A method for quickly acquiring weak Beidou satellite signals

Abstract

The present invention relates to the field of satellite signal processing technology, and in particular to a method for quickly capturing a Beidou satellite weak signal, the method comprising: dividing a satellite weak signal baseband digital signal period to obtain a capture window of each period; obtaining the baseband signal logic confusion within the period and the flip matching difference of the flip phenomenon occurring in each capture window according to each voltage value of the baseband signal within the period and preset high and low voltage standard values, and calculating the capture credibility of the period based on this; constructing an adjacent counter influence value and a local counter influence value; constructing a counter initial value of each capture window in the next round of histogram algorithm according to the capture credibility of each period and the adjacent counter influence value and local counter influence value of each capture window, and improving the histogram algorithm in combination with the counter initial value of each capture window to capture the satellite weak signal. The present invention improves the capture efficiency of the digital baseband signal of the satellite weak signal and reduces the delay of satellite communication.

Description

Technical Field

[0001] The present application relates to the technical field of satellite signal processing, and in particular to a method for quickly capturing weak signals of Beidou satellites. Background Art

[0002] BeiDou Satellite is a satellite navigation system independently developed by China. The system consists of satellites, ground monitoring and control systems, user terminal equipment, etc., and can provide positioning, navigation and time services for global users. In the current satellite signal transmission process, the signals transmitted are mostly digital signals. At the receiving end of the digital signal, it is necessary to capture the received satellite signal, obtain the bit edge position of the received signal, complete the bit synchronization of the satellite signal, and facilitate the next step of the received signal operation.

[0003] During the signal transmission process, due to problems such as long transmission distance, atmospheric refraction, and diffraction of obstructions, the digital feature information in the received signal is interfered by noise, resulting in the received satellite signal being a weak signal. When using the traditional bit synchronization histogram algorithm to capture weak satellite signals, since the histogram algorithm mainly completes bit synchronization based on the statistics of the amplitude value of the signal, noise interference may cause the amplitude value to change, affecting the capture effect of the histogram algorithm, resulting in the need to reset the counter multiple times during the histogram algorithm capture, reducing the capture speed. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for quickly capturing weak signals of Beidou satellites to solve the existing problems.

[0005] A method for quickly capturing a Beidou satellite weak signal of the present invention adopts the following technical solution:

[0006] An embodiment of the present invention provides a method for quickly acquiring a Beidou satellite weak signal, the method comprising the following steps:

[0007] Divide the satellite weak signal baseband digital signal into periods and obtain the capture window of each period;

[0008] For each cycle, the logic disorder of the baseband signal in the cycle is obtained according to each voltage value of the baseband signal in the cycle and the preset high and low voltage standard values; the flip matching difference of the flip phenomenon occurring in each capture window is constructed according to the voltage of each capture window in the cycle and the preset high and low voltage standard values; the capture credibility of the cycle is obtained according to the logic disorder of the baseband signal in the cycle, the voltage fluctuation and the flip matching difference of the capture window that captures the flip phenomenon in the cycle; the adjacent counter influence value and the local counter influence value are constructed according to the counting situation of each capture window in the cycle, the flip matching difference of the flip phenomenon occurring and the preset counter influence attenuation coefficient;

[0009] According to the capture credibility of each cycle in the current round of histogram algorithm and the influence value of the adjacent counter and the local counter of each capture window, the initial value of the counter of each capture window in the next round of histogram algorithm is constructed; the histogram algorithm is improved in combination with the initial value of the counter of each capture window to capture the weak satellite signal.

[0010] Furthermore, the period division of the satellite weak signal baseband digital signal includes: for the satellite baseband digital signal, every S milliseconds is a period, wherein S is a preset duration.

[0011] Furthermore, the acquisition of the capture window of each cycle includes: for each cycle, the cycle is divided into a preset number of parts, and the time period corresponding to each piece of data is used as a capture window.

