank of passband filters and said analyzing means is arranged to compare signals representing the position within the bank of filters of that filter which passes the Doppler frequency corresponding to the point under consideration and a signal from a reference oscillator and corresponding to the true Doppler frequency of the ground, said reference oscillator being provided with means enabling it to be reset for each operation of said analyzing means, by means of a discriminator responsive to the output from said bank of filters.
A coherent pulse radar device for use in an airborne craft to discriminate the angular positions of close terrestrial points relatively to the velocity vector of the craft, said device comprising passband filtering means for determining the Doppler frequencies associated with pairs formed by the radar antenna and by the points on the ground illuminated by the radar beam, and means for analyzing said Doppler frequencies to determine the angular positions of said points, stabilizing means being provided for maintaining said Doppler frequencies constant during each analyzing period.
A coherent pulse radar device for use in an airborne craft to discriminate the angular positions of close terrestrial points relatively to the velocity vector of the craft, said device comprising passband filtering means for determining the Doppler frequencies associated with pairs formed by the radar antenna and by the points on the ground illuminted by the radar beam, and means for analyzing said Doppler frequencies to determine the angular positions of said points, means being provided for varying a recurrence frequency of the transmitted radar pulse in accordance with the position of the radar antenna.
A coherent pulse radar device for use in an airborne craft to discriminate the angular positions of close terrestrial points relatively to the velocity vector of the craft, said device comprising passband filtering means for determining the Doppler frequencies associated with pairs formed by the radar antenna and by the points on the ground illuminated by the radar beam, and means for analyzing said Doppler frequencies to determine the angular positions of said points, said device including a stabilizing means for maintaining data relating to target range constant.
Dependencies are inferred from the claim text.