A tunnel positioning system and method

Abstract

The application is suitable for the field of tunnel positioning, and provides a tunnel positioning system and method. The tunnel positioning system comprises a plurality of cascade nodes arranged in a tunnel. Each node comprises a GNSS signal receiving device, a GNSS signal simulator and a signal controller which are electrically connected in sequence. The problems of complex equipment, difficult expansion and inability to continuously position are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of tunnel positioning, and particularly relates to a tunnel positioning system and method. BACKGROUND

[0002] Commonly used satellite signal positioning methods mainly include: pseudo-satellite positioning method, satellite signal simulation positioning method, and satellite signal retransmission positioning method. This kind of method realizes high-precision positioning in a tunnel by broadcasting processed satellite navigation signals without changing the satellite navigation receiving terminal; however, the environment inside and outside the tunnel is quite different, the high shielding angle is not good for signal continuity, and it is easy to cause navigation terminal positioning confusion or even continuous positioning failure.

[0003] Non-satellite positioning methods mainly include: visible light positioning method, RFID positioning method, WIFI positioning method, ZigBee positioning method, and UWB positioning method. The visible light positioning method has high precision and fast positioning speed, but is easily affected by light; the RFID positioning method has small volume and high precision, but has short positioning distance; the WIFI positioning method has low cost, but has large calculation amount and low precision; the ZigBee positioning method has low power consumption and high efficiency, but needs a large number of node networks and has high complexity; and the UWB positioning method has high precision, low power consumption, strong anti-multipath and anti-interference capabilities, but has high equipment cost.

[0004] A typical application of combination of multiple positioning technologies is the combination of satellite navigation and non-satellite navigation. This kind of method generally consists of two or more positioning technologies, and has complex technology, large implementation difficulty, and is not easy to maintain, and needs to install special positioning equipment. SUMMARY

[0005] The present application aims to provide a tunnel positioning system and method, and aims to solve the problems of high shielding angle, poor signal continuity, and complex equipment, difficult expansion, and not easy to maintain in tunnel positioning.

[0006] In a first aspect, the present application provides a tunnel positioning system, comprising:

[0007] a plurality of cascaded nodes arranged in the tunnel, each node comprising a GNSS signal receiving device, a GNSS signal simulator and a signal controller connected in sequence;

[0008] The GNSS signal receiving device receives navigation signals transmitted by satellites at the tunnel portal at the first node, receives navigation signals regenerated in real time by the GNSS signal simulator of the previous node at the node other than the first node, and demodulates the received navigation signals to extract ephemeris data and time information and send them to the GNSS signal simulator;

[0009] The GNSS signal simulator receives ephemeris data and time information sent by a GNSS signal receiving device, performs frequency calibration by using a time synchronization algorithm, generates a local clock frequency, reprocesses the received ephemeris data, combines a time delay control algorithm and preset position coordinate data, and regenerates navigation signals in real time, and synchronizes the real-time regenerated navigation signals to the signal controller;

[0010] The signal controller performs beamforming on the navigation signals regenerated by the GNSS signal simulator in real time, controls the transmission power of the navigation signals, and controls the projection angle and projection direction of the navigation signals, and sends the navigation signals regenerated in real time to the GNSS signal receiving device of the next node.

[0011] Further, the signal controller comprises a digital signal beamforming module, a differential power control module and a signal transmission module connected in sequence.

[0012] The digital signal beamforming module is used to direct the beam of the synchronized real-time regenerated navigation signals to the lane surface in the intended direction.

[0013] The differential power control module presets a personalized power control interval between adjacent two nodes, controls the transmission power of the navigation signals, and makes the navigation signal strength in the signal coverage area higher than the receivable signal strength threshold.

[0014] The signal transmission module calculates the optimal transmission path and optimal receiving direction of the transmitted signals, controls the projection angle and projection direction, and sends the navigation signals regenerated in real time to the GNSS signal receiving device of the next node.

[0015] Further, the digital signal beamforming module adopts digital beamforming on the navigation signals according to the curvature, slope and width of the tunnel, generates multiple beam baseband signals, changes the weighting values, i.e. amplitude and phase, of each channel signal, improves the directivity pattern, directs the beam to the lane surface in the intended direction, guides the zero signal to the direction that does not need to be interfered, and suppresses the multipath signals except the intended direction.

