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Azimuth ambiguity calculating method of variable pulse recurrence interval airborne SAR

A technique of pulse repetition interval, azimuth ambiguity, applied in the direction of reflection/re-radiation of radio waves, utilization of re-radiation, measurement devices, etc.

Active Publication Date: 2017-04-26
BEIHANG UNIV
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Problems solved by technology

However, under the condition of variable pulse repetition interval, there may be a certain deviation between the transmitted pulse and the echo received pulse. Therefore, there will be a significant difference in the position of the fuzzy area on both sides of the target area, and it cannot be simply determined by the Doppler frequency and spatial angle. Efficient way to complete simple conversion

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  • Azimuth ambiguity calculating method of variable pulse recurrence interval airborne SAR
  • Azimuth ambiguity calculating method of variable pulse recurrence interval airborne SAR
  • Azimuth ambiguity calculating method of variable pulse recurrence interval airborne SAR

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Embodiment 1

[0105] For a typical airborne SAR, the azimuth ambiguity of the system is analyzed, and the specific calculation method is realized through the following steps:

[0106] Step 1: Input the radar system parameters and radar orbit parameters, and initialize the parameters.

[0107] (a) Input radar system parameters (including radar effective speed V is 250m / s, radar operating wavelength λ is 0.032m, azimuth antenna length L a is 1m, the angle of view γ under the antenna is 45 degrees, the Doppler bandwidth is 443Hz, the reference pulse repetition frequency prf is 600Hz and the variable pulse repetition interval sequence t p ) and orbit parameters (including radar height H is 10km);

[0108] (b) Calculate the antenna azimuth beamwidth β according to formula (18) a , according to formulas (19) to (20) to calculate the target position Its coordinates are T x ,T y ,T z and the shortest slope distance T r ;

[0109]

[0110]

[0111] T r =H / cosγ (20)

[0112] Then use...

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Abstract

The invention discloses an azimuth ambiguity calculating method of a variable pulse recurrence interval airborne SAR. The method comprises the following steps of according to a pulse recurrence interval, determining a position of a radar at each pulse emission moment and a target position to be analyzed; determining an echo intensity of a target in a pulse-by-pulse mode and calculating and acquiring an energy sum of the target; and determining an echo intensity of a fuzzy region in the pulse-by-pulse mode, calculating and acquiring total fuzzy energy, and calculating a ratio of total fuzzy region energy and total target energy so as to acquire an azimuth ambiguity. In the invention, a theoretical basis and a realization method are provided for a variable pulse recurrence interval airborne SAR system. A traditional frequency domain analysis method can not be suitable for variable pulse recurrence interval airborne SAR system analysis. Because there is no requirement to antenna pointing at any moments, the method can be suitable for any non-fixed directional antenna SAR systems.

Description

technical field [0001] The invention relates to the technical field of synthetic aperture radar (Synthetic Aperture Radar, SAR), in particular to an azimuth ambiguity calculation method for airborne SAR with variable pulse repetition interval. Background technique [0002] The azimuth ambiguity is caused by the pulse sampling working system of the synthetic aperture radar in the azimuth direction. The Doppler spectrum of the echo signal of the synthetic aperture radar is weighted by the antenna azimuth to the two-way pattern of sending and receiving, and is sampled by the system with the pulse repetition frequency, and the Doppler spectrum higher than the pulse repetition frequency is folded into the azimuth processing bandwidth , mixed with the main signal, so the signal spectrum of the side lobe after sampling will affect the signal in the Doppler bandwidth, resulting in azimuth ambiguity, so the azimuth ambiguity is caused by the working principle of SAR. The impact of a...

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Application Information

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IPC IPC(8): G01S13/90G01S7/41
CPCG01S7/41G01S13/904G01S13/90
Inventor 孙兵李景文谭林姜予名
Owner BEIHANG UNIV