A navigation rescue method and system based on Beidou short message rapid positioning

Abstract

The present invention relates to a navigation rescue method and system based on Beidou short message rapid positioning, comprising the following steps: step S1, decoding the data of the Beidou navigation system received by the reference base station to obtain the Beidou short message; step S2, the rapid positioning platform performs position calculation on the decoded Beidou short message to obtain positioning information; step S3, judging the calculated positioning information and issuing an early warning. The differential platform in the present invention can perform fine tracking processing based on multiple reference message messages of the reference base station to obtain baseband observations for differential calculation that eliminate the transmission error between the base station and the differential platform, and multiple reference channels are finely tracked to obtain a carrier phase error with a smaller error, which can achieve accurate positioning in a rescue environment.

Description

Technical Field

[0001] The present invention relates to the field of ground-based augmentation, and in particular to a navigation rescue method and system based on Beidou short message rapid positioning. Background Art

[0002] Navigation and communication systems are widely used in the field of location services. The positioning and target monitoring of satellite navigation systems are widely used in life. The Beidou navigation system plays an important role in target search and rescue. Among them, the Beidou short message communication function is a unique function in the Beidou navigation system. Especially for rescue and special positioning scenarios, the rapid positioning and early warning of the Beidou short message communication improves the positioning accuracy and timeliness of the target, which is particularly important for rescue efficiency.

[0003] However, the efficiency of rescue and search and timely rescue communication based on Beidou short message communication are still the current difficulties. Summary of the invention

[0004] To achieve the above object, the present invention provides a navigation rescue method based on Beidou short message rapid positioning, which specifically includes:

[0005] Step S1, decoding the data of the Beidou navigation system received by the reference base station to obtain a Beidou short message;

[0006] Step S2: The rapid positioning platform calculates the position of the decoded Beidou short message to obtain positioning information;

[0007] Step S3: determine the obtained positioning information and issue an early warning.

[0008] Further, step S1 comprises:

[0009] Step S11, the reference base station measures and obtains Beidou satellite parameters based on the principle of navigation receiver;

[0010] Step S12, obtaining a Beidou short message by modulating Beidou satellite parameters;

[0011] Step S13, setting a reference channel based on the Beidou short message;

[0012] Step S14: Send the Beidou short message through the signal sending unit.

[0013] Further, the steps of step S12 include:

[0014] Step S121, the reference base station measurement data and the existing baseband observations are analyzed for abnormal carrier-to-noise ratio. When the carrier-to-noise ratio CNo of the measurement data is greater than or equal to or less than or equal to the carrier-to-noise ratio threshold, the measurement data is judged as abnormal, and the abnormal signal is removed to obtain Beidou measurement data without abnormal data; the baseband observations include: satellite PRN number, satellite transmission delay τ, carrier phase Doppler frequency f d ;

[0015] Step S122: The reference base station sets warning and rescue information, 0 for danger warning and rescue, 1 for safety;

[0016] Step S123, the reference base station uses the Beidou measurement data with abnormal data removed as the information bit according to the Beidou navigation message format, combines the corrected ionospheric information in the observation time, the satellite's pseudo-random noise code PRN and the navigation information code synchronously modulated on the carrier frequency band to obtain a Beidou short message.

[0017] Further, step S13 includes:

[0018] Step S131, the reference base station stores Beidou short message coding information of Beidou satellite;

[0019] Step S132: The reference base station sets two reference channels based on the Beidou satellite PRN number;

[0020] Step S133: The reference base station encodes the two reference channels to obtain a Beidou short message reference message for sending.

[0021] Further, step S2 comprises:

[0022] Step S21, the radio frequency receiving module in the rapid positioning platform receives the Beidou short message communication message;

[0023] Step S22: The decoding module in the rapid positioning platform performs position calculation on the received Beidou short message communication message;

[0024] Step S23: The location service module in the rapid positioning platform sends positioning information.

