A long-wave positioning method, system, storage medium, computer device and terminal

Abstract

The present invention belongs to the technical field of long-wave positioning, and discloses a long-wave positioning method, system, storage medium, computer device and terminal. A reference station and a positioning terminal respectively receive an MSK long-wave signal transmitted by the same transmitting station, and process to obtain signal parameters; the reference station calculates a distance difference through the MSK long-wave signal parameters; the reference station performs reverse positioning to obtain the position of the transmitting station; the positioning terminal calculates the distance from itself to the transmitting station; the positioning terminal calculates its own coordinates. Compared with the traditional long-wave positioning system, the present invention requires the information format of the long-wave signal to be known, and has higher independence and stability; compared with the traditional long-wave positioning system, the positioning accuracy is higher; the concept of a reference station is introduced, and the transmitting station can be reversely positioned through the reference station, and further positioning can be performed using the transmitting station with position coordinates; the positioning terminal can not transmit signals, realizing radio silence and improving its own concealment.

Description

Technical Field

[0001] The present invention belongs to the technical field of long-wave positioning, and particularly relates to a long-wave positioning method, system, storage medium, computer device and terminal. Background Art

[0002] In recent years, with the rapid development of China's society and technology, obtaining accurate specified location information has become an important requirement in social life and military confrontation.

[0003] Currently, satellite navigation technology has been widely applied in various industries. However, due to the weak power of satellite signals, it is extremely vulnerable to being blocked by external noise and artificially interfered with and rendered ineffective; existing wireless positioning technologies can be used as an effective supplement to satellite navigation. However, these wireless positioning systems often require cooperation between the transmitting station and the positioning terminal to complete positioning, and their anti-interference and anti-destruction capabilities are weak during special periods.

[0004] China has a vast territory and sea areas. Obtaining accurate location information on the vast land has become an important link in traffic navigation and even military applications. Currently, the commonly used positioning methods include GNSS positioning, radio positioning, and Bluetooth WiFi fusion positioning. Among them, radio positioning is further divided into short-wave positioning and long-wave positioning.

[0005] 1. GNSS Positioning

[0006] The GNSS positioning method is based on satellite signals. Among various satellite positioning systems, the GPS system of the United States is the most mature in technology. Other widely used systems include the Galileo system in Europe and the Beidou system in China. GNSS positioning usually adopts a geocentric coordinate system. By using the C / A code or P code carried by satellite signals, pseudo-range measurement is completed, and multi-circle intersection positioning is performed. At least 4 satellites are required for cooperation to calculate the position equation; it can not only broadcast the approximate position in real time through broadcast ephemeris, but also obtain accurate position information by eliminating errors through long-term calculation of precise ephemeris. However, satellite signals have the disadvantages of being greatly affected by the atmospheric environment, weak receiving power, and weak anti-interference ability, which leads to a decline in the reliability and stability of GNSS system positioning.

[0007] 2. Radio Positioning

[0008] Radio positioning is a technology that uses radio equipment to determine the coordinates of vehicles, ships, aircraft, and any other targets with positioning terminals. Since the discovery of electromagnetic waves, radio positioning has been rapidly developed and widely applied. As early as during World War I, radio positioning was first applied at sea. European countries began to install radio beacons on the coast that emitted continuous radio waves. When a ship was within a certain distance from the shore, if the directions of two or more beacons could be measured, the position of the ship could be found based on the intersection of these directions. During World War II, the Loran - A system emerged. The Loran - A system uses pulse signals with a pulse carrier frequency of approximately 2 MHz and is mainly used for ship positioning and navigation. A series of shore stations are arranged on the coast to emit pulse signals synchronously with a certain repetition period. After the shipborne receiver receives the signals from two stations, the time difference of the arrival of these signals can be measured and multiplied by the speed of light to convert it into the distance difference from the two stations. Using this difference, it can be known that the ship is located on a certain hyperbola with the two stations as the foci. By measuring the positions to another two stations, another hyperbola can be obtained, and the intersection of the two hyperbolas is the position of the ship.

[0009] Then, in the late 1950s, the U.S. Coast Guard improved and developed the Loran - C system based on Loran - A. Its principle is similar to that of the Loran - A system, but in addition to using the pulse envelope, it also uses the phase of the pulse carrier frequency to complete the synchronization between stations and measure the time difference for the user receiver. Further positioning is carried out through the hyperbola positioning method, greatly improving the positioning accuracy. When the signal - to - noise ratio is - 5 dB, the positioning accuracy reaches 460 meters, and the repeat accuracy is 18 to 90 meters. At the same time, it provides a time - of - day signal with an accuracy reaching the microsecond level.

[0010] The Loran - A and Loran - C systems use pulse envelope and phase ranging to continuously and accurately give the position of the ship, which has great advantages compared with the previous generation of marine radio beacon systems. So they quickly replaced the position of marine radio beacons and became important marine navigation systems. The Loran - C system with improved positioning accuracy was even applied to inland aviation navigation and positioning in the United States and is still in use today.

[0011] 3. Bluetooth - WiFi integrated positioning

[0012] Apple launched the iBeacon technology in 2013, promoting the development of Bluetooth positioning. Bluetooth positioning technology mainly uses the signal strength method. Its principle is to reverse - infer the distance from the emission point through the obtained Bluetooth signal strength, and then perform positioning calculation through trilateration. However, because Bluetooth signals are easily affected by the indoor environment, resulting in unstable received signals, the positioning results are not accurate.

[0013] Single positioning technology often fails to meet the requirements of positioning accuracy, and multi-technology fusion positioning has become a new research hotspot. In 2015, Professor Lu Zhiyong of Sun Yat-sen University proposed a positioning scheme that fuses Bluetooth, WiFi, and audio. This scheme first uses WiFi fingerprint positioning to obtain a preliminary positioning result, and then uses Bluetooth and audio positioning technologies to correct the WiFi positioning result. However, this method requires a large number of acoustic wave positioning devices, resulting in a relatively high overall cost. In 2017, Kanaris L et al. proposed a new method for fusing Bluetooth and WiFi positioning. This method first converts the received signal strength into the distance between the point to be located and the Bluetooth signal transmitter according to the propagation model of Bluetooth signals in the air, then filters the original WiFi fingerprint using the proximity of the received signal strength to the Bluetooth device to obtain a new WiFi fingerprint database, and finally uses the new WiFi fingerprint database for WiFi fingerprint positioning calculation. Since the area determined by the Bluetooth proximity method is too rough, although this method can improve the positioning accuracy to a certain extent, the effect of this fusion positioning is not very ideal.

[0014] Although satellite positioning systems have relatively high accuracy, they need to receive satellite signals and reference station signals to measure pseudorange, obtain ephemeris, and differential compensation information, and thus have a high degree of dependence on external signals. Satellite signals may be interfered with in the space segment, operation and control segment, and user segment. Among them, the weak anti-electromagnetic interference ability in the user segment has become a fatal flaw. Moreover, satellites usually have a transmitting power of only dozens of watts and need to travel a distance of 20,220 km to reach the receiver on the Earth's surface, while the interfering signal is closer to the receiver and has a greater power. Therefore, satellite positioning systems are vulnerable to interference and lack reliability, and other positioning systems are needed as backup systems for satellite positioning systems to ensure the reliability of positioning functions. At the same time, satellite positioning systems need to launch multiple satellites to be built, with a complex process, a long construction period, and high costs and maintenance expenses.

