阅读说明：本技术 一种射频无源tdoa定位系统数据块选择传输方法 (Data block selection transmission method of radio frequency passive TDOA (time difference of arrival) positioning system ) 是由 杜鸿 文成玉 李文藻 于 2020-10-26 设计创作，主要内容包括：本发明公开了一种射频无源TDOA定位系统数据块选择传输方法：测站从射频接收机输出的IQ数据流中提取定时数据块并缓存到队列中；测站使用基于载噪比和过0点数质量指标评估定时数据块质量,向中心站报告每个定时数据块的时间戳和质量指标；中心站接收测站报告并缓存到队列中,根据时间戳和质量参数从报告队列中选择候选数据块,通知测站上传指定时间数据块；测站收到中心站命令,从缓存定时数据块队列中搜索指定时间的数据块并上传到中心站；中心站接收测站上传的定时数据块并缓存到定时数据块队列,作为TDOA估计算法的输入数据。用于解决突发和带宽时变信号数据块优选问题,同时解决网络带宽与采样率之间的矛盾问题。(The invention discloses a data block selection transmission method of a radio frequency passive TDOA (time difference of arrival) positioning system, which comprises the following steps: the station under test extracts the timing data block from the IQ data stream output by the radio frequency receiver and buffers the timing data block into a queue; the measuring station evaluates the quality of the timing data blocks by using the quality indexes based on the carrier-to-noise ratio and the over 0 point number, and reports the timestamp and the quality index of each timing data block to the central station; the central station receives the report of the measuring station and buffers the report into a queue, selects a candidate data block from the report queue according to the timestamp and the quality parameter, and informs the measuring station to upload the data block at the appointed time; the measuring station receives the command of the central station, searches data blocks in specified time from the caching timing data block queue and uploads the data blocks to the central station; and the central station receives the timing data blocks uploaded by the observation stations and buffers the timing data blocks into a timing data block queue as input data of the TDOA estimation algorithm. The method is used for solving the problem of burst and bandwidth time-varying signal data block optimization and simultaneously solving the problem of contradiction between network bandwidth and sampling rate.)

1. A method for selective transmission of data blocks in a radio frequency passive TDOA location system, comprising the steps of:

s1, setting parameters: setting the Signal Bandwidth B_WSampling rate Fs of receiver, and acquisition time scale T of IQ data block_markLess than or equal to 1000ms, number L of sampling points of IQ data block_blockNumber of sub-segments N of IQ data block_segNot less than 1, station measurement report period T_report≥T_markMinimum number of stations S required for positioning task_minNot less than 3, the number of stations required for signal classification S_classGreater than or equal to 1, carrier-to-noise ratio threshold S_thd1And S_thd2>S_thd1Single carrier data block classification coefficient S_carrierMore than or equal to 1.0 and the like;

s2, starting period of T in whole second_markAt the time point of (3), the number of samples collected from the IQ data stream outputted from the RF receiver is L_blockThe data block, the initial sampling time stamp and the satellite positioning coordinate are packaged into a timing data block and cached to a timing data block queue;

s3, at the survey station, dividing the data block into N_segIndividual sub-segments, calculating a quality parameter Q for each sub-segment_seg；

S4 according to the sub-segment quality parameter Q_segCalculating a data block quality parameter Q_block；

S5, at the testing station, the initial sampling time stamp, the sampling number and the quality parameter Q of the data block_blockPackaging the report node into a report queue of a station, wherein the station uses T_reportSending report nodes in the station measurement report queue to the central station for a period;

s6, at the central station, receiving the reports sent by each testing station and storing the reports in a report queue, searching the report queue for the reports with aligned time stamps and counting the number of the reports as S_alignAlign the time stamp with the number of reports S_align≥S_minThe report set is packaged into a node, cached to a candidate data block queue, and the maximum report number S of timestamp alignment is calculated_maxIs S_alignAfter searching is finished, the number of reports in the deletion candidate data block queue is less than S_maxNode of (2), this time in the candidate data block queueAll nodes contain S_maxStation reports, each station report consisting of a time stamp, a number of samples and Q_blockThe like parameter composition;