[0025] Further, the step S22 comprises:

[0026] Step S221: When the satellite PRN number received by the reference base station is the same as the satellite PRN number broadcasting the Beidou short message in the Beidou navigation system, it is a common view satellite, and then the reference base station and the differential module establish a carrier phase differential observation equation based on the common view satellite;

[0027] Step S222, performing a multi-strategy ambiguity analysis on the carrier phase differential observation equation;

[0028] Step S223: perform differential analysis on the baseband observations obtained through ambiguity analysis.

[0029] Further; the method of step S3 is:

[0030] Step S31: After the rapid positioning platform obtains warning information through calculation, the warning module issues a warning based on the positioning information;

[0031] Step S32: Send warning and rescue signals based on the positioning information and warning information.

[0032] The present invention also provides a navigation rescue system based on Beidou short message rapid positioning, characterized in that it includes:

[0033] Reference base station, used to receive and decode data from the Beidou navigation system, obtain and send Beidou short messages;

[0034] Rapid positioning platform, used to receive Beidou short messages and perform position calculation, obtain and output positioning information;

[0035] The alarm module is used to receive positioning information and make risk assessments, and issue an early warning when the risk assessment conditions are met.

[0036] Beneficial Effects

[0037] Reference base stations are set up in different application scenarios. During rescue, the differential module installed on the rescue equipment performs differential position calculation based on the common view satellites of the reference base station and the navigation system. The reference base station packages and sends early warning and rescue information in dangerous environments.

[0038] 1) The differential platform in the present invention can perform fine tracking processing based on multiple reference message messages of the reference base station to obtain baseband observations for differential analysis that eliminate the transmission error between the base station and the differential platform. The multiple reference channels are finely tracked to obtain a carrier phase error with a smaller error, which can achieve accurate positioning in a rescue environment.

[0039] 2) The reference base station can also send warning information and realize rapid warning.

[0040] In summary, based on the warning information and rapid positioning results, the early warning module is used to carry out early warning and rapid rescue, thereby improving the efficiency of danger warning and rescue. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flow chart of the method of the present invention;

[0042] Figure 2This is a schematic diagram of the differential module process in the rapid positioning platform;

[0043] Figure 3 It is a schematic diagram of the framework of the system of the present invention. DETAILED DESCRIPTION

[0044] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0045] Embodiment 1: The present invention provides a navigation rescue method based on Beidou short message rapid positioning, such as Figure 1 As shown, the following steps are included:

[0046] Step S1, decoding the data of the Beidou navigation system received by the reference base station to obtain a Beidou short message;

[0047] Step S11, the reference base station measures and obtains Beidou satellite parameters based on the principle of navigation receiver;

[0048] Step S12, obtaining a Beidou short message by modulating Beidou satellite parameters;

[0049] Step S121, the reference base station measurement data and the existing baseband observations are analyzed for abnormal carrier-to-noise ratio. When the carrier-to-noise ratio CNo of the measurement data is greater than or equal to or less than or equal to the carrier-to-noise ratio threshold, the measurement data is judged as abnormal, and the abnormal signal is removed to obtain Beidou measurement data without abnormal data; the baseband observations include: satellite PRN number, satellite transmission delay τ, carrier phase Doppler frequency f d ;

[0050] The calculation method of the carrier-to-noise ratio threshold is:

[0051] Calculate the mean square error s of the carrier-to-noise ratio of historical data CNo :

[0052]

[0053] (CNo) μ is the average value of CNo; N n is the carrier-to-noise ratio statistic, μ is the mean, and n is the historical data;

[0054] Adaptively update the minimum value of the k+1-second carrier-to-noise ratio threshold:

[0055] (CNo) min，k+1 =(CNo) min，k +s CNo

[0056] (CNo) min，k is the minimum value of the carrier-to-noise ratio threshold at time k+1;

[0057] (CNo) max,k+1 =(CNo) max，k +s CNo

[0058] (CNo) max，k The maximum value of the carrier-to-noise ratio threshold at time k+1;

[0059] (CNo) min，k <CNo<(CNo) max，k The baseband observations at this time can be used for encoding in subsequent steps; CNo ≥ (CNo) max，k or (CNo) min，k When ≥CNo, the abnormal baseband observations at the above time are eliminated.

