A vehicle-used external dual-frequency single Beidou locator and positioning method thereof

Abstract

The present invention relates to the technical field of vehicle locators, and in particular to an external dual-frequency single Beidou locator for a vehicle and a positioning method thereof, the positioning method comprising: receiving each initial satellite signal from different frequency bands of the Beidou satellite navigation system; screening each initial satellite signal once according to the receiving requirements, and performing a secondary screening based on the first screening result combined with the solution and analysis results of each intermediate satellite signal to obtain an actual satellite signal set; performing positioning calculation on the target navigation information corresponding to each target satellite signal in the actual satellite signal set; outputting the actual position information of the target vehicle; comparing the deviation between each actual position information corresponding to adjacent receiving cycles, and determining whether to turn on the abnormal correction mode according to the deviation; determining whether to turn on the enhanced positioning mode according to the number of target satellite signals or the deviation corresponding to the first frequency band. The present invention provides multi-level positioning guarantees, meets high-precision positioning requirements, and reduces positioning errors.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle positioners, and in particular to an external dual-frequency single Beidou positioner for a vehicle and a positioning method thereof. Background Art

[0002] The current vehicle locators cannot correct possible positioning errors in a timely manner, resulting in poor accuracy of the position information; they cannot adapt to complex navigation environments and application requirements; they cannot ensure the continuous provision of accurate position information; they cannot meet the requirements of high-precision positioning, resulting in large positioning errors and an inability to provide more stable and accurate navigation services.

[0003] Chinese patent application publication number CN112731471A discloses a method for selecting Beidou satellite-based enhanced single-frequency positioning satellites, including the following steps: Step 1: solving time t, obtaining all satellite PRN numbers, GPSL1C / A basic navigation messages and BDSBASB1C enhanced messages observed by the user receiver at the solving time t; Step 2: judging whether the user-observed satellite PRN number has completed the cycle, if not, proceeding to step 3; otherwise, judging the health status of the next satellite, proceeding to step 13; Step 3: judging the satellite UDREI Is it equal to 14 or 15? Parse the B1C enhanced message and obtain the UDREI value of the satellite. If it is equal to 14 or 15, go to step 12. Otherwise, if UDREI is neither equal to 14 nor equal to 15, go to step 4. Step 4: Determine the user service level. If the user service level is LPV, LP or LNAV / VNAV, go to step 6 and set the corresponding information timeout limit according to the UDREI comparison table and the message information content timeout table. Otherwise, go to step 5. Step 5: According to EnRoute, Termina l, LNAV level user service level, UDREI comparison table and message information content timeout table, set the corresponding information timeout limit, and enter step 7; Step 6: Determine whether the satellite UDREI is less than or equal to 12. If the UDREI is less than or equal to 12, enter step 7; otherwise, the satellite UDREI is greater than 12, enter step 12; Step 7: Ephemeris data age matching; Match the IOD in the satellite B1C enhanced message with the IODE in the L1C / A basic navigation message. If the searched IODE and IOD values ​​are equal, the match is successful. Among the several groups of L1C / A basic navigation messages that have successfully matched, select the group closest to the solution time t for subsequent calculations and enter step 8; otherwise, the match is not successful, and enter step 12; Step 8: Correction number and UDREI timeout judgment; Perform slow-changing correction number, fast-changing correction number and U DREI timeout judgment: if any one of the slow-changing correction number, the fast-changing correction number and the UDREI times out, go to step 12; otherwise, if it does not time out, go to step 9; Step 9: ionospheric grid point search; according to the algorithm specified in RTCADO-229E, calculate the user ionospheric puncture point, and find the valid ionospheric grid points around the puncture point. If the GIVE parameter value of the IGP is less than 15 and has not timed out, the IGP is valid and go to step 10; Step 10: Determine whether the searched valid IGP is greater than or equal to 3, if it is greater than or equal to 3, go to step 11, otherwise go to step 12; Step 11: The satellite health bit flag is set to 0, the satellite is healthy and available, go to step 2; Step 12: The satellite health bit flag is set to 1, the satellite is unhealthy and unavailable, go to step 2; Step 13: Enter the BDSBAS user navigation and positioning subsequent processing.

[0004] It can be seen that the current vehicle locator technology cannot meet the requirements of high-precision positioning and cannot provide more stable and accurate navigation services. Summary of the invention

[0005] To this end, the purpose of the present invention is to provide an external dual-frequency single Beidou locator for a vehicle and a positioning method thereof, so as to overcome the problem that the current vehicle locator technology cannot meet the requirements of high-precision positioning and cannot provide more stable and accurate navigation services.

[0006] To achieve the above object, the present invention provides a vehicle-mounted external dual-frequency single Beidou positioning method, comprising:

[0007] Receive several initial satellite signals from different frequency bands of the Beidou satellite navigation system. For any frequency band, pre-identify each initial satellite signal to obtain each intermediate satellite signal that meets the reception requirements through one screening;

[0008] Solving each intermediate satellite signal to obtain each intermediate navigation information, analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal;

[0009] According to the judgment result, each intermediate satellite signal is screened and integrated for the second time to determine the number of target satellite signals and the actual satellite signal set;

[0010] Performing positioning calculation based on the target navigation information corresponding to each target satellite signal in the actual satellite signal set to output actual position information of the target vehicle;

[0011] Periodically receiving each initial satellite signal transmitted by the BeiDou satellite navigation system, and sequentially performing the primary screening and the secondary screening based on each initial satellite signal received in each receiving period to obtain the actual satellite signal set corresponding to each receiving moment;

[0012] Compare the deviations between the actual position information corresponding to the adjacent receiving cycles, and determine whether to start the abnormal correction mode according to the deviations;

[0013] Determining whether to turn on the enhanced positioning mode based on the number of target satellite signals corresponding to the first frequency band or the deviation;

[0014] The different frequency bands include the first frequency band and the second frequency band; the receiving requirements include strength requirements, delay requirements and integrity requirements.

[0015] Furthermore, the process of pre-identifying each initial satellite signal includes:

[0016] For any initial satellite signal, obtaining actual receiving parameters of the initial satellite signal, including actual strength, actual propagation time and actual bit error rate;

[0017] Identifying the number of items of the actual strength, the actual propagation duration, and the actual bit error rate that meet a single reception condition;

[0018] When the number of items is 3, it is determined that the initial satellite signal has passed the primary screening and is the intermediate satellite signal; when the number of items is less than 3, it is determined that the initial satellite signal has not passed the primary screening;

[0019] Among them, for any actual reception parameter, if the actual reception parameter meets the corresponding reception requirement, it is determined that the actual reception parameter meets the single reception condition.

