A Non-Cooperative Satellite-Earth Bistatic SAR Time-Frequency Synchronization Method
A satellite-ground dual-base, time-frequency synchronization technology, applied in radio wave reflection/re-radiation, using re-radiation, measurement devices, etc., can solve problems such as weak signal-to-noise ratio of direct wave signals and increased hardware complexity
Active Publication Date: 2016-08-31
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology
This scheme not only increases the hardware complexity, but also has the consistency problem between the two channels
In fact, the direct wave signal from the satellite can enter from the side lobe of the echo antenna. However, due to the small gain of the antenna side lobe and the weak signal-to-noise ratio of the direct wave signal, no one has used it to estimate the synchronization error.
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[0052] The present invention will be described in detail below in conjunction with the drawings.
[0053] The invention provides a time-frequency synchronization method for a non-cooperative one-station fixed satellite-to-ground bistatic SAR, which specifically includes the following steps:
[0054] Step 1. Point the main lobe of the antenna to the scene, receive the scene echo, and the side lobe to receive the direct wave signal from the satellite. When the satellite beam scans the scene, the receiver continuously collects and stores the data;
[0055] Such as figure 1 As shown, a ground-fixed coordinate system is established, in which the satellite moves at a speed V while transmitting signals to illuminate the scene area, T is any point in the scene, the coordinates are (x, y), and A is the antenna.
[0056] First, the signal received by the antenna is expressed as:
[0057] S r (t)=S d (t)+S echo (t)+w′(t) (1)
[0058] S d ( t ) = X n W d ( t ...
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The invention discloses a non-cooperative satellite-ground bistatic SAR (synthetic aperture radar) time-frequency synchronization method. The non-cooperative satellite-ground bistatic SAR time-frequency synchronization method comprises the following steps: carrying out data treatment on signals received by an antenna after two-dimensional division and pulse compression operation; extracting direct wave signal data received by a side lobe in the received signals; suppressing the influence of noise on estimation precision based on the characteristic that the cubic term coefficient of the square of a slope distance history relevant to time is zero and according to the prior information that a satellite orbit is approximate to a straight line in a short synthetic aperture time, so that the synchronization error estimation of the satellite-ground bistatic SAR system is realized under the condition that the signal to noise ratio of direct wave signals received in an antical lobe of the antenna is weak.
Description
Technical field [0001] The invention belongs to the technical field of radar signal processing, and relates to a non-cooperative satellite-to-ground bistatic SAR time-frequency synchronization method. Background technique [0002] Satellite-to-ground bistatic SAR is a bistatic SAR system that uses satellites as the launch platform and receivers placed near the ground. In addition to the all-weather and all-weather observation capabilities of the SAR itself, the bistatic SAR, due to its flexible configuration, is effective in anti-interference, It has unique advantages in forward-looking imaging and interference processing, which has attracted more and more attention. [0003] Based on the satellite-to-ground bistatic SAR system due to the separate transceiver platform, compared with the unistatic SAR signal with the same time axis and local oscillator signal at the transceiver end, the bistatic SAR signal has time and frequency synchronization errors, which will lead to an unknown ...
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IPC IPC(8): G01S7/40G01S13/90
CPCG01S7/2813
Inventor 曾涛田卫明张天胡程
Owner BEIJING INSTITUTE OF TECHNOLOGYGY