s7, at the central station, according to S in the candidate data block queue node_maxQuality parameter Q of data block of individual survey station_blockSelecting a candidate data block, and informing the test station to upload a timing data block according to an initial sampling time stamp and a sampling number issuing command of the candidate data block;

s8, at the survey station, receiving a central station command, searching a timing data block with a matched time stamp from a timing data block queue according to a data block starting time stamp and a sampling number specified by the command, and uploading the timing data block with the specified sampling number to the central station;

and S9, receiving the timing data block uploaded by the observation station at the central station, and buffering the timing data block to a central station timing data block queue to be used as input data of the TDOA estimation algorithm.

2. The method for selective transmission of data blocks in a radio frequency passive TDOA location system as recited in claim 1, wherein said calculating a quality parameter Q for each sub-segment at S3_segThe method comprises the following specific steps:

S31、Q_segis formed by sub-segments carrying noise ratio q_cnrSum Q of number of 0 points of I and Q components in time domain of subsegment_cznFormed doublets, i.e. Q_seg=(q_cnr，q_czn) When q is_cnr>V_thd1Time q_cznInversely proportional to the instantaneous bandwidth of the signal segment within the sub-segment, when q_cnr≤V_thd1Time q_cznThe reliability of the instantaneous bandwidth of the signal segment within an expression subsection decreases.

3. The method for block-selective transmission of a radio frequency passive TDOA positioning system as recited in claim 1, wherein said S4 is based on sub-segment quality parameter Q_segCalculating a data block quality parameter Q_blockThe method comprises the following specific steps:

s41, data block quality parameter Q_block=(q_{cnr_max}, q_{czn_max}, q_{cnr_avg}, q_{czn_avg}, q_{cnr_min}) Is a 5-tuple, q_{cnr_max}For the sub-segment carrier-to-noise ratio q in a data block_cnrMaximum value of (a), q_{czn_max}Q number of over 0 points for the largest carrier-to-noise ratio subsection in the data block_czn，q_{cnr_avg}For the sub-segment carrier-to-noise ratio q in a data block_cnrMean value of q_{czn_avg}Counting q number of 0-crossing points for a subsection in a data block_cznMean value of q_{cnr_min}For the sub-segment carrier-to-noise ratio q in a data block_cnrMinimum value of (a), q_{cnr_max}And q is_{czn_max}For expressing the quality of short-time burst signal segments, q_{cnr_avg}And q is_{czn_avg}For expressing the quality of the continuous signal, q_{cnr_min}For classification of burst and continuous signal types.

4. The method for selective transmission of data blocks in a radio frequency passive TDOA positioning system as recited in claim 1, wherein the step of selecting candidate data blocks in S7 is as follows:

s71, traversing the candidate data block queue, and when not less than S exists in one node_classQ of a measuring station_blockMember parameter q_{czn_max} >S_carrier×q_{czn_avg}Classifying the node into a single carrier signal segment and discarding the node;

s72, traversing the candidate data block queue, and when all nodes exist, the number of nodes is not less than S_classQ of a measuring station_blockMember parameter q_{cnr_min} < V_thd1And q is_{cnr_max} - q_{cnr_min} > V_thd2If so, judging the signal type to be a burst type, otherwise, judging the signal type to be a continuous type;

s73, when the signal is continuous, traversing the candidate data block queue, and when no less than S exists in one node_classQ of a measuring station_blockMember parameter q_{cnr_avg} > V_thd1Then classifying the node into a high carrier-to-noise ratio subset, otherwise classifying into a low carrier-to-noise ratio subset, and after traversing is finished, selecting a measuring station Q from the high carrier-to-noise ratio subset_blockMember parameter q_{czn_avg}The node with the minimum sum is used as a candidate node, and when the high carrier-to-noise ratio subset is empty, the node with the minimum sum is selected from the low carrier-to-noise ratio subsetsCentralized selection survey station Q_blockMember parameter q_{cnr_avg}Taking the node with the largest sum as a candidate node;