[0016] Further, the differential power control module performs differential power control on the navigation signals of each node, controls different transmission powers of wireless signals used by each node according to the different link states between each node, controls the beam in one direction among the nodes between adjacent two nodes in the tunnel, forms a personalized power control interval between the two nodes, reduces the mutual interference of the navigation signals of the adjacent two nodes in the interval, improves the navigation signal gain of the adjacent two nodes, compensates for the fading of the navigation signals, and makes the signal coverage area always in an environment where the navigation signal strength is higher than the receivable signal strength threshold.

[0017] In a second aspect, the application provides a tunnel positioning method, comprising:

[0018] A GNSS signal receiving device of a first cascade node disposed in the tunnel receives a satellite transmitted navigation signal and demodulates the received satellite transmitted navigation signal to extract ephemeris data and time information, and transmits the ephemeris data and time information to a GNSS signal simulator of the first cascade node;

[0019] The GNSS signal simulator receives the ephemeris data and time information, performs frequency calibration on the time information by using a time synchronization algorithm to generate a local clock frequency, reprocesses the ephemeris data, combines a time delay control algorithm and preset position coordinate data, and performs real-time regeneration on the satellite transmitted navigation signal, and synchronizes the real-time regenerated navigation signal to a signal controller of the first cascade node;

[0020] The signal controller of the first cascade node performs beamforming on the real-time regenerated navigation signal, controls the transmission power, transmission angle and direction of the navigation signal, and transmits the real-time regenerated navigation signal to a GNSS signal receiving device of a next cascade node.

[0021] Further, after the real-time regenerated navigation signal is transmitted to the GNSS signal receiving device of the next cascade node, the method further comprises:

[0022] The GNSS signal receiving device of the second cascade node receives the real-time regenerated navigation signal transmitted by the signal controller of the first cascade node, repeats the operation steps of the first cascade node in the second cascade node, and outputs a navigation signal of the second cascade node;

[0023] The operation steps are repeated multiple times to output a navigation signal of an nth cascade node, and n is a natural number greater than or equal to three.

[0024] Further, the signal controller performs beamforming on the real-time regenerated navigation signal, controls the transmission power, transmission angle and direction of the navigation signal, and transmits the real-time regenerated navigation signal to the GNSS signal receiving device of the next cascade node, specifically:

[0025] According to the tunnel environment, the beam of the synchronized real-time regenerated navigation signal is directed to a lane surface in an expected direction, and multipath signals other than the expected direction are suppressed;

[0026] A personalized power control interval is preset between adjacent two cascade nodes to control the transmission power of the real-time regenerated navigation signal, so that the navigation signal strength in a signal coverage area is higher than a receivable signal strength threshold;

[0027] The system calculates the optimal transmission path and optimal reception direction of the transmitted signal, controls the projection angle and projection direction to transmit the real-time regenerated navigation signal, and sends the navigation signal of the first-level node to the GNSS signal receiving equipment of the next-level node.

[0028] Furthermore, the step of directing the beam of the synchronized navigation signal toward the lane surface in the expected direction, based on the tunnel environment, and suppressing multipath signals other than those in the expected direction, specifically involves:

[0029] Based on the tunnel's curvature, gradient, and width, digital beamforming is applied to the navigation signal to generate multiple baseband beams. This alters the weighting values ​​of each channel's signal (amplitude and phase) to improve the radiation pattern, directing the beam towards the lane surface in the desired direction, guiding zero-signal signals to directions where interference is unnecessary, and suppressing multipath signals other than those in the desired direction. In short:

[0030] N beams are pre-defined to form on the lane. The number of beams is selected based on the node location and tunnel structure, with the main lobe direction aligned to σ1, σ2, σ3, ... σ N The spatial coordinates σ of the i-th element i For σ i (σ xi ,σ yi ,σ zi The weighted vector is:

[0031]

[0032] The output signal after beamforming is:

[0033]

[0034] Where, ω i (θ i ,φ i ,σ i ω is the weight vector, r(t) = AS(t) + n(t), n(t) is the noise signal, S(t) is the useful signal, and r(t) represents the received signal; i * Represents the weight vector ω i Conjugate;