[0060] The above method can be used to process abnormal information of basic observation quantities and improve the accuracy of Beidou short message coding.

[0061] Step S122: The reference base station sets warning and rescue information, 0 for danger warning and rescue, 1 for safety;

[0062] Step S123, the reference base station uses the Beidou measurement data with abnormal data removed as the information bit according to the Beidou navigation message format, combines the corrected ionospheric information in the observation time, the satellite's pseudo-random noise code PRN and the navigation information code synchronously modulated on the carrier frequency band to obtain a Beidou short message.

[0063] Beidou short message encoding method is as follows:

[0064] According to the Beidou ICD file, first of all, based on the encoding of the Beidou satellite PRN number: ASCII code is used to represent the Beidou satellite PRN number: the decimal ASCII code from 000 to 040 represents the satellite PRN number of the GPS system, the ASCII code from 041 to 080 represents the satellite PRN number of the Beidou system, the decimal ASCII code from 081 to 120 represents the satellite PRN number of Galileo, and the decimal extended ASCII code from 121 to 160 represents the satellite PRN number of GLONASS; the D1 navigation message rate is 50bps, and it is modulated with a secondary code rate of 1kbps. The content includes basic navigation information (basic satellite navigation information, all satellite almanac information, and time synchronization information with other systems); the Beidou navigation message D1 navigation message consists of a super frame, a main frame and a subframe. Each superframe is 36,000 bits and lasts for 12 minutes. Each superframe consists of 24 main frames (24 pages); each main frame is 1,500 bits and lasts for 30 seconds. Each main frame consists of 5 subframes; each subframe is 300 bits and lasts for 6 seconds. Each subframe consists of 10 words; each word is 30 bits and lasts for 0.6 seconds; each word consists of two parts: navigation message data and check code. The first 15 bits of the first word of each subframe are not error-corrected, and the last 11 bits are corrected using the BCH (15, 11, 1) method, with a total of 26 bits of information bits; the other 9 words are all corrected using the BCH (15, 11, 1) plus interleaving method, with a total of 22 bits of information bits; the Beidou signal with abnormal data removed uses the warning information as the information bit according to the Beidou navigation message format, and is synchronously modulated with the spread spectrum code and the navigation information code on the carrier frequency band as the Beidou short message sent.

[0065] Step S13: setting two reference channels based on the Beidou short message; and simultaneously sending the Beidou short message communication of the reference channels based on the above encoding method.

[0066] Step S131, the reference base station stores Beidou short message coding information of Beidou satellite;

[0067] Step S132: The reference base station sets two reference channels based on the Beidou satellite PRN number;

[0068] Step S133: The reference base station encodes the two reference channels to obtain a Beidou short message reference message for sending.

[0069] Step S14: Send the Beidou short message through the signal sending unit.

[0070] Step S2: The rapid positioning platform calculates the position of the decoded Beidou short message to obtain positioning information;

[0071] Step S21, the radio frequency receiving module in the rapid positioning platform receives the Beidou short message communication message;

[0072] Step S22: The decoding module in the rapid positioning platform performs position calculation on the received Beidou short message communication message;

[0073] Step S221: When the satellite PRN number received by the reference base station is the same as the satellite PRN number broadcasting the Beidou short message in the Beidou navigation system, it is a common view satellite, and then the reference base station and the differential module establish a carrier phase differential observation equation based on the common view satellite;

[0074] Step S222, performing a multi-strategy ambiguity analysis on the carrier phase differential observation equation;

[0075] Step S223: perform differential analysis on the baseband observations obtained through ambiguity analysis.

[0076] Decode the Beidou short message communication according to the carrier frequency in the Beidou navigation system, and obtain the position information based on the decoded information.

[0077] First, based on the tracking frequency of the BeiDou navigation system, the BeiDou satellite PRN number of the BeiDou navigation system and the corresponding first tracking information are locked and recorded as: Among them A g is the signal power of the g-th Beidou satellite; Dg is the navigation data bit information; is the carrier frequency information of the g-th Beidou satellite, is the carrier phase information of the g-th BeiDou satellite at observation time k, is the code phase information of the g-th Beidou satellite at observation time k.