s74, when the signal is burst type, traversing the candidate data block queue, when one node has not less than S_classQ of a measuring station_blockMember parameter q_{cnr_max} > S_thd1Classifying the node into a high carrier-to-noise ratio subset, otherwise classifying the node into a low carrier-to-noise ratio subset, and after traversing is finished, selecting a measuring station Q from the high carrier-to-noise ratio subset_blockMember parameter q_{czn_max}And selecting the node with the minimum sum as a candidate node, and selecting the survey station q from the low carrier-to-noise ratio subset when the high carrier-to-noise ratio subset is empty_{cnr_max}Taking the node with the largest sum as a candidate node;

and S75, taking the initial sampling time stamp in the station measurement report of the candidate node as the initial sampling time stamp of the candidate data block, and taking the minimum sampling number of all the station measurement reports of the candidate node as the sampling number of the candidate data block.

Technical Field

The invention belongs to the field of wireless communication, and relates to a data block selection transmission method of a radio frequency passive TDOA (time difference of arrival) positioning system.

Background

The radio frequency passive TDOA positioning system consists of a central station and 3 or more stations with a distance of between a few kilometers and a hundred kilometers. The central station comprises a data processing computer and application software, issues a TDOA positioning task to the measuring stations, receives IQ data blocks of signals acquired by the measuring stations, estimates the TDOA between the measuring stations, and calculates a signal transmitting position according to satellite positioning coordinates of the measuring stations and the TDOA between the measuring stations. The measuring station consists of a radio frequency receiver, a satellite positioning/time service module and a computer, and acquires a measured signal IQ data block with a time stamp and a satellite positioning coordinate according to a central station task command and transmits the acquired measured signal IQ data block to the central station through a network. The survey station deployment mode comprises a ground fixed survey station, a vehicle-mounted survey station, an airborne survey station and the like, the survey station and the central station can communicate through a wired network, a public wireless mobile network, a wireless self-organizing network and the like, and the wired network can only be used for the ground fixed station.

The positioning accuracy of the TDOA positioning system is influenced by the TDOA estimation accuracy, the hyperbolic intersection positioning algorithm accuracy, the satellite positioning accuracy, the geometric distribution shape of the measuring station and the like, wherein the TDOA estimation accuracy is the primary influence factor.

In principle, the TDOA estimation algorithm performs a correlation operation on two time-stamp aligned instrumented data blocks to obtain a TDOA estimate. The accuracy of the TDOA estimate is affected by the accuracy of the time stamp, the sampling rate of the receiver, the instantaneous bandwidth of the signal samples within the data block, the carrier-to-noise ratio, and multipath propagation. The precision of the timestamp is limited by the precision of a satellite time service module, and the timestamp belongs to the problem of hardware performance; multipath propagation is a problem that needs to be overcome by the TDOA estimation algorithm itself; the accuracy of the TDOA estimate is proportional to the input data block sample rate, which is a compromise between receiver and station computer performance, satellite timing module accuracy, and measured signal bandwidth and network performance. It is emphasized that the accuracy of TDOA estimation is proportional to the carrier-to-noise ratio of the input data block and the instantaneous bandwidth of the signal, and is particularly sensitive to the instantaneous bandwidth. A data block with higher carrier-to-noise ratio and wider instantaneous bandwidth is screened out from IQ data stream output by a receiver for a TDOA estimation algorithm, relates to a cooperation mechanism between a central station and a measuring station, and is a basic problem to be solved by a TDOA positioning system at a system level.