[0020] Furthermore, the process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal includes:

[0021] For any intermediate navigation information, identifying the intermediate navigation information to obtain phase change;

[0022] Based on the phase change being a rapid change or an irregular fluctuation or an interruption, it is determined that the intermediate navigation information is unreliable, and the unreliable intermediate satellite signal is excluded;

[0023] Based on the fact that the phase change is a continuous stable fluctuation, it is determined that the intermediate navigation information is reliable, and the reliable intermediate satellite signal is retained.

[0024] Furthermore, the process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal also includes:

[0025] Identify the intermediate navigation information to obtain time information, and acquire a transmission timestamp and a reception timestamp of the intermediate satellite signal according to the time information;

[0026] Calculate a standard propagation duration according to the transmission timestamp and the reception timestamp;

[0027] The standard transmission time is compared with the actual transmission time, and a time evaluation grade is determined according to the time comparison result.

[0028] Furthermore, the process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal also includes:

[0029] Identify all intermediate navigation information to obtain satellite position information, and obtain the number of received satellites and satellite distribution according to the satellite position information;

[0030] Determining whether the target vehicle can be positioned according to the number of received satellites and a preset threshold of locatable satellites;

[0031] Determining whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution;

[0032] The positioning accuracy is determined based on the time evaluation level and a judgment result of the positioning error.

[0033] Further, the process of determining whether the target vehicle can be positioned according to the number of received satellites and a preset locatable satellite threshold includes:

[0034] Calculating a first difference absolute value according to the number of received satellites and the locatable satellite threshold, and comparing the first difference absolute value with a preset first evaluation value;

[0035] Based on the absolute value of the first difference being less than or equal to the first evaluation value, determining that the target vehicle can be positioned;

[0036] Based on the fact that the absolute value of the first difference is greater than the first evaluation value, it is determined that positioning of the target vehicle is not possible.

[0037] Further, the process of judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution includes:

[0038] Taking the center of the earth as the center of the sphere, the sphere is evenly divided into blocks according to preset fixed angle intervals to form several interval areas;

[0039] For any interval area, counting the number of regional satellites in the interval area, and calculating the regional distribution density according to the number of regional satellites;

[0040] Determining whether the interval area meets the single distribution condition according to the area distribution density combined with a preset standard distribution density;

[0041] Merging the interval areas that meet the single distribution condition to obtain the total distribution area;

[0042] It is determined whether the satellite direction distribution is within the allowable range according to a first ratio of the total distribution area to the overall area.

[0043] Further, the process of judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution situation also includes:

[0044] Get the relative distance between each satellite and the center of the earth, and calculate the distance difference between any two relative distances;

[0045] Determining whether the two satellites are at the same relative altitude according to the distance difference and a preset distance evaluation value;

[0046] Count the satellites that are not at the same relative altitude to obtain the number of difference satellites;

[0047] Determining whether the satellite altitude distribution is within the allowable range according to a second ratio of the difference satellite number to the total satellite number;

[0048] The satellite distribution includes: the satellite direction distribution and the satellite altitude distribution.

[0049] Furthermore, the process of comparing the deviations between the actual position information corresponding to adjacent receiving cycles and determining whether to start the abnormal correction mode according to the deviations includes:

[0050] Acquire corresponding actual space coordinates according to the actual position information;

[0051] Calculating an actual deviation distance according to the actual spatial coordinates of the adjacent periods;

[0052] The deviation condition is determined based on the actual deviation distance combined with a preset standard deviation distance, and when the deviation condition is a serious deviation, the abnormal correction mode is started.

[0053] Another aspect of the present invention provides an external dual-frequency single Beidou locator for a vehicle, comprising:

[0054] A receiving end, which is used to receive initial satellite signals from different frequency bands of the Beidou satellite navigation system;

[0055] A screening module, which performs a primary screening on each initial satellite signal according to the receiving requirement, and performs a secondary screening based on the primary screening result combined with the solution and analysis results of each intermediate satellite signal to obtain the actual satellite signal set;

[0056] A determination module, which is used to perform positioning calculation on the target navigation information corresponding to each target satellite signal in the actual satellite signal set;

[0057] An output terminal, used for outputting the actual position information of the target vehicle;

[0058] A first auxiliary module, which is used to compare the deviations between the actual position information corresponding to the adjacent receiving cycles, and determine whether to start the abnormal correction mode according to the deviations;

[0059] The second auxiliary module is used to determine whether to start the enhanced positioning mode according to the number of target satellite signals or the deviation corresponding to the first frequency band.

[0060] Compared with the prior art, the beneficial effects of the present invention are that, through two rounds of screening, the optimal target satellite signal can be selected from the initial satellite signal to ensure high-quality positioning data; it helps to reduce errors and improve positioning accuracy; by periodically receiving and processing the signals of Beidou satellites, the positioning calculation can be dynamically adjusted and optimized in different time periods to cope with changes in satellite signal quality and environmental interference; after comparing the positioning deviations in adjacent receiving cycles, it can automatically determine whether it is necessary to turn on the abnormal correction mode, so as to correct possible positioning errors in time and improve the accuracy and stability of position information; improve the accuracy and reliability of positioning, and adapt to complex navigation environments and application requirements; through continuous signal reception and processing, the stability and accuracy of the positioning results can be monitored in real time, and adjustments and optimizations can be made in time to ensure continuous Provide accurate location information; meet the requirements of high-precision positioning and maintain stability and reliability under complex environmental conditions; through the pre-identification and screening process, only satellite signals that meet the reception requirements can be used for subsequent navigation information solution and positioning calculation, and those signals that may be unreliable due to various reasons (such as signal interference, transmission loss, etc.) are excluded, thereby improving the overall positioning accuracy; through the analysis and evaluation of intermediate satellite signals, their reliability and positioning accuracy can be judged, and high-quality signals can be further screened out for integration, which helps to improve the accuracy and stability of the final output target vehicle position information; combined with satellite signals of different frequency bands, it can provide multi-level positioning guarantees, meet high-precision positioning needs, effectively reduce positioning errors, and provide more stable and accurate navigation services.