[0015] Terrestrial radio positioning systems have irreplaceable advantages over satellite positioning systems. Although they have deficiencies in terms of coverage and accuracy, they are convenient to build and have low costs. Relying on ground base stations for networked positioning has higher reliability and stability in certain scenarios. However, in existing wireless positioning systems, a system is formed between the transmitting station and the positioning terminal. The characteristics of the transmitting station are included in the transmitted radio signals, and the positioning terminal is completely known, that is, the positioning terminal and the transmitting station cooperate to complete positioning.

[0016] In the fusion positioning of Bluetooth and WiFi, although existing WiFi positioning technology, Bluetooth positioning technology, and the positioning technology that fuses WiFi and Bluetooth have certain developments, they still have some drawbacks: single-module positioning accuracy is poor, multi-module fusion positioning has high complexity, is only applicable to positioning in a small range, and does not match the target functions expected to be completed by the present invention.

[0017] To enhance the reliability of the positioning system, provide positioning functions when the satellite navigation system fails or the existing wireless positioning system fails, and improve the flexibility of the positioning system, it is urgent to design a new long-wave positioning method and system to make up for the defects of the existing technology.

[0018] Through the above analysis, the problems and defects of the existing technology are as follows:

[0019] (1) The existing satellite positioning system is greatly affected by the atmospheric environment, has weak receiving power, weak anti-interference ability, poor reliability and stability, and has a high degree of dependence on external signals; at the same time, the satellite positioning system needs to launch multiple satellites to build, the process is complex, the construction period is long, and the cost and maintenance cost are also very high.

[0020] (2) The existing wireless positioning system has defects in terms of coverage and accuracy, and often requires cooperation between the transmitting station and the positioning terminal to complete positioning, and has weak anti-interference and anti-destruction capabilities during special periods.

[0021] (3) In the existing Bluetooth-WiFi fusion positioning method, the single-module positioning accuracy is poor, and the multi-module fusion positioning complexity is high; at the same time, the Bluetooth-WiFi fusion positioning technology is only applicable to positioning in a small range. Summary of the Invention

[0022] In view of the problems existing in the existing technology, the present invention provides a long-wave positioning method, system, storage medium, computer device and terminal, especially a long-wave positioning method, system and application based on reference station assistance.

[0023] The present invention is implemented as follows. A long-wave positioning method, the long-wave positioning method includes:

[0024] The reference station processes the MSK long-wave signal to complete the function of the reverse positioning transmitting station; the positioning terminal processes the MSK long-wave signal to complete the function of obtaining the target position.

[0025] Further, the long-wave positioning method includes the following steps:

[0026] Step 1, the reference station and the positioning terminal in the receiving station respectively receive the MSK long-wave signal transmitted by the same transmitting station, and process to obtain signal parameters; provide a basis for extracting the MSK signal parameters, so as to calculate the distance difference through the signal parameters.

[0027] Step 2, the reference station calculates the distance difference through the MSK long-wave signal parameters; provides basic parameters for the hyperbolic positioning method, so as to complete the reverse positioning function.

[0028] Step 3, the reference station performs reverse positioning to obtain the position of the transmitting station; provides coordinate parameters for calculating the absolute distance from the transmitting station to the positioning terminal.

[0029] Step 4: The positioning terminal calculates its own distance to the transmitting station, providing basic parameters for the circle-circle positioning method to complete the terminal positioning function.

[0030] Step 5: The positioning terminal calculates its own coordinates.

[0031] Furthermore, in Step 1, the reference station and the positioning terminal in the receiving station respectively receive the MSK long-wave signals transmitted by the same transmitting station, and the processed signal parameters include:

[0032] By differentiating different MSK long-wave signals through frequency, when the signal amplitude measured by reference station i is A i , the carrier phase is P i (f1), P i (f2); the signal amplitude measured by reference station j is A j , the carrier phase is P j (f1), P j (f2), where i and j represent the reference station numbers; the signal amplitude measured by the positioning terminal is A z , the carrier phase is P z (f1), P z (f2); The received MSK long-wave signals per second are processed and calculated according to the following formula:

[0033] The MSK signal is expressed as a function related to time t:

[0034]

[0035] where f c is the carrier frequency, a(t) is the signal symbol sequence, θ(t) is the initial phase sequence of each MSK symbol at the starting moment, R b is the symbol rate. After squaring the S(t) function expression, the influence of the DC component is removed:

[0036]

[0037] where θ0 is the initial signal phase;

[0038] After squaring, the spectrum has two obvious spectral lines, and their frequencies are respectively:

[0039]

[0040] Therefore, the symbol rate R b = f1 - f2, and the carrier frequency

[0041] By performing FFT transformation, the frequency difference and phase corresponding to these two spectral lines are respectively obtained. Let:

[0042]

[0043] Then the phase at frequency f is:

[0044]

[0045] The phases at two carrier frequencies are obtained as P(f1) and P(f2) respectively:

[0046] P(f1) = 2πf1t + 2θ0, P(f2) = 2πf2t + 2θ0;

[0047] The formula for solving the signal strength or amplitude corresponding to a certain carrier frequency by FFT is:

[0048]

[0049] where N is the number of sampling points, and F(f) is the spectrum value of FFT at a specific frequency point.

[0050] Furthermore, the distance differences calculated by the reference station in step two through the MSK long-wave signal parameters include:

[0051] After communication between reference stations i and j, the parameters of the same MSK long-wave signal arriving at different reference stations are obtained; among them, the parameters include amplitude and double-carrier phase.

[0052] The distance difference ΔR from the transmitting station to reference stations i and j is calculated through the following formula ij :

[0053] (1) Calculating the number of complete symbol periods Δm in the distance difference ΔR deduced from the carrier amplitude:

[0054] The fading of electromagnetic waves in the transmission path, and the free space loss is:

[0055] L bf = 32.5 + 20lgF + 20lgD;

[0056] where F is the frequency in MHz; D is the distance in km; then the amplitude change in the single-symbol propagation distance is ΔL = 6dB.

[0057] When the transmitting station reaches reference stations 1 and 2 and experiences m1 and m2 complete symbol periods respectively, combined with the measured amplitudes A1 and A2, the number of complete symbols Δm included in the distance difference ΔR is calculated after rounding:

[0058]

[0059] where represents rounding down, represents rounding up.

[0060] (2) Double - carrier phase calculation of the complete number of carrier waves \(n\):

[0061] After the reference station receives the MSK long - wave signal, it performs square and FFT spectrum analysis operations on the signal to obtain the spectrum values at two carrier - frequency points, and calculates the phases at the two carrier - frequency points respectively.

[0062] When the phases measured by the reference station at the two frequency points are \(P(f1)\) and \(P(f2)\) respectively, with the unit of radian, we have:

[0063]

[0064] The time \(t\) for the signal to be transmitted within a single symbol or the last symbol period is calculated through the double - carrier phase difference; and a complete symbol period contains multiple complete carrier periods. The complete number of carrier waves \(n\) within the last symbol period is reflected by \(t\).

[0065] When the symbol rate is 200 bps and the phase measurement accuracy is \(0.5^{\circ}\), the time resolution \(t'\) is:

[0066]

[0067] When the carrier frequency is 20 kHz, the duration \(t\) of 1 carrier period c is \(5\times10\) -5 s; the resolution \(t'\) of the double - carrier phase calculation result is \(t'\lt\) the carrier period \(t\) c , so through the calculation result of the double - carrier phase, the complete number of carrier waves \(n\) contained in the propagation time \(t\) is inferred:

[0068]

[0069] (3) Carrier - phase calculation of the fractional - carrier value \(k\):

[0070] After the reference station receives the MSK long - wave signal, it directly performs FFT spectrum analysis on the signal and takes the carrier phase \(P(f1)\) at the moment when the signal arrives; the fractional part \(k\) of the last carrier period of the signal is calculated through the carrier phase \(P(f1)\):

[0071]

[0072] (4) Calculation of the complete distance difference \(\Delta R\):

[0073] When calculating the complete distance difference, when the transmitting station reaches reference stations 1 and 2 respectively after experiencing \(m1\) and \(m2\) complete symbol periods, the carrier phases at the arrival times are taken as \(P1(f1)\) and \(P2(f1)\) respectively.

