Auxiliary positioning method, device, receiver and storage medium of navigation system

Abstract

The embodiment of the application provides a kind of navigation system's auxiliary positioning method, device, receiver and storage medium, wherein the method comprises: according to the data frame number of current navigation message of week in second time count determination current navigation message;According to data frame number, determine the target data frame number of navigation message to be predicted;From historical navigation message, determine the target navigation message matched with target data frame number;According to target navigation message, obtain the predicted navigation message corresponding to target data frame number;The actual capture navigation message corresponding to target data frame number is received;When the signal-to-noise ratio of actual capture navigation message is lower than preset signal-to-noise ratio threshold, according to predicted navigation message, positioning calculation is carried out.In this way, in weak signal scenario, according to predicted navigation message, positioning calculation can be carried out, accurate positioning information can be obtained, and positioning accuracy is improved.

Description

Technical Field

[0001] The present application relates to the field of navigation technology, and in particular to an auxiliary positioning method, device, receiver and storage medium for a navigation system. Background Art

[0002] In communication systems, the bit error rate (BER) is often used as a measure of reliability. It measures the accuracy of data transmission within a specified timeframe and is inversely proportional to the signal-to-noise ratio (SNR). As the SNR decreases, the BER increases. A higher BER indicates lower reliability in a digital system.

[0003] In the prior art, when capturing and tracking navigation information, if the signal-to-noise ratio (SNR) is very low, the satellite navigation signal is damaged during transmission, resulting in a high bit error rate when the receiver tracks the satellite navigation signal. If the SNR falls below the critical value of the decision threshold, the navigation message decoding will be erroneous and fail verification. When traditional receivers track navigation signals with very low SNRs, if the SNR falls below a certain decision threshold, the navigation message will not be decoded, or the decoded navigation message will be erroneous, resulting in positioning anomalies such as excessively long positioning times or even inability to locate the position. Summary of the Invention

[0004] In order to solve the above technical problems, embodiments of the present application provide an auxiliary positioning method, device, receiver and storage medium for a navigation system.

[0005] In a first aspect, an embodiment of the present application provides an assisted positioning method for a navigation system, the method comprising:

[0006] Acquire a current navigation message, and determine a data frame number of the current navigation message according to a second-of-week time count of the current navigation message;

[0007] Determining a target data frame number of the navigation message to be predicted according to the data frame number;

[0008] Determining a target navigation message that matches the target data frame number from historical navigation messages;

[0009] Obtaining a predicted navigation message corresponding to the target data frame number according to the target navigation message;

[0010] receiving an actual captured navigation message corresponding to the target data frame number;

[0011] When the signal-to-noise ratio of the actually captured navigation message is lower than a preset signal-to-noise ratio threshold, positioning calculation is performed according to the predicted navigation message.

[0012] In an embodiment, the step of determining the data frame number of the current navigation message according to the week-second time count of the current navigation message comprises:

[0013] determining the data frame number corresponding to the current navigation message according to the week-second time count of the current navigation message and the transmission duration of the current navigation message frame.

[0014] In an embodiment, the step of obtaining the predicted navigation message corresponding to the target data frame number according to the target navigation message comprises:

[0015] determining the week-second predicted time count corresponding to the target data frame number according to the week-second time count of the current navigation message;

[0016] updating the week-second time count of the target navigation message to the week-second predicted time count to obtain a corrected navigation message;

[0017] encoding the corrected navigation message to obtain the predicted navigation message.

[0018] In an embodiment, the current navigation message comprises a B1I navigation message subframe under the Beidou navigation system, and the data frame number comprises a superframe number, a mainframe number and a subframe number.

[0019] The step of determining the data frame number corresponding to the current navigation message according to the week-second time count of the current navigation message and the transmission duration of the current navigation message frame comprises:

[0020] determining the superframe number, the mainframe number and the subframe number corresponding to the B1I navigation message subframe according to the week-second time count of the B1I navigation message subframe, the superframe transmission duration of the B1I navigation message, the mainframe transmission duration of the B1I navigation message and the subframe transmission duration of the B1I navigation message.

[0021] In an embodiment, the predicted navigation message comprises a predicted B1I navigation message subframe.

[0022] The step of determining the week-second predicted time count corresponding to the target data frame number according to the week-second time count of the current navigation message comprises:

[0023] determining the week-second predicted time count corresponding to the target data frame number according to the week-second time count of the B1I navigation message subframe;

[0024] The step of updating the week-second time count of the target navigation message to the week-second predicted time count to obtain a corrected navigation message comprises:

[0025] Updating the target B1I navigation message subframe's time count in seconds per week to the predicted time count in seconds per week to obtain a modified B1I navigation message subframe;

[0026] The step of encoding the corrected navigation message to obtain the predicted navigation message includes:

[0027] The modified B1I navigation message subframe is encoded to obtain the predicted B1I navigation message subframe.

[0028] In one embodiment, the target B1I navigation message subframe includes 10 words, and the first preset bit field of word 1 and the second preset bit field of word 2 jointly represent the week seconds time count of the target B1I navigation message subframe; the length and value of the first preset bit field and the second preset bit field are equal to the length of the week seconds time count;

[0029] The step of updating the week second time count of the target B1I navigation message subframe to the week second time count prediction to obtain a modified B1I navigation message subframe includes:

[0030] determining a target bit from the predicted seconds-of-week time count, the target bit dividing the predicted seconds-of-week time count into a first target bit field and a second target bit field, wherein the length of the first target bit field is equal to the length of the first preset bit field, and the length of the second target bit field is equal to the length of the first preset bit field;

[0031] Updating the first preset bit field and the second preset bit field to the first target bit field and the second target bit field, respectively, to obtain a correction word 1 and a correction word 2, respectively;

[0032] The modified B1I navigation message subframe is generated according to the modified word 1, the modified word 2, and words 3 to 10.

[0033] In one embodiment, the step of encoding the modified B1I navigation message subframe to obtain the predicted B1I navigation message subframe includes:

[0034] Performing BCH encoding on the correction word 1 and the correction word 2 respectively to obtain encoded word 1 and encoded word 2;

[0035] The encoded word 1, the encoded word 2, and the words 3 to 10 are interleaved and coded to obtain the predicted B1I navigation message subframe.

