CN-119805398-B - Non-coherent and coherent accumulation combined processing method based on external radiation source non-cooperative radar

CN119805398BCN 119805398 BCN119805398 BCN 119805398BCN-119805398-B

Abstract

The invention provides a non-coherent and coherent accumulation combined processing method based on an external radiation source radar, firstly, non-coherent accumulation is used for scattered echo after pulse compression to obtain a relative arrival time coarse estimation value, and then, the coherent accumulation is carried out after range selection by combining with the actual requirements of engineering. In order to reduce the operation amount, accurate echo relative arrival time information of each pulse is obtained by utilizing segmented coherent accumulation traversal, the echo is guided to carry out multi-pulse FFT according to the obtained time information, and after the signal to noise ratio is improved, echo signal detection is carried out, and the time difference between the echo and the direct wave is extracted. The combined processing method provided by the invention improves the detection accuracy of the scattered echo relative to the arrival time of the direct wave under the condition of lower operation quantity, more accurately realizes the extraction of the time difference between the direct wave and the scattered echo, realizes the detection accuracy of the scattered echo relative to the arrival time information of the direct wave, and has feasibility and great use value in engineering application.

Inventors

LUO XI
ZHANG YAWEN
JIANG XINGANG
WANG BIN
XU KE
HE YANGYAN

Assignees

上海微波设备研究所（中国电子科技集团公司第五十一研究所）

Dates

Publication Date: 20260508
Application Date: 20241226

Claims (10)

1. The non-coherent and coherent accumulation combined processing method based on the external radiation source radar is characterized by being capable of detecting accurate arrival time information of an echo of the external radiation source radar relative to a direct arrival wave, and specifically comprises the following steps: step 1, according to the echo characteristics of pulse signals, radar with external radiation source received in a period of time Pulse compression is carried out on the echo signals; step 2, non-coherent accumulation is carried out on the echo signals after pulse compression, and the maximum relative arrival time rough estimation value of the echo pulse is found out ; Step 3, rough estimating the value by the relative arrival time according to engineering experience Selecting the time interval of each pulse signal as the reference Is accumulated by coherent integration of part of (C) When the selected section is For the maximum sampling duration, the selected interval is ; The said In the engineering experience, ; Step 4, first go through the front Of pulses Performing phase-coherent accumulation in a time interval, searching the maximum value of the phase-coherent accumulation, and marking the relative arrival time of the echo of each pulse corresponding to the maximum value Traversing again Of pulses Performing coherent accumulation in a time period, searching the maximum value of the coherent accumulation, and marking the echo relative arrival time of each pulse corresponding to the maximum value ; Step 5, utilizing the marked pulse echo to correspond to the relative arrival time Guiding the echo to carry out multi-pulse FFT, carrying out echo signal detection and extracting the time difference between the echo and the direct wave after the signal to noise ratio is improved; The FFT is a fast fourier transform.
2. The method for combining non-coherent and coherent accumulation based on the external radiation source radar according to claim 1 is characterized in that in step 1, the external radiation source radar specifically comprises 1 radar external radiation source which emits a linear frequency modulation pulse signal on the ground, and the radar external radiation source is assumed to start up, meanwhile, an external radiation source receiver on the my side is also started up, at the moment, 1 maneuvering target exists in the air, and at the moment t, the linear frequency modulation pulse signal of the radar external radiation source is as follows: where T is the fast time, A is the signal amplitude, T is the pulse width, Is the carrier frequency of the signal, And at the time t, the scattered echo signal of the nth pulse signal received by the external radiation source receiver is expressed as: Wherein the method comprises the steps of For the n-th echo pulse relative direct wave time delay, for the target with the slow change of the air radar scattering cross section, the target is considered to be in one pulse time
3. The method for combined non-coherent and coherent accumulation based on an external source radar according to claim 2, wherein the direct wave data of each echo pulse is extracted to obtain a carrier frequency result, and the scattered echo signal is guided Performing digital down-conversion to obtain echo data, and performing pulse compression on the echo data after frequency conversion and then storing the echo data; the pulse compression is itself to realize the matched filtering of the signal, so that the impulse response of the matched filter The echo signal is output by the filtering system as: Wherein Represented as a convolution of the two, As a result of the pulse compression, Is that Is used for the transformation of the values.
4. The method for combined processing of non-coherent and coherent accumulation based on external radiation source radar according to claim 1, wherein said non-coherent and coherent accumulation is defined by n pulses received continuously by a fast-slow time domain process, each segment is defined as a single pulse, the time within a single pulse segment is a fast time, the time between pulse segments is a slow time, the time is a fast time on an abscissa, the time is a slow time on an ordinate, said pulse compressed signal is a fast time on an ordinate Expressed as: 。
5. The method of claim 1, wherein in step 2, the non-coherent accumulation of the pulse-compressed echo signals is performed as envelope superposition, i.e. n slow time values corresponding to fast time points are added, which is expressed as: After envelope superposition, finding the maximum relative arrival time coarse estimation value of echo pulse I.e. the abscissa of the maximum value after non-coherent accumulation, which is the maximum value after non-coherent accumulation traversed at each fast time point, the Expressed as: 。
6. The method of claim 1, wherein in the step 3, the interval selected according to engineering experience has an error of 2-3 sampling time intervals during the detection of the relative arrival time of each pulse, and the pulse signal needs to be selected with the time coarse estimation value as the center The interval is the subsequent phase-coherent accumulation range The method comprises the following steps: Wherein, the In terms of sampling time units, the time of the sample, in engineering experience, ; The rough estimated time point satisfies When the phase parameters are selected, the accumulation range of the phase parameters is selected The method comprises the following steps: The rough estimated time point satisfies In the time-course of which the first and second contact surfaces, For the maximum sampling time length, selecting a coherent accumulation time range The method comprises the following steps: 。
7. The method for combined processing of non-coherent and coherent accumulation based on an external radiation source radar according to claim 1, wherein the coherent accumulation in step 4 is a stepwise coherent accumulation, and the reduction of the calculation amount is realized by splitting pulse signals in a selected range; dividing the received n pulses into two parts, finding out the accurate relative arrival time of the n pulses in a faster time, and representing the two-part data matrix after grouping as Wherein said The method comprises the following steps: the said The method comprises the following steps: 。
8. the method for combined non-coherent and coherent accumulation based on external-source radar according to claim 7, wherein the steps of Represented as front The data needed for coherent accumulation is made by pulse, the Corresponding back The data accumulated by the pulse phase correlation; For the said Performing coherent accumulation, namely performing coherent accumulation by taking only one sampling time point for each pulse echo, traversing each time point to obtain values of each group of FFT, taking a fast time point corresponding to each pulse in the maximum value, namely finding out the front after coherent accumulation The precise relative arrival time points of the individual pulses are expressed as: For the said Performing phase-coherent accumulation to obtain The exact relative arrival time values of the individual pulses are expressed as: 。
9. The method for combined processing of non-coherent and coherent accumulation based on an external radiation source radar according to claim 7, wherein the step-by-step coherent accumulation can find a unit where the echo arrives at the time relatively, the unit is marked, the marked time marks of the two parts are combined to obtain a group of relative arrival time matrixes of echo pulses, and the accurate relative arrival time values obtained after the step-by-step coherent accumulation are: the precise relative arrival time can guide the scattered echo to perform subsequent signal processing on the target.
10. The method for combining non-coherent and coherent accumulation based on the external radiation source radar according to claim 7, wherein the unit of step-by-step coherent accumulation is processed by taking pulses as units, so that a result is output in each pulse period, when each pulse is aligned relative to a time point to perform coherent accumulation, the corresponding accumulation amplitude is higher than that of other non-aligned time points, so that the relative arrival time of each pulse can be finally obtained by traversing the time points in each value range by performing coherent accumulation, and more accurate reference is provided for subsequent signal processing.