[0035] A i (θ i ,φ i ,σ i )=[p1(θ1,φ1,σ1)…p N (θ N ,φ N ,σ N [], i = 1, 2, 3…N is the direction matrix, and (θ, φ) represents σ N Beam characteristics of the location, desired response pi (θ i ,φ i ,σ i ) is:

[0036] Wherein, x, y, z represent the coordinate values of the three directions of the sigma coordinate, and λ represents the wavelength of the incident signal;

[0037] The weight vector and the direction matrix are multiplied and summed to change the value of (θ, φ) to obtain beams of different directions and different gains;

[0038] The linear constraint minimum variance LCMV is used to maximize the gain in the expected navigation signal direction; after adjusting multiple (θ, φ) parameters, a set of data parameters with the best control effect is selected.

[0039] Further, the individualized power control interval between the adjacent two levels of nodes is preset to control the transmission power of the navigation signal, so that the navigation signal strength in the signal coverage area is higher than the receivable signal strength threshold, specifically:

[0040] The navigation signals of each level of nodes are subjected to differential power control, different transmission powers are used by any level of nodes to transmit wireless signals according to the different link states between each level of nodes, the beam in one of the directions in the control node is controlled between the adjacent two levels of nodes in the tunnel, so that an individualized power control interval is formed between the two levels of nodes, the mutual interference of the navigation signals of the adjacent two levels of nodes is reduced in the interval, the navigation signal gain of the adjacent two levels of nodes is improved, the fading of the navigation signal is compensated, and the signal coverage area is always in an environment where the navigation signal strength is higher than the receivable signal strength threshold.

[0041] Further, the node power differential control of the navigation signals of each level of nodes is specifically:

[0042] The loss Lc of the cable and the cable head and the beamforming gain Ga are calculated;

[0043] The spatial transmission attenuation Lbf of the signal transmitted by the signal transmission module of the signal controller to the lane surface is calculated as Lbf = 32.5 + 20lgF + 20lgD;

[0044] According to the signal reception sensitivity Rs of the signal controller, the signal reception strength RSS = Pt + Gr - Lc - Lbf + Ga + Gt is determined; wherein, Pt is the transmission power, Gr is the reception antenna gain, and Gt is the transmission antenna gain;

[0045] According to the tunnel environment, the system margin SFM = RSS - Rs is determined;

[0046] According to the calculated system margin SFM, any level of node transmits the navigation signal with different transmission power.

[0047] In the present application, the tunnel positioning system adopts cascaded signal nodes, and the GNSS signal receiving device can continuously, real-time and accurately track and demodulate navigation signals; the GNSS signal simulator realizes real-time regeneration of navigation signals in the tunnel, and transmits the real-time regenerated navigation signals to the next node, so that the connection of the navigation signals in the tunnel is uninterrupted; the digital signal beamforming module solves the problems of small coverage range, poor signal strength, strong interference of adjacent nodes and inconsistent signal arrival time at the terminal on the lane caused by the tunnel environment, the differentiated power control module can reduce energy consumption, power compensation fading and interference, and the signal transmitting module controls the projection angle and direction, avoids the signal wall reaction and reduces the interference of the terminal processing signal.

[0048] The tunnel positioning method extracts ephemeris data and time information by demodulating the received navigation signals, and uses time synchronization technology and time delay control technology to regenerate navigation signals in real time, solving the problem of continuous positioning caused by inconsistent signals in the tunnel; through beamforming, the beam is directed to the desired lane surface, increasing the strength of the useful signal and avoiding the influence of the tunnel environment; through differentiated power control, power compensation fading and interference are reduced; the projection angle and direction are controlled to reduce the probability of collision of regenerated signals between nodes, solving the problem of terminal positioning confusion. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a structural diagram of a tunnel positioning system provided by an embodiment of the present application.

[0050] Figure 2 is a three-differentiated control effect diagram of a signal controller provided by an embodiment of the present application.

[0051] Figure 3 is a flowchart of a tunnel positioning method provided by another embodiment of the present application.

[0052] Figure 4 is a principle block diagram of digital intermediate frequency signal beamforming provided by another embodiment of the present application.

[0053] Figure 5 is a normalized directivity pattern of a beam in a tunnel provided by another embodiment of the present application. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and beneficial effects of the present application clearer and more apparent, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0055] In order to illustrate the technical solutions described in the present application, the following specific embodiments are used to illustrate the technical solutions described in the present application.