[0074] The overall distance difference ΔR consists of three parts: the distance difference of integer symbol propagation + the distance difference of integer carrier propagation + the distance difference of fractional carrier propagation.

[0075] ΔR = Δm × r b + [(n1 + k1) - (n2 + k2)] × r f 。

[0076] Furthermore, the obtaining of the transmitter position by reverse positioning at the reference station in step three includes:

[0077] Taking the reference stations i and j as the foci of a hyperbola, and taking the distance difference ΔR ij as the difference in distances from the hyperbola to the foci, draw a hyperbola; if there are two or more intersecting hyperbolas, the position coordinates (x u , y u ) of the transmitter can be calculated through the following formula:

[0078] Using the distance difference ΔR to reverse position the transmitter position (x u , y u ): After the distance differences ΔR 12 , ΔR 34 ... to the same transmitter are calculated respectively by three or more reference stations, taking two reference stations as the foci of the hyperbola, and ΔR x as the distance difference from the hyperbola to the foci, draw multiple hyperbolas, and the intersection point of the hyperbolas is the position coordinates of the transmitter, there are:

[0079]

[0080] d i 2 = (x u - x i ) 2 + (y u - y i ) 2 , i = 1, 2, 3, 4...;

[0081] When solving the equation, the result value of (x u , y u ) is solved by the least squares method, and the final matrix equation is:

[0082]

[0083] Among them, x ij = x i - x j , y ij = y i - y j; Abbreviate the matrix as Aq = B, and obtain the result solution of matrix q by calculation (x u , y u ) coordinate values:

[0084] q = (A T A) -1 A T B;

[0085] If the parameters are insufficient, the hyperbolas do not intersect or the quantity is insufficient, then return to Step 1 and wait for more reference stations to continue listening to the MSK signal transmitted by the transmitting station.

[0086] Furthermore, the positioning terminal in Step 4 calculates its own distance to the transmitting station, including:

[0087] If the reverse positioning of the transmitting station position in Step 3 is completed, the reference station i calculates the distance d from itself to the transmitting station i ; The reference station communicates with the positioning terminal, and measures the MSK long-wave signal parameters by the reference station i. The parameters include amplitude A i , double-carrier phase P i (f1), P i (f2) and distance d i to inform the positioning terminal.

[0088] The positioning terminal measures the amplitude A of the MSK long-wave signal parameters by itself z , double-carrier phase P z (f1), P z (f2), combines the obtained MSK long-wave signal parameters of the reference station i, and calculates the distance difference ΔR from the transmitting station to the reference station and the positioning terminal iz .

[0089] The positioning terminal in Step 5 calculates its own coordinates, including:

[0090] The positioning terminal calculates the distance r from the terminal to the transmitting station through the following formula iz ;

[0091] r iz = d i +ΔR iz ;

[0092] If the distances from two or more transmitting stations to the terminal are known, draw circles with the transmitting stations as the centers and the distance r iz as the radii. According to the circle-circle positioning method, calculate the terminal position coordinates (x z , y z ) through the following formula:

[0093] Solve the terminal position (x through the least squares solution formulaz , y z ):

[0094] (x z - x i ) 2 +(y z - y i ) 2 = r iz 2 , i = 1, 2, 3, 4...;

[0095] The matrix equation listed by the least - squares method is:

[0096]

[0097] Among them, x ij = x i - x j , y ij = y i - y j ; Abbreviate the matrix as Cp = D, and obtain the result of solving the matrix p to calculate the coordinate values of (x z , y z ):

[0098] p = (C T C) -1 C T D;

[0099] If the parameters are insufficient, the circles do not intersect or the number of circles is insufficient, then return to Step 1 and wait to detect more MSK long - wave signals emitted by long - wave transmitting stations.

[0100] Another object of the present invention is to provide a long - wave positioning system applying the described long - wave positioning method. The long - wave positioning system is composed of three parts: a transmitting station, a reference station, and a positioning terminal.

[0101] Among them, the position of the transmitting station is unknown, and it only sends long - wave signals and cannot communicate with the reference station or the positioning terminal; the transmitting station is used to transmit specified MSK signals, and the communication range is the whole world.

[0102] The position of the reference station is known. It is used to receive long-wave signals, communicate with other reference stations, and send signals to the positioning terminal. The reference station is used to receive and process long-wave signals, measure the carrier phase and amplitude of the long-wave signals, reverse-locate the position of the transmitting station, and communicate with the reference station or the positioning terminal to complete the target positioning function. The reference stations are divided into fixed reference stations and mobile reference stations. The reference station is used to obtain its own position information, while the positions of the transmitting station and the positioning terminal are unknown and need to be obtained through calculation and measurement. The reference stations communicate with each other to calculate and compensate for the clock deviation between the reference stations. After clock synchronization is completed at the reference station, the reverse positioning of the transmitting station is completed through the hyperbolic positioning method.

[0103] The position of the positioning terminal is unknown. It is used to receive long-wave signals and the information sent by the reference station. The positioning terminal is used to receive long-wave signals and the information sent by the reference station, obtain the coordinates of the transmitting station by receiving and analyzing the wireless signals sent by the reference station, measure the carrier phase and amplitude of the long-wave signals, calculate the distance from itself to the transmitting station, and complete the positioning process of itself through the circle-circle positioning method.

[0104] Another object of the present invention is to provide a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the following steps:

[0105] The reference station and the positioning terminal respectively receive the MSK long-wave signals transmitted by the same transmitting station, and process them to obtain signal parameters. The reference station calculates the distance difference through the MSK long-wave signal parameters. The reference station reverse-locates the position of the transmitting station. The positioning terminal calculates the distance from itself to the transmitting station. The positioning terminal calculates its own coordinates.

[0106] Another object of the present invention is to provide a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the following steps:

[0107] The reference station and the positioning terminal respectively receive the MSK long-wave signals transmitted by the same transmitting station, and process them to obtain signal parameters. The reference station calculates the distance difference through the MSK long-wave signal parameters. The reference station reverse-locates the position of the transmitting station. The positioning terminal calculates the distance from itself to the transmitting station. The positioning terminal calculates its own coordinates.

[0108] Another object of the present invention is to provide an information data processing terminal, which is used to implement the long-wave positioning system described above.

[0109] Combined with the above technical solutions and the technical problems to be solved, the advantages and positive effects of the technical solution to be protected by the present invention are analyzed from the following aspects:

[0110] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving such problems, closely combined with the technical solution to be protected by the present invention and the results and data in the R & D process, etc., analyze in detail and profoundly how the technical solution of the present invention solves the technical problems and the creative technical effects brought after solving the problems. The specific description is as follows:

[0111] To enhance the reliability of the positioning system and provide a positioning function when the satellite navigation system fails or the existing wireless positioning system fails, and at the same time improve the flexibility of the positioning system, the present invention provides a long-wave positioning method and system that does not require cooperation between the transmitting station and the positioning terminal and is assisted by a reference station.