[0061] In particular, by evaluating the actual receiving parameters of the received initial satellite signal, it is determined whether the initial satellite signal meets the receiving conditions, and then the intermediate satellite signals that meet the requirements are screened out; by evaluating the three key receiving parameters of actual strength, actual propagation time and actual bit error rate, and requiring that the signals that all three parameters meet the single receiving condition can pass the screening, the accuracy and reliability of the screening results are ensured; only those initial satellite signals whose actual receiving parameters all meet the preset standards are selected as intermediate satellite signals, which can effectively improve the quality of subsequent processing signals and reduce interference and errors caused by satellite signals that do not meet the standards; by strictly controlling the bit error rate, it is ensured that the selected intermediate satellite signals have It has a lower bit error rate, which helps to improve the accuracy and reliability of data transmission; excluding initial satellite signals with too long a propagation time during the screening process can improve the transmission efficiency of satellite signals, reduce delays, and enhance response speed; by controlling the actual strength, it ensures that the received satellite signal has sufficient strength, which helps to improve the stability and anti-interference capability of positioning, and reduce reception failures caused by insufficient satellite signal strength; through automated pre-identification and screening of initial satellite signals, it reduces manual intervention and improves processing efficiency and accuracy; it can effectively improve the quality and reliability of satellite signals, provide a solid foundation for subsequent signal processing and applications, and at the same time improve the efficiency and stability of the positioning process.

[0062] In particular, by identifying the phase changes of navigation information, it is possible to quickly determine which satellite signals are unreliable (such as rapidly changing, irregularly fluctuating or interrupted signals) and exclude them; while for signals with continuous and stable phase changes, they are deemed reliable and retained; this helps to eliminate interference signals at an early stage and improve the overall quality of navigation data; by calculating the transmission and reception timestamps, the standard propagation time can be obtained and compared with the actual propagation time; based on the comparison results, it is divided into level one (propagation time is less than the standard time) and level two (propagation time is greater than or equal to the standard time) evaluation levels; signals affected by the atmosphere can be accurately identified to further optimize signal reliability; by identifying the satellite position information in the navigation information, the number and distribution of receiving satellites can be obtained; based on Based on these data, it is possible to determine whether the preset locatable satellite threshold has been reached, thereby determining whether the target vehicle can be located; at the same time, based on the satellite distribution, it is possible to evaluate whether the positioning error is within the allowable range, and finally determine the degree of positioning accuracy in combination with the time evaluation level; by calculating the difference between the number of received satellites and the locatable satellite threshold, it is possible to determine whether the positioning operation can be performed, ensuring that a comprehensive evaluation of the signal and satellite configuration is performed before the positioning operation, to ensure the reliability and accuracy of the positioning operation; by comprehensively analyzing multiple factors in the navigation information, such as phase changes, propagation time, satellite positions and distribution, strict judgment and evaluation criteria are used to screen and optimize the navigation signals, which significantly improves the reliability and accuracy of the positioning system and ensures the efficiency and accuracy of the target vehicle positioning.

[0063] In particular, by taking the center of the earth as the center of the sphere and uniformly dividing the sphere at preset fixed angle intervals, the number of satellites in each interval area is counted, and the regional distribution density is calculated; it is judged whether the distribution density of each area reaches the preset standard distribution density to determine whether it meets the single distribution condition; the situation of uneven satellite distribution can be effectively identified, which affects the positioning accuracy; the interval areas that meet the single distribution condition are merged to obtain the total distribution area, and the proportion of the total distribution area to the overall area is calculated; by comparing whether the proportion of the total distribution area is greater than or equal to 0.7, it is judged whether the satellite direction distribution is within the allowable range; the uniformity of satellite distribution is effectively evaluated, which affects the accuracy and reliability of positioning; the relative distance between each satellite and the center of the earth is obtained, and the difference between any two relative distances is calculated; according to the preset distance evaluation value, it is judged whether the two satellites are at the same relative altitude; it is helpful to determine the distribution of satellites in altitude, which further affects the accuracy of the positioning information of the target vehicle; the influence of the satellite altitude distribution on the positioning error is effectively considered, and the accuracy of positioning is improved; by comprehensively analyzing the direction distribution and altitude distribution of satellites, the positioning error can be eliminated more comprehensively, the overall performance and accuracy of positioning can be improved, and the positioning operation of the target vehicle can be ensured to be more reliable and accurate.

[0064] In particular, the positioning accuracy is comprehensively evaluated through multiple dimensions such as time evaluation level, satellite direction distribution and satellite altitude distribution, making the evaluation more comprehensive and detailed; the positioning accuracy is divided into different levels of excellent and low, and the signals are screened and processed according to the positioning accuracy, so as to ensure that only high-quality signals are used for positioning, thereby improving the positioning accuracy; by secondary screening and integration of each intermediate satellite signal, only signals with high positioning accuracy are retained, so that those signals that may have low accuracy due to various reasons can be excluded, further improving the accuracy and reliability of positioning; by integrating the screened signals, a more optimized actual satellite signal set is obtained, which should contain the most valuable and accurate positioning information, providing a higher quality data basis for subsequent positioning calculations or applications; for those signals whose satellite direction distribution and satellite altitude distribution are not within the allowable range, they are directly judged as low-level. Such processing can avoid the influence of inaccurate or erroneous signal data on the final positioning results, thereby enhancing the robustness and stability of the entire positioning system; ensuring the quality and efficiency of positioning services.

[0065] In particular, by comparing the deviations of actual position information in adjacent receiving cycles, it is possible to promptly detect anomalies in positioning data and, when the deviation is serious, start the anomaly correction mode to improve positioning accuracy. It is able to monitor the deviations of positioning data in real time, and take appropriate measures according to the degree of deviation to make corrections in a timely manner to ensure positioning accuracy and reliability. By promptly detecting and handling anomalies in positioning data, it is possible to improve the reliability and stability of the entire positioning process and reduce problems and risks caused by positioning errors.

[0066] In particular, by combining the number of target satellite signals and deviations to determine whether to turn on the enhanced positioning mode, the positioning accuracy can be improved when needed to provide more accurate location information; by determining whether to perform enhanced positioning based on the number of target satellite signals, it is possible to avoid unnecessarily turning on the enhanced positioning mode when the satellite signal is poor, thereby optimizing resource utilization; the number of target satellite signals and deviations can be monitored in real time, and the positioning mode can be adjusted in a timely manner based on this information to ensure positioning accuracy and stability.