[0036] In an embodiment, the current navigation message comprises a GLONASS navigation message frame under a GLONASS satellite navigation system; and the data frame number comprises a superframe number, a frame number and a string number;

[0037] The step of determining the data frame number corresponding to the current navigation message according to the intra-week second time count of the current navigation message and the transmission duration of the current navigation message frame comprises:

[0038] The superframe number, the frame number and the string number corresponding to the GLONASS navigation message frame are determined according to the intra-week second time count of the GLONASS navigation message frame, the superframe transmission duration of the GLONASS navigation message, the frame transmission duration of the GLONASS navigation message and the string transmission duration of the GLONASS navigation message.

[0039] In an embodiment, the predicted navigation message comprises a predicted GLONASS navigation message frame; and the target data frame number comprises a target frame number and a target string number of the predicted GLONASS navigation message frame;

[0040] The step of obtaining the predicted navigation message corresponding to the target data frame number according to the target navigation message comprises:

[0041] The target satellite number corresponding to the target frame number is determined, the almanac of the target satellite number is obtained, the almanac of the target satellite number is updated into the target GLONASS navigation message frame, and a combined GLONASS navigation message frame is obtained.

[0042] When the target string number is 1, the current day frame start reference time of the first string of the combined GLONASS navigation message frame is processed by 1, and a corrected GLONASS navigation message frame is obtained.

[0043] When the target string number is any integer from 2 to 15, the combined GLONASS navigation message frame is taken as a corrected GLONASS navigation message frame.

[0044] The corrected GLONASS navigation message frame is encoded, and the predicted GLONASS navigation message frame is obtained.

[0045] In an embodiment, the corrected GLONASS navigation message frame comprises 15 strings, and the step of encoding the corrected GLONASS navigation message frame to obtain the predicted GLONASS navigation message frame comprises:

[0046] The navigation data of each string of the modified GLONASS navigation message frame is Hamming encoded to obtain encoded navigation data, and the predicted GLONASS navigation message frame is generated according to the encoded navigation data and the time mark of each string of the modified GLONASS navigation message frame.

[0047] In a second aspect, an embodiment of the present application provides an auxiliary positioning device of a navigation system, the device comprising:

[0048] A first obtaining module is configured to obtain a current navigation message, and determine a data frame number of the current navigation message according to a week-second time count of the current navigation message.

[0049] A first determining module is configured to determine a target data frame number of a to-be-predicted navigation message according to the data frame number.

[0050] A second determining module is configured to determine a target navigation message matching the target data frame number from historical navigation messages.

[0051] A second obtaining module is configured to obtain a predicted navigation message corresponding to the target data frame number according to the target navigation message.

[0052] A receiving module is configured to receive an actually captured navigation message corresponding to the target data frame number.

[0053] A positioning module is configured to perform positioning calculation according to the predicted navigation message when a signal-to-noise ratio of the actually captured navigation message is lower than a preset signal-to-noise ratio threshold.

[0054] In a third aspect, an embodiment of the present application provides a receiver, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program performs the auxiliary positioning method of the navigation system provided in the first aspect when the processor runs.

[0055] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program performs the auxiliary positioning method of the navigation system provided in the first aspect when the processor runs.

[0056] The auxiliary positioning method, device, receiver, and storage medium of the navigation system provided by the present application obtain the current navigation message, determine the data frame number of the current navigation message based on the second time count of the week of the current navigation message; determine the target data frame number of the navigation message to be predicted based on the data frame number; determine the target navigation message that matches the target data frame number from the historical navigation message; obtain the predicted navigation message corresponding to the target data frame number based on the target navigation message; receive the actual captured navigation message corresponding to the target data frame number; and perform positioning calculation based on the predicted navigation message when the signal-to-noise ratio of the actual captured navigation message is lower than a preset signal-to-noise ratio threshold. In this way, when the signal-to-noise ratio of the current navigation message obtained in a weak signal scenario is relatively low and is not suitable for positioning calculation, positioning can be performed based on the predicted navigation message to obtain relatively accurate positioning information, which can meet the positioning calculation requirements of the receiver in harsh environments with low signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of this application and should not be regarded as limiting the scope of protection of this application. In each of the drawings, similar components are numbered similarly.

[0058] Figure 1 A schematic diagram of a flow chart of an assisted positioning method of a navigation system provided in an embodiment of the present application is shown;

[0059] Figure 2 A schematic diagram of a frame structure of a navigation message in the Beidou system provided by an embodiment of the present application is shown;

[0060] Figure 3 A schematic diagram of a frame structure of a navigation message in the GLONASS satellite navigation system provided by an embodiment of the present application is shown;

[0061] Figure 4 Another schematic diagram of the frame structure of a navigation message in the GLONASS satellite navigation system provided by an embodiment of the present application is shown;

[0062] Figure 5 A structural schematic diagram of an auxiliary positioning device of a navigation system provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0063] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0064] The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but rather merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0065] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present application, are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0066] Furthermore, the terms “first,” “second,” “third,” etc., are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0067] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meaning as in the context of the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present application.

[0068] Example 1

[0069] An embodiment of the present application provides an auxiliary positioning method for a navigation system, which can be applied to a receiver.

[0070] For details, see Figure 1 , the auxiliary positioning methods of the navigation system include:

[0071] Step S101: obtaining a current navigation message, and determining a data frame number of the current navigation message according to a time count of seconds in a week of the current navigation message.

[0072] In this embodiment, the current navigation message is a corresponding navigation message under various navigation systems. For example, the current navigation message can be a B1I navigation message subframe under the Beidou navigation system, or a GLONASS navigation message frame under the GLONASS satellite navigation system.

[0073] In this embodiment, the second-of-week (SOW) count is a zero-based counting scheme used in navigation systems. Specifically, in the Beidou navigation system, the second-of-week count starts at 00:00:00:00 Beidou time every Sunday. Combined with the transmission duration of the navigation message frame, the data frame number of a navigation message can be determined.

[0074] In one embodiment, the step of determining the data frame number of the current navigation message according to the second-of-week time count of the current navigation message includes:

[0075] The data frame number corresponding to the current navigation message is determined according to the second-of-week time count of the current navigation message and the sending duration of the current navigation message frame.

[0076] In this embodiment, the B1I navigation message subframe under the Beidou navigation system and the GLONASS navigation message frame under the GLONASS satellite navigation system have different frame structures, and thus their corresponding sending durations are different.