[0112] The positioning system provided by the present invention is based on long-wave signals. Compared with short-wave signals, long-waves have stronger diffraction ability, are less affected by environmental factors such as the atmosphere, have a good coverage range and high stability. At the same time, the propagation mode of long-waves is generally ground waves, and the propagation delay can well reflect the propagation distance, which is conducive to completing the ranging function in the positioning system. Since the transmitting station often has a huge volume and extremely high power consumption, the transmitting station is often fixed in location. Currently, there are its own transmitting stations in countries such as Europe, the United States, Japan, and China, and the transmitting frequencies of each transmitting station are fixed. The present invention uses the positioning terminal to receive multiple long-wave signals, and realizes high-precision positioning by introducing the reception of long-wave signals by the reference station and the communication between the reference station and the positioning terminal. The present invention can realize the non-cooperative positioning function without knowing the content of the wireless signal transmitted by the transmitting station.

[0113] The present invention gradually improves the measurement accuracy through the characteristics of three long-wave MSK signals to achieve high-precision measurement of the propagation distance difference; uses the cooperation between reference stations to reverse-locate the position of the transmitting station; and uses the method of cooperation between the reference station and the terminal to complete the positioning process of the terminal in combination with long-wave signals.

[0114] The present invention can also calculate the number of complete code elements in the distance difference by correlating the demodulated code elements of receiver 1 and receiver 2; solve the carrier phase by using DFT instead of FFT in this patent; and use other error processing techniques to replace the least squares algorithm of the present invention.

[0115] Second, regarding the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are as follows:

[0116] Compared with the traditional long-wave positioning system, the present invention requires the information format of the known long-wave signal, and has higher independence and stability; compared with the traditional long-wave positioning system, the positioning accuracy is higher; the concept of a reference station is introduced, and the transmitting station can be reversely positioned through the reference station, and further positioning can be performed using the transmitting station with position coordinates; the positioning terminal can not transmit signals, realizing radio silence and improving its own concealment.

[0117] Thirdly, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0118] (1) The expected benefits and commercial value after the transformation of the technical solution of the present invention are:

[0119] The technology of the present invention can be made into a positioning terminal device. When navigation systems such as GPS / BDS fail, a positioning system can be quickly built by deploying reference stations to provide reliable and effective positioning services for terminal devices. In harsh environments or usage scenarios with strong signal interference, the technology of the present invention can be used as a reliable backup or even the preferred solution, with high commercial value.

[0120] (2) The technical solution of the present invention fills the technical gaps at home and abroad:

[0121] Existing positioning technologies, including satellite positioning and land-based long-wave positioning, require the receiver to know the protocol and format of the received signal in order to correctly demodulate the signal and obtain the complete content. The positioning method proposed by the present invention emphasizes positioning in a non-cooperative situation, and completes the positioning by calculating the distance through long-wave signal parameters, filling the technical gaps at home and abroad. BRIEF DESCRIPTION OF THE DRAWINGS

[0122] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0123] Figure 1 is a schematic diagram of distance difference calculation provided by an embodiment of the present invention Figure 1 ;

[0124] Figure 2 is a schematic diagram of distance difference calculation provided by an embodiment of the present invention Figure 2 ;

[0125] Figure 3 is a schematic diagram of reverse positioning provided by an embodiment of the present invention;

[0126] Figure 4 is a schematic diagram of terminal positioning provided by an embodiment of the present inventionFigure 1 ;

[0127] Figure 5 is the algorithm flowchart provided by the embodiments of the present invention;

[0128] Figure 6 is the reverse positioning schematic diagram of the transmitting station 1 provided by the embodiments of the present invention;

[0129] Figure 7 is the reverse positioning schematic diagram of the transmitting station 2 provided by the embodiments of the present invention;

[0130] Figure 8 is the accurate coordinate positioning map of the transmitting station 1 provided by the embodiments of the present invention;

[0131] Figure 9 is the terminal positioning schematic provided by the embodiments of the present invention Figure 2 ;

[0132] Figure 10 is the flowchart of the long-wave positioning method provided by the embodiments of the present invention. Detailed implementation manners

[0133] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0134] In view of the problems existing in the prior art, the present invention provides a long-wave positioning method, system, storage medium, computer device and terminal, which will be described in detail below with reference to the accompanying drawings.

[0135] I. Explanation of embodiments. In order to enable those skilled in the art to fully understand how the present invention is specifically implemented, this part is an explanatory embodiment that expands and explains the technical solutions of the claims.

[0136] 1. Term explanation

[0137] GNSS: (Global Navigation Satellite System), Global Navigation Satellite System;

[0138] GPS: (Global Positioning System), Global Positioning System;

[0139] C / A code or P code: Pseudorandom code, which has good autocorrelation characteristics and is used to measure pseudorange in satellite positioning;

[0140] Long wave: The frequency range is lower than 100KHz, and the main propagation modes are ground wave and sky wave, with a long propagation distance;

[0141] Short wave: The frequency range is 30 MHz - 6 MHz. The main propagation mode is space wave, and the propagation distance is short.

[0142] Ground wave: The radio wave that propagates along the Earth's surface is called the ground wave. It is relatively stable, less affected by the atmosphere, and has a long propagation distance. Since its path is an arc along the Earth's surface, when the propagation distance is not far, it can be approximately considered to directly reflect the distance between two places.

[0143] Sky wave: The radio wave that is radiated into the sky and reflected by the ionosphere and then received is called the sky wave. The sky wave is greatly affected by the ionosphere conditions, and the propagation time delay cannot directly reflect the distance.

[0144] Space wave: The radio wave that propagates in a straight line in space is called the space wave. The space wave is generally a high-frequency radio wave with poor diffraction ability and must have a direct path or a reflection path to reach.

[0145] TOA: (Time Of Arrival), time of arrival.

[0146] TDOA: (Time Difference Of Arrival), time difference of arrival. 2. Summary of the Invention

[0148] To enhance the reliability of the positioning system, provide positioning functions when the satellite navigation system fails or the existing wireless positioning system fails, and at the same time improve the flexibility of the positioning system, the present invention provides a long-wave positioning method and system that do not require cooperation between the transmitting station and the positioning terminal and are assisted by a reference station.

[0149] The positioning system provided by the present invention is based on long-wave signals. Compared with short-wave signals, long waves have strong diffraction ability, are less affected by environmental factors such as the atmosphere, have a good coverage range and high stability. At the same time, the propagation mode of long waves is generally ground wave, and the propagation time delay can well reflect the propagation distance, which is conducive to completing the ranging function in the positioning system. Since the transmitting station often has a huge volume and extremely high power consumption, the transmitting station is often fixed in location. Currently, countries such as Europe, the United States, Japan, and China have their own transmitting stations, and the transmitting frequencies of each transmitting station are fixed.

[0150] The present invention uses the positioning terminal to receive multiple long-wave signals and realizes high-precision positioning by introducing the reception of long-wave signals by the reference station and the communication between the reference station and the positioning terminal. The present invention can realize the non-cooperative positioning function without knowing the content of the wireless signal transmitted by the transmitting station.

[0151] As Figure 10 shown, the long-wave positioning method provided by the embodiment of the present invention includes the following steps:

[0152] S101. The reference station and the positioning terminal in the receiving station respectively receive the MSK long-wave signal emitted by the same transmitting station, and process it to obtain signal parameters.

[0153] S102. The reference station calculates the distance difference through the MSK long-wave signal parameters.

[0154] S103. The reference station performs reverse positioning to obtain the position of the transmitting station.

[0155] S104. The positioning terminal calculates the distance from itself to the transmitting station.

[0156] S105. The positioning terminal calculates its own coordinates.

[0157] I. Characteristics of MSK signals:

[0158] MSK modulation is minimum shift keying, also known as fast frequency shift keying, which is a special binary frequency shift keying (2FSK). Its signal can be expressed as:

[0159]

[0160] where A is the carrier amplitude, T c is the carrier frequency, and T b is the symbol width.