For frequency modulation broadcast incoming and intercom signals, the instantaneous bandwidth of the signals has time-varying property, in the speech pause period, the transmitter only transmits carrier waves, the carrier-to-noise ratio is higher, but the instantaneous bandwidth of the signals in the period is equivalent to a single carrier, and the TDOA estimation algorithm fails; similarly, for some frequency shift keying digital signals, the instantaneous bandwidth of the signal is also of a time-varying nature, continuous 0 or continuous 1 symbol periods are transmitted, only a few spectral lines exist in the modulated signal bandwidth, the instantaneous bandwidth is narrow, and the accuracy of TDOA estimation is reduced or even fails; for radar and aircraft transponder signals, the signal duration is only tens to hundreds of microseconds, the signal occurrence interval is long, and short-time burst signal segments are accurately intercepted from the data stream, so that an effective TDOA estimation result can be obtained.

The data acquisition and transmission scheme used by the current radio frequency passive TDOA positioning system has the following advantages and disadvantages:

1) the observation station transmits all the acquired IQ data to the central station: for example, the acquisition time scale is 10ms, the measurement station starts from each whole second, samples and packages the signal of each 10ms time period in the whole second into a data block, and transmits the data block to the central station in sequence; the advantage is that no samples are discarded; the method has the disadvantages that the requirements on network bandwidth and the performance of a central station computer are high, the sampling rate is limited by transmission bandwidth, the method can only be used for a ground fixed survey station, and the engineering cost is high; for on-board and on-board stations, this solution is difficult to implement in engineering terms, subject to the limitations of communication link bandwidth and reliability.

2) The measurement station periodically collects an IQ data segment to be transmitted to the central station: for example, the acquisition time scale is 500ms, the observation station acquires a plurality of signal sampling points every 500ms from the whole second, packages the signal sampling points into a data block, transmits the data block to the central station, and discards other sampling points; the method has the advantages that the method can adapt to various network transmission environments and sampling rates by adjusting the acquisition time scale and the number of sampling points; the method has the disadvantages that when the measured signal is a short-time burst signal, such as signals of interphones, answering machines, radars and the like, the measuring station cannot ensure that the extracted data segment contains an effective signal segment; when the instantaneous bandwidth of the measured signal has a time-varying property, it cannot be guaranteed that the data block contains a signal segment with a wider instantaneous bandwidth.

Disclosure of Invention

The invention aims to provide a data block selection transmission method of a radio frequency passive TDOA (time difference of arrival) positioning system, which evaluates the quality of a data block through a load-noise ratio and 0 point crossing combined index, selects a data block with better quality from an IQ (in-phase Quadrature-frequency) data block sequence acquired by a measuring station and transmits the data block to a central station as input data of a TDOA (time difference of arrival) estimation algorithm.

A method for selective transmission of data blocks in a radio frequency passive TDOA location system, comprising the steps of:

s1, setting parameters: setting the Signal Bandwidth B_WSampling rate Fs of receiver, and acquisition time scale T of IQ data block_markLess than or equal to 1000ms, number L of sampling points of IQ data block_blockNumber of sub-segments N of IQ data block_segNot less than 1, station measurement report period T_report≥T_markMinimum number of stations S required for positioning task_minNot less than 3, the number of stations required for signal classification S_classGreater than or equal to 1, carrier-to-noise ratio threshold S_thd1And S_thd2>S_thd1Determination of coefficient S for single carrier data block_carrierMore than or equal to 1.0 and the like;

s2, starting period of T in whole second_markAt the time point of (3), the number of samples collected from the IQ data stream outputted from the RF receiver is L_blockThe data block, the initial sampling time stamp and the satellite positioning coordinate are packaged into a timing data block and cached to a timing data block queue;

s3, at the survey station, dividing the data block into N_segIndividual sub-segments, calculating a quality parameter Q for each sub-segment_seg；

S4 according to the sub-segment quality parameter Q_segCalculating a data block quality parameter Q_block；