[0078] Based on the first tracking information Set the tracking reference channel for precise tracking processing as follows:

[0079] based on Generate the reference tracking signal S in the tracking reference channel:

[0080]

[0081] Based on the above reference tracking signal model, the Beidou short message information is processed according to the reference channel cyclic tracking to obtain the baseband information tracking carrier phase error.

[0082] Based on the carrier phase error Fine selection of reference channel is performed based on carrier phase error The tracking channel information under the detection condition is subjected to carrier phase differentiation by the differential module to obtain differential position information.

[0083] Based on the carrier phase error in all reference channels under the same satellite number PRN Minimum value of As for carrier phase differential data, compared with the prior art, the RF signal sent by the base station and the reference channel RF signal are based on the tracking preprocessing information of the visible satellite signal Generate information S in the tracking reference channel, and perform fine tracking processing on tracking reference channel 1 and tracking reference channel 2 based on S to obtain the wave phase error By selecting the carrier phase error in the first tracking information Carrier phase error in the reference channel tracking information The minimum value in Phase tracking errors in base station signal transmission can be avoided. This processing step can improve the robustness of signal transmission between the reference base station and the rapid positioning platform and improve the position solution accuracy in the rapid positioning platform.

[0084] like Figure 2 As shown: The differential steps of the differential module in the rapid positioning platform are as follows: When the satellite signals with the same PRN number in the reference base station and the Beidou short message in the Beidou navigation system are used as the input RF signals of the differential module at the same time, they can be used as the common-view satellites of the differential module. The differential observation equation is established based on the reference base station at different observation times k and the common-view satellites in the differential module:

[0085] Based on the local analysis method, the relative change of ambiguity of each satellite between adjacent epochs is detected; based on the above ambiguity change results, multiple strategies of ambiguity analysis are performed, as follows:

[0086] Satellites without relative ambiguity changes are directly used for carrier phase differential resolution; satellites with relative ambiguity changes use the least squares method to estimate the inter-epoch relative ambiguity floating-point solutions and their variance covariance matrices of the current epoch and the previous epoch of the remaining satellites, and the traditional LAMBDA method is used to complete the fixation of the relative ambiguity of the current and previous observation times based on the obtained variance covariance matrix and the inter-epoch relative ambiguity floating-point solutions, and obtain the fixed solution of the relative change of the ambiguity at adjacent observation times and the ambiguity ratio test value; if the relative change of the ambiguity at adjacent observation times can be fixed and passes the ratio consistency test, the satellite tested above is used for differential position resolution; the above steps are processed cyclically to obtain the baseband observations used for carrier phase differential resolution;

[0087] The carrier phase difference observation equation is established based on the baseband observations used for carrier phase difference calculation, and the floating-point solution of the global relative position change parameter is estimated using the Kalman filter method:

[0088]

[0089] In the above formula, g represents the satellite number, b and r represent the reference station and differential module respectively, λ represents the carrier wavelength of the received signal (m), and Respectively represent the difference r and the geometric distance between the base station b and the satellite, and They represent the clock difference between the differential module r and the reference base station b, t represents the satellite clock difference, and represents the atmospheric (ionosphere and troposphere) delay correction, and represents the ambiguity of the g-th satellite, represents the observation noise;

[0090] By subtracting the difference carrier phase observation values ​​of the two, most of the atmospheric delay and satellite clock error can be eliminated, and the single difference carrier phase observation equation for the current observation time k is obtained:

[0091]

[0092] ct br,i =ct br,i,G +ISB

[0093] in, The unit line of sight matrix between the differential module r and the satellite s is: br,i is the clock error of the GPS system ct br,i,G The sum of the deviations of the remaining systems relative to the GPS system.