[0161] In addition, the MSK signal can be expressed as a function related to time t:

[0162]

[0163] where f c is the carrier frequency, a(t) is the signal symbol sequence, θ(t) is the initial phase sequence of each MSK symbol starting moment, R b is the symbol rate. After squaring formula (2) to remove the influence of the DC component:

[0164]

[0165] where θ0 is the initial phase of the signal; it is not difficult to see that after squaring, its spectrum has two obvious spectral lines, and their frequencies are respectively:

[0166]

[0167] The symbol rate R b = f1 - f2, and the carrier frequency

[0168] Through FFT transformation, the frequency difference and phase corresponding to these two spectral lines can be obtained respectively. Let:

[0169]

[0170] Then the phase at frequency f is:

[0171]

[0172] According to equations (6) and (7), the phases at two carrier frequencies are obtained as P(f1) and P(f2) respectively:

[0173] P(f1) = 2πf1t + 2θ0, P(f2) = 2πf2t + 2θ0 (7)

[0174] The formula for solving the signal strength (amplitude) corresponding to a certain carrier frequency by FFT is:

[0175]

[0176] where N is the number of sampling points and F(f) is the spectrum value of FFT at a specific frequency point.

[0177] II. System Composition

[0178] The ground-based long-wave positioning system consists of a transmitting station, a reference station, and a positioning terminal. The functions and roles of each part are as follows:

[0179] (1) Transmitting station: Its location is unknown. It only sends long-wave signals and cannot communicate with the reference station or the positioning terminal.

[0180] The main function of the transmitting station is to transmit specified long-wave signals (MSK signals are mainly used in this invention), and its communication range is global. Due to the very large size of the long-wave antenna and the transmitting power, the transmitting station is often immovable and has a fixed position. Currently, only a few countries such as Europe, the United States, Japan, and China have transmitting stations, and the number is very small. Since the information transmitted by these transmitting stations is generally confidential information, the signal format and content of their communication are unknown, and the reference station or the positioning terminal cannot obtain the content of the long-wave signal.

[0181] (2) Reference station: Its location is known. It can receive long-wave signals, communicate with other reference stations, and send signals to the positioning terminal.

[0182] The main function of the reference station is to receive and process long-wave signals, measure the carrier phase and amplitude of the long-wave signals, reverse-locate the position of the transmitting station, and communicate with the reference station or the positioning terminal to complete the target positioning function.

[0183] In actual application scenarios, reference stations are often divided into fixed reference stations (such as ground reference base stations in satellite positioning systems, etc.) and mobile reference stations (such as airborne command aircraft in the military, etc.). Reference stations can often obtain their own position information, while the positions of the transmitting station and the positioning terminal are unknown and need to be obtained through calculation and measurement.

[0184] Reference stations can communicate with each other and compensate for clock deviations between reference stations through calculation; after the reference stations complete clock synchronization, the reverse positioning of the transmitting station can be completed through the hyperbolic positioning method.

[0185] (3) Positioning terminal: The location is unknown, it can receive long-wave signals and information sent by the reference station.

[0186] The main function of the positioning terminal is to receive long-wave signals and information sent by the reference station. It can obtain the coordinates of the transmitting station by receiving and analyzing the wireless signals sent by the reference station, measure the carrier phase and amplitude of the long-wave signal, and calculate the distance from itself to the transmitting station, and complete the positioning process of itself through the circle-circle positioning method.

[0187] 3. Algorithm Analysis

[0188] 1. The method used by the receiving station to determine the source of the signal: frequency distinction.

[0189] The receiving station can distinguish the signal source by signal characteristics such as signal frequency, amplitude, and code rate, or by the data obtained after demodulation.

[0190] Since the present invention emphasizes the non-cooperativeness of the transceiver system and does not require the interpretation of the signal content, the frequency is used to distinguish the signal source. In addition, the principle of being able to select frequency distinction is determined by the long-wave communication system. The transmission frequencies of different long-wave base stations are basically fixed, and different transmitting stations have different transmission frequency bands, so the frequency can be used to distinguish different transmitting stations.

[0191] 2. Use the long-wave signal characteristics to calculate the distance difference ΔR:

[0192] By estimating three scales from large to small, the estimation accuracy of ΔR is gradually improved, thereby improving the accuracy of reverse positioning.

[0193] The three scale standards are:

[0194] 1) The number of complete symbol periods Δm contained in the propagation distance difference ΔR - calculated from the amplitude difference;

[0195] 2) The number of integer carriers n is calculated from the dual-carrier phase difference;

[0196] 3) The number of fractional carriers k is calculated from the carrier phase.

[0197] The complete calculation process is as follows:

[0198] (1) The number of complete symbol periods Δm in the distance difference ΔR calculated using the carrier amplitude:

[0199] After the reference station receives the long-wave MSK signal, it performs FFT spectrum analysis on the signal, and then calculates the intensity of the signal when it reaches the receiver according to formula (8).

[0200] Assume that the intensities of the same MSK long-wave signal reaching receivers 1 and 2 are A1 and A2 respectively. The overall distance difference ΔR from the transmitting station to receivers 1 and 2 can be deduced through the amplitude difference of the signals arriving at the two receivers. Since the signal intensity is easily affected by external environment interference (atmospherics, Gaussian white noise, etc.), the amplitude difference often cannot accurately reflect the distance difference, but this value can be used to roughly calculate how many complete symbol propagation distances are included in ΔR.

[0201] The fading of electromagnetic waves in the transmission path, that is, the free space loss (dB) is:

[0202] L bf = 32.5 + 20lgF + 20lgD (9)

[0203] where F is the frequency (unit: MHz) and D is the distance (unit: km). Then the amplitude change under the single symbol propagation distance is ΔL = 6dB.

[0204] Assume that the transmitting station to reference stations 1 and 2 have experienced m1 and m2 complete symbol periods respectively. According to formula (8), combined with the measured amplitudes A1 and A2, the number of complete symbols Δm included in the distance difference ΔR can be calculated after rounding down:

[0205]

[0206] where represents rounding down, represents rounding up.

[0207] (2) Deducing the number of complete carriers n by double-carrier phase:

[0208] After the reference station receives the MSK long-wave signal, it performs squaring and FFT spectrum analysis operations on the signal according to formulas (2) to (7) to obtain the spectrum values at two carrier frequencies, and then calculates the phases at the two carrier frequencies respectively.

[0209] Assume that the phases measured by the reference station at the two frequencies are P(f1) and P(f2) respectively, with the unit of radian. According to formula (7), we can get:

[0210]

[0211] It can be seen from formula (11) that the time t for the signal to be transmitted within the period of a single symbol (the last symbol) at the reference station can be calculated through the double-carrier phase difference. And a complete symbol period contains multiple complete carrier periods. Through t, the number n of complete carriers within the last symbol period can be reflected.

[0212] When the symbol rate is 200 bps, assuming the phase measurement accuracy is 0.5°, the time resolution t′ obtained according to formula (12) is:

[0213]

[0214] When the carrier frequency is 20 kHz, the duration t of one carrier period c is 5×10 -5 s; it can be obtained that the resolution t′ of the double-carrier phase calculation result < the carrier period t c , so the number n of complete carriers contained in the propagation time t can be inferred from the calculation result of the double-carrier phase:

[0215]

[0216] (3) Inferring the fractional carrier value k from the carrier phase:

[0217] After the reference station receives the MSK long-wave signal, it directly performs FFT spectrum analysis on the signal, and then takes the carrier phase P(f1) at the signal arrival time. The fractional part k of the last transmission carrier period of the signal can be calculated through the carrier phase P(f1).