Description

Non-coherent and coherent accumulation combined processing method based on external radiation source non-cooperative radar Technical Field The invention belongs to the field of signal processing of an external radiation source non-cooperative radar, and particularly relates to a non-coherent and coherent accumulation combined processing method based on an external radiation source non-cooperative radar, which can realize the estimation of the arrival time of a direct wave relative to a radar scattering echo of the non-cooperative external radiation source. Background External-source radar, also known as passive radar, is a bistatic radar that can perform covert detection by receiving target forward and side scatter echoes. The radar transmits and receives signals separately and does not emit signals, so that the radar has the advantages of strong anti-stealth, strong anti-interference capability, environment friendliness, no electromagnetic pollution and the like, and the radar has been paid attention to in the last decade. External radiation source radars typically select non-cooperative radar signals, broadcast signals, etc. as radiation sources, but due to the problem of uncontrolled transmission of their transmitted signals, obtaining high purity scattered echoes is an important research direction. The receiving device based on the radar body of the external radiation source is generally provided with two types of channels, namely a direct wave channel for receiving a direct wave signal of the external radiation source and a scattered echo channel for receiving an echo signal scattered by a target. The receiving device guides the time domain alignment of the scattered echo channel and carries out signal correlation processing through the arrival information of the direct wave and the scattered echo, and accumulation detection is further completed. Time synchronization is the key point of the work of an external radiation source radar, and the core is to acquire absolute time by combining direct waves and scattered echoes. The direct wave signal can directly acquire when the external radiation source emits, absolute time can be acquired by scattering echo relative to the arrival time of the direct wave, the problem of coherent accumulation between system pulses caused by time errors can be avoided by time synchronization, and meanwhile, the time difference between the echo signal and the direct wave signal can be utilized and the prior information of the position of the radiation source is combined to complete the calculation of the target position. However, the echo information includes multipath signals, clutter, noise, and the like, and a complex electromagnetic environment affects the detection of arrival time of scattered echo, so that when the echo signals are aligned in the time domain, an offset is generated, and thus, an error is generated for positioning the target. In signal processing, therefore, a plurality of pulse echo signals are generally accumulated, i.e., equivalently, the reception time of the echo signals is increased, so that a high gain is obtained. The accumulation method is divided into non-coherent accumulation and coherent accumulation, wherein the non-coherent accumulation does not need to use target phase information, and the coherent accumulation simultaneously comprises amplitude and phase information. Therefore, a pulse-to-pulse accumulation method of echoes can be utilized to carry out non-coherent and coherent accumulation on a certain number of pulse echo signals, so that the arrival time point of the echoes relative to the direct wave can be extracted more accurately, more accurate time guidance is provided for subsequent scattered echo signal processing, and the accuracy of subsequent calculation of target information is improved. Disclosure of Invention Aiming at the problem that the arrival time detection of the echo relative direct wave can deviate, the invention utilizes a method of combining non-coherent and coherent accumulation to obtain a coarse estimation value of the arrival time by firstly using the non-coherent accumulation, and then utilizes the coherent accumulation to obtain the maximum value to obtain the accurate relative direct wave arrival time information of each echo pulse. The method can accurately obtain the arrival time information, and guide the echo to perform multi-pulse FFT by utilizing the arrival time information, thereby improving the signal to noise ratio and detecting the time difference between the extracted echo and the direct wave. The specific technical scheme of the invention is as follows: A non-coherent and coherent accumulation combined processing method based on an external radiation source radar comprises the following specific steps: step 1, carrying out pulse compression on n echo signals of an external radiation source radar received in a period of time according to the echo characteristics of the pulse signals, wherein: t