[0067] In particular, the use of dual-frequency positioning technology can reduce the impact of signal interference and multipath effects and improve the reliability of positioning; the locator can screen and process according to different reception requirements to adapt to different scenarios and environments; by comparing the actual position information deviations of adjacent receiving cycles, it can promptly detect abnormalities in positioning data and turn on the abnormality correction mode when the deviation is serious, thereby improving positioning accuracy; by reasonably turning on the enhanced positioning mode, the performance of the entire positioning system can be improved, providing users with a better service experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a flow chart of a vehicle external dual-frequency single Beidou positioning method according to an embodiment of the present invention;

[0069] Figure 2 This is a pre-identification flow chart of the external dual-frequency single Beidou positioning method for a vehicle according to an embodiment of the present invention;

[0070] Figure 3 This is a flow chart for determining whether the abnormal correction mode is turned on in the external dual-frequency single Beidou positioning method for a vehicle according to an embodiment of the present invention;

[0071] Figure 4 This is a schematic diagram of the structure of an external dual-frequency single Beidou locator for a vehicle according to an embodiment of the present invention;

[0072] The figure includes: 1-receiving end, 2-screening module, 3-determining module, 4-output end, 5-first auxiliary module, 6-second auxiliary module. DETAILED DESCRIPTION

[0073] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0074] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0075] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0076] See also Figure 1 As shown, it is a flow chart of a vehicle external dual-frequency single Beidou positioning method, including:

[0077] Step S100, receiving a plurality of initial satellite signals from different frequency bands of the Beidou satellite navigation system, and for any frequency band, pre-identifying each initial satellite signal to obtain each intermediate satellite signal that meets the reception requirements through a single screening;

[0078] Step S200, solving each intermediate satellite signal to obtain each intermediate navigation information, analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal;

[0079] Step S300, performing secondary screening and integration of each intermediate satellite signal according to the judgment result to determine the number of target satellite signals and the actual satellite signal set;

[0080] Step S400, performing positioning calculation based on the target navigation information corresponding to each target satellite signal in the actual satellite signal set to output actual position information of the target vehicle;

[0081] Step S500, periodically receiving each initial satellite signal transmitted by the Beidou satellite navigation system, and sequentially performing the primary screening and the secondary screening based on each initial satellite signal received in each receiving period to obtain the actual satellite signal set corresponding to each receiving time;

[0082] Step S600, comparing the deviations between the actual position information corresponding to the adjacent receiving cycles, and determining whether to start the abnormal correction mode according to the deviations;

[0083] Step S700, determining whether to start the enhanced positioning mode based on the number of target satellite signals corresponding to the first frequency band or the deviation;

[0084] The different frequency bands include the first frequency band and the second frequency band; the receiving requirements include strength requirements, delay requirements and integrity requirements.

[0085] Specifically, the embodiment of the present invention can select the best target satellite signal from the initial satellite signal through two rounds of screening to ensure high-quality positioning data; it helps to reduce errors and improve positioning accuracy; it periodically receives and processes the signals of Beidou satellites, and can dynamically adjust and optimize the positioning calculation in different time periods to cope with changes in satellite signal quality and environmental interference; after comparing the positioning deviations in adjacent receiving cycles, it can automatically determine whether it is necessary to turn on the abnormal correction mode, so as to correct possible positioning errors in time and improve the accuracy and stability of position information; it improves the accuracy and reliability of positioning and adapts to complex navigation environments and application requirements; through continuous signal reception and processing, it can monitor the stability and accuracy of the positioning results in real time, and make adjustments and optimizations in time to ensure the continuous provision of accurate position information; to meet the requirements of high-precision positioning and maintain stability and reliability under complex environmental conditions; through the pre-identification and screening process, only satellite signals that meet the reception requirements can be used for subsequent navigation information solution and positioning calculation, and those signals that may be unreliable due to various reasons (such as signal interference, transmission loss, etc.) are excluded, thereby improving the overall positioning accuracy; through the analysis and evaluation of intermediate satellite signals, their reliability and positioning accuracy can be judged, and high-quality signals can be further screened out for integration, which helps to improve the accuracy and stability of the target vehicle position information that is finally output; combining satellite signals of different frequency bands can provide multi-level positioning guarantees, meet high-precision positioning needs, effectively reduce positioning errors, and provide more stable and accurate navigation services.

[0086] Specifically, see Figure 2 As shown, it is a pre-identification flow chart, wherein the process of pre-identifying each initial satellite signal includes:

[0087] Step S101, for any initial satellite signal, obtaining actual receiving parameters of the initial satellite signal, including actual strength, actual propagation time and actual bit error rate;

[0088] Step S102, identifying the number of items in the actual strength, the actual propagation duration, and the actual bit error rate that meet a single receiving condition;

[0089] Step S103, when the number of items is 3, determining that the initial satellite signal passes the first screening and is the intermediate satellite signal;

[0090] Step S104, when the number of items is less than 3, determining that the initial satellite signal fails to pass the first screening;

[0091] Among them, for any actual reception parameter, if the actual reception parameter meets the corresponding reception requirement, it is determined that the actual reception parameter meets the single reception condition.

[0092] Specifically, judging whether the strength requirement is met according to the actual strength combined with the preset standard strength;

[0093] If the actual strength is greater than or equal to the standard strength, it is determined that the initial satellite signal meets the strength requirement, and the actual strength meets the single reception condition;

[0094] If the actual strength is less than the standard strength, it is determined that the initial satellite signal does not meet the strength requirement, and it is determined that the actual strength does not meet the single reception condition;

[0095] Determining whether the delay requirement is met according to the actual propagation time and a preset standard propagation time;

[0096] If the actual propagation time is less than or equal to the standard propagation time, it is determined that the initial satellite signal meets the delay requirement, and the actual propagation time meets the single reception condition;

[0097] If the actual propagation time is greater than the standard propagation time, it is determined that the initial satellite signal does not meet the delay requirement, and it is determined that the actual propagation time does not meet the single reception condition;

[0098] Determining whether the complete requirement is met according to the actual bit error rate combined with a preset standard bit error rate;

[0099] If the actual bit error rate is less than or equal to the standard bit error rate, it is determined that the initial satellite signal meets the integrity requirement, and the actual bit error rate meets the single reception condition;

[0100] If the actual bit error rate is greater than the standard bit error rate, it is determined that the initial satellite signal does not meet the complete requirement, and it is determined that the actual bit error rate does not meet the single reception condition;

[0101] In this embodiment, the standard strength is used to measure the energy level of the initial satellite signal during the propagation process; the standard propagation time is used to measure the real-time performance of data transmission; the standard bit error rate is used to measure the integrity of data transmission; the standard strength is set to -50dBm--40dBm; the standard propagation time is set to 0.2 milliseconds-0.6 milliseconds; the standard bit error rate is set to 10 -6 ; and make adaptive selections based on actual application requirements and the geographical location of the target vehicle.