[0218]

[0219] (4) Calculating the complete distance difference ΔR:

[0220] When calculating the complete distance difference, it is assumed that the transmitter to the reference stations 1 and 2 have experienced m1 and m2 complete symbol periods respectively, and the carrier phases at arrival are taken as P1(f1) and P2(f1) respectively, as Figure 1 shown.

[0221] The overall distance difference ΔR consists of three parts: integer symbol propagation distance difference + integer carrier propagation distance difference + fractional carrier propagation distance difference, as Figure 2 shown.

[0222] ΔR = Δm×r b +[(n1 + k1)-(n2 + k2)]×r f (15)

[0223] Positioning accuracy analysis:

[0224] At the carrier frequency fc When the frequency is 20 kHz and assuming that the phase measurement error reaches 0.5°, the distance calculation accuracy can be given by Equation (16). It can be seen that the positioning accuracy meets the positioning requirements of the ground-based long-wave positioning system.

[0225]

[0226] Where c is the speed of light in a vacuum.

[0227] 3. Use the distance difference ΔR to inversely locate the position (x u , y u ) of the transmitting station: When multiple (three or more) reference stations respectively calculate the distance differences ΔR 12 , ΔR 34 ... to the same transmitting station, taking two reference stations as the foci of the hyperbola and ΔR x as the distance difference from the hyperbola to the foci, draw multiple hyperbolas. The intersection point of the hyperbolas is the coordinate of the transmitting station position. As shown in Figure 3 , there are in the figure:

[0228]

[0229] d i 2 =(x u - x i ) 2 +(y u - y i ) 2 , i = 1, 2, 3, 4... (18)

[0230] In the hyperbola positioning method, since there are often certain errors in the measurement of the distance difference, and its error R' is given by Equation (16), multiple hyperbolas often do not intersect at the same coordinate point but are distributed in a region, as shown by the red circle in Figure 3 . To reduce the influence of the distance difference calculation error, when solving the equation, the least squares method is used to solve the result value of (x u , y u ). Finally, the matrix equation obtained is:

[0231]

[0232] Where, x ij =x i - x j , y ij =y i - y j ; Abbreviate the above matrix as Aq = B. By solving the result of matrix q, the value of (x u, y u ) Coordinate value:

[0233] q = (A T A) -1 A T B (20)

[0234] 4. Calculate the terminal position (x z , y z ):

[0235] As Figure 3 shown, after obtaining the position of the transmitting station (x u , y u ) by reverse positioning, the distance d from the reference station i to the transmitting station can be calculated through formula (18) i . The positioning terminal communicates with the reference station i, and can obtain the MSK long-wave signal parameters calculated by the reference station i. Combining the parameters of the terminal itself and the reference station i, the distance difference ΔR between the reference station i and the positioning terminal reaching the same transmitting station can be calculated through formulas (9) to (15) iz ; at the same time, obtain the distance d i from the reference station i to the transmitting station, then the distance from the terminal to the transmitting station is given by formula (19):

[0236] r iz = d i + ΔR iz (21)

[0237] Multiple distance parameters r iz can be obtained through different transmitting stations. After calculating the distances from two or more transmitting stations to itself by the same terminal, a circle can be drawn with the reference station i as the center and the distance r iz as the radius. Due to certain errors in reference station positioning, multiple circle position lines will not intersect at the same coordinate point, but are distributed in an area, as Figure 4 shown by the red circle in

[0238] To reduce the influence of errors, by solving formula (20) using the least squares method, the terminal position (x z , y z ) can be solved:

[0239] (x z - x i ) 2 + (y z - y i ) 2 = r iz 2 , i = 1, 2, 3, 4... (22)

[0240] The matrix equation listed by the least squares method is as follows:

[0241]

[0242] Wherein, x ij = x i - x j and y ij = y i - y j ; Abbreviate the above matrix as Cp = D, and the result of matrix p can be obtained by calculation, and then the coordinate values of (x z , y z ) can be calculated:

[0243] p = (C T C) -1 C T D (24)

[0244] IV. Algorithm Flow Description

[0245] The algorithm flow chart is as Figure 5 shown, mainly divided into two processing branches: the reference station processes the MSK long-wave signal (to complete the function of reverse positioning the transmitting station), and the positioning terminal processes the MSK long-wave signal (to complete the function of obtaining the target position):

[0246] The specific steps are described as follows:

[0247] 1. The receiving stations (reference station and positioning terminal) respectively receive the MSK long-wave signals transmitted by the same transmitting station, and process to obtain the signal parameters:

[0248] Different MSK long-wave signals can be distinguished by frequency, and the received MSK long-wave signals are processed and calculated per second according to formulas (2) - (8). Assume that the signal amplitude measured by reference station i is A i , and the carrier phases are P i (f1), P i (f2); the signal amplitude measured by reference station j is A j , and the carrier phases are P j (f1), P j (f2), where i and j represent the reference station numbers; the signal amplitude measured by the positioning terminal is A z , and the carrier phases are P z (f1), P z (f2).

[0249] 2. The reference station calculates the distance difference through the MSK long-wave signal parameters:

[0250] After communication between reference stations i and j, the parameters (amplitude and double carrier phase) of the same MSK long-wave signal arriving at different reference stations are obtained;

[0251] The distance difference ΔR from the transmitting station to the reference stations i and j can be calculated through formulas (9) to (15). ij .

[0252] 3. The position of the transmitting station is obtained by reverse positioning of the reference stations:

[0253] Taking the reference stations i and j as the foci of the hyperbola and the distance difference ΔR ij as the difference in distances from the hyperbola to the foci, a hyperbola is drawn;

[0254] If there are multiple hyperbolas (two or more) intersecting, then the position coordinates (x u , y u ) of the transmitting station can be calculated through formulas (17) to (20);

[0255] If the above parameters are insufficient, that is, the hyperbolas do not intersect or the quantity is insufficient, then return to step 1 and wait for more reference stations to continue listening to the MSK signal emitted by the transmitting station.

[0256] 4. The positioning terminal calculates the distance from itself to the transmitting station:

[0257] If the reverse positioning of the transmitting station position is completed in step 3, the reference station i can calculate the distance d from itself to the transmitting station i , and then the reference station communicates with the positioning terminal and transmits the MSK long-wave signal parameters measured by the reference station i, namely the amplitude A i , the dual-carrier phases P i (f1), P i (f2) and the distance d i to the positioning terminal.

[0258] The positioning terminal, through the MSK long-wave signal parameters measured by itself, namely the amplitude A z , the dual-carrier phases P z (f1), P z (f2), combined with the MSK long-wave signal parameters of the reference station i obtained above, can calculate the distance difference ΔR from the transmitting station to the reference station and the positioning terminal through formulas (9) to (15) iz ;

[0259] 5. The positioning terminal calculates its own coordinates:

[0260] The positioning terminal can calculate the distance r from the terminal to the transmitting station through formula (21) iz ;

[0261] If the distances from multiple transmitting stations (two or more) to the terminal are known, circles can be drawn with the transmitting stations as the centers and the distance r izDraw a circle with a radius. According to the circle-circle positioning method, the terminal position coordinates (x z , y z ) can be calculated through formulas (22) to (24);

[0262] If the above parameters are insufficient, that is, the circles do not intersect or the number of circles is insufficient, then return to step 1 and wait to monitor more MSK long-wave signals emitted by long-wave transmitting stations.

[0263] It should be noted that the embodiments of the present invention can be implemented through hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips and transistors, or programmable logic devices such as field programmable gate arrays, and can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software, such as firmware.

