WO2019196371A1 - 一种基于单频时变阈值的一比特回波数据采集方法及系统 - Google Patents

一种基于单频时变阈值的一比特回波数据采集方法及系统 Download PDF

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WO2019196371A1
WO2019196371A1 PCT/CN2018/110452 CN2018110452W WO2019196371A1 WO 2019196371 A1 WO2019196371 A1 WO 2019196371A1 CN 2018110452 W CN2018110452 W CN 2018110452W WO 2019196371 A1 WO2019196371 A1 WO 2019196371A1
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varying threshold
bit
sar
frequency time
echo
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PCT/CN2018/110452
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French (fr)
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赵博
黄磊
孙维泽
何春龙
张沛昌
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深圳大学
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques

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  • the present invention relates to the field of signal processing technologies, and in particular, to a method and system for acquiring a bit echo data based on a single frequency time varying threshold.
  • SAR synthetic aperture radar
  • the technical problem to be solved by the present invention is to provide a single-frequency time-varying threshold-based one-bit echo data acquisition method and system for solving the above-mentioned defects of the prior art, aiming at solving the one-bit sampling SAR in the prior art.
  • the echo data acquisition, storage, transmission, and processing processes are complicated, low in efficiency, and it is difficult to ensure image quality and the like.
  • a single-frequency time-varying threshold-based one-bit echo data acquisition method wherein the method includes:
  • Step A The SAR transmits a chirp signal to the detected target
  • Step B The SAR receiver receives an echo signal reflected back by the detected target, and generates a single frequency time varying threshold;
  • Step C Perform one-bit quantization processing on the echo signal by using the single-frequency time-varying threshold
  • Step D The SAR repeatedly transmits a chirp signal to the detected target, and repeats steps A to C to obtain one-bit SAR echo data.
  • step D further includes:
  • Step E imaging the acquired one-bit SAR echo data by using an imaging algorithm, and outputting the imaging result.
  • step B specifically includes:
  • Step B1 The chirp signal emitted by the SAR is propagated to the detected target; and reflected by the detected target;
  • Step B2 The SAR receiver receives the reflected echo signal, and samples the received echo signal at a predetermined sampling rate to obtain an echo signal sampling sequence.
  • Step B3 The SAR receiver generates a single frequency time varying threshold, and samples the single frequency time varying threshold at the sampling rate.
  • step B further includes:
  • the echo signal sample sequence and the single frequency time varying threshold are represented in the form of a vector.
  • the single-frequency time-varying threshold-based one-bit echo data acquisition method wherein the single-frequency time-varying threshold in the step B3 is generated by: the SAR receiver generates by using a local oscillator or a direct digital frequency synthesizer Single frequency time varying threshold.
  • the single-frequency time-varying threshold-based one-bit echo data acquisition method wherein the step C includes: performing one-bit quantization on the echo signal by using a time-varying threshold of a sawtooth wave or a time-varying threshold of a triangular wave. deal with.
  • step C specifically includes:
  • Step C1 sequentially comparing the vector form of the echo signal sampling sequence with the corresponding element in the vector form of the single frequency time varying threshold
  • Step C2 If the element in the echo signal sampling sequence is larger than the element in the single-frequency time-varying threshold, the echo data is stored as 1;
  • Step C3 If the element in the echo signal sampling sequence is smaller than the element in the single-frequency time-varying threshold, the echo data is stored as 0.
  • a single-bit time-varying threshold-based one-bit echo data acquisition system according to any one of the preceding claims, wherein the system comprises:
  • a detected target configured to receive the chirp signal and reflect the chirp signal
  • the SAR receiver is configured to receive an echo signal reflected by the detected target, and perform one-bit quantization processing on the echo signal by using a single-frequency time-varying threshold; the SAR receiver is disposed on the SAR.
  • the single-frequency time-varying threshold-based one-bit echo data acquisition system wherein the SAR receiver further comprises: generating a single-frequency time-varying threshold by using a local oscillator or a direct digital frequency synthesizer.