[0094] Repeating the above steps, we can obtain the single-difference carrier phase observation equation at epoch k:

[0095]

[0096] ct br,j =ct br,j,G +ISB

[0097] Then the single difference carrier phase observation values ​​of the common view satellite at observation time i and observation time j are subtracted to eliminate the influence of ipb. ipb refers to the initial phase deviation, which will cause the ambiguity to not have integer characteristics and cannot be fixed. The ISB parameter remains unchanged between epochs, and the direction cosine matrix changes little between epochs, which can be used in the solution. replace The differential carrier phase observation equation between epochs can be obtained:

[0098]

[0099] in are constants, Δx0, Δy0 and Δz0 represent the initial values ​​of the three-dimensional relative position, and Δx, Δy and Δz represent the three-dimensional relative position correction parameters between epochs.

[0100] According to the above epoch-to-epoch differential carrier phase observation equation, when the relative ambiguity change λ between adjacent epochs can be accurately obtained When the relative position between epochs can be calculated with high precision.

[0101] Based on the local analysis method, the relative change of the ambiguity of each satellite between adjacent epochs is detected; based on the above ambiguity change results, multi-strategy ambiguity analysis is performed: by performing multi-strategy ambiguity analysis on the common-view satellites between the reference base station and the differential module according to different PRN numbers, the satellites detected by the ambiguity can be used for differential position solution to obtain the position information based on Beidou short message communication.

[0102] Through the above method, the ambiguity changes of the common view satellites can be cyclically detected to improve the satellite tracking efficiency, prevent the satellite from losing lock, star and frequency, and perform differential position solution on the satellites detected by ambiguity to obtain the differential position based on the Beidou short message.

[0103] Step S23: The location service module in the rapid positioning platform sends positioning information.

[0104] Step S3: determine the obtained positioning information and issue an early warning;

[0105] Step S31: After the rapid positioning platform obtains warning information through calculation, the warning module issues a warning based on the positioning information;

[0106] Step S32: Send warning and rescue signals based on the positioning information and warning information.

[0107] The present invention also provides a navigation rescue system based on Beidou short message rapid positioning, comprising:

[0108] Reference base station, used to receive and decode data from the Beidou navigation system, obtain and send Beidou short messages;

[0109] Rapid positioning platform, used to receive Beidou short messages and perform position calculation, obtain and output positioning information;

[0110] The alarm module is used to receive positioning information and make risk assessments, and issue an early warning when the risk assessment conditions are met.

[0111] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0112] Embodiment 2:

[0113] like Figure 3 As shown, the present invention also provides a navigation rescue system based on Beidou short message rapid positioning, including: a reference base station, a rapid positioning platform, and a remote alarm module.

[0114] Reference base station: used to receive and decode data from the Beidou navigation system, obtain and send Beidou short messages;

[0115] Rapid positioning platform: used to receive Beidou short messages and perform position calculation, obtain and output positioning information;

[0116] Remote alarm module: used to receive positioning information and make danger judgments. After the positioning platform decodes the warning signal, the remote alarm module is activated, and an alarm and distress signal are issued based on the current location. Rapid rescue of dangerous targets is achieved based on the Beidou short message rapid positioning results.