[0012] Further, obtaining the logic chaos degree of the baseband signal within the period according to each voltage value of the baseband signal within the period and the preset high and low voltage standard values ​​includes:

[0013] Preset high and low voltage standard values, take the average of the high and low voltage standard values ​​as the standard voltage median, take the voltage higher than the standard voltage median in the cycle as the high voltage, and vice versa as the low voltage;

[0014] Obtain the absolute value of the difference between the mean of all high voltages in the cycle and the high voltage standard value, obtain the absolute value of the difference between the mean of all low voltages in the cycle and the low voltage standard value, and calculate the sum of the two absolute values ​​of the difference;

[0015] The average of the absolute values ​​of the differences between each voltage value of the baseband signal within the period and the median value of the standard voltage is calculated, and the ratio of the sum to the result of adding 1 to the average is used as the logic chaos degree of the baseband signal within the period.

[0016] Furthermore, the flip matching difference of the flip phenomenon occurring in each capture window is constructed according to the voltage of each capture window in the cycle and the preset high and low voltage standard values, including:

[0017] For each capture window in each cycle, the absolute value of the difference between the voltage mean of the capture window and the median of the standard voltage is calculated as the first absolute value, the difference between the high voltage standard value and the low voltage standard value is obtained, and the ratio of the first absolute value to half of the difference is taken as the flip matching difference when the capture window undergoes a flip phenomenon.

[0018] Furthermore, obtaining the capture credibility of the cycle according to the baseband signal logic disorder, voltage fluctuation and flip matching difference of the capture window that captures the flip phenomenon in the cycle includes:

[0019] Calculate the difference between 1 and the flip matching difference of each capture window where the flip phenomenon occurs, and obtain the average of the difference of all capture windows that capture the flip phenomenon within the period;

[0020] Obtaining the sum of the standard deviations of all high voltages and the standard deviations of all low voltages within a period, calculating the product of the baseband signal logic confusion within the period and the sum, and obtaining the sum of the product and a preset value;

[0021] The ratio of the mean value to the summation result is taken as the capture reliability of the cycle.

[0022] Furthermore, the adjacent counter impact value includes:

[0023] The count value of each capture window within the statistical period, and the preset counter influence attenuation coefficient;

[0024] The product of the count value, 1, the difference between the counter influence attenuation coefficient, and the flip matching difference of the flip phenomenon occurring in each capture window is used as the adjacent counter influence value of each capture window.

[0025] Furthermore, the local counter impact value includes:

[0026] The product of 1 and the sum of the counter attenuation coefficient, 1 and the flip matching difference of the flip phenomenon occurring in each capture window, and the count value is used as the local counter influence value of each capture window.

[0027] Furthermore, the initial value of the counter corresponds to the calculation formula: Among them, Cl a It is the initial value of the counter corresponding to the a-th capture window in the next round of histogram algorithm; is the rounding symbol for rounding the value in brackets upward; β is the preset counter initial value strength weight; T is the number of cycles; lj a-1，t 、lj a+1，t 、lj 1，t 、lj 2，t 、lj A-1，t 、lj A，t are the neighboring counter impact values ​​of the a-1th, a+1th, 1st, 2nd, A-1th, and Ath capture windows in the tth period respectively; bw a，t kx is the impact value of the local counter of the ath capture window in the tth period; t is the capture reliability of the flip phenomenon captured in the tth cycle; A is the number of capture windows in the cycle.

[0028] Furthermore, the improved histogram algorithm in combination with the initial value of the counter of each capture window to capture the weak satellite signal includes:

[0029] If the count times of the counters of two capture windows simultaneously exceed the first threshold, the initial value of the counter of each capture window is used as the value of the counter corresponding to each capture window in the next round of histogram algorithm, and the satellite weak signal is captured by the improved histogram algorithm;

[0030] If the number of counts of the counter of only one capture window exceeds the second threshold and the number of counts of the counters of other capture windows is lower than the first threshold, then weak satellite signal capture is achieved;

[0031] The first threshold is smaller than the second threshold.