  • the single-frequency time-varying threshold-based one-bit echo data acquisition system wherein the SAR receiver is further configured to perform the echo signal by using a time-varying threshold of a sawtooth wave or a time-varying threshold of a triangular wave. Bit quantization processing.
  • the invention has the beneficial effects that the present invention utilizes a single-frequency time-varying threshold to perform one-bit quantization processing on the echo signal, thereby obtaining one-bit echo data, which simplifies the collection complexity and cost of the echo data, and improves the data collection efficiency. And can achieve similar imaging quality as conventional SAR.
  • FIG. 1 is a flow diagram of a preferred embodiment of a one-bit echo data acquisition method based on a single frequency time varying threshold.
  • FIG. 2 is a SAR imaging result diagram of a one-bit echo data acquisition method based on the present invention.
  • FIG. 3 is a SAR imaging result diagram based on a conventional echo data acquisition method.
  • FIG. 4 is a schematic block diagram of a one-bit echo data acquisition system based on a single frequency time varying threshold of the present invention.
  • SAR imaging has all-day, all-weather, far-distance, high-resolution detection capabilities, and plays an important role in many fields such as remote sensing mapping, regional detection, geological exploration, disaster relief, etc. It is a research hotspot for scholars at home and abroad.
  • the burden of data acquisition, storage, transmission, and processing increases.
  • the SAR system needs high-precision sampling of echo data, which retains the complete signal characteristics, resulting in an increase in data processing bit width and higher requirements on the hardware performance of the system.
  • the signal sampling rate is also required.
  • the aliasing of the signal spectrum is avoided to increase the amount of data and reduce the efficiency of data processing.
  • FIG. 1 is a flow chart of a preferred embodiment of a single-frequency time-varying threshold-based one-bit echo data acquisition method according to the present invention.
  • the single-frequency time-varying threshold-based one-bit echo data acquisition method includes the following steps:
  • Step S100 The SAR transmits a chirp signal to the detected target.
  • a SAR synthetic aperture radar
  • T r The duration of the pulse is T r , assuming t r at a certain time in T r , the frequency of the signal is centered on the carrier frequency f c , and increases with the increase of t r , and the rate of change is ⁇ . Therefore, the form of the chirp signal can be expressed by:
  • step S200 the SAR receiver receives the echo signal reflected back by the detected target, and generates a single frequency time varying threshold.
  • the chirp signal transmitted by the SAR is propagated to the detected target; the detected target reflects the signal, and the reflected echo signal is received by the SAR receiver.
  • the SAR receiver receives the received echo signal at a predetermined sampling rate to obtain a sequence of echo signal samples, and represents the sequence of echo signal samples in the form of a vector.
  • the echo signal received by the SAR can be expressed as:
  • an echo signal sampling sequence can be obtained, which can be represented as an M ⁇ 1 vector S.
  • the s m represents the mth number of S, where 1 ⁇ m ⁇ M, then S can be expressed as [s 1 , s 2 , ..., s m , ..., s M ].
  • the SAR receiver generates a single frequency time varying threshold, and samples the single frequency time varying threshold at the sampling rate, and also represents the single frequency time varying threshold in the form of a vector.
  • the SAR receiver can generate a single-frequency time-varying threshold by using a local oscillator or a direct digital synthesizer (DDS), and its frequency is f 0 , and the phase is among them Is a number that varies randomly within the range [-1,1].
  • DDS direct digital synthesizer
  • a s represents the amplitude of the single-frequency time-varying threshold, and its value is the maximum value of the amplitude of the echo signal.
  • the single-frequency time-varying threshold is sampled by F s , and the threshold can be expressed as an M ⁇ 1 vector h, that is, [h 1 , h 2 , . . . , h m , . . . , h M ].
  • step S300 the echo signal is subjected to one-bit quantization processing by using the single-frequency time-varying threshold.
  • the present invention sequentially compares the vector form of the echo signal sampling sequence with the corresponding element in the vector form of the single frequency time varying threshold. If the element in the echo signal sampling sequence is larger than the element in the single-frequency time-varying threshold, the echo data is stored as 1; if the element in the echo signal sampling sequence is smaller than the element in the single-frequency time-varying threshold, it will be returned The wave data is stored as 0.