[0056] Referring to Figure 1 The tunnel positioning system provided by an embodiment of the present application comprises a plurality of cascaded nodes (a first node to an nth node) arranged in a tunnel, each node comprising a GNSS signal receiving device 01, a GNSS signal simulator 02 and a signal controller 03 connected in sequence.

[0057] The GNSS signal receiving device 01 receives navigation signals transmitted by satellites at the tunnel portal at the first node, receives navigation signals regenerated in real time by the GNSS signal simulator 02 of the previous node at the nodes other than the first node, and demodulates the received navigation signals to extract ephemeris data and time information and send them to the GNSS signal simulator.

[0058] The GNSS signal simulator 02 receives the ephemeris data and time information sent by the GNSS signal receiving device 01, performs frequency calibration using a time synchronization algorithm to generate a local clock frequency, reprocesses the received ephemeris data, combines a time delay control algorithm and preset position coordinate data, regenerates navigation signals in real time, and synchronizes the regenerated navigation signals to the signal controller 03.

[0059] The signal controller 03 performs beamforming on the navigation signals regenerated in real time by the GNSS signal simulator 02, controls the transmission power of the navigation signals, controls the projection angle and projection direction of the navigation signals, and sends the regenerated navigation signals to the GNSS signal receiving device of the next node.

[0060] In an embodiment of the present application, the signal controller comprises a digital signal beamforming module, a differential power control module and a signal transmission module connected in sequence.

[0061] The digital signal beamforming module is configured to direct the beam of the synchronized and regenerated navigation signals to the lane surface in the intended direction.

[0062] The differential power control module presets a personalized power control interval between adjacent two nodes, controls the transmission power of the navigation signals, and makes the navigation signal strength in the signal coverage area higher than the threshold value of the receivable signal strength.

[0063] The signal transmission module calculates the optimal transmission path and optimal receiving direction of the transmitted signals, controls the projection angle and projection direction, and sends the regenerated navigation signals to the GNSS signal receiving device of the next node.

[0064] In an embodiment of the present application, the digital signal beamforming module is configured to perform digital beamforming on the navigation signal according to the tunnel curvature, slope and width, to generate multiple beam baseband signals, to change the weighting values, i.e. amplitude and phase, of the signals of the channels, to improve the directivity pattern, to direct the beam to the lane surface in the intended direction, to direct the zero signal to the direction where no interference is needed, and to suppress the multipath signals other than the intended direction.

[0065] In an embodiment of the present application, the differential power control module is configured to perform differential power control on the navigation signal of each level node, to control the use of different transmission power of the wireless signal by any level node according to the different link states between the nodes of each level, to control the beam in one of the directions between the nodes in the two adjacent level nodes in the tunnel, to form a personalized power control interval between the two level nodes, to reduce the mutual interference of the navigation signals of the two adjacent level nodes in the interval, to improve the navigation signal gain of the two adjacent level nodes, to compensate for the fading of the navigation signal, and to keep the signal coverage area in an environment where the navigation signal strength is higher than the threshold of the receivable signal strength.

[0066] In an embodiment of the present application, the GNSS signal receiving device comprises a receiver and a receiving antenna connected thereto, the receiving antenna is configured to receive the navigation signal transmitted by the satellite or the real-time regenerated navigation signal, and the receiver is configured to demodulate the navigation signal transmitted by the satellite or the real-time regenerated navigation signal.

[0067] In an embodiment of the present application, the signal transmission of the signal transmission module is performed by adjusting the direction and transmission angle of the signal transmission device, relying on air as the medium to transmit the navigation signal wave into the tunnel, to achieve full coverage of the satellite navigation signal in the tunnel; or through the optical fiber to the GNSS signal receiving device of the next level node.

[0068] Figure 2 is a three-differential control effect diagram of the signal controller 03;

[0069] The receiver uses Ublox NEO-M8T, which can be configured to output ephemeris information and 1PPS time signal, the ephemeris information is used to regenerate the satellite signal, and the 1PPS time signal is used for time synchronization.