[0077] In the BeiDou system, the B1I message includes the D1 navigation message and the D2 navigation message. The frame structures of the D1 navigation message and the D2 navigation message are similar. Figure 2 This section explains the D1 navigation message in the B1I message. Figure 2 The D1 navigation message consists of one superframe, each containing 36,000 bits. It takes 12 minutes for a receiver to receive one superframe. Each superframe consists of 24 main frames, which can be numbered as main frame 1, main frame 2, ..., main frame n, ..., main frame 24. These 24 main frames can also be called 24 pages. Each main frame contains 1,300 bits, and it takes 30 seconds for a receiver to receive one mainframe. A mainframe consists of five subframes, which can be numbered as subframe 1, subframe 2, subframe 3, subframe 4, and subframe 5. Each subframe contains 300 bits, and it takes 6 seconds for a receiver to receive one subframe. Each subframe consists of 10 words, namely word 1, word 2, word 3, word 4, word 5, word 6, word 7, word 8, word 9, and word 10. Each word contains 30 bits and takes 0.6 seconds.

[0078] Subframes 1 through 3 of each master frame broadcast ephemeris and other parameter information, with a one-hour period. Subframes 4 and 5 broadcast almanac information for all satellites, with a seven-day period. Pages 1-24 of subframe 4 broadcast almanac information for BeiDou satellites 1-24. Pages 1-6 of subframe 5 broadcast almanac information for BeiDou satellites 25-30. Pages 11-23 of subframe 5 broadcast satellite almanac information in a time-sharing manner. The broadcast almanac information is shown in Table 1.

[0079] Table 1 Almanac information table

[0080]

[0081] In Table 1, AmEpID represents the extended identifier of the almanac information, AmID represents the time-sharing broadcast identification identifier, and Pnum represents the page number.

[0082] Please refer again Figure 2 Each word of the D1 navigation message consists of two parts: navigation message data and a check code. Word 1 of each subframe contains 30 bits. The first 26 bits of word 1 are the navigation message information, and the last 4 bits are the check code. The first 15 bits of the navigation message information in the first 26 bits of word 1 are not error-corrected, and the last 11 bits of the navigation message information in the first 26 bits of word 1 are error-corrected using the BCH (15, 11, 1) method. The first 22 bits of each word from word 2 to word 10 are the navigation message information, and the last 8 bits of each word from word 2 to word 10 are the check code. The 30 bits of each word from word 2 to word 10 are error-corrected using the BCH (15, 11, 1) interleaving method.

[0083] It should be noted that bits 19 to 26 and bits 31 to 42 of each subframe are the seconds of the week count, totaling 20 bits. The count starts at zero every Sunday at 00:00:00 BDT. The seconds of the week count corresponds to the rising edge of the first pulse of the synchronization header in the subframe.

[0084] In this embodiment, the assisted positioning method of the navigation system can be applied to a receiver, which can sequentially receive each navigation message data frame in the order in which the navigation message data frames were transmitted. After the receiver actually captures the current B1I message data frame, it can determine the current major frame number and current subframe number of the current B1I message data frame based on the current seconds-of-week count of the current B1I message data frame.

[0085] Specifically, the current week second count can be read from bits 19 to 26 and bits 31 to 42 of subframe 1 of the current B1I telegram data frame, and the current main frame number and current subframe number of the current B1I telegram data frame can be determined based on the current week second count.

[0086] It should be noted that GLONASS navigation message frames are sent in the form of data, consisting of superframes, frames and character strings, and are generated in the form of continuously repeated superframes. Figure 3 ,like Figure 3As shown, each superframe of a GLONASS navigation message frame consists of five frames, each of which consists of 15 character strings, each of which includes data bits and a timestamp. The superframe period of a GLONASS navigation message frame is 2.5 minutes, the frame period of a GLONASS navigation message frame is 30 seconds, and the character string period of a GLONASS navigation message frame is 2 seconds. Character strings 1 through 4 of each frame broadcast parameter information such as the ephemeris, which changes every hour. Character strings 6 through 15 of each frame broadcast the almanac of 24 satellites, which changes every day. The correspondence between frame numbers and satellite numbers is shown in Table 1. Frames 1 through 4 each contain almanacs for five satellites, and frame 5 contains almanacs for four satellites. The almanac of one satellite occupies two character strings.

[0087] Table 2 Arrangement of GLONASS almanac in superframe

[0088]

[0089]

[0090] See also Figure 3 ,like Figure 3 As shown in the figure, each GLONASS navigation message frame transmits 85 bits of navigation data in the first 1.7 seconds, and a 30-bit timestamp in the last 0.3 seconds. The 85 bits of navigation data consist of binary data bits and a check bit, with a Tc of 10 ms. Bits 1 to 8 of the binary relative code are Hamming code bits, and bits 9 to 84 of the binary relative code are data bits. For example, the timestamp is 111110001101110101000010010110 in binary, with a Tc of 10 ms.

[0091] In one embodiment, the step of determining the data frame number corresponding to the current navigation message based on the second-of-week time count of the current navigation message and the transmission duration of the current navigation message frame includes:

[0092] A modulo operation is performed on the week second count of the current navigation message and the sending duration of the current navigation message frame to obtain a data frame number corresponding to the current navigation message.

[0093] In this embodiment, different modulo operations may be used to calculate corresponding data frame numbers for B1I navigation message subframes under the Beidou navigation system and GLONASS navigation message frames under the GLONASS satellite navigation system.

[0094] In one embodiment, the current navigation message includes: a B1I navigation message subframe under the Beidou navigation system; the data frame number includes a superframe number, a main frame number, and a subframe number;

[0095] The step of determining the data frame number corresponding to the current navigation message according to the week second time count of the current navigation message and the transmission duration of the current navigation message frame includes:

[0096] The superframe number, main frame number and subframe number corresponding to the B1I navigation message subframe are determined according to the intra-week second time count of the B1I navigation message subframe, the superframe sending duration of the B1I navigation message, the main frame sending duration of the B1I navigation message, and the subframe sending duration of the B1I navigation message.

[0097] It should be noted that the transmitter's message data frames are broadcast in real time, and the receiver also continuously receives message data frames from a certain moment. The essence of the message data is the binary number 0 or 1, that is, Figure 2 The bits of the telegram data frame shown are: 1 binary number corresponds to 1 bit. 30 bits correspond to word i , the next 30 bits correspond to the next word mod(i+1,10)+1 , and so on. Figure 2 The B1I navigation message subframe under the BeiDou navigation system shown in the figure has 10 words, i.e. 300 bits. Assume that the i-th subframe corresponds to subframe SF i , the next 300 bits correspond to the next subframe SF mod(i+1,5)+1 , mod(,) is the remainder operation.