  • the corresponding elements of the vector S and h are sequentially compared, taking the mth element as an example. If s m ⁇ h m , the echo data is stored as 1; if s m ⁇ h m , the echo data is stored as 0.
  • one-bit SAR echo admission data consisting of 0 and 1 can be obtained.
  • the invention utilizes a single-frequency time-varying threshold to perform one-bit quantization on the echo signal, thereby greatly reducing the complexity and implementation difficulty of SAR data acquisition, storage, transmission and processing, and reducing the cost of the SAR system, which is more economical and effective.
  • the single-frequency time-varying threshold may be replaced by a time-varying threshold of a sawtooth wave or a triangular wave, that is, the echo signal is subjected to one-bit quantization processing using a time-varying threshold of the sawtooth wave or a time-varying threshold of the triangular wave.
  • other forms of time varying thresholds are also within the scope of the present invention.
  • each data is represented as a binary number consisting of 0 or 1.
  • its binary representation is 11.
  • 0 means positive and 1 means negative
  • ie 3 means 011 and -3 means 111.
  • Each bit of the binary occupies 1 bit (1 bit) of the storage space, 8 bits is a byte (Byte), and 1 MB of the storage space can store 1048576 bytes.
  • the data is quantized into 16 bits, and the present invention quantizes the data into 1 bit, so the amount of data stored and transmitted is reduced to 1/16, which simplifies the storage and transmission of the echo data. .
  • the present invention quantizes data to 1 bit and performs 16-bit quantization with respect to conventional data, the complexity and cost of the required analog-to-digital converter (ADC) are lower.
  • ADC analog-to-digital converter
  • some multiplication budgets are required during SAR imaging, and the invention is also performed in binary form. Taking 3 ⁇ 3 as an example (acquisition data ⁇ matched filter), the binary calculation required to be performed is 011 ⁇ 011.
  • the invention quantizes the data into 1 bit, so it is only 0 or 1, so it is 0 ⁇ 011 (1 bit acquisition data ⁇ matched filter), and the specific calculation method is to logically operate the symbol bit 0 in 1 bit data 0 and 011. Implementation, greatly reducing the complexity of the hardware and the cost, can achieve similar imaging quality with traditional SAR.
  • step S400 the SAR repeatedly transmits a chirp signal to the detected target, and repeats steps S100 to S300 to obtain one-bit SAR echo data.
  • the present invention causes the SAR to repeatedly transmit a chirp signal to the detected target and to make the single-frequency time-varying threshold Randomly, the received echo signal is subjected to one-bit quantization processing, and the echo data is sequentially stored until the entire process of SAR imaging ends, and one-bit SAR echo data is obtained. Further, after the one-bit SAR echo data is obtained, the acquired one-bit SAR echo data is imaged by using an imaging algorithm, and the imaging result is output.
  • the present invention further requires the interfering machine to acquire the pulse repetition interval of the SAR transmission signal by means of electronic reconnaissance, wherein the pulse repetition interval is that the SAR continuously transmits the pulse signal for a certain period of time to perform imaging, and the adjacent two are adjacent. The time interval between the pulse signals.
  • a series of normalized processes such as distance pulse compression, distance warping correction, and azimuth compression are required to obtain a SAR image.
  • FIG. 2 is a SAR imaging result diagram based on the one-bit echo data acquisition method of the present invention.
  • FIG. 3 is a SAR imaging result diagram based on a conventional echo data acquisition method. Since the present invention quantizes the echo data into one bit, the complexity of data acquisition, storage, transmission, and operation is greatly simplified. Compared with FIG. 3, the targets of buildings, roads, vehicles, and the like in the scene in FIG. 2 are still better. The ground is resolved, and the image quality similar to that of the conventional SAR can be obtained.
  • the present invention provides a one-bit echo data acquisition system based on a single frequency time varying threshold, as shown in FIG.