[0102] Specifically, the embodiments of the present invention evaluate the actual receiving parameters of the received initial satellite signals to determine whether the initial satellite signals meet the receiving conditions, and then screen out the intermediate satellite signals that meet the requirements; evaluate the three key receiving parameters of the actual strength, the actual propagation time and the actual bit error rate, and require that only the signals that meet the single receiving condition of the three parameters can pass the screening, thereby ensuring the accuracy and reliability of the screening results; only those initial satellite signals whose actual receiving parameters all meet the preset standards are selected as the intermediate satellite signals, which can effectively improve the quality of the subsequent processing signals and reduce the interference and errors caused by the satellite signals that do not meet the standards; and ensure that the selected intermediate satellite signals are of good quality by strictly controlling the bit error rate. Satellite signals have a lower bit error rate, which helps to improve the accuracy and reliability of data transmission; excluding initial satellite signals with too long a propagation time during the screening process can improve the transmission efficiency of satellite signals, reduce delays, and enhance response speed; by controlling the actual strength, ensuring that the received satellite signal has sufficient strength, it helps to improve positioning stability and anti-interference capabilities, and reduce reception failures caused by insufficient satellite signal strength; through automated pre-identification and screening of initial satellite signals, human intervention is reduced, and processing efficiency and accuracy are improved; it can effectively improve the quality and reliability of satellite signals, provide a solid foundation for subsequent signal processing and applications, and at the same time improve the efficiency and stability of the positioning process.

[0103] Specifically, the process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal in this embodiment includes:

[0104] Step S211, for any intermediate navigation information, identifying the intermediate navigation information to obtain phase change;

[0105] Step S212, based on the phase change being a rapid change or an irregular fluctuation or an interruption, determining that the intermediate navigation information is unreliable, and excluding the unreliable intermediate satellite signal;

[0106] Step S213: Based on the phase change being a continuous stable fluctuation, it is determined that the intermediate navigation information is reliable, and the reliable intermediate satellite signal is retained.

[0107] Specifically, the process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal in this embodiment also includes:

[0108] Step S221, identifying the intermediate navigation information to obtain time information, and acquiring a transmission timestamp and a reception timestamp of the intermediate satellite signal according to the time information;

[0109] Step S222, calculating a standard propagation duration according to the transmission timestamp and the reception timestamp;

[0110] Step S223, comparing the standard transmission time with the actual transmission time, and determining a time evaluation level according to the time comparison result.

[0111] Specifically, the standard propagation time length in this embodiment = receiving timestamp - transmitting timestamp;

[0112] If the actual transmission time is less than the standard transmission time, the time evaluation level is determined to be level one;

[0113] If the actual transmission time is greater than or equal to the standard transmission time, the time evaluation level is determined to be level 2;

[0114] During the specific implementation process, when receiving satellite signals, the standard propagation time determined based on the receiving timestamp and the transmitting timestamp is the standard time required for the satellite signal to be transmitted from the satellite to reach the receiver; the actual propagation time actually obtained refers to the time required for the satellite signal to be actually transmitted from the satellite to be captured by the receiver, and the actual propagation time will be affected by the refraction or reflection of the satellite signal by the atmosphere.

[0115] Specifically, the process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal in this embodiment also includes:

[0116] Step S231, identifying all intermediate navigation information to obtain satellite position information, and acquiring the number of received satellites and satellite distribution according to the satellite position information;

[0117] Step S232, judging whether the target vehicle can be positioned according to the number of received satellites and a preset threshold of positionable satellites;

[0118] Step S233, judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution;

[0119] Step S234: Determine the positioning accuracy based on the time evaluation level and the judgment result of the positioning error.

[0120] Specifically, the process of determining whether the target vehicle can be positioned according to the number of received satellites and a preset locatable satellite threshold includes:

[0121] Calculating a first difference absolute value according to the number of received satellites and the locatable satellite threshold, and comparing the first difference absolute value with a preset first evaluation value;

[0122] Based on the absolute value of the first difference being less than or equal to the first evaluation value, determining that the target vehicle can be positioned;

[0123] Based on the absolute value of the first difference being greater than the first evaluation value, determining that the target vehicle cannot be positioned;

[0124] The absolute value of the first difference = |number of received satellites - threshold of locatable satellites|;

[0125] In this embodiment, the number of received satellites is used to measure the number of actual satellite signals that the target vehicle can receive at the same time; the locatable satellite threshold is used to measure the number of standard satellite signals that can be received when the target vehicle can be positioned; the locatable satellite threshold is set to 8-10; the first evaluation value is set to 2; and the selection is adapted according to the actual application requirements and the geographical location of the target vehicle.

[0126] Specifically, the embodiments of the present invention can quickly determine which satellite signals are unreliable (such as rapidly changing, irregularly fluctuating or interrupted signals) and exclude them by identifying the phase changes of navigation information; and for signals with continuous and stable phase changes, they are deemed reliable and retained; it helps to eliminate interference signals at an early stage and improve the overall quality of navigation data; by calculating the transmission and reception timestamps, the standard propagation time can be obtained and compared with the actual propagation time; according to the comparison results, it is divided into primary (propagation time is less than the standard time) and secondary (propagation time is greater than or equal to the standard time) evaluation levels; signals affected by the atmosphere can be accurately identified to further optimize the reliability of the signal; by identifying the satellite position information in the navigation information, the number and distribution of received satellites can be obtained situation; based on these data, it can be determined whether the preset locatable satellite threshold has been reached, thereby determining whether the target vehicle can be located; at the same time, based on the satellite distribution, it can be evaluated whether the positioning error is within the allowable range, and combined with the time evaluation level, the accuracy of positioning can be finally determined; by calculating the difference between the number of received satellites and the locatable satellite threshold, it is determined whether the positioning operation can be performed, ensuring that a comprehensive evaluation of the signal and satellite configuration is carried out before the positioning operation, so as to ensure the reliability and accuracy of the positioning operation; by comprehensively analyzing multiple factors such as phase changes, propagation time, satellite positions and distribution in the navigation information, strict judgment and evaluation criteria are adopted to screen and optimize the navigation signals, which significantly improves the reliability and accuracy of the positioning system and ensures the efficiency and accuracy of the target vehicle positioning.