[0264] III. Evidence of the related effects of the embodiments. Some positive effects have been achieved during the research and development or use of the embodiments of the present invention, and there are indeed great advantages compared with the prior art. The following content is described in combination with the data, charts, etc. of the test process.

[0265] The present invention uses Matlab simulation software for simulation verification. The simulation system sets up 3 long-wave transmitting stations, 4 reference stations, and 1 positioning terminal to simulate and complete the function of obtaining the terminal position coordinates. The spherical coordinates of the earth can be converted into a plane through Mercator projection and calculated in a two-dimensional coordinate system; the coordinates of the positions of the above-mentioned stations in the two-dimensional coordinate system are given in Table 1.

[0266] Table 1 Simulation system coordinates

[0267] Station Name Station Coordinates (unit: m) Transmitting Station 1 (0，6000k) Transmitting Station 2 (-1000k, -1000k) Transmitting Station 3 (6000k, 4000k) Reference Station 1 (-200k, 4000k) Reference Station 2 (300k, 3500k) Reference Station 3 (1000k, 1000k) Reference Station 4 (5000k, 1500k) Positioning Terminal (-100k, 2000k)

[0268] 1. Distance difference calculation:

[0269] After setting the positions of the transmitting station, receiving stations, and positioning terminals in the system, the transmitting station simulates and generates a long-wave MSK signal with a signal frequency of 100 kHz, and processes the signals reaching different receiving stations according to the propagation distance and attenuation coefficient; after the reference stations and positioning terminals receive the MSK long-wave signal, they complete parameter detection, estimate multiple parameters of the long-wave MSK signal, and according to formulas (9) to (18), the distance difference parameters between the transmitting station and the receiving stations can be calculated. Some of the parameters are given in Table 2, which respectively represent the distance differences from the transmitting station i to the receiving stations n and m. In the case of a frequency of 100 kHz, the phase estimation accuracy of the simulation system is better than 0.5°. Through formula (16), the theoretical distance difference calculation error can be deduced to be 8.3 m. In the actual system, due to the addition of Gaussian white noise and atmospheric noise models, the measurement error will be further enlarged.

[0270] Table 2 Table of distance difference calculation results

[0271]

[0272]

[0273] 2. Reverse positioning of the transmitting station:

[0274] Based on the calculated distance differences, taking two reference stations as a set of foci of a hyperbola, the position coordinates of the transmitting station can be obtained by reverse positioning, as Figures 7 - 8 shown.

[0275] In Figure 6 , the green hyperbola takes reference stations 1 and 2 as foci; the red hyperbola takes reference stations 3 and 4 as foci; through least squares estimation, the position coordinates of the intersection of the two hyperbolas are (54.78, 5999982.16), with the unit of m. According to the accurate coordinates of transmitting station 1, the reverse positioning error of transmitting station 1 obtained by single positioning is 57.06 m.

[0276] In Figure 7 , the blue hyperbola takes reference stations 2 and 3 as foci; the purple hyperbola takes reference stations 1 and 4 as foci; through least squares estimation, the position coordinates of the intersection of the two hyperbolas are (-1000022.94, -1000038.36), with the unit of m. According to the accurate coordinates of transmitting station 2, the reverse positioning error of transmitting station 2 obtained by single positioning is 44.69 m.

[0277] Next, using more reference stations as the intersection points of hyperbolas and increasing the number of rows and columns of the matrix in formula (19) can further improve the positioning accuracy of the transmitting station, as Figure 8As shown. There are 4 groups of hyperbolas intersecting pairwise near the transmitting station 1. The position coordinates of the transmitting station at this time can be solved by the least squares method as (-4.91, 6000036.70), with the unit being m; the positioning error compared with the accurate coordinates is 37.03 m.

[0278] 3. Terminal position positioning:

[0279] From the distance difference results given in Table 2 and the positions of transmitting stations 1 to 3 obtained by reverse positioning, the position coordinates of the terminal can be calculated using formulas (19) to (20), as Figure 9 shown. In Figure 9 , through the least squares method, the position coordinates of the intersection of multiple circles are (-99990.67, 2000030.52), with the unit being m; the positioning error can be calculated as 31.91 m based on the terminal position coordinates.

[0280] As described above, only the specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A long-wave positioning method, characterized in that, The long-wave positioning method includes: The reference station processes the MSK long-wave signal to complete the function of reverse positioning the transmitting station; the positioning terminal processes the MSK long-wave signal to complete the function of obtaining the target position. The long-wave positioning method includes the following steps: Step 1, the reference station and the positioning terminal in the receiving station respectively receive the MSK long-wave signal transmitted by the same transmitting station, and process to obtain signal parameters. Step 2, the reference station calculates the distance difference through the MSK long-wave signal parameters. Step 3, the reference station performs reverse positioning to obtain the position of the transmitting station. Step 4, the positioning terminal calculates the distance from itself to the transmitting station. Step 5, the positioning terminal calculates its own coordinates. The reference station in Step 2 calculates the distance difference through the MSK long-wave signal parameters, including: After the reference stations i and j communicate, they obtain the parameters of the same MSK long-wave signal arriving at different reference stations; among them, the parameters include amplitude and double-carrier phase. The distance difference ΔR from the transmitting station to the reference stations i and j is calculated by the following formula ij :[[]]END]] (1) Deduce the number of complete symbol periods Δm in the distance difference ΔR according to the carrier amplitude: For the fading of electromagnetic waves in the transmission path, the free space loss is: L bf = 32.5 + 20 lg F + 20 lg D; where F is the frequency in MHz; D is the distance in km; then the amplitude change in the single-symbol propagation distance is ΔL = 6 dB. When the transmitting station reaches the reference stations 1 and 2 respectively experiencing m1 and m2 complete symbol periods, combined with the measured amplitudes A1 and A2, the number of complete symbols Δm included in the distance difference ΔR is calculated after rounding. Among them, represents rounding down, represents rounding up. (2) Calculate the complete number of carrier waves \(n\) based on the double - carrier phase t : After the reference station receives the MSK long-wave signal, it performs squaring and FFT spectrum analysis operations on the signal to obtain the spectrum values at two carrier frequency points, and calculates the phases of the two carrier frequency points respectively. When the phases measured by the reference station at the two frequency points are P(f1) and P(f2) respectively, in radians, we have: The time t for the reference station to transmit signals within a single symbol or the last symbol period is calculated through the double-carrier phase difference; and a complete symbol period contains multiple complete carrier periods, and the number n of complete carriers within the last symbol period is reflected by t t ; In the case of a symbol rate of 200 bps, the phase measurement accuracy is 0.5°, and the time resolution t' is: When the carrier frequency is 20 kHz, the duration t of one carrier cycle c is 5×10 -5 s; the resolution t' of the double-carrier phase calculation result < the carrier cycle t c Therefore, through the calculation result of the double-carrier phase, infer the complete number of carrier waves n contained in the propagation time t t : (3) Deduce the fractional carrier value k according to the carrier phase: After the reference station receives the MSK long-wave signal, it directly performs FFT spectrum analysis on the signal and takes the carrier phase P(f1) at the signal arrival time; the fractional part k of the last transmission carrier period of the signal is calculated through the carrier phase P(f1). (4) Calculate the complete distance difference ΔR: When calculating the complete distance difference, when the transmitting station reaches the reference stations 1 and 2 respectively experiencing m1 and m2 complete symbol periods, the carrier phases at arrival are taken as P1(f1) and P2(f1) respectively. The overall distance difference ΔR consists of three parts, including the integer symbol propagation distance difference, the integer carrier propagation distance difference, and the fractional carrier propagation distance difference. ΔR = Δm × r b +[(n1 + k1)-(n2 + k2)]×r f 。 2. The long-wave positioning method according to claim 1, characterized in that, The reference station and the positioning terminal in the receiving station in Step 1 respectively receive the MSK long-wave signal transmitted by the same transmitting station, and the signal parameters obtained by processing include: Distinguish different MSK long-wave signals by frequency. When the signal amplitude measured by reference station i is A i , the carrier phase is P i (f1), P i (f2); the signal amplitude measured by reference station j is A j , the carrier phase is P j (f1), P j (f2), where i and j represent the reference station numbers; the signal amplitude measured by the positioning terminal is A z , the carrier phase is P z (f1), P z (f2); Process and calculate the received MSK long-wave signal per second according to the following formula: The MSK signal is expressed as a function related to time t: where f c is the carrier frequency, a(t) is the signal symbol sequence, θ(t) is the initial phase sequence at the start time of each MSK symbol, and R b is the symbol rate. After squaring the expression of the S(t) function, the influence of the DC component is removed: where θ0 is the initial phase of the signal. After squaring, the spectrum has two obvious spectral lines, and their frequencies are respectively: Therefore, the symbol rate R b = f1 - f2, and the carrier frequency The frequency difference and phase corresponding to these two spectral lines are respectively obtained through FFT transformation. Let: Then the phase at the frequency point f is: The phases at the two carrier frequency points are obtained as P(f1) and P(f2) respectively: P(f1) = 2πf1t + 2θ0, P(f2) = 2πf2t + 2θ0; The formula for the FFT to solve the signal strength or amplitude corresponding to a certain carrier frequency is: Where N is the number of sampling points, and F(f) is the spectrum value of the FFT at a specific frequency point.