  • the system includes: a SAR (synthetic aperture radar) 100 for repeatedly transmitting a chirp signal to the detected target; a detected target 200; for receiving the chirp signal, and the linear a frequency modulated pulse signal reflection; the SAR receiver 110 is configured to receive an echo signal reflected by the detected target, and perform one-bit quantization processing on the echo signal by using a single frequency time varying threshold; the SAR receiver 110 is disposed at On the SAR 100.
  • a SAR synthetic aperture radar
  • the SAR receiver 110 further includes generating a single frequency time varying threshold using a local oscillator or a direct digital frequency synthesizer.
  • the single-frequency time-varying threshold may also be replaced by a time-varying threshold of a sawtooth wave or a triangular wave, that is, one-bit quantization processing of the echo signal by using a time-varying threshold of a sawtooth wave or a time-varying threshold of a triangular wave. Specifically as described in the examples.
  • the invention utilizes a single-frequency time-varying threshold to perform one-bit quantization on the echo signal, which greatly reduces the complexity and implementation difficulty of SAR data acquisition, storage, transmission and processing, reduces the cost of the SAR system, and improves the imaging quality.
  • the present invention provides a single-frequency time-varying threshold-based one-bit echo data acquisition method and system, the method comprising: the SAR transmitting a chirp signal to a detected target; and the SAR receiver receiving the SAR receiver Detecting an echo signal reflected back by the target, and generating a single-frequency time-varying threshold; performing one-bit quantization processing on the echo signal by using the single-frequency time-varying threshold; the SAR repeatedly transmitting a chirp signal to the detected target And repeatedly receiving the echo signal and performing one-bit quantization on the echo signal to obtain one-bit SAR echo data.