[0098] It should be further explained that the second of the week is a time counting method with a 7-day cycle, and its value range is [0, 604799]. 604800 = 7 × 24 × 3600. The current time count of the second of the week can be calculated using the following formula:

[0099] TOW=720(FrameNum-1)+30(PageNum-1)+6(SFNum-1);

[0100] The superframe number FrameNum has a value range of [1, 840], the main frame number PageNUm has a value range of [1, 24], and the subframe number SFNum has a value range of [1, 5]. TOW is the current time in seconds of the week. Given TOW, the main frame number can be calculated using the following formula:

[0101] PN=mod(TOW,720) / 30+1;

[0102] Wherein, mod(TOW,720) is a remainder operation, TOW represents the current time count in seconds of the week, and PN represents the major frame number.

[0103] The subframe number can be calculated according to the following formula:

[0104] SF = mod((TOW - div(TOW, 720) x 720), 30) / 6 + 1;

[0105] Wherein, SF represents subframe number, TOW represents current time count of seconds within a week, div(TOW, 720) represents integer, mod((TOW - div(TOW, 720) x 720), 30) represents remainder.

[0106] In an embodiment, the current navigation message comprises: a GLONASS navigation message frame under a GLONASS satellite navigation system; the data frame number comprises: a superframe number, a frame number and a string number;

[0107] The step of determining the data frame number corresponding to the current navigation message according to the current time count of seconds within a week of the current navigation message and the transmission duration of the current navigation message frame, comprises:

[0108] According to the current time count of seconds within a week of the GLONASS navigation message frame, the superframe transmission duration of the GLONASS navigation message, the frame transmission duration of the GLONASS navigation message, the string transmission duration of the GLONASS navigation message, the superframe number, the frame number and the string number corresponding to the GLONASS navigation message frame are determined.

[0109] For the GLONASS navigation message frame under the GLONASS satellite navigation system shown in the figure, the seconds within a week can be calculated according to the following formula: Figure 3

[0110] TOW = 150(FrameNum - 1) + 30(SFNum - 1) + 2(StringNum - 1)

[0111] Wherein, TOW represents the count of seconds within a week, the superframe number FrameNum takes the value range [1, 576], the frame number SFNUm takes the value range [1, 5], and the string number StringNum takes the value range [1, 15].

[0112] The superframe number, the frame number and the string number of the GLONASS navigation message frame under the GLONASS satellite navigation system can be calculated according to the following formula.

[0113] FrameNum = mod(TOW, 150);

[0114] SFNum = mod(TOW / 150, 30);

[0115] StringNum = mod(TOW / 300, 2);

[0116] ​TOW represents the second of the week, FrameNum represents the superframe number, SFNum represents the frame number, StringNum represents the string number, and mod(.) represents the remainder operation.

[0117] Step S102: determining a target data frame number of the navigation message to be predicted according to the data frame number.

[0118] In this embodiment, to predict navigation messages in weak signal scenarios, it is necessary to predict future navigation messages when the current navigation message is actually captured and its signal-to-noise ratio (SNR) falls below a preset SNR threshold. This future navigation message can be the next frame after the current one or the Nth frame after the current one, without limitation.

[0119] In one embodiment, if the current navigation message is a B1I navigation message subframe under the Beidou navigation system, the data frame number includes: a current main frame number and a current subframe number; and the navigation message to be predicted is the B1I navigation message subframe to be predicted, then step S102 may include:

[0120] Determining the current major frame number as the target major frame number of the B1I navigation message subframe to be predicted;

[0121] The sum of the current subframe number and a preset value is determined as the target subframe number of the B1I navigation message subframe to be predicted.

[0122] Specifically, the preset value is any value from 1 to 4, and specifically, the preset value may be 1. For example, if the current main frame number is main frame 1 and the current subframe number is subframe 1, then the current B1I telegram data frame indicates the B1I telegram data frame corresponding to subframe 1 in main frame 1. If the preset value is 1, then the B1I telegram data frame corresponding to subframe 2 in main frame 1 is determined to be the B1I navigation message subframe to be predicted.

[0123] In this way, the predicted B1I navigation message subframe can be determined, which facilitates the prediction of Beidou B1I signals in weak signal scenarios, and facilitates the receiver to perform positioning based on the predicted B1I signals, thereby improving positioning accuracy.

[0124] In another embodiment, if the current navigation message is a GLONASS navigation message frame under the GLONASS satellite navigation system, the data frame number includes: a current frame number and a current string number; and the to-be-predicted navigation message is a to-be-predicted GLONASS navigation message frame, then step S102 may include:

[0125] Determining the current frame number as the target frame number of the GLONASS navigation message frame to be predicted;

[0126] The sum of the current string number and a preset value is determined as the target string number of the GLONASS navigation message frame to be predicted.

[0127] Specifically, the preset value is any value between 1 and 4, and specifically, the preset value may be 1. For example, if the current frame number is frame 1 and the current string number is string 1, then the current GLONASS navigation message frame indicates the data frame corresponding to string 1 in frame 1. If the preset value is 1, then the data frame corresponding to string 2 in frame 1 is determined to be the GLONASS navigation message frame to be predicted.

[0128] Step S103: determining a target navigation message that matches the target data frame number from historical navigation messages.

[0129] It should be noted that for the Beidou navigation system, within a change cycle, the navigation information between different superframes is the same, except for the week-second time counter data. Therefore, the B1I message information from the previous change cycle can be used to predict the B1I message information for the current cycle. For example, a receiver acquires a previous superframe over a 12-minute period. This previous superframe consists of 24 main frames, each of which includes 5 subframes. When a superframe is acquired in the next 12 minutes, the superframe corresponding to the current cycle has the same navigation information except for the week-second time counter data. If the receiver acquires main frame 1, subframe 1 corresponding to the current cycle, the data frame to be predicted is main frame 1, subframe 2, and main frame 1, subframe 2 of the previous superframe is the target historical B1I message data frame corresponding to main frame 1, subframe 1 of the current cycle. Navigation data from the GLONASS satellite navigation system has a similar periodicity and is not further explained here.

[0130] Step S104: obtaining a predicted navigation message corresponding to the target data frame number according to the target navigation message.