[0070] The GNSS signal simulator first performs time synchronization using the time information provided by the GNSS signal receiving device, so that the entire system in the tunnel is in a time synchronization state, the time information is a 1PPS second pulse, the frequency of the crystal oscillator is corrected through the counting value of the externally input 1PPS second pulse, and the synchronized local 1PPS pulse is generated in the form of pulse. Secondly, the ephemeris data received is reprocessed, combined with the time delay control technology and the pre-set position coordinate data, and after internal real-time calculation of pseudo-range and other information, the corresponding navigation message is generated, and after modulation and D / A conversion, the satellite intermediate frequency signal is regenerated in real time.

[0071] In an embodiment of the present application, the tunnel positioning system adopts the optical fiber cascade signal node, solves the problems of complex equipment, difficult expansion and difficult maintenance; the GNSS signal receiving device can continuously, real-timely and accurately track and demodulate the navigation signal; the GNSS signal simulator realizes the real-time regeneration of the navigation signal in the tunnel; the digital signal beamforming module solves the problems of small coverage range, poor signal strength, strong interference of adjacent nodes and inconsistent signal arrival time on the lane caused by the tunnel environment, the differentiated power control module can reduce energy consumption, power compensation fading and interference, and the signal transmitting module controls the projection angle and direction, avoids the signal wall reaction and reduces the interference of the terminal processing signal.

[0072] Please refer to Figure 3 The tunnel positioning method provided by another embodiment of the present application includes the following steps: it should be noted that the tunnel positioning method of the present application is not limited to the flow order shown in the figure if there is substantially the same result. Figure 1

[0073] S101, the GNSS signal receiving device of the first level node in the cascade node arranged in the tunnel receives the navigation signal transmitted by the satellite, demodulates the received navigation signal transmitted by the satellite, extracts ephemeris data and time information, and transmits the ephemeris data and time information to the GNSS signal simulator of the first level node;

[0074] S102, the GNSS signal simulator receives the ephemeris data and time information, uses a time synchronization algorithm to perform frequency calibration on the time information, generates a local clock frequency, reprocesses the ephemeris data, combines a time delay control algorithm and preset position coordinate data, performs real-time regeneration on the navigation signal transmitted by the satellite, and synchronizes the real-time regenerated navigation signal to the signal controller of the first level node;

[0075] S103, the signal controller of the first level node performs beamforming on the real-time regenerated navigation signal, controls the transmission power, transmission angle and direction of the navigation signal, and sends the real-time regenerated navigation signal to the GNSS signal receiving device of the next level node.

[0076] In another embodiment of the present application, after the real-time regenerated navigation signal is sent to the GNSS signal receiving device of the next level node, the method further includes:

[0077] The GNSS signal receiving device of the second level node receives the real-time regenerated navigation signal transmitted by the signal controller of the first level node, repeats the operation steps of the first level node in the second level node, and outputs the navigation signal of the second level node;

[0078] ​The navigation signal of the nth level node is outputted repeatedly, and n is a natural number greater than or equal to 3.

[0079] In another embodiment of the present application, the signal controller performs beamforming on the real-time regenerated navigation signal, controls the transmission power of the navigation signal, and controls the transmission angle and direction of the navigation signal, and sends the real-time regenerated navigation signal to the GNSS signal receiving device of the next level node, specifically:

[0080] According to the tunnel environment, the beam of the real-time regenerated navigation signal after synchronization is directed to the lane surface in the expected direction, and the multipath signals other than the expected direction are suppressed;

[0081] A personalized power control interval is preset between adjacent two level nodes to control the transmission power of the real-time regenerated navigation signal, so that the navigation signal strength in the signal coverage area is higher than the threshold of receivable signal strength;

[0082] The optimal transmission path and optimal receiving direction of the transmitted signal are calculated to control the projection angle and projection direction to transmit the real-time regenerated navigation signal, and the navigation signal of the first level node is sent to the GNSS signal receiving device of the next level node.