[0127] Specifically, the process of judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution in this embodiment includes:

[0128] Taking the center of the earth as the center of the sphere, the sphere is evenly divided into blocks according to preset fixed angle intervals to form several interval areas;

[0129] For any interval area, counting the number of regional satellites in the interval area, and calculating the regional distribution density according to the number of regional satellites;

[0130] Determining whether the interval area meets the single distribution condition according to the area distribution density combined with a preset standard distribution density;

[0131] Merging the interval areas that meet the single distribution condition to obtain the total distribution area;

[0132] It is determined whether the satellite direction distribution is within the allowable range according to a first ratio of the total distribution area to the overall area.

[0133] Specifically, for any interval region, based on the fact that the regional distribution density is greater than or equal to the standard distribution density, it is determined that the interval region meets the single distribution condition;

[0134] Based on the regional distribution density being less than the standard distribution density, determining that the interval region does not meet the single distribution condition;

[0135] The first proportion = total distribution area / overall area;

[0136] If the first proportion is greater than or equal to 0.7, it is determined that the satellite direction distribution is within the allowed range;

[0137] If the first proportion is less than 0.7, it is determined that the satellite direction distribution is not within the allowable range;

[0138] In this embodiment, the standard distribution density is used to measure the number of satellites in the interval area; the total distribution area is used to measure the regional distribution range of each satellite relative to the target vehicle; the overall area is a complete range with the center of the earth as the center of the sphere; the total distribution area is less than or equal to the overall area; the standard distribution density is set to 0.2 or 0.3; and is adapted and selected according to actual application requirements and the geographical location of the target vehicle.

[0139] Specifically, the process of judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution situation further includes:

[0140] Get the relative distance between each satellite and the center of the earth, and calculate the distance difference between any two relative distances;

[0141] Determining whether the two satellites are at the same relative altitude according to the distance difference and a preset distance evaluation value;

[0142] Count the satellites that are not at the same relative altitude to obtain the number of difference satellites;

[0143] Determining whether the satellite altitude distribution is within the allowable range according to a second ratio of the difference satellite number to the total satellite number;

[0144] The satellite distribution includes: the satellite direction distribution and the satellite altitude distribution.

[0145] Specifically, based on the distance difference being greater than or equal to the distance evaluation value, it is determined that the two satellites are not at the same relative altitude;

[0146] Based on the distance difference being less than the distance evaluation value, it is determined that the two satellites are at the same relative altitude;

[0147] The second proportion = the number of difference satellites / the total number of satellites;

[0148] In this embodiment, the distance evaluation value is used to measure whether two satellites are at the same relative altitude; the difference satellite number is used to measure the altitude distribution range of each satellite relative to the target vehicle; the specific setting of the distance evaluation value is affected by the actual application requirements and the geographical location of the target vehicle.

[0149] Specifically, the embodiment of the present invention uses the center of the earth as the center of the sphere, divides the sphere into blocks uniformly according to a preset fixed angle interval, counts the number of satellites in each interval area, and calculates the regional distribution density; determines whether the distribution density of each area reaches the preset standard distribution density to determine whether it meets the single distribution condition; can effectively identify the situation of uneven satellite distribution, thereby affecting the positioning accuracy; merges the interval areas that meet the single distribution condition to obtain the total distribution area, and calculates the proportion of the total distribution area to the overall area; by comparing whether the proportion of the total distribution area is greater than or equal to 0.7, it is determined whether the satellite direction distribution is within the allowable range; effectively evaluates the uniformity of satellite distribution, thereby affecting the accuracy and reliability of positioning; obtains the relative distance between each satellite and the center of the earth, and calculates the difference between any two relative distances; according to the preset distance evaluation value, determines whether the two satellites are at the same relative altitude; helps to determine the distribution of satellites in altitude, which further affects the accuracy of the positioning information of the target vehicle; effectively considers the influence of the satellite altitude distribution on the positioning error, and improves the accuracy of positioning; by comprehensively analyzing the direction distribution and altitude distribution of the satellite, the positioning error can be eliminated more comprehensively, the overall performance and accuracy of positioning can be improved, and the positioning operation of the target vehicle can be ensured to be more reliable and accurate.

[0150] Specifically, in this embodiment, when the time evaluation level is level one and the satellite direction distribution and the satellite altitude distribution are both within the allowable range, the positioning accuracy is determined to be excellent;

[0151] When the time evaluation level is level 2, the positioning accuracy is determined to be low;

[0152] When any one of the satellite direction distribution and the satellite altitude distribution is not within the allowable range, the positioning accuracy is determined to be low;

[0153] Performing secondary screening and integration of each intermediate satellite signal according to the actual positioning accuracy;

[0154] For any intermediate satellite signal;

[0155] If the positioning accuracy of the intermediate satellite signal is high, the intermediate satellite signal passes the secondary screening;

[0156] If the positioning accuracy of the intermediate satellite signal is low, the intermediate satellite signal fails the secondary screening;

[0157] The intermediate satellite signals that pass the secondary screening are integrated to obtain the actual satellite signal set.

[0158] Specifically, the embodiment of the present invention comprehensively evaluates the positioning accuracy through multiple dimensions such as time evaluation level, satellite direction distribution and satellite height distribution, so that the evaluation is more comprehensive and detailed; the positioning accuracy is divided into different levels of excellent and low, and the signal is screened and processed according to the positioning accuracy, so that only high-quality signals are used for positioning, thereby improving the positioning accuracy; by performing secondary screening and integration of each intermediate satellite signal, only signals with high positioning accuracy are retained, so that those signals that may have low accuracy due to various reasons can be excluded, and the accuracy and reliability of positioning can be further improved; by integrating the screened signals, a more optimized actual satellite signal set is obtained, and this signal set should contain the most valuable and accurate positioning information, providing a higher quality data basis for subsequent positioning calculations or applications; for those signals whose satellite direction distribution and satellite height distribution are not within the allowable range, they are directly judged as low-level, and such processing can avoid the influence of inaccurate or erroneous signal data on the final positioning result, thereby enhancing the robustness and stability of the entire positioning system; ensuring the quality and efficiency of positioning services.