  • the present invention utilizes a single-frequency time-varying threshold to perform one-bit quantization processing on the echo signal, thereby obtaining one-bit echo data, which simplifies the collection complexity and cost of the echo data, improves the data collection efficiency, and can obtain the traditional Similar imaging quality of SAR.

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Abstract

一种基于单频时变阈值的一比特回波数据采集方法及系统，方法包括：SAR向被探测目标发射线性调频脉冲信号（S100）；SAR接收机接收经被探测目标反射回的回波信号，并产生单频时变阈值（S200）；利用单频时变阈值对回波信号进行一比特量化处理（S300）；SAR重复向被探测目标发射线性调频脉冲信号，并重复接收回波信号以及对回波信号进行一比特量化，得到一比特SAR回波数据（S400）。利用单频时变阈值对回波信号进行一比特量化处理，从而得到一比特回波数据，有效简化了回波数据的采集复杂程度以及成本，提高了数据采集效率，能够获得与传统SAR相似的成像质量。

Description

一种基于单频时变阈值的一比特回波数据采集方法及系统 技术领域
本发明涉及信号处理技术领域，具体涉及一种基于单频时变阈值的一比特回波数据采集方法及系统。
背景技术
SAR(synthetic aperture radar，合成孔径雷达)成像具有全天时、全天候、远作用距离、高分辨的探测能力，在遥感测绘、区域检测、地质勘探、灾难救援等众多领域发挥着重要的作用，是国内外学者的研究热点。但随着SAR信号带宽的增加，其数据采集、存储、传输、处理的负担逐渐加重。
为了简化数据采集、存储、传输、处理的复杂程度，现有技术中也有基于一比特采样的SAR成像解决方案，来降低了成像处理的数据量，简化了成像处理实现复杂度，但是传统的一比特量化是将回波数据与0进行比较，会造成信号幅度信息的丢失，影响成像质量。虽然现有技术中也有将时变阈值引入一比特采样中，例如引入随机时变阈值以及高斯时变阈值，但是其适用场景有限，难以在SAR成像的非稀疏场景中进行应用，且难以保证成像质量。
因此，现有技术还有待于改进和发展。
发明内容
本发明要解决的技术问题在于，针对现有技术的上述缺陷，提供一种基于单频时变阈值的一比特回波数据采集方法及系统，旨在解决现有技术中的一比特采样的SAR成像方法中回波数据采集、存储、传输、处理过程复杂、效率低，且难以保证成像质量等问题。
本发明解决技术问题所采用的技术方案如下：
一种基于单频时变阈值的一比特回波数据采集方法，其中，所述方法包括：
步骤A、SAR向被探测目标发射线性调频脉冲信号；
步骤B、SAR接收机接收经被探测目标反射回的回波信号，并产生单频时 变阈值；
步骤C、利用所述单频时变阈值对所述回波信号进行一比特量化处理；
步骤D、所述SAR重复向被探测目标发射线性调频脉冲信号，并重复执行步骤A至步骤C，得到一比特SAR回波数据。
所述的基于单频时变阈值的一比特回波数据采集方法，其中，所述步骤D之后还包括：
步骤E、利用成像算法对采集到的一比特SAR回波数据进行成像处理，输出成像结果。
所述的基于单频时变阈值的一比特回波数据采集方法，其中，所述步骤B中具体包括：
步骤B1、所述SAR发射的线性调频脉冲信号传播到被探测目标；并经所述被探测目标反射；
步骤B2、所述SAR接收机接收反射的回波信号，并以预定的采样率对接收到的回波信号采样，得到回波信号采样序列；
步骤B3、所述SAR接收机产生单频时变阈值，并以所述采样率对所述单频时变阈值进行采样。
所述的基于单频时变阈值的一比特回波数据采集方法，其中，所述步骤B还包括：
将所述回波信号采样序列以及所述单频时变阈值以向量的形式表示。
所述的基于单频时变阈值的一比特回波数据采集方法，其中，所述步骤B3中单频时变阈值的产生方式包括：SAR接收机利用本地振荡器或者直接数字式频率合成器产生单频时变阈值。
所述的基于单频时变阈值的一比特回波数据采集方法，其中，所述步骤C中包括：利用锯齿波的时变阈值或者三角波的时变阈值对所述回波信号进行一比特量化处理。
所述的基于单频时变阈值的一比特回波数据采集方法，其中，所述步骤C具体包括：