[0083] In another embodiment of the present application, the beam of the real-time regenerated navigation signal after synchronization is directed to the lane surface in the expected direction according to the tunnel environment, and the multipath signals other than the expected direction are suppressed, specifically:

[0084] According to the tunnel curvature, slope and width, digital beamforming is adopted for the navigation signal to generate multiple beam baseband signals, change the weighting values of each channel signal, i.e. amplitude and phase, improve the directivity pattern, direct the beam to the lane surface in the expected direction, guide the zero signal to the direction that does not need to be interfered, and further suppress the multipath signals other than the expected direction; that is:

[0085] N beams are preset on the lane, and the number of beams is selected according to the node position and the tunnel structure, so as to obtain the main lobe direction alignment σ1, σ2, σ3, … σ N The spatial coordinates σ i of the i-th array element are σ i (σ xi ,σ yi ,σ zi ), and the weight vector is:

[0086]

[0087] The output signal after beamforming is:

[0088]

[0089] Where ω i (θi ,φ i ,σ i ω is the weight vector, r(t) = AS(t) + n(t), n(t) is the noise signal, S(t) is the useful signal, and r(t) represents the received signal; i * Represents the weight vector ω i Conjugate;

[0090] A i (θ i ,φ i ,σ i )=[p1(θ1,φ1,σ1)…p N (θ N ,φ N ,σ N [], i = 1, 2, 3…N is the direction matrix, and (θ, φ) represents σ N Beam characteristics of the location, desired response p i (θ i ,φ i ,σ i )for:

[0091] Where x, y, z represent the coordinate values ​​of the three directions of the σ coordinate, and λ represents the wavelength of the incident signal;

[0092] By multiplying and summing the weight vector and the direction matrix, and changing the values ​​of (θ,φ), beams with different directions and different gains can be obtained.

[0093] The gain of the expected navigation signal direction is maximized by using the linear constraint minimum variance (LCMV). After adjusting multiple (θ, φ) parameters, a set of data parameters with the best control effect is selected.

[0094] For example: simultaneously generating 6 independent beams in the directions of (0°, 30°), (30°, 0°), (60°, 90°), (90°, 60°), (120°, 150°), and (150°, 120°). Figure 4 This is a block diagram illustrating the principle of digital intermediate frequency signal beamforming. Figure 5 The normalized beam pattern obtained through simulation is shown in the tunnel. The half-power beamwidth is greater than 100°, which can basically cover the entire tunnel cross-section. The gain is large in the direction where the navigation terminal has strong receiving capability, which can meet the positioning requirements in the tunnel.

[0095] In another embodiment of this application, the step of pre-setting a personalized power control interval between two adjacent level nodes to control the transmission power of the navigation signal, so that the navigation signal strength in the signal coverage area is higher than the receivable signal strength threshold, specifically involves:

[0096] The navigation signals of each level node are subjected to differential power control, different transmission powers are used by any level node to transmit wireless signals according to the link state between each level node, the beam in one direction among the nodes is controlled between two adjacent level nodes in the tunnel, so that a personalized power control interval is formed between the two level nodes, the mutual interference of the navigation signals of the adjacent two level nodes is reduced in the interval, the navigation signal gain of the adjacent two level nodes is improved, the fading of the navigation signal is compensated, and the signal coverage area is always in an environment where the navigation signal strength is higher than the receivable signal strength threshold.

[0097] In another embodiment of the present application, the node power differential control of the navigation signals of each level node is specifically:

[0098] The loss Lc of the cable and the cable head and the beamforming gain Ga are calculated;

[0099] The spatial transmission attenuation Lbf of the radio signal transmitted by the signal transmission module of the signal controller to the lane surface is calculated as Lbf = 32.5 + 20lgF + 20lgD;

[0100] According to the signal reception sensitivity Rs of the signal controller, the signal reception strength RSS is determined as RSS = Pt + Gr - Lc - Lbf + Ga + Gt; wherein Pt is the transmission power, Gr is the reception antenna gain, and Gt is the transmission antenna gain;

[0101] According to the tunnel environment, the system margin SFM is determined as SFM = RSS - Rs;

[0102] According to the calculated system margin SFM, any level node transmits the navigation signal with different transmission powers.

[0103] In the tunnel environment, the noise and interference strength value is higher than 20-30 dB, and the link system margin is greater than 20-30 dB.

[0104] In another embodiment of the present application, the tunnel positioning method extracts ephemeris data and time information by demodulating the received navigation signal, uses time synchronization technology and time delay control technology to regenerate the navigation signal in real time, solves the problem of continuous positioning caused by inconsistent signals in the tunnel; through beamforming, the beam is directed to the desired lane surface, the useful signal is increased, the influence of the tunnel environment is avoided, the differential power control reduces the power compensation for fading and reduces interference; the projection angle and direction are controlled to reduce the probability of collision between regenerated signals of nodes, and the problem of terminal positioning confusion is solved.