S5, at the testing station, the initial sampling time stamp, the sampling number and the quality parameter Q of the data block_blockPackaging the report node into a report queue of a station, wherein the station uses T_reportSending report nodes in the station measurement report queue to the central station for a period;

s6, at the central station, receiving the reports sent by each testing station and storing the reports in a report queue, searching the report queue for the reports with aligned time stamps and counting the number of the reports as S_alignAlign the time stamp with the number of reports S_align≥S_minIs packaged as a node, cached to a candidate data block queue, and calculatedTime stamp aligned maximum number of reports S_maxIs S_alignAfter searching is finished, the number of reports in the deletion candidate data block queue is less than S_maxWhen all nodes in the candidate data block queue contain S_maxStation reports, each station report consisting of a time stamp, a number of samples and Q_blockThe like parameter composition;

s7, at the central station, according to S in the candidate data block queue node_maxQuality parameter Q of data block of individual survey station_blockSelecting a candidate data block, and informing the test station to upload a timing data block according to an initial sampling time stamp and a sampling number issuing command of the candidate data block;

s8, at the survey station, receiving a central station command, searching a timing data block with a matched time stamp from a timing data block queue according to a data block starting time stamp and a sampling number specified by the command, and uploading the timing data block with the specified sampling number to the central station;

and S9, receiving the timing data block uploaded by the observation station at the central station, and buffering the timing data block to a central station timing data block queue to be used as input data of the TDOA estimation algorithm.

Further, calculating the quality parameter Q of each sub-segment as described in S3_segThe method comprises the following specific steps:

S31、Q_segis formed by sub-segments carrying noise ratio q_cnrSum Q of number of 0 points of I and Q components in time domain of subsegment_cznFormed doublets, i.e. Q_seg=(q_cnr，q_czn) When q is_cnr>V_thd1Time q_cznInversely proportional to the instantaneous bandwidth of the signal segment within the sub-segment, when q_cnr≤V_thd1Time q_cznThe reliability of the instantaneous bandwidth of the signal segment within an expression subsection decreases.

Further, the quality parameter Q according to sub-segments according to S4_segCalculating a data block quality parameter Q_blockThe method comprises the following specific steps:

s41, data block quality parameter Q_block=(q_{cnr_max}, q_{czn_max}, q_{cnr_avg}, q_{czn_avg}, q_{cnr_min}) Is a 5-tuple, q_{cnr_max}For the sub-segment carrier-to-noise ratio in a data blockq_cnrMaximum value of (a), q_{czn_max}Q number of over 0 points for the largest carrier-to-noise ratio subsection in the data block_czn，q_{cnr_avg}For the sub-segment carrier-to-noise ratio q in a data block_cnrMean value of q_{czn_avg}Counting q number of 0-crossing points for a subsection in a data block_cznMean value of q_{cnr_min}For the sub-segment carrier-to-noise ratio q in a data block_cnrMinimum value of (a), q_{cnr_max}And q is_{czn_max}For expressing the quality of short-time burst signal segments, q_{cnr_avg}And q is_{czn_avg}For expressing the quality of the continuous signal, q_{cnr_min}For the decision of burst and continuous signal types.

Further, the specific step of selecting the candidate data block in S7 is as follows:

s71, traversing the candidate data block queue, and when not less than S exists in one node_classQ of a measuring station_blockMember parameter q_{czn_max} >S_carrier×q_{czn_avg}Classifying the node into a single carrier signal segment and discarding the node;

s72, traversing the candidate data block queue, and when all nodes exist, the number of nodes is not less than S_classQ of a measuring station_blockMember parameter q_{cnr_min} < V_thd1And q is_{cnr_max} - q_{cnr_min} > V_thd2If so, judging the signal type to be a burst type, otherwise, judging the signal type to be a continuous type;

