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Linear frequency modulation pulse signal frequency modulation bandwidth selection method applied to ultra-low-altitude detection

A technology of linear frequency modulation pulse and frequency modulation bandwidth, which is applied in the direction of radio wave measurement systems, instruments, etc., can solve the problems of radar angle measurement error increase, target signal splitting, radar beam deviating from the direction of target signal, etc., and achieve the effect of small angle error

Pending Publication Date: 2022-02-25
AIR FORCE UNIV PLA
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  • Application Information

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Problems solved by technology

However, when the frequency modulation bandwidth is increased to a certain extent, the target signal may be split on the one-dimensional echo range image or the two-dimensional range-Doppler image, which will cause the radar angle measurement error to increase, making the radar beam deviate from the target signal direction

Method used

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  • Linear frequency modulation pulse signal frequency modulation bandwidth selection method applied to ultra-low-altitude detection
  • Linear frequency modulation pulse signal frequency modulation bandwidth selection method applied to ultra-low-altitude detection
  • Linear frequency modulation pulse signal frequency modulation bandwidth selection method applied to ultra-low-altitude detection

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Embodiment 1

[0041] Embodiment 1: A method for selecting the frequency modulation bandwidth of a chirp signal applied to ultra-low altitude detection, comprising the following steps:

[0042] Step 1: For the five constraint conditions, calculate the range of frequency modulation bandwidth under each constraint condition, see figure 1 .

[0043] 1) The FM bandwidth must meet the sampling conditions, namely:

[0044] B≤f s (1)

[0045] Among them, f s is the sampling frequency, the unit is MHz. This condition is the basis of radar signal processing and a limiting condition of the upper bound of the frequency modulation bandwidth.

[0046] 2) Signal-to-clutter ratio SCR must meet the detection conditions, namely:

[0047] B≥B 1 (SCR≥detection threshold) (2)

[0048] Among them, the received radar echo pulse signals are converted into baseband signals through frequency mixing and low-pass filtering, and then pulse compressed to obtain matched filter signals, and then the one-dimensiona...

Embodiment 2

[0068] Embodiment 2: In order to verify the effectiveness and feasibility of the present invention, an example is used to illustrate.

[0069] The radar is an active system, that is, both the transmitting and receiving antennas are inside the radar, the antenna side lobe level is -20dB, the antenna beam points to the center of the target, the incident and receiving are both VV polarization, the operating frequency is in the Ku band, the intermediate frequency is 45MHz, and the sampling frequency f s 180MHz, pulse width 2μs, pulse repetition frequency 100kHz, pulse accumulation number 256, relative permittivity ε r =6–j4, environmental root mean square height h x 1×10 -3 m, the target is a metal cylinder with a diameter of 0.5m and a length of 6m, and its axis is along the x-axis. The radar position vector is S p (3000m, 0m, 1500m), the velocity vector is V s (-200m / s, 0, 0), the target position vector is T p (0, 0, 50m), velocity vector V t is (200m / s, 0, 0), the elevat...

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Abstract

The invention discloses a linear frequency modulation pulse signal frequency modulation bandwidth selection method applied to ultra-low-altitude detection. The Linear frequency modulation pulse signal frequency modulation bandwidth selection method applied to ultra-low-altitude detection comprises the following steps: setting constraint conditions of ultralow-altitude target frequency modulation bandwidth; and obtaining the range of the frequency modulation bandwidth according to the constraint conditions. According to the method, the range of the frequency modulation bandwidth is determined by setting the constraint condition of the frequency modulation bandwidth, in the frequency modulation bandwidth range, the target signal can be correctly detected, the target signal is not split, the target signal and the mirror image interference signal are separated in the one-dimensional distance image and the distance-Doppler image, and the angle error of the target signal is small.

Description

technical field [0001] The invention belongs to the technical field of radar detection ultra-low-altitude target emission waveforms, and in particular relates to a method for selecting frequency modulation bandwidth of a linear frequency modulation pulse signal applied to ultra-low altitude detection. Background technique [0002] There are two main challenges when radar looks down to detect ultra-low-altitude targets. First, the speed of ultra-low-altitude targets is slow, the altitude is low, and the radar scattering cross-sectional area is small, making it difficult for radar to detect and accurately detect target signals. The second is that when the radar looks down to detect ultra-low-altitude targets, it will be subject to two passive interferences, namely: environmental clutter interference under the radar wave irradiation and multi-path echo interference generated by target environment coupling. Environmental clutter interference reduces the radar's detection probab...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S7/282G01S7/40
CPCG01S7/282G01S7/4056
Inventor 孙华龙童创明彭鹏王童宋涛
Owner AIR FORCE UNIV PLA
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