[0105] Those skilled in the art can understand that all or part of the steps of various methods in the above embodiments can be completed by a program instructing relevant hardware, and the program can be stored in a computer readable storage medium, which can include Read Only Memory (ROM), Random Access Memory (RAM), a magnetic disk or an optical disk, etc.

[0106] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A tunnel positioning system, characterized by, The application relates to a tunnel navigation signal system. The application comprises: a plurality of cascade nodes arranged in a tunnel, each node comprising a GNSS signal receiving device, a GNSS signal simulator and a signal controller connected in sequence; the GNSS signal receiving device receives navigation signals transmitted by satellites at the tunnel entrance at the first node, receives real-time regenerated navigation signals of the GNSS signal simulator at the node outside the first node, demodulates the received navigation signals, extracts ephemeris data and time information and sends the ephemeris data and time information to the GNSS signal simulator; the GNSS signal simulator receives the ephemeris data and time information sent by the GNSS signal receiving device, performs frequency calibration by using a time synchronization algorithm, generates a local clock frequency, reprocesses the received ephemeris data, combines a time delay control algorithm and preset position coordinate data, performs real-time regeneration on the navigation signals and synchronizes the real-time regenerated navigation signals to the signal controller; the signal controller performs beamforming on the real-time regenerated navigation signals of the GNSS signal simulator, controls the transmission power of the navigation signals and controls the projection angle and projection direction of the navigation signals and sends the real-time regenerated navigation signals to the GNSS signal receiving device of the next node; the signal controller comprises a digital signal beamforming module, a differential power control module and a signal transmission module connected in sequence; the digital signal beamforming module is used for guiding the beam of the synchronized real-time regenerated navigation signals to the lane surface in the expected direction; the differential power control module presets a personalized power control interval between the adjacent two nodes, controls the transmission power of the navigation signals and makes the navigation signal strength in the signal coverage area higher than a receivable signal strength threshold; 2. The system of claim 1, wherein, the signal transmission module calculates the optimal transmission path and optimal receiving direction of the transmission signals, controls the projection angle and projection direction and sends the real-time regenerated navigation signals to the GNSS signal receiving device of the next node.

3. The system of claim 1, wherein, The digital signal beamforming module adopts digital beamforming on the navigation signals according to the bending degree, slope and width of the tunnel, generates a plurality of beam baseband signals, changes the weighting value, i.e. amplitude and phase, of each channel signal, improves the directional diagram, guides the beam to the lane surface in the expected direction, guides the zero signal to the direction without interference and suppresses the multipath signals except the expected direction.

4. A method of tunnel positioning, characterized by, The differential power control module performs differential power control on the navigation signals of each node, controls the use of different transmission powers of wireless signals by each node according to the different link states between the nodes, controls the beam in one direction in the nodes between the adjacent two nodes in the tunnel, forms a personalized power control interval between the two nodes, reduces the mutual interference of the navigation signals of the adjacent two nodes in the interval, improves the navigation signal gain of the adjacent two nodes, compensates the fading of the navigation signals and makes the signal coverage area always in the environment where the navigation signal strength is higher than the receivable signal strength threshold. The application relates to a tunnel navigation signal system. The application comprises: The GNSS signal receiving device of the first level node in the cascade nodes arranged in the tunnel receives the satellite transmitted navigation signal, demodulates the received satellite transmitted navigation signal, extracts ephemeris data and time information, and transmits to the GNSS signal simulator of the first level node; The GNSS signal simulator receives the ephemeris data and time information, uses a time synchronization algorithm to frequency calibrate the time information to generate a local clock frequency, reprocesses the ephemeris data, combines a time delay control algorithm and preset position coordinate data, and real-time regenerates the satellite transmitted navigation signal, and synchronizes the real-time regenerated navigation signal to the signal controller of the first level node; The signal controller of the first level node performs beamforming on the real-time regenerated navigation signal, controls the transmission power of the navigation signal, and controls the transmission angle and direction of the navigation signal, and sends the real-time regenerated navigation signal to the GNSS signal receiving device of the next level node; The signal controller performs beamforming on the real-time regenerated navigation signal, controls the transmission power of the navigation signal, and controls the transmission angle and direction of the navigation signal, and sends the real-time regenerated navigation signal to the GNSS signal receiving device of the next level node, specifically: According to the tunnel environment, the beam of the synchronized real-time regenerated navigation signal is directed to the lane surface of the expected direction, and the multipath signals other than the expected direction are suppressed; A personalized power control interval is preset between adjacent two level nodes to control the transmission power of the real-time regenerated navigation signal, so that the navigation signal strength in the signal coverage area is higher than the receivable signal strength threshold; The optimal transmission path and optimal receiving direction of the transmitted signal are calculated, the projection angle and projection direction are controlled to transmit the real-time regenerated navigation signal, and the navigation signal of the first level node is sent to the GNSS signal receiving device of the next level node.