s73, when the signal is continuous, traversing the candidate data block queue, and when no less than S exists in one node_classQ of a measuring station_blockMember parameter q_{cnr_avg} > V_thd1Then classifying the node into a high carrier-to-noise ratio subset, otherwise classifying into a low carrier-to-noise ratio subset, and after traversing is finished, selecting a measuring station Q from the high carrier-to-noise ratio subset_blockMember parameter q_{czn_avg}And selecting the node with the minimum sum as a candidate node, and selecting the measuring station Q from the low carrier-to-noise ratio subset when the high carrier-to-noise ratio subset is empty_blockMember parameter q_{cnr_avg}Taking the node with the largest sum as a candidate node;

s74, when the signal is burst type, traversing the candidate data block queue, when one node existsIs not less than S_classQ of a measuring station_blockMember parameter q_{cnr_max} > S_thd1Classifying the node into a high carrier-to-noise ratio subset, otherwise classifying the node into a low carrier-to-noise ratio subset, and after traversing is finished, selecting a measuring station Q from the high carrier-to-noise ratio subset_blockMember parameter q_{czn_max}And selecting the node with the minimum sum as a candidate node, and selecting the survey station q from the low carrier-to-noise ratio subset when the high carrier-to-noise ratio subset is empty_{cnr_max}Taking the node with the largest sum as a candidate node;

and S75, taking the initial sampling time stamp in the report of any station of the candidate node as the initial sampling time stamp of the candidate data block, and taking the minimum sampling number reported by all stations of the candidate node as the sampling number of the candidate data block.

The invention has the beneficial effects that:

1. in practical engineering, some signal instantaneous bandwidths have strong time-varying property, and the electromagnetic environment difference of a survey station is large, so that the problem of low reliability of the instantaneous bandwidth sampled in a signal data block detected through a frequency spectrum exists, and the carrier-to-noise ratio Q is solved_cnrAnd 0 point number Q_cznTwo parameters commonly used in the field of signal processing, the carrier-to-noise ratio Q is used in the method_cnrAnd 0 point number Q_cznCombined doublet Q_seg=(Q_cnr, Q_czn) Expressing the signal quality of the IQ data segment is advantageous when the carrier-to-noise ratio Q_cnr>S_thd1Time-over-0 point index Q_cznCapable of reliably expressing the instantaneous bandwidth, Q of the signal_cznInversely proportional to instantaneous bandwidth, as carrier to noise ratio Q_cnr<S_thd1Time-over-0 point index Q_cznReliability reduction of the instantaneous bandwidth of the representation signal, threshold S_thd1Using sub-section quality parameter Q proportional to noise figure of radio frequency receiver_segCalculated data block quality parameter Q_blockThe data block with good quality can be reliably selected from the signal data block sequence to be used as the input data of the TDOA estimation algorithm, and the aim of improving the accuracy of the TDOA positioning system is fulfilled from a data source head;

2. by data block quality parameter Q_blockSelecting IQ data block while considering bandwidth stability and continuityThe method has the advantages that the method solves the problem of selecting data blocks of several types of signals, such as signals, bandwidth time-varying continuous signals, short-time burst signals and the like, is suitable for TDOA positioning tasks of various radio frequency signals, and has universality;

3. quality binary Q_seg=(Q_cnr, Q_czn) The calculation complexity is moderate, and the method is suitable for being realized in the observation station computers with various performances;

4. the station-finding reporting node only relates to the starting timestamp, the number of sampling points and the quality 5-tuple Q_blockAnd when the central station receives the multi-station report and the time alignment data block exists, the central station sends an optimized data block uploading command to the observation station, so that the method can adapt to transmission networks with various performances.

Drawings

FIG. 1 is a flow chart of the method.

Detailed Description

The implementation mode of the method is explained by taking an FM broadcast station signal positioning task as an example, a TDOA positioning system uses 1 central station and 4 measuring stations to execute a two-dimensional TDOA positioning task, a radio frequency receiver uses 1pps pulse of a receivable satellite positioning module to stamp a sampling point, the radio frequency receiver is provided with a continuous baseband IQ data stream output API interface, a measuring station computer uses a computer capable of receiving IQ data stream of the radio frequency receiver, and the method is realized in the central station computer and the measuring station computer in a computer program mode.