[0131] It should be noted that for the BeiDou navigation system, since adjacent superframes received by the receiver share the same navigation information except for the seconds-of-week time count, the predicted B1I navigation message subframe can be obtained by calculating the seconds of the week corresponding to the predicted B1I navigation message subframe based on the current seconds of the week time count. The calculated seconds of the week are then substituted for the seconds of the week in the target historical B1I message data frame to obtain the predicted B1I navigation message subframe corresponding to the predicted B1I navigation message subframe. Navigation data from the GLONASS satellite navigation system also exhibits similar periodicity and is not further explained here.

[0132] In one embodiment, step S104 includes:

[0133] Determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the current navigation message;

[0134] Updating the target navigation message's time count in seconds per week to the predicted time count in seconds per week to obtain a corrected navigation message;

[0135] The corrected navigation message is encoded to obtain the predicted navigation message.

[0136] In one embodiment, the predicting the navigation message includes: predicting a B1I navigation message subframe;

[0137] The step of determining the predicted time count of seconds in the week corresponding to the target data frame number according to the time count of seconds in the week of the current navigation message includes:

[0138] Determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the B1I navigation message subframe;

[0139] The step of updating the week second time count of the target navigation message to the week second time count prediction to obtain a corrected navigation message includes:

[0140] Updating the target B1I navigation message subframe's time count in seconds per week to the predicted time count in seconds per week to obtain a modified B1I navigation message subframe;

[0141] The step of encoding the corrected navigation message to obtain the predicted navigation message includes:

[0142] The modified B1I navigation message subframe is encoded to obtain the predicted B1I navigation message subframe.

[0143] In this way, update processing can be directly performed based on the bit field storing the seconds of the week in the superframe, thereby improving the update efficiency of the seconds of the week time counting data.

[0144] In one embodiment, the target B1I navigation message subframe includes 10 words, and the first preset bit field of word 1 and the second preset bit field of word 2 jointly represent the week seconds time count of the target B1I navigation message subframe; the length and value of the first preset bit field and the second preset bit field are equal to the length of the week seconds time count;

[0145] The step of updating the week second time count of the target B1I navigation message subframe to the week second time count prediction to obtain a modified B1I navigation message subframe includes:

[0146] determining a target bit from the predicted seconds-of-week time count, the target bit dividing the predicted seconds-of-week time count into a first target bit field and a second target bit field, wherein the length of the first target bit field is equal to the length of the first preset bit field, and the length of the second target bit field is equal to the length of the first preset bit field;

[0147] Updating the first preset bit field and the second preset bit field to the first target bit field and the second target bit field, respectively, to obtain a correction word 1 and a correction word 2;

[0148] The modified B1I navigation message subframe is generated according to the modified word 1, the modified word 2, and words 3 to 10.

[0149] In one embodiment, the step of encoding the modified B1I navigation message subframe to obtain the predicted B1I navigation message subframe includes:

[0150] Performing BCH encoding on the correction word 1 and the correction word 2 respectively to obtain encoded word 1 and encoded word 2;

[0151] The encoded word 1, the encoded word 2, and the words 3 to 10 are interleaved and coded to obtain the predicted B1I navigation message subframe.

[0152] The BCH encoding is described below. Specifically, the BCH encoding can be BCH (15, 11, 1) encoding. The 15-bit data of BCH (15, 11, 1) consists of 11 data bits and 4 check bits. Subframe SF i (i=1,...,5) is the word i (i=1,...,10), Word i There are two ways to construct it, one is 26-bit data bits and 4-bit check bits, and the other is 22-bit data bits and 8-bit check bits. i (i=1) uses 26-bit data bits and 4-bit check bits. Word i (i=2,...,10) uses 22-bit data bits and 8-bit check bits. The generation methods of 4-bit and 8-bit check bits are different. Assume Word i By BitB j ={0,1}(j=1,...,30), the 4-bit check bit can be expressed as:

[0153] B j =BCH(B k )(j=27,...,30,k=16,...,26);

[0154] The 8-bit check bit can be expressed as:

[0155] B j =BCH(B k )(j=23,...,30,k=1,...,22);

[0156] Where BCH(.) represents BCH encoding.

[0157] In one embodiment, the predicted navigation message includes: a predicted GLONASS navigation message frame; the target data frame number includes a target frame number and a target string number of the GLONASS navigation message frame to be predicted;

[0158] The step of obtaining the predicted navigation message corresponding to the target data frame number according to the target navigation message includes:

[0159] determining a target satellite number corresponding to the target frame number, obtaining an almanac of the target satellite number, and updating the almanac of the target satellite number into the target GLONASS navigation message frame to obtain a combined GLONASS navigation message frame;

[0160] When the target string number is 1, adding 1 to the current frame start reference time of the first string of the combined GLONASS navigation message frame to obtain a corrected GLONASS navigation message frame;

[0161] When the target string number is any integer from 2 to 15, the combined GLONASS navigation message frame is used as a modified GLONASS navigation message frame;

[0162] The corrected GLONASS navigation message frame is encoded to obtain the predicted GLONASS navigation message frame.

[0163] Specifically, for GLONASS navigation message frames under the GLONASS satellite navigation system, the almanac satellite number is obtained based on the target data frame number, and the almanac information of the characters 6 to 15 is replaced. For example, if the target data frame number is 3, the almanac information of satellites 11 to 15 is inserted into the prediction message.

[0164] In the GLONASS navigation message frame, the reference time t at the beginning of the day frame k The first 65th to 76th bits of the first string in each frame are 12 bits in total. The first 5 bits represent the number of hours that have passed since the start of the day. The next 6 bits represent the number of minutes that have passed since the start of the hour. The remaining 1 bit represents the number of 30-second time intervals that have passed since the start of the day. When the predicted string is 1, tk =t k +1, other cases, t k Remain unchanged.

[0165] In one embodiment, the modified GLONASS navigation message frame includes 15 character strings, and the step of encoding the modified GLONASS navigation message frame to obtain the predicted GLONASS navigation message frame includes:

[0166] The navigation data of each character string of the modified GLONASS navigation message frame is Hamming-encoded to obtain coded navigation data, and the predicted GLONASS navigation message frame is generated according to the coded navigation data and the time stamps of each character string of the modified GLONASS navigation message frame.

[0167] Specifically, when the message is reassembled, the first 1.7s of the string are Hamming coded, and the last 0.3s of the time stamp remain unchanged. Figure 4 As shown in Figure 4, in the first 1.7 seconds of the string, bit 85 is 0, bits 9 to 84 are the message data, and bits 1 to 8 are the check bits. These 8-bit check bits are generated by Hamming encoding bits 9 to 85.

