CN113985357A

CN113985357A - Synthetic aperture radar coherent pulse signal generation method

Info

Publication number: CN113985357A
Application number: CN202111306843.0A
Authority: CN
Inventors: 吴赛赛; 陈德民; 牛诚翔
Original assignee: Leihua Electronic Technology Research Institute Aviation Industry Corp of China
Current assignee: Leihua Electronic Technology Research Institute Aviation Industry Corp of China
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2022-01-28

Abstract

The application belongs to the field of radar system design, and particularly relates to a synthetic aperture radar coherent pulse signal generation method. The method comprises the following steps: step one, acquiring a waveform parameter of a radar signal in an imaging mode, and sending the waveform parameter of the radar signal to a signal generation unit, wherein the signal generation unit receives and stores the waveform parameter of the radar signal; step two, the signal generating unit detects the frame pulse signal of the timer in real time, and when the frame pulse signal is detected, the signal generating unit generates a PRF signal according to the waveform parameter of the radar signal and the frame pulse signal; and thirdly, the signal generating unit generates coherent pulse signals according to the PRF signals and the waveform parameters of the radar signals, and sends the coherent pulse signals to the transmitting unit to be amplified and then radiated by the antenna. The radar imaging function stability can be greatly improved, the images obtained after radar imaging are well focused and have no ghost images, and the radar image quality can be effectively improved.

Description

Synthetic aperture radar coherent pulse signal generation method

Technical Field

The application belongs to the field of radar system design, and particularly relates to a synthetic aperture radar coherent pulse signal generation method.

Background

Synthetic aperture radars are widely used for topographic mapping, and during working, the radars continuously transmit a plurality of coherent pulse signals and receive echo signals, and a topographic image with good focus is obtained by synthesizing the echo signals. In the signal acquisition process of each frame of radar image, high coherence is kept between different pulse signals transmitted by the radar, so that the radar can perform subsequent imaging processing. Coherence between pulse signals requires that different pulses have the same starting phase during a frame of an image. The coherent pulse signal is generated by a signal generating unit based on a PRF signal of a timer, the timer and the signal generating unit in the synthetic aperture radar are generally two independent parts, when the radar generates each pulse signal, the initial phase of the pulse signal is determined by sampling and detecting the PRF signal transmitted by the timer by the signal generating unit in a certain period, when the signal generating unit detects the rising edge of the timing signal, the timing signal is considered to be the initial of the timing signal at the moment, and the coherent pulse signal is generated by taking the initial phase as a reference.

The traditional coherent pulse signal generation mode has the following defects: in practice, a PRF signal generated by a timer is an undesirable rectangular wave, a rising edge of the rectangular wave has a certain width, and due to self factors and external interference, a timing signal may have a certain jitter, and a signal generation unit may have a deviation of a sampling clock when sampling and detecting the PRF signal, which may cause a deviation of a sampling time interval between adjacent pulse signals, and as a result, when a radar samples an echo signal, a certain deviation may occur between adjacent pulses, coherence between different pulse signals during a frame of image becomes poor, and a ghost and defocus phenomenon may occur in an imaged radar image.

Accordingly, a technical solution is desired to overcome or at least alleviate at least one of the above-mentioned drawbacks of the prior art.

Disclosure of Invention

The present application is directed to a method for generating coherent pulse signals for synthetic aperture radar, which solves at least one of the problems of the prior art.

The technical scheme of the application is as follows:

a method for generating a coherent pulse signal for a synthetic aperture radar, comprising:

the method comprises the steps of firstly, acquiring waveform parameters of radar signals in an imaging mode, sending the waveform parameters of the radar signals to a signal generation unit, and receiving and storing the waveform parameters of the radar signals by the signal generation unit;

step two, the signal generating unit detects a frame pulse signal of a timer in real time, and when the frame pulse signal is detected, the signal generating unit generates a PRF signal according to the waveform parameter of the radar signal and the frame pulse signal;

and thirdly, the signal generating unit generates a coherent pulse signal according to the PRF signal and the waveform parameters of the radar signal, and sends the coherent pulse signal to a transmitting unit for amplification and then radiates the coherent pulse signal out through an antenna.