步骤C1、将回波信号采样序列的向量形式与单频时变阈值的向量形式中的对应元素依次进行比较；
步骤C2、若回波信号采样序列中的元素大于单频时变阈值中的元素，则将回波数据存储为1；
步骤C3、若回波信号采样序列中的元素小于单频时变阈值中的元素，则将回波数据存储为0。
一种基于上述任一项所述的基于单频时变阈值的一比特回波数据采集系统，其中，所述系统包括：
SAR，用于重复向被探测目标发射线性调频脉冲信号；
被探测目标，用于接收所述线性调频脉冲信号，并将所述线性调频脉冲信号反射；
SAR接收机，用于接收经被探测目标反射的回波信号，并利用单频时变阈值对所述回波信号进行一比特量化处理；所述SAR接收机设置在所述SAR上。
所述的基于单频时变阈值的一比特回波数据采集系统，其中，所述SAR接收机还包括：利用本地振荡器或者直接数字式频率合成器产生单频时变阈值。
所述的基于单频时变阈值的一比特回波数据采集系统，其中，所述SAR接收机还用于，利用锯齿波的时变阈值或者三角波的时变阈值对所述回波信号进行一比特量化处理。
本发明的有益效果：本发明利用单频时变阈值对回波信号进行一比特量化处理，从而得到一比特回波数据，有效简化了回波数据的采集复杂程度以及成本，提高了数据采集效率，且能够获得与传统SAR相似的成像质量。
附图说明
图1是基于单频时变阈值的一比特回波数据采集方法的较佳实施例的流程 图。
图2是基于本发明的一比特回波数据采集方法的SAR成像结果图。
图3是基于传统的回波数据采集方法的SAR成像结果图。
图4是本发明基于单频时变阈值的一比特回波数据采集系统的原理框图。
具体实施方式
为使本发明的目的、技术方案及优点更加清楚、明确，以下参照附图并举实施例对本发明进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
SAR成像具有全天时、全天候、远作用距离、高分辨的探测能力，在遥感测绘、区域检测、地质勘探、灾难救援等众多领域发挥着重要的作用，是国内外学者的研究热点。但随着SAR信号带宽的增加，其数据采集、存储、传输、处理的负担逐渐加重。一方面，SAR系统需要对回波数据进行高精度的采样已保留完整的信号特征，导致数据处理位宽增加，对系统的硬件性能提出了更高的要求；另一方面，信号采样率也需要相应地提升以避免信号频谱的混叠，从而使得数据量增加，降低了数据处理的效率。因此，对于研究低复杂度、高效率的SAR回波数据采集方法很有必要。本发明提供一种基于深度残差网络的细胞分类方法，如图1所示，图1是本发明基于单频时变阈值的一比特回波数据采集方法的较佳实施例的流程图。所述基于单频时变阈值的一比特回波数据采集方法包括以下步骤：
步骤S100、SAR向被探测目标发射线性调频脉冲信号。
具体地，SAR(syntheticapertureradar，合成孔径雷达)向被探测目标发射线性调频脉冲信号。脉冲的持续时间为T r，假设在T r内的某一时刻为t r，信号的频率以载波频率f c为中心，随着t r的增加而增大，其变化率为γ。因此，线性调频脉冲信号的形式可以用下式表示：
Figure PCTCN2018110452-appb-000001
进一步地，步骤S200、SAR接收机接收经被探测目标反射回的回波信号，并产生单频时变阈值。
具体地，所述SAR发射的线性调频脉冲信号传播到被探测目标；所述被探测目标对信号进行反射，反射的回波信号被SAR接收机接收。SAR接收机接收以预定的采样率对接收到的回波信号采样，得到回波信号采样序列，并将所述回波信号采样序列以向量的形式表示。
假设从发射信号到接收到回波的时间为τ，而目标的后向散射系数为σ，则SAR接收到的回波信号可以表示为：
Figure PCTCN2018110452-appb-000002
假设以采样率F s对接收到的信号进行采样，可以得到一个回波信号采样序列，这个序列可以表示为一个M×1的向量S。用s m表示S的第m个数，其中1≤m≤M，则S可以表示为[s 1,s 2,…,s m,…,s M]。
进一步地，所述SAR接收机产生单频时变阈值，并以所述采样率对所述单频时变阈值进行采样，并将所述单频时变阈值也以向量的形式表示。
在本实施例中，所述SAR接收机可以利用本地振荡器或者直接数字式频率合成器(DirectDigitalSynthesizer，DDS)的方式产生单频时变阈值，它的频率为f 0，相位为
Figure PCTCN2018110452-appb-000003
其中
Figure PCTCN2018110452-appb-000004
是一个在[-1,1]范围内随机变化的数。具体形式为：
Figure PCTCN2018110452-appb-000005