[0159] Specifically, see Figure 3As shown, it is a flow chart for determining whether to start the abnormal correction mode, wherein the process of comparing the deviation between the actual position information corresponding to adjacent receiving cycles and determining whether to start the abnormal correction mode according to the deviation includes:

[0160] Step S610, acquiring corresponding actual space coordinates according to the actual position information;

[0161] Step S620, calculating the actual deviation distance according to the actual space coordinates of the adjacent periods;

[0162] Step S630, determining the deviation condition based on the actual deviation distance in combination with a preset standard deviation distance, and starting the abnormality correction mode when the deviation condition is a serious deviation.

[0163] Specifically, for any receiving cycle, the actual space coordinate A1 (X1, Y1, Z1) corresponding to the receiving cycle is obtained; and the actual space coordinate A2 (X2, Y2, Z2) corresponding to the adjacent receiving cycle is obtained;

[0164] Calculate the actual deviation distance D according to A1 (X1, Y1, Z1) and A2 (X2, Y2, Z2);

[0165]

[0166] If the actual deviation distance is greater than or equal to the standard deviation distance, the deviation situation is determined to be the severe deviation;

[0167] If the actual deviation distance is greater than 0 and less than the standard deviation distance, the deviation is determined to be a slight deviation;

[0168] If the actual deviation distance is equal to 0, the deviation situation is determined to be no deviation;

[0169] In this embodiment, the standard deviation distance is used to measure the positioning deviation between adjacent receiving cycles; the specific setting of the standard deviation distance is affected by actual application requirements and the geographical location of the target vehicle.

[0170] Specifically, the embodiments of the present invention can promptly detect anomalies in positioning data by comparing the deviations of actual position information of adjacent receiving cycles, and start an abnormality correction mode when the deviation is serious, thereby improving positioning accuracy; it can monitor the deviation of positioning data in real time, and take corresponding measures according to the degree of deviation, and make corrections in time to ensure the accuracy and reliability of positioning; by promptly detecting and processing anomalies in positioning data, the reliability and stability of the entire positioning process can be improved, and problems and risks caused by positioning errors can be reduced.

[0171] Specifically, the process of determining whether to turn on the enhanced positioning mode based on the number of target satellite signals or the deviation corresponding to the first frequency band in this embodiment includes:

[0172] Step S710, judging whether enhanced positioning in the second frequency band can be performed according to the number of target satellite signals and a preset high-precision positioning signal threshold;

[0173] Step S720: If the number of target satellite signals is greater than or equal to the high-precision positioning signal threshold, it is determined to start the enhanced positioning mode;

[0174] Step S730: When the deviation is the slight deviation, determine to start the enhanced positioning mode.

[0175] In this embodiment, the high-precision positioning signal threshold is set to 4 or 5; and is adaptively selected according to actual application requirements and the geographical location of the target vehicle.

[0176] Specifically, the embodiments of the present invention determine whether to turn on the enhanced positioning mode by combining the number of target satellite signals and the deviation, so as to improve the positioning accuracy when needed and provide more accurate location information; determine whether to perform enhanced positioning based on the number of target satellite signals, so as to avoid unnecessary turning on the enhanced positioning mode when the satellite signal is poor, thereby optimizing resource utilization; the number of target satellite signals and the deviation can be monitored in real time, and the positioning mode can be adjusted in time according to this information to ensure the accuracy and stability of positioning.

[0177] Specifically, see Figure 4 As shown, it is a structural diagram of an external dual-frequency single Beidou locator for a vehicle, including:

[0178] A receiving end 1, which is used to receive initial satellite signals from different frequency bands of the Beidou satellite navigation system;

[0179] A screening module 2, which performs a primary screening on each initial satellite signal according to the receiving requirement, and performs a secondary screening based on the primary screening result combined with the solution and analysis results of each intermediate satellite signal to obtain the actual satellite signal set;

[0180] A determination module 3, which is used to perform positioning calculation on the target navigation information corresponding to each target satellite signal in the actual satellite signal set;

[0181] An output terminal 4, which is used to output the actual position information of the target vehicle;

[0182] A first auxiliary module 5, which is used to compare the deviations between the actual position information corresponding to the adjacent receiving cycles, and determine whether to start the abnormal correction mode according to the deviations;

[0183] The second auxiliary module 6 is used to determine whether to start the enhanced positioning mode according to the number of target satellite signals or the deviation corresponding to the first frequency band.

[0184] Specifically, the embodiment of the present invention adopts dual-frequency positioning technology, which can reduce the influence of signal interference and multipath effect and improve the reliability of positioning; the locator can screen and process according to different receiving requirements to adapt to different scenarios and environments; by comparing the actual position information deviation of adjacent receiving cycles, it can timely discover the abnormality of positioning data, and turn on the abnormality correction mode when the deviation is serious, thereby improving the positioning accuracy; by reasonably turning on the enhanced positioning mode, the performance of the entire positioning system can be improved, providing users with a better service experience.

[0185] The calculation compensation parameters and the calculation adjustment parameters described in the present invention have two functions: one is to balance the left and right dimensions of the formula, and the other is to adjust the numerical results. No specific assignment is performed in this embodiment. In addition, the calculation formulas in this embodiment are used to intuitively reflect the adjustment relationship between the numerical values, such as positive correlation and negative correlation. Unless otherwise specified, the parameter values ​​that are not specifically limited to numerical values ​​are all positive.