In at least one embodiment of the present application, the waveform parameters of the radar signal include a pulse period, a pulse width, a chirp rate, and a time delay.

In at least one embodiment of the present application, the imaging mode includes a 1m resolution mode.

The invention has at least the following beneficial technical effects:

the coherent pulse signal generation method of the synthetic aperture radar can be used for time sequence control of coherent pulse signal generation in the imaging function of the synthetic aperture radar and effectively improve the image quality of the radar.

Drawings

FIG. 1 is a schematic diagram of a coherent pulse signal generated by the prior art;

fig. 2 is a schematic diagram of a coherent pulse signal according to an embodiment of the present application.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are a subset of the embodiments in the present application and not all embodiments in the present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present application and for simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore should not be construed as limiting the scope of the present application.

The present application is described in further detail below with reference to fig. 1-2.

The application provides a method for generating coherent pulse signals of a synthetic aperture radar, which comprises the following steps:

step one, acquiring a waveform parameter of a radar signal in an imaging mode, and sending the waveform parameter of the radar signal to a signal generation unit, wherein the signal generation unit receives and stores the waveform parameter of the radar signal;

step two, the signal generating unit detects the frame pulse signal of the timer in real time, and when the frame pulse signal is detected, the signal generating unit generates a PRF signal according to the waveform parameter of the radar signal and the frame pulse signal;

and thirdly, the signal generating unit generates coherent pulse signals according to the PRF signals and the waveform parameters of the radar signals, and sends the coherent pulse signals to the transmitting unit to be amplified and then radiated by the antenna.

According to the method for generating the coherent pulse signal of the synthetic aperture radar, after a radar is switched to a certain imaging mode, system control software sends waveform parameters of the radar signal in the imaging mode to a signal generation unit, the waveform parameters of the radar signal comprise a pulse period, a pulse width, a frequency modulation slope and time delay, and the signal generation unit stores the information after receiving the waveform parameters of the radar signal; the signal generating unit detects the frame pulse signal of the timer in real time, and generates a PRF signal by combining the previously stored waveform parameter information with the signal generating unit after the frame pulse signal of the timer is detected; and finally, the signal generating unit generates a highly stable coherent pulse signal according to the self-generated PRF signal and the previously stored waveform parameter information, and the coherent pulse signal is sent to the transmitting unit for amplification and then radiated by an antenna.

In a preferred embodiment of the present application, the generation of a waveform of a synthetic aperture radar is taken as an example for illustration. In this embodiment, the radar imaging resolution is 1m, and the waveform parameters of the radar signal include: the pulse period is 4.096s, the pulse width is 20us, the frequency modulation slope is 1 x 10^13, and the pulse delay is 40 us. Wherein PRF is 1000Hz, the radar generates coherent pulse signals as follows, as shown in fig. 2:

when the radar is switched to work in an imaging mode with the resolution of 1m, the radar system control software sends the waveform parameter information of the radar signal to the signal generating unit;

the signal generating unit detects a frame pulse signal of the timer at fs frequency, and generates a PRF signal according to the previously stored waveform parameter information by the signal generating unit after the frame pulse signal of the timer is detected;

the signal generating unit generates a coherent pulse signal according to a timing pulse PRF signal generated by the signal generating unit and the waveform parameter information stored in advance.

According to the method for generating the coherent pulse signal of the synthetic aperture radar, during a frame of image, the signal generating unit only detects the frame signal, and generates the PRF signal according to the frame signal and other waveform parameters, so that the problem that the signal generating unit deviates one sampling clock at any time when the PRF signal transmitted from the timer is sampled for many times is avoided, the high coherence among different radar pulse signals is ensured during the frame of image, and a radar image with good focusing is obtained.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for generating coherent pulse signals for synthetic aperture radar, comprising:

2. The method of generating a synthetic aperture radar coherent pulse signal according to claim 1, wherein the waveform parameters of the radar signal include pulse period, pulse width, chirp rate, and delay.

3. The method for synthetic aperture radar coherent pulse signal generation according to claim 1, wherein the imaging mode comprises a 1m resolution mode.