其中A s表示单频时变阈值的幅度，它的取值为回波信号幅度的最大值。同样以F s对单频时变阈值进行采样，则阈值可以表示为一个M×1的向量h，即[h 1,h 2,…,h m,…,h M]。
进一步地，步骤S300、利用所述单频时变阈值对所述回波信号进行一比特量化处理。
具体实施时，本发明将回波信号采样序列的向量形式与单频时变阈值的向量形式中的对应元素依次进行比较。若回波信号采样序列中的元素大于单频时变阈值中的元素，则将回波数据存储为1；若回波信号采样序列中的元素小于单频时变阈值中的元素，则将回波数据存储为0。例如将向量S与h的对应元素依次进行比较，以第m个元素为例，若s m≥h m，将回波数据存储为1；若s m＜h m将回波数据存储为0。从而可以得到由0和1组成的一比特SAR回波录取数据。
本发明利用单频时变阈值对回波信号进行一比特量化，大大降低了SAR数据采集、存储、传输、处理的复杂度和实现难度，降低了SAR系统的成本，是一种更加经济有效的实现方法。较佳地，所述单频时变阈值还可用锯齿波或者三角波的时变阈值代替，即利用锯齿波的时变阈值或者三角波的时变阈值对所述回波信号进行一比特量化处理。当然，其他形式的时变阈值也应该属于本发明的保护范围。
具体地，由于SAR回波数据的采集、存储、传输、处理的过程都是以数字信号的形式进行，每个数据都被表示为由0或1组成的二进制数字。比方说数字3，它的二进制表示是11。在此基础上，为了进一步表示数字的正负，则会在二进制之前再添加一位符号位，0表示正，1表示负，即3表示为011，-3表示为111。二进制的每一位数占据存储空间1位(1bit)，8bit则是一个字节(Byte)，1MB的存储空间可以存储1048576字节。在传统的回波数据采集方法中是把数据量化为16bit，而本发明是将数据量化为1bit，因此存储、传输的数据量都降为1/16，有效简化了回波数据的存储与传输。
并且，由于本发明将数据量化为1bit，相对于传统的数据进行16bit量化，所需要的模数转换器(ADC)的复杂度以及成本更加低。此外，在SAR成像的过程中需要进行一些乘法预算，本发明同样是以二进制的形式进行。以3×3为例(采集数据×匹配滤波器)，需要进行的二进制计算式为011×011。本发明把数据量化为1bit，因此只有0或者1，所以就是0×011(1bit采集数据×匹配滤波器)，具体的计算方法就是将1bit数据0和011中的符号位0进行逻辑运算就可实现，大大降低了硬件的复杂深度以及成本，能够获得与传统SAR相似的成像质量。
进一步地，步骤S400、所述SAR重复向被探测目标发射线性调频脉冲信号，并重复执行步骤S100至步骤S300，得到一比特SAR回波数据。
本发明使所述SAR重复向被探测目标发射线性调频脉冲信号，并使单频时变阈值中的
Figure PCTCN2018110452-appb-000006
随机变化，重复对接收的回波信号进行一比特量化处理，并将回波数据依次存储，直至SAR成像的整个过程结束，得到一比特SAR回波数据。进一步地，当得到一比特SAR回波数据之后，利用成像算法对采集到的一比特SAR回波数据进行成像处理，输出成像结果。较佳地，本发明还需要干扰机通过电子侦察的手段来获取SAR发射信号的脉冲重复间隔，所述脉冲重复间隔为SAR通过在一定的时间段内连续发射脉冲信号进行成像，相邻两个脉冲信号之间的时间间隔。在成像过程中，当SAR接收机接收到回波信号之后，需要进行距离脉冲压缩、距离弯曲校正、方位压缩等一系列规范化的处理然后得到SAR图像。
为了进一步说明采用本发明方法所采集的回波数据的成像质量优于使用传统方法采集的回波数据的成像质量，本发明通过仿真实验进行比对。如图2和图3所示，图2基于本发明的一比特回波数据采集方法的SAR成像结果图。图3是基于传统的回波数据采集方法的SAR成像结果图。由于本发明是将回波数据量化成一比特，大大简化了数据采集、存储、传输、运算的复杂度，相对于图3，图2中的场景中的建筑、道路、车辆等目标依然能够较好地分辨，且能够获得与传统SAR相似的成像质量。
基于上述实施例，本发明提供了一种基于单频时变阈值的一比特回波数据采 集系统，如图4所示。所述系统包括：SAR(synthetic aperture radar，合成孔径雷达)100，用于重复向被探测目标发射线性调频脉冲信号；被探测目标200；用于接收所述线性调频脉冲信号，并将所述线性调频脉冲信号反射；SAR接收机110，用于接收经被探测目标反射的回波信号，并利用单频时变阈值对所述回波信号进行一比特量化处理；所述SAR接收机110设置在所述SAR100上。
进一步地，所述SAR接收机110还包括：利用本地振荡器或者直接数字式频率合成器产生单频时变阈值。在本发明中，所述单频时变阈值还可以用锯齿波或者三角波的时变阈值代替,即利用锯齿波的时变阈值或者三角波的时变阈值对所述回波信号进行一比特量化处理；具体如述实施例所述。
