Delay optimization method for linear frequency-modulated signal active cancellation

A technology of linear frequency modulation signal and optimization method, which is applied in the field of active stealth to achieve the effect of improving the cancellation effect and improving the cancellation performance.

Inactive Publication Date: 2017-04-19
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

However, system delay is also an important factor that cannot be ignored

Method used

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  • Delay optimization method for linear frequency-modulated signal active cancellation
  • Delay optimization method for linear frequency-modulated signal active cancellation
  • Delay optimization method for linear frequency-modulated signal active cancellation

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Embodiment Construction

[0037] The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] (1) The output characteristics of the matched filter of the chirp signal

[0039] Complex envelope function of a chirp signal:

[0040]

[0041] In formula (1), μ is the frequency modulation rate, T is the pulse width, Represents a rectangular function with respect to time t and obtains the instantaneous frequency of the chirp signal:

[0042]

[0043] Equation (2) shows that the instantaneous frequency of the chirp signal varies linearly with time.

[0044] The matched filter is the best linear time-invariant filter, which can obtain the maximum output signal-to-noise ratio (SNR) when the input signal-to-noise ratio is constant. When the input noise bilateral power spectral density is N 0 / 2(W / Hz), the expression of the system function of the matched filter is as follows:

[0045]

[0046] In formula (3), k=2α / N 0 , α ...

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Abstract

The invention discloses a delay optimization method for linear frequency-modulated signal active cancellation. First, a mathematical model of a synthetic echo signal after cancellation is built according to the generation process of a cancellation signal; then, an expression of cancellation gain is derived according to the energy change of the echo signal before and after cancellation; and finally, the influence of system delay on amplitude error and phase error of wave absorbing is obtained through numerical calculation, and the system delay is optimized. The cancellation effect is improved, and the cancellation performance of a cancellation system is improved.

Description

technical field [0001] The invention belongs to the technical field of active stealth, and particularly relates to a delay optimization method for active cancellation of linear frequency modulation signals. Background technique [0002] There are roughly five approaches to aircraft radar cross section (RCS) reduction: fuselage shaping, material and structure selection, passive cancellation, active cancellation, and plasma stealth. Among them, active cancellation is a promising direction for modern stealth technology. The active cancellation system can generate and transmit a cancellation signal. The cancellation signal has the same amplitude and frequency as the target echo, but the phase is opposite to that of the target echo, so that the target echo will be cancelled due to the principle of coherent wave interference. In the low frequency band, the traditional passive stealth technology is very ineffective, and at the same time, the difficulty of active cancellation decre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S7/38
CPCG01S7/38
Inventor 汪飞吴海晨李海林周建江
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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