[0032] The present invention has at least the following beneficial effects:

[0033] The present invention aims at the situation that the counter needs to be reset multiple times by using a histogram algorithm in the process of capturing a digital baseband signal of a weak satellite signal, resulting in a slow capture speed. The logic disorder of the baseband signal is calculated by the difference between the actual voltage and the standard logic voltage in the digital baseband signal, and the logic disorder degree of the baseband signal is characterized; the flip matching difference is calculated by the difference between the voltage mean value and the standard voltage median value in the capture window to characterize the matching degree between the capture window and the flip phenomenon; the capture credibility is further obtained by combining the logic disorder of the baseband signal and the flip matching difference, and the credibility of the statistical counting data of the histogram algorithm in the tth cycle is characterized;

[0034] Furthermore, the present invention combines the capture credibility and the flip match difference to construct the counter initial value, completes the data enhancement of the histogram statistical data, and serves as the initial value of the next round of histogram algorithm. Compared with the traditional histogram algorithm, the histogram algorithm can capture the digital baseband signal of the satellite weak signal faster and reduce the satellite communication delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A flowchart of the steps of a method for quickly capturing a Beidou satellite weak signal provided by the present invention;

[0037] Figure 2 This is a schematic diagram of the baseband signal. DETAILED DESCRIPTION

[0038] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the method for quickly capturing weak signals of Beidou satellites proposed by the present invention, its specific implementation, structure, features and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0039] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0040] The specific scheme of a method for quickly capturing weak Beidou satellite signals provided by the present invention is described in detail below with reference to the accompanying drawings.

[0041] An embodiment of the present invention provides a method for quickly acquiring a Beidou satellite weak signal. Specifically, the following method for quickly acquiring a Beidou satellite weak signal is provided. Figure 1 , the method comprises the following steps:

[0042] Step S001: data collection, obtaining data related to the histogram algorithm of satellite weak signals.

[0043] The obtained satellite weak signal baseband digital signal is subjected to flip phenomenon detection. It should be noted that the flip phenomenon refers to the polarity flip phenomenon in which the voltage in the baseband signal jumps from logic "0" to logic "1" or from logic "1" to logic "0". The detection method is a well-known technology in the art. During the detection, the satellite baseband digital signal is divided into a cycle every S milliseconds, where S is the preset duration, which is 600 in this embodiment. Each cycle is divided into A parts, and the time period corresponding to each data is called a capture window. The number of capture windows in each cycle is A. When detecting the signal of the tth cycle, a statistical sequence zf can be obtained. t =(n1n2...n a ...n A ), n A is the count value of the counter of the Ath capture window in the tth period detection signal, that is, the value of the Ath element in the statistical vector. If a flip is suspected to occur in the ath capture window in the tth period detection signal, the ath element of the tth statistical vector is recorded as 1, otherwise it is recorded as 0. The method for detecting the flip phenomenon is a well-known technology in the art and will not be described in detail in this embodiment. A is the number of capture windows in the period, and the empirical value A=20.

[0044] The baseband signal diagram is as follows: Figure 2 As shown, U uis the high voltage standard value, U d is the low voltage standard value, SS1 is the capture window, SS2 is the flip phenomenon, and SS3 is the digital baseband signal.

[0045] Step S002, extract features from the histogram data of the satellite weak signal, construct the baseband signal logic chaos, calculate the flip matching difference and capture reliability, and based on this, obtain the neighboring counter influence value and the local counter influence value.

[0046] First, this embodiment analyzes the logic chaos of the baseband signal and constructs the logic chaos of the baseband signal. The specific construction process is as follows:

[0047] In the traditional histogram algorithm, each capture window corresponds to a counter. When the signal flips within the corresponding time period of the capture window, the counter count is increased by one. Finally, a histogram is formed with the counter number as the horizontal axis and the counter count number as the vertical axis.

[0048] When there is only one capture window (assuming it is the ath capture window) whose corresponding counter counts exceed the second threshold, and the corresponding counter counts of other capture windows are lower than the first threshold, a bit edge appears in the digital baseband signal in the ath capture window, and signal capture is completed, wherein the first threshold is less than the second threshold; when the counters of two capture windows exceed the first threshold at the same time, the counting result of this time is poor, the signal capture effect is poor, all counters are cleared, and the digital baseband signal capture is performed again. Obviously, the operation of re-clearing the counter completely discards the information before clearing. If this part of information is used to assign initial values ​​to the counters in the next round, the capture of the digital baseband signal can be accelerated.