[0168] Check bits C1 to C8, message data b9 to b85, the Hamming encoding process is as follows:

[0169] C1=XOR(bi),i=9,10,12,13,15,17,19,20,22,24,26,28,30,32,34,35,37,39,4 1,43,45,47,49,51,53,55,57,59,61,63,65,66,68,70,72,74,76,78,80,82,84;

[0170] C2=XOR(bj),j=9,11,12,14,15,18,19,21,22,25,26,29,30,33,34,36,37,40,4 1,44,45,48,49,52,53,56,57,60,61,64,65,67,68,71,72,75,76,79,80,83,84;

[0171] C3=XOR(bk),k=10~12,16~19,23~26,31~34,38~41,46~49,54~57,62~65,69~72,77~80,85;

[0172] C4=XOR(bl), l=13~19, 27~34, 42~49, 58~65, 73~80;

[0173] C5=XOR(bm), m=20~34, 50~65, 81~85;

[0174] C6=XOR(bn), n=35~65;

[0175] C7=XOR(bm), m=66~85;

[0176] C8=XOR(bq), q=9~85;

[0177] Wherein, XOR(*) represents XOR operation.

[0178] Step S105, receiving the actual captured navigation message corresponding to the target data frame number.

[0179] In the embodiment, the receiver receives the actual captured navigation message corresponding to the target data frame number. Specifically, the receiver can include a baseband signal processing module, which is used to capture, track, receive satellite signals, and demodulate the received satellite signals. Specifically, for the receiver applied to the Beidou navigation system, the baseband signal processing module of the receiver can receive the actual captured B1I message data frame corresponding to the B1I navigation message subframe to be predicted. For the receiver applied to the GLONASS navigation system, the baseband signal processing module of the receiver can receive the actual captured GLONASS navigation message frame corresponding to the GLONASS navigation message frame to be predicted.

[0180] Step S106, when the signal-to-noise ratio of the actual captured navigation message is lower than a preset signal-to-noise ratio threshold, performing positioning calculation according to the predicted navigation message.

[0181] Specifically, when the signal-to-noise ratio of the actual captured navigation message is lower than a certain decision threshold, it is indicated that the navigation message obtained in the weak signal scenario is not suitable for positioning calculation, so that the positioning according to the predicted navigation message provided in the embodiment can obtain more accurate positioning information.

[0182] In an embodiment, the auxiliary positioning method of the navigation system can further include the following steps:

[0183] The historical B1I message information is parsed to determine the main frame number and the subframe number of each B1I message data frame of the historical B1I message information;

[0184] Each B1I message data frame is stored in the corresponding structure body memory according to the main frame number and the subframe number of each B1I message data frame.

[0185] Specifically, at least 12k memory can be allocated in the receiver for storing all the navigation message information of Beidou B1I; according to the navigation message information parsed by the receiver, information such as the main frame number and the subframe number is parsed, and the navigation message is stored in the corresponding structure memory according to the parsed information, and the structure memory can be an array. In this way, the corresponding historical B1I navigation message information can be quickly found from the structure memory.

[0186] In another embodiment, for the GLONASS navigation message frame of the GLONASS satellite navigation system, memory space is allocated for storing GLONASS navigation message information; according to the GLONASS navigation message information parsed by the receiver, information such as the frame number and the string number is parsed. The navigation message is stored in the corresponding structure memory according to the parsed information, and the process is similar to the storage process of the B1I navigation message data frame of the Beidou system, which will not be described here.

[0187] The auxiliary positioning method of the navigation system provided in the embodiment includes: acquiring a current navigation message, determining a data frame number of the current navigation message according to a week-second time count of the current navigation message; determining a target data frame number of a to-be-predicted navigation message according to the data frame number; determining a target navigation message matched with the target data frame number from historical navigation messages; acquiring a predicted navigation message corresponding to the target data frame number according to the target navigation message; receiving an actually captured navigation message corresponding to the target data frame number; and performing positioning calculation according to the predicted navigation message when a signal-to-noise ratio of the actually captured navigation message is lower than a preset signal-to-noise ratio threshold. In this way, when the signal-to-noise ratio of the current navigation message acquired in a weak signal scenario is relatively low and the current navigation message is not suitable for positioning calculation, positioning can be performed according to the predicted navigation message, accurate positioning information can be acquired, and positioning calculation of the receiver in a harsh environment with a relatively low signal-to-noise ratio can be met. The positioning abnormality problem that the receiver has a long positioning time or cannot be positioned when the signal-to-noise ratio is lower than a certain decision threshold in the prior art is solved.

[0188] Embodiment 2

[0189] In addition, the disclosure provides an auxiliary positioning device of a navigation system.

[0190] Specifically, as shown in FIG. 5, the auxiliary positioning device 500 of the navigation system includes: Figure 5 A first acquisition module 501 is configured to acquire a current navigation message and determine a data frame number of the current navigation message according to a week-second time count of the current navigation message.

[0191]

[0192] ​A first determining module 502 is configured to determine a target data frame number of the navigation message to be predicted according to the data frame number;

[0193] A second determining module 503 is configured to determine a target navigation message that matches the target data frame number from historical navigation messages;

[0194] The second acquisition module 504 is configured to acquire a predicted navigation message corresponding to the target data frame number according to the target navigation message;

[0195] A receiving module 505 is configured to receive an actual captured navigation message corresponding to the target data frame number;

[0196] The positioning module 506 is configured to perform positioning calculation according to the predicted navigation message when the signal-to-noise ratio of the actually captured navigation message is lower than a preset signal-to-noise ratio threshold.

[0197] In one embodiment, the first acquisition module 501 is further configured to determine a data frame number corresponding to the current navigation message according to the second count of the week of the current navigation message and the sending duration of the current navigation message frame.

[0198] In one embodiment, the first acquisition module 501 is further configured to perform a modulo operation on the week second count of the current navigation message and the sending duration of the current navigation message frame to obtain a data frame number corresponding to the current navigation message.

[0199] In one embodiment, the second obtaining module 504 is further configured to determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the current navigation message;

[0200] Updating the target navigation message's time count in seconds per week to the predicted time count in seconds per week to obtain a corrected navigation message;

[0201] The corrected navigation message is encoded to obtain the predicted navigation message.