[0117] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A navigation rescue method based on Beidou short message rapid positioning, characterized by: The following steps are involved: Step S1, decoding the data of the Beidou navigation system received by the reference base station to obtain a Beidou short message, including: Step S11, the reference base station measures and obtains Beidou satellite parameters based on the principle of navigation receiver; Step S12, obtaining a Beidou short message by modulating Beidou satellite parameters, including: Step S121, the reference base station measurement data and the existing baseband observations are analyzed for abnormal carrier-to-noise ratio. When the carrier-to-noise ratio CNo of the measurement data is greater than or equal to or less than or equal to the carrier-to-noise ratio threshold, the measurement data is judged as abnormal, and the abnormal signal is removed to obtain Beidou measurement data without abnormal data; the baseband observations include: satellite PRN number, satellite transmission delay τ, carrier phase Doppler frequency f d ; Step S122: the reference base station sets warning and rescue information, 0 means danger warning and rescue, 1 means safety; Step S123, the reference base station uses the Beidou measurement data excluding abnormal data as the information bit according to the Beidou navigation message format, combines the corrected ionospheric information in the observation time, the satellite's pseudo-random noise code PRN and the navigation information code synchronously modulated on the carrier frequency band to obtain a Beidou short message; Step S13, setting a reference channel based on the Beidou short message, includes: Step S131, the reference base station stores Beidou short message coding information of Beidou satellite; Step S132: The reference base station sets two reference channels based on the Beidou satellite PRN number, including: Set the tracking reference channel to get the benchmark tracking signal in: A g is the signal power of the g-th Beidou satellite; D g It is the navigation data bit information; is the carrier frequency information of the g-th Beidou satellite, is the carrier phase information of the g-th BeiDou satellite at observation time k, is the code phase information of the g-th BeiDou satellite at observation time k; Step S133: The reference base station encodes the two reference channels to obtain a Beidou short message reference message for transmission; Step S14, sending a Beidou short message through a signal sending unit; Step S2: The rapid positioning platform calculates the position of the decoded Beidou short message to obtain positioning information; Step S21, the radio frequency receiving module in the rapid positioning platform receives the Beidou short message communication message, including: based on the reference tracking signal Accurately track the reference channel to obtain the baseband tracking carrier phase error Step S22: The decoding module in the rapid positioning platform performs position calculation on the received Beidou short message communication message, including: based on the carrier phase error Fine selection of reference channels to meet the carrier phase error The tracking channel information under the detection condition is subjected to carrier phase differentiation by the differential module to obtain differential position information; Step S23: The location service module in the rapid positioning platform sends the positioning information; Step S221: When the satellite PRN number received by the reference base station is the same as the satellite PRN number broadcasting the Beidou short message in the Beidou navigation system, it is a common view satellite, and then the reference base station and the differential module establish a carrier phase differential observation equation based on the common view satellite; Step S222: Based on the reference tracking signal Perform fine tracking processing on tracking reference channel 1 and tracking reference channel 2 to obtain the carrier phase error and When the tracking information is filtered through the carrier phase error to obtain the carrier phase error Minimum value of As baseband observation data for carrier phase differentiation; Step S223, establishing an improved differential observation equation based on the baseband observation data obtained by precise tracking processing and using it for high-precision position information solution; First, based on the carrier phase differential observation equation, a multi-strategy ambiguity analysis is performed. For satellites without relative ambiguity changes, the carrier phase differential analysis is directly used. For satellites with relative ambiguity changes, the ambiguity change detection is performed through a cyclic search. The carrier phase difference observation equation is established based on the baseband observations used for carrier phase difference calculation: Where g represents the satellite number, b and r represent the reference station and differential module respectively, λ represents the carrier wavelength of the received signal (m), and Respectively represent the difference r and the geometric distance between the base station b and the satellite, and They represent the clock difference between the differential module r and the reference base station b, t represents the satellite clock difference, and represents the atmospheric delay correction, and represents the ambiguity of the g-th satellite, Represents observation noise; the single difference carrier phase observation value of the common view satellite at observation time i and observation time j is subtracted and expressed as replace The differential carrier phase observation equation between epochs is obtained: in is a constant, Δx0, Δy0 and Δz0 represent the initial values ​​of the three-dimensional relative position, Δx, Δy and Δz represent the three-dimensional relative position correction parameters between epochs, and the equation is solved to obtain Step S224: Detection through fuzzy analysis Afterwards, differential analysis is performed based on the baseband observations; Step S3: determine the obtained positioning information and issue an early warning; Step S31: After the rapid positioning platform obtains warning information through calculation, the warning module issues a warning based on the positioning information; Step S32: Send warning and rescue signals based on the positioning information and warning information.

2. A navigation rescue system based on Beidou short message rapid positioning, characterized in that: include: Reference base station, used to receive and decode data from the Beidou navigation system, obtain and send Beidou short messages; Rapid positioning platform, used to receive Beidou short messages and perform position calculation, obtain and output positioning information; An alarm module is used to receive positioning information and make risk assessments, and issue an early warning when risk assessment conditions are met; To realize the navigation rescue method based on Beidou short message rapid positioning as described in claim 1.

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