JP2011141241A - Gnss receiving device and positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve positioning accuracy by reducing an influence of multipath. <P>SOLUTION: A GNSS (Global Navigation Satellite System) receiving device includes: a first delay synchronous loop circuit for generating a replica signal of a C/A code, and synchronizing the replica signal of the C/A code with a positioning signal from a GNSS satellite, to thereby determine a phase of the C/A code; a second delay synchronous loop circuit for generating a replica signal of a P code, and synchronizing the replica signal of the P code with the positioning signal from the GNSS satellite, to thereby determine a phase of the P code; a weighting setting part for setting weighting to a pseudo distance acquired by the phase of the C/A code based on moving speed of the GNSS receiving device; a pseudo distance operation part for determining the pseudo distance based on weighting, the phase of the C/A code determined by the first delay synchronous loop circuit, and the phase of the P code determined by the second delay synchronous loop circuit; and a positioning operation part for positioning based on the pseudo distance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a GNSS receiver and a positioning method for receiving and positioning a signal from a GNSS orbiting satellite.

  The Global Navigation Satellite System (GNSS) is a system that obtains the distance from each GNSS satellite by capturing three navigation satellites (GNSS orbiting satellites) (hereinafter referred to as GNSS satellites) from the aircraft. It is a navigation system that can obtain the flight position in three dimensions of the aircraft by adjusting the time with the signal from the eye navigation satellite. Satellite navigation includes the Global Positioning System (GPS), Galileo, and others.

  For example, the GNSS receiver is mounted on a moving body and measures the position and speed of the moving body. For example, the GNSS receiver receives radio waves from a plurality of GNSS satellites, calculates the distances (pseudo distances) from the plurality of GNSS satellites to the GNSS receiver, and receives the GNSS reception based on the pseudo distances. Measures the moving object equipped with the device. The signal emitted by the GNSS satellite arrives at the GNSS receiver with a delay in the distance between the GNSS satellite and the GNSS receiver by the time the radio wave propagates. Therefore, if the time required for radio wave propagation is obtained for a plurality of GNSS satellites, the position of the GNSS receiver can be obtained by positioning calculation. For example, for radio waves emitted by a plurality of GNSS satellites, the distance from each GNSS satellite to the GNSS receiver is determined by the distance measuring unit of the GNSS receiver. Then, the positioning calculation unit obtains the position of the GNSS receiver based on the distance obtained by the ranging unit.

  In order to measure the exact position of a mobile unit equipped with a GNSS receiver, it is sufficient to capture at least four GNSS satellites. For example, in the suburbs, there are few objects blocking the radio wave path, so it is easy to capture four or more GNSS satellites with a mobile object. On the other hand, in urban areas, high-rise buildings and other buildings are densely populated, and there are many objects that block radio wave paths, so it is difficult to capture four or more GNSS satellites with a mobile object. In urban areas, even when a GNSS satellite can be captured, not only a direct wave from the GNSS satellite but also a radio wave reflected and diffracted by a building such as a high-rise building may be received. The phenomenon in which radio waves transmitted from GNSS satellites are reflected and diffracted and received from multiple propagation paths is also called multipath. Due to the multipath effect, an error occurs in ranging between the receiving antenna and the GNSS satellite.

JP 2000-266836

  As a method for reducing the positioning error due to multipath, it has been proposed to reduce the bandwidth of a delay-locked loop (DLL). A GPS receiver receives a pseudo-noise code (PN (pseudo-noise) Sequence) transmitted by a GPS satellite, and obtains a correlation between the pseudo-noise code and a local pseudo-noise code generated by the GPS receiver. Synchronize. A delay locked loop is employed to achieve the synchronization.

  FIG. 1 shows an example of a GPS receiver. FIG. 1 mainly shows a delay locked loop circuit.

  The GPS receiver converts a high frequency signal transmitted from a GPS satellite and outputs an intermediate frequency signal, and a C / A code phase based on the intermediate frequency signal output by the high frequency circuit 1. A delay locked loop circuit 10 to be obtained and a distance calculating unit 7 for calculating a satellite distance based on the C / A code phase output from the delay locked loop circuit 10 are provided.

  The intermediate frequency signal input by the high frequency circuit 1 is input to the multiplier 2. The multiplier 2 multiplies the intermediate frequency signal by the C / A code input from the C / A code generator 6 to remove the C / A code from the intermediate frequency signal. The intermediate frequency signal from which the C / A code has been removed is input to the integrator 3. The integrator 3 integrates the intermediate frequency signal (code residual) from which the C / A code has been removed. The residual integrated value (C / A code phase) is input to an LPF (Low-pass filter) 4 and a distance calculation unit 7. LPF4 filters the C / A code phase and outputs a phase residual. The bandwidth filtered by the LPF 4 is controlled based on the vehicle speed. The phase residual output by the LPF 4 is input to the numerically controlled oscillator 5. The numerically controlled oscillator 5 converts the phase residual into a frequency residual and outputs the frequency residual. The frequency residual is applied to the C / A code generator 6. The C / A code generator 6 adjusts the oscillation period based on the frequency residual applied by the numerically controlled oscillator 5. On the other hand, the distance calculation unit 7 calculates a pseudo distance from the C / A code phase input by the integrator 3.