[0049] In order to retain the information in the cleared counters, this embodiment needs to evaluate the data reliability in the counters, and retain more counts for counters with high data reliability to enhance the data, so as to make the rapid capture of digital baseband signals more accurate.

[0050] In weak satellite signals, due to the more serious noise interference, the counter is more likely to count non-signal flips as suspected signal flips compared to strong signals, which leads to poor statistical effects of the histogram and slow capture speed of the histogram algorithm. Therefore, the degree of signal chaos can be evaluated and recorded each time the counting statistics are performed to distinguish the statistical effects of each counting statistics.

[0051] Therefore, the logical chaos of the baseband signal is calculated as: Among them, hl t is the logic chaos of the baseband signal in the tth cycle; μV u，t is the average value of all high voltages in the baseband signal of the tth cycle; μVd，t is the mean value of all low voltages in the baseband signal of the tth cycle; U u is the high voltage standard value; U d is the low voltage standard value; V t，b is the voltage value of the bth position in the baseband signal of the tth period; B is the number of baseband signal voltage samples in the tth period, and the empirical value B=100; U mid It is the median value of the standard voltage, and its value is the average of the high voltage standard value and the low voltage standard value. It should be noted that the high voltage is a voltage whose voltage value is greater than the median value of the standard voltage, and the low voltage is a voltage whose voltage value is less than the median value of the standard voltage. The high and low voltage standard values ​​can be set by the implementer at will, and there is no special limitation in this embodiment. In this embodiment, they are set to 0.2V and 4.5V respectively.

[0052] It should be understood that the difference between the high voltage mean and the high voltage standard value, or the difference between the low voltage mean and the low voltage standard value, are both the degree of deviation of the logic voltage in the baseband signal. The larger the value, the greater the degree of deviation, which means that the baseband digital signal is more seriously affected by noise, the detected voltage reversal phenomenon is more likely to be a voltage change caused by noise, and the logic of the digital baseband signal is more chaotic; the actual voltage value in the baseband signal minus the median value of the standard voltage, the larger the difference, which means that at the non-reversal moment, the voltage is farther away from the median value of the standard voltage, which means that the detected voltage reversal phenomenon is less likely to be a voltage change caused by noise, and the logic of the digital baseband signal is less chaotic.

[0053] Finally, the logic chaos degree of the baseband signal is obtained. The larger the value, the more chaotic and unreliable the logic flip in the baseband signal is.

[0054] Then, this embodiment will calculate the flip matching difference and capture reliability, and the specific calculation process is as follows:

[0055] When capturing weak satellite signals, the flipping phenomenon of the digital baseband signal will be captured. Obviously, when the flipping phenomenon occurs in the capture window, if the flipping moment is closer to the center of the capture window, the better the matching effect between the flipping phenomenon at this time and the current capture window, the less likely it is that the flipping phenomenon is the flipping phenomenon of the adjacent window that is moved into the current capture window due to noise interference; on the contrary, when the flipping moment is farther away from the center of the capture window, the worse the matching effect between the flipping phenomenon at this time and the current capture window, the flipping phenomenon may be the flipping phenomenon of the adjacent window that is moved into the current capture window due to noise interference.

[0056] Therefore, this embodiment will construct a flip matching difference, and the specific calculation formula is: Among them, fz t,a is the flip matching difference of the flip phenomenon occurring in the ath capture window of the tth cycle; μV t,aThe voltage mean of the ath capture window in the tth cycle; U mid is the standard voltage median; U u is the high voltage standard value; U d It is the low voltage standard value.

[0057] It should be understood that when the flipping moment is at the center of the capture window, the duration of the high voltage part and the low voltage part in the capture window should be equal, and the voltage mean should be equal to the median of the standard voltage at this time; the greater the difference between the voltage mean in the capture window and the median of the standard voltage, the farther the flipping moment is from the center of the capture window, and the smaller the flip matching difference at this time; the high voltage standard value minus the low voltage standard value divided by 2 is the maximum value of the difference between the voltage mean in the capture window and the median of the standard voltage, which is used to normalize the flip matching difference; finally, the flip matching difference is obtained, and the larger the value, the farther the flipping moment of the flipping phenomenon occurring in the capture window is from the center of the capture window, and the greater the flip matching difference, and the flipping phenomenon may be a flipping phenomenon in an adjacent window that is moved to the current capture window due to noise interference.