[0202] In one embodiment, the current navigation message includes: a B1I navigation message subframe under the Beidou navigation system; the data frame number includes a superframe number, a main frame number, and a subframe number;

[0203] The first acquisition module 501 is further configured to determine the superframe number, main frame number, and subframe number corresponding to the B1I navigation message subframe based on the week second time count of the B1I navigation message subframe, the superframe transmission duration of the B1I navigation message, the main frame transmission duration of the B1I navigation message, and the subframe transmission duration of the B1I navigation message.

[0204] In one embodiment, the predicting the navigation message includes: predicting a B1I navigation message subframe;

[0205] The second acquisition module 504 is further configured to determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the B1I navigation message subframe;

[0206] Updating the target B1I navigation message subframe's time count in seconds per week to the predicted time count in seconds per week to obtain a modified B1I navigation message subframe;

[0207] The modified B1I navigation message subframe is encoded to obtain the predicted B1I navigation message subframe.

[0208] In one embodiment, the target B1I navigation message subframe includes 10 words, and the first preset bit field of word 1 and the second preset bit field of word 2 jointly represent the week seconds time count of the target B1I navigation message subframe; the length and value of the first preset bit field and the second preset bit field are equal to the length of the week seconds time count;

[0209] The second acquisition module 504 is further configured to determine a target bit from the predicted time count of seconds within the week, where the target bit divides the predicted time count of seconds within the week into a first target bit field and a second target bit field, where the length of the first target bit field is equal to the length of the first preset bit field, and the length of the second target bit field is equal to the length of the first preset bit field;

[0210] Updating the first preset bit field and the second preset bit field to the first target bit field and the second target bit field, respectively, to obtain a correction word 1 and a correction word 2, respectively;

[0211] The modified B1I navigation message subframe is generated according to the modified word 1, the modified word 2, and words 3 to 10.

[0212] In one embodiment, the second acquisition module 504 is further configured to perform BCH encoding on the correction word 1 and the correction word 2, respectively, to obtain the encoded word 1 and the encoded word 2;

[0213] The encoded word 1, the encoded word 2, and the words 3 to 10 are interleaved and coded to obtain the predicted B1I navigation message subframe.

[0214] In one embodiment, the current navigation message includes: a GLONASS navigation message frame under the GLONASS satellite navigation system; the data frame number includes a superframe number, a frame number, and a string number;

[0215] The first acquisition module 501 is further used to determine the superframe number, frame number and string number corresponding to the GLONASS navigation message frame based on the week second time count of the GLONASS navigation message frame, the superframe transmission duration of the GLONASS navigation message, the frame transmission duration of the GLONASS navigation message, and the string transmission duration of the GLONASS navigation message.

[0216] In one embodiment, the predicted navigation message includes: a predicted GLONASS navigation message frame; the target data frame number includes a target frame number and a target string number of the GLONASS navigation message frame to be predicted;

[0217] The second acquisition module 504 is further configured to determine a target satellite number corresponding to the target frame number, obtain an almanac of the target satellite number, and update the almanac of the target satellite number into the target GLONASS navigation message frame to obtain a combined GLONASS navigation message frame.

[0218] When the target string number is 1, adding 1 to the current frame start reference time of the first string of the combined GLONASS navigation message frame to obtain a corrected GLONASS navigation message frame;

[0219] When the target string number is any integer from 2 to 15, the combined GLONASS navigation message frame is used as a modified GLONASS navigation message frame;

[0220] The corrected GLONASS navigation message frame is encoded to obtain the predicted GLONASS navigation message frame.

[0221] In one embodiment, the modified GLONASS navigation message frame includes 15 character strings. The second acquisition module 504 is further used to perform Hamming encoding on the navigation data of each character string of the modified GLONASS navigation message frame to obtain coded navigation data, and generate the predicted GLONASS navigation message frame based on the coded navigation data and the time stamps of each character string of the modified GLONASS navigation message frame.

[0222] The auxiliary positioning device 500 of the navigation system provided in this embodiment can implement the steps of the auxiliary positioning method of the navigation system provided in Example 1 to achieve the corresponding technical effects. To avoid repetition, they are not described here.

[0223] The auxiliary positioning device of the navigation system provided in this embodiment obtains the current navigation message, determines the data frame number of the current navigation message based on the second time count of the week of the current navigation message; determines the target data frame number of the navigation message to be predicted based on the data frame number; determines the target navigation message that matches the target data frame number from the historical navigation message; obtains the predicted navigation message corresponding to the target data frame number based on the target navigation message; receives the actual captured navigation message corresponding to the target data frame number; and performs positioning calculation based on the predicted navigation message when the signal-to-noise ratio of the actual captured navigation message is lower than a preset signal-to-noise ratio threshold. In this way, when the signal-to-noise ratio of the current navigation message obtained in a weak signal scenario is relatively low and unsuitable for positioning calculation, positioning can be performed based on the predicted navigation message to obtain relatively accurate positioning information, which can meet the positioning calculation requirements of the receiver in harsh environments with relatively low signal-to-noise ratio.

[0224] Example 3

[0225] An embodiment of the present disclosure further provides a receiver, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is run by the processor, the auxiliary positioning method of the navigation system provided in embodiment 1 is executed.

[0226] The receiver provided in this embodiment can implement the auxiliary positioning method of the navigation system provided in Example 1, and will not be described again here to avoid repetition.

[0227] Example 4

[0228] An embodiment of the present disclosure further provides a computer-readable storage medium, on which a computer program is stored. The computer program is executed by a processor to implement the auxiliary positioning method for the navigation system provided in embodiment 1.

[0229] In this embodiment, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0230] The computer-readable storage medium provided in this embodiment can implement the auxiliary positioning method of the navigation system provided in Example 1, and will not be described again here to avoid repetition.

[0231] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or terminal comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or terminal comprising the element.

[0232] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method.

[0233] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. An auxiliary positioning method for a navigation system, characterized in that: The method comprises: Acquire a current navigation message, and determine a data frame number of the current navigation message according to a second-of-week time count of the current navigation message; Determining a target data frame number of the navigation message to be predicted according to the data frame number; Determining a target navigation message that matches the target data frame number from historical navigation messages; Obtaining a predicted navigation message corresponding to the target data frame number according to the target navigation message; receiving an actual captured navigation message corresponding to the target data frame number; When the signal-to-noise ratio of the actually captured navigation message is lower than a preset signal-to-noise ratio threshold, performing positioning calculation according to the predicted navigation message; The step of obtaining the predicted navigation message corresponding to the target data frame number according to the target navigation message includes: Determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the current navigation message; Updating the target navigation message's time count in seconds per week to the predicted time count in seconds per week to obtain a corrected navigation message; The corrected navigation message is encoded to obtain the predicted navigation message.