本发明利用单频时变阈值对回波信号进行一比特量化，大大降低了SAR数据采集、存储、传输、处理的复杂度和实现难度，降低了SAR系统的成本，提高了成像质量。
综上所述，本发明提供的一种基于单频时变阈值的一比特回波数据采集方法及系统，所述方法包括：SAR向被探测目标发射线性调频脉冲信号；SAR接收机接收经被探测目标反射回的回波信号，并产生单频时变阈值；利用所述单频时变阈值对所述回波信号进行一比特量化处理；所述SAR重复向被探测目标发射线性调频脉冲信号，并重复接收回波信号以及对回波信号进行一比特量化，得到一比特SAR回波数据。本发利用单频时变阈值对回波信号进行一比特量化处理，从而得到一比特回波数据，有效简化了回波数据的采集复杂程度以及成本，提高了数据采集效率，且能够获得与传统SAR相似的成像质量。
应当理解的是，本发明的应用不限于上述的举例，对本领域普通技术人员来说，可以根据上述说明加以改进或变换，所有这些改进和变换都应属于本发明所附权利要求的保护范围。

Claims (10)

  1. 一种基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述方法包括：
    步骤A、SAR向被探测目标发射线性调频脉冲信号；
    步骤B、SAR接收机接收经被探测目标反射回的回波信号，并产生单频时变阈值；
    步骤C、利用所述单频时变阈值对所述回波信号进行一比特量化处理；
    步骤D、所述SAR重复向被探测目标发射线性调频脉冲信号，并重复执行步骤A至步骤C，得到一比特SAR回波数据。
  2. 根据权利要求1中所述的基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述步骤D之后还包括：
    步骤E、利用成像算法对采集到的一比特SAR回波数据进行成像处理，输出成像结果。
  3. 根据权利要求1中所述的基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述步骤B中具体包括：
    步骤B1、所述SAR发射的线性调频脉冲信号传播到被探测目标；并经所述被探测目标反射；
    步骤B2、所述SAR接收机接收反射的回波信号，并以预定的采样率对接收到的回波信号采样，得到回波信号采样序列；
    步骤B3、所述SAR接收机产生单频时变阈值，并以所述采样率对所述单频时变阈值进行采样。
  4. 根据权利要求3中所述的基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述步骤B还包括：
    将所述回波信号采样序列以及所述单频时变阈值以向量的形式表示。
  5. 根据权利要求3中所述的基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述步骤B3中单频时变阈值的产生方式包括：SAR接收机利用本 地振荡器或者直接数字式频率合成器产生单频时变阈值。
  6. 根据权利要求1中所述的基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述步骤C中包括：利用锯齿波的时变阈值或者三角波的时变阈值对所述回波信号进行一比特量化处理。
  7. 根据权利要求1中所述的基于单频时变阈值的一比特回波数据采集方法，其特征在于，所述步骤C具体包括：
    步骤C1、将回波信号采样序列的向量形式与单频时变阈值的向量形式中的对应元素依次进行比较；
    步骤C2、若回波信号采样序列中的元素大于单频时变阈值中的元素，则将回波数据存储为1；
    步骤C3、若回波信号采样序列中的元素小于单频时变阈值中的元素，则将回波数据存储为0。
  8. 一种基于权利要求1-7任一项所述的基于单频时变阈值的一比特回波数据采集系统，其特征在于，所述系统包括：
    SAR，用于重复向被探测目标发射线性调频脉冲信号；
    被探测目标，用于接收所述线性调频脉冲信号，并将所述线性调频脉冲信号反射；
    SAR接收机，用于接收经被探测目标反射的回波信号，并利用单频时变阈值对所述回波信号进行一比特量化处理；所述SAR接收机设置在所述SAR上。
  9. 根据权利要求8中所述的基于单频时变阈值的一比特回波数据采集系统，其特征在于，所述SAR接收机还包括：利用本地振荡器或者直接数字式频率合成器产生单频时变阈值。
  10. 根据权利要求8中所述的基于单频时变阈值的一比特回波数据采集系统，其特征在于，所述SAR接收机还用于，利用锯齿波的时变阈值或者三角波的时变阈值对所述回波信号进行一比特量化处理。
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