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AssigneeEADS Deutschland GmbH
InventorsBernhard Bickert, Jochen Meyer-Hilberg
Estimating the term…
In a process for computing the radar signals present at the output of two subapertures of an antenna of a two-channel radar system, the two subaperture channels are combined by means of a wave guide part to a sum and difference channel, and the signals of the sum and difference channel are used to compute the radar signals at the subaperture channels. The signals of the two subaperture channels are computed from the amplitude- and phase-shifted sum and difference channel signal by being placed in the following equations: X 1 ( r , f ) = X S ( r , f ) - X D ( r , f ) · exp ( - j Φ 0 ) 2 ( 1 ) X 2 ( r , f ) = a 0 · ( X S ( r , f ) + x D ( r , f ) · exp ( - j Φ 0 2 ) ( 2 ) wherein X1(r,f), X2(r,f): Frequency spectrum of the two subaperture channels; XS(r,f),XD(r,f): Frequency spectrum of the sum and difference channel, r: distance cell, f: Doppler frequency, Φ0: phase correction factor, and a0: amplitude correction factor.
A process for computing radar signals present at subapertures of an antenna of a two-channel radar system, comprising:
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SAR image post-processing techniques: specially adapted for moving target detection within a single SAR image or within multiple SAR images taken…
Of parts of a radar system: of receivers
SAR modes: combined with monopulse techniques
Using transmissions of interrupted pulse modulated waves: based upon the phase or frequency shift resulting from movement of objects, with…
Term ended 23 Sep 2022 (estimated)
This application claims the priority of 101 46 643.9, filed Sep. 21, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process of calibrating the radar signals at the subapertures of the antenna of a two-channel SAR (Synthetic Aperture)/MTI (Moving Target Indication) radar system.
In a two-channel radar system, the two subaperture channels (1, 2) of an antenna (A), in the antenna front end, can be combined by means of a wave guide element (T) (normally a so-called MagicT), to a sum channel (Σ) and a difference (Δ) channel, in a known manner. Such an arrangement is illustrated in FIG. 1, which also shows that the sum (Σ) and difference (Δ) channel signals are fed to analog and digital signal processors (AS, DS).
FIG. 1 is a block diagram which shows the structure of a two channel radar system after the two subapertures in the front end to the digital signal processing;
FIG. 2 shows an example of a distance Doppler image in the sum channel after the detection of the fixed/moving targets;
FIG. 3 is a view of the course of the phase difference between the sum and the difference channel over the normalized frequency in the manner of an example;
For estimating the phase correction factor Φ0, the following computation steps are carried out in an advantageous embodiment of the invention:
computing the Doppler frequency position of the major lobe clutter,
correcting the sum and difference channel signal XS(r,t), XD(r,t), wherein, for each of the various distance gates in the phase, the sum and difference channel signal is shifted as a function of the pulse repetition time into the frequency zero position,