[0058] Furthermore, this embodiment will analyze the capture credibility within the capture window. The greater the flip matching difference, the worse the capture effect, the more likely it is to be affected by other adjacent windows, and the lower the capture credibility. At the same time, the greater the logical chaos of the baseband signal, the more chaotic the baseband signal, and the lower the credibility of the captured flip phenomenon.

[0059] Therefore, this embodiment constructs the capture credibility and analyzes the capture credibility of the flip phenomenon in each capture window. The capture credibility expression is: Wherein, v is a preset value used to avoid the situation where the denominator is zero. In this embodiment, the value is 1, kx t is the capture confidence of the tth cycle; fz t,c is the flip matching difference of the flip phenomenon that occurs in the capture window of the cth capture of the flip phenomenon in the tth cycle; C is the number of flip phenomena captured in the tth cycle; σ t,u is the standard deviation of all high voltages in the tth cycle; σ t,d is the standard deviation of all low voltages in the tth cycle; hl t It is the logic chaos of the baseband signal in the tth period.

[0060] It should be understood that 1 minus the matching difference of the flip phenomenon, the larger the value, the higher the matching degree of the flip phenomenon, and the more credible the flip phenomenon captured in the tth cycle; the standard deviation of the high voltage part and the low voltage part of the tth cycle characterizes the degree of fluctuation of the digital baseband signal in the tth cycle, and represents the impact of noise on the digital signal. The larger the value, the greater the impact of noise on the digital signal, and the less credible the flip phenomenon captured in the tth cycle; the baseband signal logic chaos is the chaos of the digital signal logic caused by noise. The greater the chaos, the less credible the flip phenomenon captured in the tth cycle.

[0061] Finally, this embodiment will calculate the neighboring counter impact value and the local counter impact value, which are used to set the initial value of each timer in the histogram algorithm. First, according to the flip matching difference of the flip phenomenon of each capture window in the cycle and the counting situation of the capture window, the impact of each capture window on the neighboring counter is analyzed, and the neighboring counter impact value is constructed. The specific expression is: a，t =n a，t ×fz t，a ×(1-γ), where lj a，t is the neighboring counter impact value of the a-th capture window in the t-th period; n a，t is the count value of the a-th capture window in the t-th cycle, obtained through artificial statistics; fz t，a is the flip matching difference of the flip phenomenon occurring in the a-th capture window in the t-th cycle. γ is the counter influence attenuation coefficient, and the empirical value γ=0.2.

[0062] It should be understood that when the flip matching difference of the a-th capture window in the t-th period is larger, its counting result is more likely that the adjacent capture window is misjudged into the a-th capture window due to noise, and the corresponding initial value of the surrounding window when counting next time should be larger, and the corresponding adjacent counter impact value is larger. The larger the counter impact attenuation coefficient is, the smaller the impact of the count result of the a-th capture window on the surrounding capture windows is, and the smaller the adjacent counter impact value is.

[0063] Furthermore, this embodiment calculates the impact value of the local counter, and the specific expression is: bw a，t =n a，t ×(1-fz t，a )×(1+γ); where bw a，t is the impact value of the local counter of the ath capture window in the tth period; n a，t is the count value of the a-th capture window in the t-th cycle; fz t，a is the flip matching difference of the flip phenomenon occurring in the a-th capture window in the t-th period. γ is a preset counter influence attenuation coefficient, and in this embodiment, the value is γ=0.2.

[0064] It should be understood that when the flip match difference of the a-th capture window in the t-th period is smaller, the greater the flip match difference of 1 minus the flip match difference, the more likely the counting result is that the matching effect of the a-th capture window is better, the corresponding initial value of the corresponding counter of the a-th capture window should be larger, and the corresponding local counter impact value is larger. The larger the counter impact attenuation coefficient is, the greater the impact of the counting result of the a-th capture window on the initial value of its corresponding counter, and the greater the impact value of the local counter is.