3. The long-wave positioning method according to claim 1, wherein, The reverse positioning of the reference station in step three to obtain the position of the transmitting station includes: Taking reference stations i and a as the foci of a hyperbola, and taking the distance difference ΔR ij as the hyperbola arrival focus difference value, a hyperbola is drawn; if two or more hyperbolas intersect, the position coordinates (x u , y u ) of the emission station are calculated through the following formula: Use the distance difference ΔR to inversely locate the position of the transmitting station (x u , y u ): When there are three or more reference stations, calculate the distance differences ΔR 12 , ΔR 34 … that reach the same transmitting station respectively. Then, taking two reference stations as the foci of the hyperbola and ΔR x as the distance difference from the hyperbola to the foci, draw multiple hyperbolas. The intersection point of the hyperbolas is the position coordinates of the transmitting station, and there is: d i 2 = (x u - x i ) 2 + (y u - y i ) 2 , i = 1, 2, 3, 4...; When solving the equation, the least squares method is used to solve the result values of (x u , y u ). Finally, the matrix equation is obtained as follows: Among them, x ia = x i - x a , y ia = y i - y a ; Abbreviate the matrix as A a q = B, and obtain the result solution of matrix q by calculation (x u , y u ) coordinate values: q = (A a T A a ) -1 A a T B; If the parameters are insufficient, the hyperbolas do not intersect or the number is insufficient, then return to step one and wait for more reference stations to continue listening to the MSK signal transmitted by the transmitting station.

4. The long-wave positioning method according to claim 1, wherein, The positioning terminal in step four calculates its own distance to the transmitting station, including: If the reverse positioning of the transmitter station location in step three is completed, the reference station i calculates the distance d from itself to the transmitter station i ; The reference station communicates with the positioning terminal, and the reference station i measures the MSK long-wave signal parameters, and the parameters include the amplitude A i , the dual-carrier phase P i (f1), P i (f2) and the distance d i to inform the positioning terminal; The positioning terminal measures the amplitude A of the MSK long-wave signal parameter by itself z , the phase P of the dual-carrier z (f1), P z (f2), combines with the MSK long-wave signal parameters of the reference station i obtained, and calculates the distance difference ΔR from the transmitting station to the reference station and the positioning terminal iz ; The positioning terminal in step five calculates its own coordinates, including: The positioning terminal calculates the distance r from the terminal to the transmitting station through the following formula iz ; r iz = d i + ΔR iz ; If the distances from two or more transmitting stations to the terminal are known, taking the transmitting stations as the centers and a distance r iz as the radius to draw circles, according to the circle-circle positioning method, the terminal position coordinates (x z , y z ) can be calculated through the following formula: The terminal position (x z , y z ) is calculated by the least squares method: (x z -x i ) 2 +(y z -y i ) 2 = r iz 2 , i = 1, 2, 3, 4…; The matrix equation listed by the least squares method is: Among them, x ia = x i - x a , y ia = y i - y a ; Abbreviate the matrix as Cp = D, and obtain the result solution of matrix p by calculation (x z , y z ) coordinate values: p = (C T C) -1 C T D; If the parameters are insufficient, the circles do not intersect or the number of circles is insufficient, then return to step one and wait to listen to the MSK long-wave signals transmitted by more long-wave transmitting stations.

5. A long-wave positioning system applying the long-wave positioning method according to any one of claims 1 to 4, characterized in that The long-wave positioning system consists of three parts: a transmitting station, a reference station, and a positioning terminal; Among them, the position of the transmitting station is unknown, and it only sends long-wave signals and cannot communicate with the reference station or the positioning terminal; the transmitting station is used to transmit specified MSK signals, and the communication range is global; The position of the reference station is known, and it is used to receive long-wave signals, communicate with other reference stations, and send signals to the positioning terminal; the reference station is used to receive and process long-wave signals, measure the carrier phase and amplitude of the long-wave signals, reverse-position the position of the transmitting station, and communicate with the reference station or the positioning terminal to complete the target positioning function; the reference station is divided into a fixed reference station and a mobile reference station. The reference station is used to obtain its own position information, while the positions of the transmitting station and the positioning terminal are both unknown and need to be obtained through calculation and measurement; the reference stations communicate with each other to calculate and compensate for the clock deviation between the reference stations; after the reference stations complete clock synchronization, the reverse positioning of the transmitting station is completed through the hyperbola positioning method; The position of the positioning terminal is unknown, and it is used to receive long-wave signals and the information sent by the reference station; the positioning terminal is used to receive long-wave signals and the information sent by the reference station, obtain the coordinates of the transmitting station by receiving and analyzing the wireless signals sent by the reference station, measure the carrier phase and amplitude of the long-wave signals, calculate the distance from itself to the transmitting station, and complete the positioning process of itself through the circle-circle positioning method.

6. A computer device, characterized in that The computer device includes a memory and a processor. When the computer program stored in the memory is executed by the processor, the processor executes the long-wave positioning method according to any one of claims 1 to 4, including the following steps: The reference station and the positioning terminal respectively receive the MSK long-wave signals transmitted by the same transmitting station, process them to obtain signal parameters; the reference station calculates the distance difference through the MSK long-wave signal parameters; the reference station reverse-positions the position of the transmitting station; the positioning terminal calculates its own distance to the transmitting station; the positioning terminal calculates its own coordinates.

7. A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor is caused to execute the long-wave positioning method according to any one of claims 1 to 4, including the following steps: The reference station and the positioning terminal respectively receive the MSK long-wave signals emitted by the same transmitting station, and process to obtain signal parameters; the reference station calculates the distance difference through the MSK long-wave signal parameters; the reference station performs reverse positioning to obtain the position of the transmitting station; the positioning terminal calculates the distance from itself to the transmitting station; the positioning terminal calculates its own coordinates.

8. An information data processing terminal, characterized in that The information data processing terminal is used to implement the long-wave positioning system as described in claim 5.

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