[0186] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0187] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A vehicle-based external dual-frequency single Beidou positioning method, characterized in that: include: Receive several initial satellite signals from different frequency bands of the Beidou satellite navigation system. For any frequency band, pre-identify each initial satellite signal to obtain each intermediate satellite signal that meets the reception requirements through one screening; Solving each intermediate satellite signal to obtain each intermediate navigation information, analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal; According to the judgment result, each intermediate satellite signal is screened and integrated for the second time to determine the number of target satellite signals and the actual satellite signal set; Performing positioning calculation based on the target navigation information corresponding to each target satellite signal in the actual satellite signal set to output actual position information of the target vehicle; Periodically receiving each initial satellite signal transmitted by the BeiDou satellite navigation system, and sequentially performing the primary screening and the secondary screening based on each initial satellite signal received in each receiving period to obtain the actual satellite signal set corresponding to each receiving moment; Compare the deviations between the actual position information corresponding to the adjacent receiving cycles, and determine whether to start the abnormal correction mode according to the deviations; Determining whether to turn on the enhanced positioning mode based on the number of target satellite signals corresponding to the first frequency band or the deviation; The different frequency bands include the first frequency band and the second frequency band; the receiving requirements include strength requirements, delay requirements and integrity requirements.

2. The vehicle external dual-frequency single Beidou positioning method according to claim 1, characterized in that: The process of pre-identifying each initial satellite signal includes: For any initial satellite signal, obtaining actual receiving parameters of the initial satellite signal, including actual strength, actual propagation time and actual bit error rate; Identifying the number of items of the actual strength, the actual propagation duration, and the actual bit error rate that meet a single reception condition; When the number of items is 3, it is determined that the initial satellite signal has passed the primary screening and is the intermediate satellite signal; when the number of items is less than 3, it is determined that the initial satellite signal has not passed the primary screening; Among them, for any actual reception parameter, if the actual reception parameter meets the corresponding reception requirement, it is determined that the actual reception parameter meets the single reception condition.

3. The vehicle external dual-frequency single Beidou positioning method according to claim 2, characterized in that: The process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal includes: For any intermediate navigation information, identifying the intermediate navigation information to obtain phase change; Based on the phase change being a rapid change or an irregular fluctuation or an interruption, it is determined that the intermediate navigation information is unreliable, and the unreliable intermediate satellite signal is excluded; Based on the fact that the phase change is a continuous stable fluctuation, it is determined that the intermediate navigation information is reliable, and the reliable intermediate satellite signal is retained.

4. The vehicle external dual-frequency single Beidou positioning method according to claim 3, characterized in that: The process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal also includes: Identify the intermediate navigation information to obtain time information, and acquire a transmission timestamp and a reception timestamp of the intermediate satellite signal according to the time information; Calculate a standard propagation duration according to the transmission timestamp and the reception timestamp; The standard transmission time is compared with the actual transmission time, and a time evaluation grade is determined according to the time comparison result.

5. The vehicle external dual-frequency single Beidou positioning method according to claim 4, characterized in that: The process of analyzing each intermediate navigation information to determine the reliability and positioning accuracy of each intermediate satellite signal also includes: Identify all intermediate navigation information to obtain satellite position information, and obtain the number of received satellites and satellite distribution according to the satellite position information; Determining whether the target vehicle can be positioned according to the number of received satellites and a preset threshold of locatable satellites; Determining whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution; The positioning accuracy is determined based on the time evaluation level and a judgment result of the positioning error.

6. The vehicle external dual-frequency single Beidou positioning method according to claim 5, characterized in that: The process of determining whether the target vehicle can be positioned according to the number of received satellites and a preset threshold of positionable satellites includes: Calculating a first difference absolute value according to the number of received satellites and the locatable satellite threshold, and comparing the first difference absolute value with a preset first evaluation value; Based on the absolute value of the first difference being less than or equal to the first evaluation value, determining that the target vehicle can be positioned; Based on the fact that the absolute value of the first difference is greater than the first evaluation value, it is determined that positioning of the target vehicle is not possible.

7. The vehicle external dual-frequency single Beidou positioning method according to claim 6, characterized in that: The process of judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution includes: Taking the center of the earth as the center of the sphere, the sphere is evenly divided into blocks according to preset fixed angle intervals to form several interval areas; For any interval area, counting the number of regional satellites in the interval area, and calculating the regional distribution density according to the number of regional satellites; Determining whether the interval area meets the single distribution condition according to the area distribution density combined with a preset standard distribution density; Merging the interval areas that meet the single distribution condition to obtain the total distribution area; It is determined whether the satellite direction distribution is within the allowable range according to a first ratio of the total distribution area to the overall area.

8. The vehicle external dual-frequency single Beidou positioning method according to claim 7, characterized in that: The process of judging whether the positioning error of the target vehicle is within an allowable range according to the satellite distribution situation also includes: Get the relative distance between each satellite and the center of the earth, and calculate the distance difference between any two relative distances; Determining whether the two satellites are at the same relative altitude according to the distance difference and a preset distance evaluation value; Count the satellites that are not at the same relative altitude to obtain the number of difference satellites; Determining whether the satellite altitude distribution is within the allowable range according to a second ratio of the difference satellite number to the total satellite number; The satellite distribution includes: the satellite direction distribution and the satellite altitude distribution.

9. The vehicle external dual-frequency single Beidou positioning method according to claim 8, characterized in that: The process of comparing the deviations between the actual position information corresponding to adjacent receiving cycles and determining whether to start the abnormal correction mode according to the deviations includes: Acquire corresponding actual space coordinates according to the actual position information; Calculating an actual deviation distance according to the actual spatial coordinates of the adjacent periods; The deviation condition is determined based on the actual deviation distance combined with a preset standard deviation distance, and when the deviation condition is a serious deviation, the abnormal correction mode is started.

10. An external dual-frequency single Beidou positioning device for vehicle, based on the external dual-frequency single Beidou positioning method for vehicle according to any one of claims 1 to 9, characterized in that: include: A receiving end, which is used to receive initial satellite signals from different frequency bands of the Beidou satellite navigation system; A screening module, which performs a primary screening on each initial satellite signal according to the receiving requirement, and performs a secondary screening based on the primary screening result combined with the solution and analysis results of each intermediate satellite signal to obtain the actual satellite signal set; A determination module, which is used to perform positioning calculation on the target navigation information corresponding to each target satellite signal in the actual satellite signal set; An output terminal, used for outputting the actual position information of the target vehicle; A first auxiliary module, which is used to compare the deviations between the actual position information corresponding to the adjacent receiving cycles, and determine whether to start the abnormal correction mode according to the deviations; The second auxiliary module is used to determine whether to start the enhanced positioning mode according to the number of target satellite signals or the deviation corresponding to the first frequency band.

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