5. The method of claim 4, wherein, After the real-time regenerated navigation signal is sent to the GNSS signal receiving device of the next level node, the following steps are further included: The GNSS signal receiving device of the second level node receives the real-time regenerated navigation signal transmitted by the signal controller of the first level node, and repeats the operation steps of the first level node at the second level node to output the navigation signal of the second level node; The navigation signal of the nth level node is outputted by repeating multiple times, and n is a natural number greater than or equal to three.

6. The method of claim 4, wherein, According to the tunnel environment, the beam of the synchronized navigation signal is directed to the lane surface of the expected direction, and the multipath signals other than the expected direction are suppressed, specifically: According to the tunnel curvature, slope and width, digital beamforming is used for the navigation signal to generate multiple beam baseband signals, the weighting values, i.e. amplitudes and phases, of the signals in each channel are changed, the directivity pattern is improved, the beam is directed to the lane surface of the expected direction, the zero signal is guided to the direction that does not need to be interfered, and the multipath signals other than the expected direction are further suppressed; That is: Pre-set N beams on the lane, the number of beams is selected according to the node position and the tunnel structure, in order to obtain the main lobe direction alignment The spatial coordinates of the ith array element For The weight vector is: ； The output signal after beamforming is: ； wherein is a weight vector, , is a noise signal, is a useful signal, denotes a received signal; represents a conjugate of the weight vector . for a direction matrix, representing a position of a beam feature, a desired response is: ； wherein N is a positive integer, x, y, z represent coordinate values of three directions of the coordinates, denotes the wavelength of the incident signal; The weight vector and the direction matrix are multiplied and summed to change the value of obtaining beams with different directions and different gains. The linear constrained minimum variance (LCMV) is used to maximize the gain of the expected navigation signal direction, and a set of data parameters with the best control effect is selected through the adjustment of multiple parameters. parameters.

7. The method of claim 4, wherein, The personalized power control interval is preset between adjacent two level nodes to control the transmission power of the navigation signal, so that the navigation signal strength in the signal coverage area is higher than the receivable signal strength threshold, specifically: The navigation signals of each level node are subjected to differentiated power control, different transmission powers are used by any level node to transmit wireless signals according to the link state between each level node, the beam in one direction among the nodes is controlled between the two adjacent level nodes in the tunnel, a personalized power control interval is formed between the two level nodes, the mutual interference of the navigation signals of the two adjacent level nodes is reduced, the navigation signal gain of the two adjacent level nodes is improved, the fading of the navigation signal is compensated, and the signal coverage area is always in an environment where the navigation signal strength is higher than the receivable signal strength threshold.

8. The method of claim 7, wherein, The node power differentiated control of the navigation signals of each level node is specifically: The loss Lc of the cable and the cable head and the beamforming gain Ga are calculated; The spatial transmission attenuation of the radio signal transmitted by the signal transmission module of the signal controller to the lane surface is calculated; According to the signal controller receiving sensitivity Rs, the signal receiving strength RSS=Pt+Gr-Lc-Lbf+Ga+Gt is determined; wherein, Pt is the transmission power, Gr is the receiving antenna gain, Lbf is the spatial transmission attenuation, and Gt is the transmission antenna gain; According to the tunnel environment, the system margin SFM=RSS-Rs is determined; According to the calculated system margin SFM, any level node transmits the navigation signal with different transmission powers.

Images