Step 1, parameter setting:

setting the Signal Bandwidth B_W=100kHz, receiver sampling rate Fs =4MSPS,

IQ data block acquisition time scale T_markNumber of samples L of IQ data block (= 2 ms)_block=8192, number of subsections per data block N_seg = 4，

Station measurement report period T_report=100ms，

Minimum number of stations S required for positioning task_min=3, number of stations required for signal classification S_class=3，

Carrier to noise ratio threshold S_thd1=6dB、S_thd2=9dB, single carrier band decision coefficient S_carrier=1.5，

Calculating sub-segment quality parameter Q_segTemporal down-sampling rate decimation factor M_dec=8 such that the down-sampling rate F is reduced_S/M_dec≥2×B_W，

Setting the data holding time T in the timing data block buffer queue according to the network transmission bandwidth and time delay_keep=4000ms；

Step 2, the starting period of the whole second is T_markAt the time point of (3), the number of samples collected from the IQ data stream outputted from the RF receiver is L_blockThe data block, the initial sampling time stamp and the satellite positioning coordinate are packaged into a timing data block, the timing data block is cached to a timing data block queue, and the deletion time stamp is earlier than T_keepPrevious nodes to avoid memory drain;

step 3, dividing the data block into N at the survey station_segIndividual sub-segments, calculating a quality parameter Q for each sub-segment_seg；

Step 4, in the survey station, according to the quality parameter Q of the subsegment_segCalculating a data block quality parameter Q_block；

Step 5, at the testing station, the initial sampling time stamp, the sampling number and the quality parameter Q of the data block_blockPackaging the report node into a report queue of a station, wherein the station uses T_reportSending report nodes in the station survey report queue to the central station periodically, and emptying the report queue after sending;

step 6, receiving the reports sent by each testing station and storing the reports in a report queue at the central station, searching the reports with aligned time stamps from the report queue and counting the number of the reports as S_alignAlign the time stamp with the number of reports S_align≥S_minThe report set is packaged into a node, cached to a candidate data block queue, and the maximum report number S of timestamp alignment is calculated_maxIs S_alignAfter searching is finished, the number of reports in the deletion candidate data block queue is less than S_maxWhen all nodes in the candidate data block queue contain S_maxReporting by each test station;

step 7, at the central station, under the condition that the data block uploading is not started or the transmission is overtime, according to the data block quality parameter Q carried by the survey station report in the candidate data block queue node_blockSelecting a candidate data block, deleting a node with a timestamp aligned with the timestamp of the candidate data block from the report queue, notifying the testing station of uploading the timed data block according to the initial sampling timestamp and the sampling number issuing command of the candidate data block, and setting a data block transmission starting mark and transmission overtime initial time;

step 8, receiving a central station command at the survey station, searching a timing data block with a matched time stamp from a timing data block queue according to a data block starting time stamp and a sampling number specified in the command, and uploading the timing data block with the specified sampling number to the central station;

9, receiving the timing data block uploaded by the observation station at the central station, caching the timing data block to a timing data block queue of the central station as input data of a TDOA estimation algorithm, and when S is detected_maxWhen all the data blocks of the specified time stamp of each station arrive, the data block transmission starting mark is reset.

Further, calculating the quality parameter Q of each sub-segment in step 3_segThe method comprises the following specific steps:

step 31, Q_segIs formed by sub-segments carrying noise ratio q_cnrSum Q of number of 0 points of I and Q components in time domain of subsegment_cznFormed doublets, i.e. Q_seg=(q_cnr，q_czn) When q is_cnr>V_thd1Time q_cznInversely proportional to the instantaneous bandwidth of the signal segment within the sub-segment, when q_cnr≤V_thd1Time q_cznThe reliability of the instantaneous bandwidth of the signal section in the expression subsegment is reduced;