[0065] Step S003, calculate the initial value of the counter, and use the improved histogram algorithm to capture the weak satellite signal.

[0066] This embodiment analyzes the initial value of the counter corresponding to the capture window according to the neighboring counter influence value of the capture window, the local counter influence value and the capture credibility within the period, and constructs the initial value of the counter: Among them, Cl a It is the initial value of the counter corresponding to the a-th capture window in the next round of histogram algorithm; is the rounding symbol for rounding the value in the brackets upward; β is the preset counter initial value strength weight, in this embodiment, β=0.25; T is the number of cycles; lj a-1，t 、lj a+1，t 、lj 1，t 、lj 2，t 、lj A-1，t 、lj A，t are the neighboring counter impact values ​​of the a-1th, a+1th, 1st, 2nd, A-1th, and Ath capture windows in the tth period respectively; bw a，t kx is the impact value of the local counter of the ath capture window in the tth period; t is the capture reliability of the flip phenomenon captured in the tth cycle; A is the number of capture windows in the cycle.

[0067] It should be understood that the initial value of the counter of the a-th capture window is obtained by adding the local counter influence value of the a-th capture window and the adjacent counter influence value of its adjacent capture window and multiplying it by the capture credibility. The higher the initial value of the counter, the greater the possibility of flipping in the a-th capture window in this round of histogram algorithm, the more credible the flipping phenomenon, and the more likely it is to be a bit edge position. In the next round of calculation of the histogram algorithm, the larger its initial value is, the more likely it is to be selected as the bit edge position.

[0068] Finally, when the histogram algorithm is run: when there is only one capture window (assuming it is the a-th capture window) whose corresponding counter counts exceed the second threshold, and the counts of the counters of other capture windows are lower than the first threshold, a bit edge appears in the digital baseband signal in the a-th capture window, that is, signal capture is completed, wherein the first threshold is lower than the second threshold;

[0069] If the counter counts of two capture windows exceed the first threshold at the same time, the counting result of this histogram is poor. In the traditional histogram algorithm, each counter is directly cleared to zero, while this embodiment sets the initial value of the counter of each capture window according to the initial value of the counter of each capture window to prevent all counters from being reset to zero, resulting in discarding the information before clearing and causing the next capture to be inaccurate. The specific setting is: calculate the initial value of the counter of each capture window, use the initial value of the counter as the value of the counter corresponding to the capture window, complete the improvement of the histogram algorithm, and capture the weak satellite signal through the improved histogram algorithm.

[0070] Compared with the traditional histogram algorithm, in the process of capturing digital baseband signals of weak satellite signals, the histogram algorithm requires resetting the counter multiple times, resulting in a slow capture speed. The embodiment of the present invention performs data enhancement on the statistical results of each round of the histogram algorithm, and then sets the initial value of the next round of the histogram algorithm, so that the histogram algorithm can capture the digital baseband signal faster and reduce satellite communication delay.

[0071] It should be noted that the sequence of the above embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0072] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0073] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Modifications to the technical solutions recorded in the aforementioned embodiments, or equivalent replacement of some of the technical features therein, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for quickly capturing weak Beidou satellite signals, characterized in that: The method comprises the following steps: Divide the satellite weak signal baseband digital signal into periods and obtain the capture window of each period; For each cycle, the logic disorder of the baseband signal in the cycle is obtained according to each voltage value of the baseband signal in the cycle and the preset high and low voltage standard values; the flip matching difference of the flip phenomenon occurring in each capture window is constructed according to the voltage of each capture window in the cycle and the preset high and low voltage standard values; the capture credibility of the cycle is obtained according to the logic disorder of the baseband signal in the cycle, the voltage fluctuation and the flip matching difference of the capture window that captures the flip phenomenon in the cycle; the adjacent counter influence value and the local counter influence value are constructed according to the counting situation of each capture window in the cycle, the flip matching difference of the flip phenomenon occurring and the preset counter influence attenuation coefficient; According to the capture credibility of each cycle in the current round of histogram algorithm and the neighboring counter influence value and the local counter influence value of each capture window, the initial value of the counter of each capture window in the next round of histogram algorithm is constructed; the histogram algorithm is improved in combination with the initial value of the counter of each capture window to capture the weak satellite signal; The improved histogram algorithm is combined with the initial value of the counter of each capture window to capture the weak satellite signal, including: If the count times of the counters of two capture windows simultaneously exceed the first threshold, the initial value of the counter of each capture window is used as the value of the counter corresponding to each capture window in the next round of histogram algorithm, and the satellite weak signal is captured by the improved histogram algorithm; If the number of counts of the counter of only one capture window exceeds the second threshold and the number of counts of the counters of other capture windows is lower than the first threshold, then weak satellite signal capture is achieved; The first threshold is smaller than the second threshold.

2. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 1, characterized in that: The period division of the satellite weak signal baseband digital signal includes: for the satellite baseband digital signal, every S milliseconds is a period, wherein S is a preset duration.

3. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 1, characterized in that: The method of obtaining the capture window of each cycle includes: for each cycle, dividing the cycle into a preset number of parts, and using the time period corresponding to each piece of data as a capture window.

4. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 1, characterized in that: The step of obtaining the logic chaos degree of the baseband signal within the period according to each voltage value of the baseband signal within the period and the preset high and low voltage standard values ​​includes: Preset high and low voltage standard values, take the average of the high and low voltage standard values ​​as the standard voltage median, take the voltage higher than the standard voltage median in the cycle as the high voltage, otherwise take the voltage as the low voltage; Obtain the absolute value of the difference between the mean of all high voltages in the cycle and the high voltage standard value, obtain the absolute value of the difference between the mean of all low voltages in the cycle and the low voltage standard value, and calculate the sum of the two absolute values ​​of the difference; The average of the absolute values ​​of the differences between each voltage value of the baseband signal within the period and the median value of the standard voltage is calculated, and the ratio of the sum to the result of adding 1 to the average is used as the logic chaos degree of the baseband signal within the period.

5. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 4, characterized in that: The flip matching difference of each capture window flipping phenomenon is constructed according to the voltage of each capture window in the cycle and the preset high and low voltage standard values, including: For each capture window in each cycle, the absolute value of the difference between the voltage mean of the capture window and the median of the standard voltage is calculated as the first absolute value, the difference between the high voltage standard value and the low voltage standard value is obtained, and the ratio of the first absolute value to half of the difference is taken as the flip matching difference when the capture window undergoes a flip phenomenon.

6. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 1, characterized in that: The capture credibility of the cycle is obtained according to the baseband signal logic disorder, voltage fluctuation and flip matching difference of the capture window that captures the flip phenomenon in the cycle, including: Calculate the difference between 1 and the flip matching difference of each capture window where the flip phenomenon occurs, and obtain the average of the difference of all capture windows that capture the flip phenomenon within the period; Obtaining the sum of the standard deviations of all high voltages and the standard deviations of all low voltages within a period, calculating the product of the baseband signal logic confusion within the period and the sum, and obtaining the sum of the product and a preset value; The ratio of the mean value to the summation result is taken as the capture reliability of the cycle.

7. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 5, characterized in that: The adjacent counter impact value includes: The count value of each capture window within the statistical period, and the preset counter influence attenuation coefficient; The product of the count value, 1, the difference between the counter influence attenuation coefficient, and the flip matching difference of the flip phenomenon occurring in each capture window is used as the adjacent counter influence value of each capture window.

8. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 7, characterized in that: The impact value of the local counter includes: The product of 1 and the sum of the counter influence attenuation coefficient, 1 and the flip matching difference of the flip phenomenon occurring in each capture window, and the count value is used as the local counter influence value of each capture window.

9. A method for quickly capturing a Beidou satellite weak signal as claimed in claim 1, characterized in that: The initial value of the counter corresponds to the calculation formula: ;in, It is the first The initial value of the counter corresponding to the capture window; It is the rounding symbol for rounding the value in brackets upwards; is the preset counter initial value strength weight; is the number of cycles; , , , , , They are Cycle No. , , , , , No. The neighboring counter impact value of the capture window; It is Cycle No. The impact value of the local counter of a capture window; It is The capture confidence of the flip phenomenon captured within a cycle; The number of capture windows in a cycle.

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