2. The method according to claim 1, characterized in that The step of determining the data frame number of the current navigation message according to the second-of-week time count of the current navigation message comprises: The data frame number corresponding to the current navigation message is determined according to the second-of-week time count of the current navigation message and the sending duration of the current navigation message frame.

3. The method according to claim 1, characterized in that The current navigation message includes: a B1I navigation message subframe under the Beidou navigation system; the data frame number includes a superframe number, a main frame number and a subframe number; The step of determining the data frame number corresponding to the current navigation message according to the week second time count of the current navigation message and the transmission duration of the current navigation message frame includes: The superframe number, main frame number and subframe number corresponding to the B1I navigation message subframe are determined according to the intra-week second time count of the B1I navigation message subframe, the superframe sending duration of the B1I navigation message, the main frame sending duration of the B1I navigation message, and the subframe sending duration of the B1I navigation message.

4. The method according to claim 1, wherein The predicted navigation message includes: predicting a B1I navigation message subframe; The step of determining the predicted time count of seconds in the week corresponding to the target data frame number according to the time count of seconds in the week of the current navigation message includes: Determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the B1I navigation message subframe; The step of updating the week second time count of the target navigation message to the week second time count prediction to obtain a corrected navigation message includes: The target B1I navigation message subframe is updated with the predicted week second time count to obtain a modified B1I navigation message subframe; The step of encoding the corrected navigation message to obtain the predicted navigation message includes: The modified B1I navigation message subframe is encoded to obtain the predicted B1I navigation message subframe.

5. The method according to claim 4, characterized in that The target B1I navigation message subframe includes 10 words, and the first preset bit field of word 1 and the second preset bit field of word 2 together represent the time count of seconds in a week of the target B1I navigation message subframe; The length and value of the first preset bit field and the second preset bit field are equal to the length of the predicted time count of seconds within a week; The step of updating the week second time count of the target B1I navigation message subframe to the week second time count prediction to obtain a modified B1I navigation message subframe includes: determining a target bit from the predicted seconds-of-week time count, the target bit dividing the predicted seconds-of-week time count into a first target bit field and a second target bit field, wherein the length of the first target bit field is equal to the length of the first preset bit field, and the length of the second target bit field is equal to the length of the first preset bit field; Updating the first preset bit field and the second preset bit field to the first target bit field and the second target bit field, respectively, to obtain a correction word 1 and a correction word 2, respectively; The modified B1I navigation message subframe is generated according to the modified word 1, the modified word 2, and words 3 to 10.

6. The method according to claim 5, characterized in that The step of encoding the modified B1I navigation message subframe to obtain the predicted B1I navigation message subframe includes: Performing BCH encoding on the correction word 1 and the correction word 2 respectively to obtain encoded word 1 and encoded word 2; The encoded word 1, the encoded word 2, and the words 3 to 10 are interleaved and coded to obtain the predicted B1I navigation message subframe.

7. The method according to claim 2, characterized in that The current navigation message includes: a GLONASS navigation message frame under the GLONASS satellite navigation system; the data frame number includes a superframe number, a frame number and a string number; The step of determining the data frame number corresponding to the current navigation message according to the week second time count of the current navigation message and the transmission duration of the current navigation message frame includes: The superframe number, frame number and string number corresponding to the GLONASS navigation message frame are determined according to the week second time count of the GLONASS navigation message frame, the superframe sending duration of the GLONASS navigation message, the frame sending duration of the GLONASS navigation message, and the string sending duration of the GLONASS navigation message.

8. The method according to claim 2, characterized in that The predicted navigation message includes: a predicted GLONASS navigation message frame; the target data frame number includes a target frame number and a target string number of the GLONASS navigation message frame to be predicted; The step of obtaining the predicted navigation message corresponding to the target data frame number according to the target navigation message includes: determining a target satellite number corresponding to the target frame number, obtaining an almanac of the target satellite number, and updating the almanac of the target satellite number into a target GLONASS navigation message frame to obtain a combined GLONASS navigation message frame; When the target string number is 1, adding 1 to the current frame start reference time of the first string of the combined GLONASS navigation message frame to obtain a corrected GLONASS navigation message frame; When the target string number is any integer from 2 to 15, the combined GLONASS navigation message frame is used as a modified GLONASS navigation message frame; The corrected GLONASS navigation message frame is encoded to obtain the predicted GLONASS navigation message frame.

9. The method according to claim 8, characterized in that The modified GLONASS navigation message frame includes 15 character strings. The step of encoding the modified GLONASS navigation message frame to obtain the predicted GLONASS navigation message frame includes: The navigation data of each character string of the modified GLONASS navigation message frame is Hamming-encoded to obtain coded navigation data, and the predicted GLONASS navigation message frame is generated according to the coded navigation data and the time stamps of each character string of the modified GLONASS navigation message frame.

10. An auxiliary positioning device for a navigation system, characterized in that: The device comprises: a first acquisition module, configured to acquire a current navigation message and determine a data frame number of the current navigation message according to a second count of a week in the current navigation message; A first determining module is configured to determine a target data frame number of the navigation message to be predicted according to the data frame number; A second determining module is used to determine a target navigation message that matches the target data frame number from the historical navigation messages; A second acquisition module is used to acquire a predicted navigation message corresponding to the target data frame number according to the target navigation message; A receiving module, configured to receive an actual captured navigation message corresponding to the target data frame number; a positioning module, configured to perform positioning calculation based on the predicted navigation message when the signal-to-noise ratio of the actually captured navigation message is lower than a preset signal-to-noise ratio threshold; The second acquisition module is further configured to determine the predicted time count in seconds of the week corresponding to the target data frame number according to the time count in seconds of the week of the current navigation message; Updating the target navigation message's time count in seconds per week to the predicted time count in seconds per week to obtain a corrected navigation message; The corrected navigation message is encoded to obtain the predicted navigation message.

11. A receiver, characterized in that: The system comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is run by the processor, the assisted positioning method of the navigation system according to any one of claims 1 to 9 is executed.

12. A computer-readable storage medium, characterized in that The computer program is stored therein, and when the computer program is run on a processor, the computer program executes the auxiliary positioning method of the navigation system according to any one of claims 1 to 9.

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