step 32, in order to reduce the calculation cost to adapt to the performance of the computer of the measuring station, a decimation factor M is used for the sub-segment sampling_decPerforming down-sampling rate extraction to obtain a sampling number L_block/(N_seg×M_dec) Sample set S of =256_decLower sampling rate F_S/ M_dec=500KSPS, carrier to noise ratio q_cnrBy sampling the set S_decFast fourier transform ofBy changing the amplitude spectrum, in order to eliminate out-of-band strong signal pairs q_cznInfluence of the result, in calculating q_cznFront, using a cutoff bandwidth of B_wOf the low-pass filter pair sample set S_decFiltering, calculating the sum of the 0 point number of I component and Q component of the output sample of the filter to obtain Q_czn。

Further, the quality parameter Q according to sub-segments in step 4_segCalculating a data block quality parameter Q_blockThe method comprises the following specific steps:

step 41, data block quality parameter Q_block=(q_{cnr_max}, q_{czn_max}, q_{cnr_avg}, q_{czn_avg}, q_{cnr_min}) Is a 5-tuple, q_{cnr_max}For the sub-segment carrier-to-noise ratio q in a data block_cnrMaximum value of (a), q_{czn_max}Q number of over 0 points for the largest carrier-to-noise ratio subsection in the data block_czn，q_{cnr_avg}For the sub-segment carrier-to-noise ratio q in a data block_cnrMean value of q_{czn_avg}Counting q number of 0-crossing points for a subsection in a data block_cznMean value of q_{cnr_min}For the sub-segment carrier-to-noise ratio q in a data block_cnrMinimum value of (a), q_{cnr_max}And q is_{czn_max}For expressing the quality of short-time burst signal segments, q_{cnr_avg}And q is_{czn_avg}For expressing the quality of the continuous signal, q_{cnr_min}For the decision of burst and continuous signal types.

Further, the step 7 specifically selects the candidate data block as follows:

step 71, traversing the candidate data block queue, and when not less than S exists in one node_classQ of a measuring station_blockMember parameter q_{czn_max} >S_carrier×q_{czn_avg}Classifying the node into a single carrier signal segment and discarding the node;

step 72, traversing the candidate data block queue, and when all nodes exist, the number of nodes is not less than S_classQ of a measuring station_blockMember parameter q_{cnr_min} < V_thd1And q is_{cnr_max} - q_{cnr_min} > V_thd2If not, the signal type is judged to be continuousMolding;

step 73, when the signal is continuous, traversing the candidate data block queue, and when no less than S exists in one node_classQ of a measuring station_blockMember parameter q_{cnr_avg} > V_thd1Then classifying the node into a high carrier-to-noise ratio subset, otherwise classifying into a low carrier-to-noise ratio subset, and after traversing is finished, selecting a measuring station Q from the high carrier-to-noise ratio subset_blockMember parameter q_{czn_avg}And selecting the node with the minimum sum as a candidate node, and selecting the measuring station Q from the low carrier-to-noise ratio subset when the high carrier-to-noise ratio subset is empty_blockMember parameter q_{cnr_avg}Taking the node with the largest sum as a candidate node;

step 74, when the signal is a burst type, traversing the candidate data block queue, and when one node has not less than S_classQ of a measuring station_blockMember parameter q_{cnr_max} > S_thd1Classifying the node into a high carrier-to-noise ratio subset, otherwise classifying the node into a low carrier-to-noise ratio subset, and after traversing is finished, selecting a measuring station Q from the high carrier-to-noise ratio subset_blockMember parameter q_{czn_max}And selecting the node with the minimum sum as a candidate node, and selecting the survey station q from the low carrier-to-noise ratio subset when the high carrier-to-noise ratio subset is empty_{cnr_max}Taking the node with the largest sum as a candidate node;

and 75, taking the initial sampling time stamp in the report of any station of the candidate nodes as the initial sampling time stamp of the candidate data block, and taking the minimum sampling number of the report of all stations of the candidate nodes as the sampling number of the candidate data block.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.