  It is known that the following relationship holds between the fluctuation period (fading bandwidth) Bf of the reflected wave of a radio wave from a GPS satellite, the loop bandwidth B1 of the DLL, and the positioning error due to multipath. . When Bf / B1 is large, no positioning error occurs, and when Bf / B1 is small, a positioning error occurs. Bf is proportional to the moving speed of the GPS receiver. Therefore, since a positioning error occurs when the moving speed of the GPS receiver is low, the positioning error can be reduced by narrowing the DLL loop bandwidth B1.

  However, when the moving speed of the GPS receiver becomes lower than a predetermined speed, it is difficult to set the loop bandwidth B1 of the DLL below a predetermined limit according to the moving speed. Specifically, when the loop bandwidth is 2 MHz or less, the bandwidth is less than the bandwidth capable of demodulating the C / A code. Below the bandwidth that can demodulate the C / A code, the signal from the GPS satellite cannot be decoded. The bandwidth capable of demodulating the C / A code may be the Nyquist frequency of the modulation band of the C / A code. Since it is difficult to make the loop bandwidth less than the bandwidth that can demodulate the C / A code, the moving speed of the GPS receiver is slower than the predetermined speed that makes the bandwidth that can demodulate the C / A code. In this case, the DLL loop bandwidth B1 is set to a bandwidth capable of demodulating the C / A code.

  However, if you continue to set the loop bandwidth B1 of the DLL to a bandwidth that can demodulate the C / A code even when the GPS receiver's moving speed becomes even slower, the positioning error due to multipath will vary depending on the moving speed. It cannot be reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a GNSS receiver and a positioning method that can reduce the influence of multipath and improve positioning accuracy.

This GNSS receiver
A GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first delay locked loop circuit that generates a C / A code replica signal and obtains the phase of the C / A code by synchronizing the C / A code replica signal with the positioning signal from the GNSS satellite. When,
A second delay locked loop circuit for generating a P code replica signal, and obtaining a phase of the P code by synchronizing the P code replica signal with the positioning signal from the GNSS satellite;
Based on the moving speed of the GNSS receiver, a weight setting unit that sets a weight for the pseudorange obtained by the phase of the C / A code;
Based on the weight set by the weight setting unit, the phase of the C / A code determined by the first delay locked loop circuit, and the phase of the P code determined by the second delay locked loop circuit , A pseudo distance calculation unit for obtaining a pseudo distance;
A positioning calculation unit that performs positioning based on the pseudo distance obtained by the pseudo distance calculation unit.

This method
A method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
Generating a C / A code replica signal;
Obtaining the phase of the C / A code by synchronizing the replica signal of the C / A code and the positioning signal from the GNSS satellite;
Generating a P-code replica signal; and
Obtaining the phase of the P code by synchronizing the replica signal of the P code and the positioning signal from the GNSS satellite;
Based on the moving speed of the GNSS receiver, a weight setting step for setting a weight for the pseudorange obtained by the phase of the C / A code;
The weight set in the weight setting step, the phase of the C / A code obtained by the step of obtaining the phase of the C / A code, and the phase of the P code obtained by the step of obtaining the phase of the P code. A pseudo-range calculation step for obtaining a pseudo-range based on:
A positioning calculation step for performing positioning based on the pseudo distance obtained by the positioning calculation step.

  According to the disclosed GNSS receiver and positioning method, it is possible to reduce the influence of multipath and improve positioning accuracy.

It is an example of the functional block diagram of a GNSS receiver. It is a functional block diagram of a GNSS receiver according to an embodiment. It is a functional block diagram which shows the smoothing process part in the GNSS receiver according to one Example. It is explanatory drawing which shows the example of a setting of the weighting coefficient in the GNSS receiver according to one Example. It is a flowchart which shows operation | movement of the GNSS receiver according to one Example. It is a functional block diagram of a GNSS receiver according to an embodiment. It is explanatory drawing which shows the fluctuation | variation of the C / A code phase with respect to time when the speeds of vehicles differ. It is explanatory drawing which shows the example of a setting of the loop bandwidth of DLL in the GNSS receiver according to one Example. It is a flowchart which shows operation | movement of the GNSS receiver according to one Example. It is a functional block diagram which shows the P code phase distance estimation part in the GNSS receiver according to one Example. It is a flowchart which shows operation | movement of the GNSS receiver according to one Example.

Next, the best mode for carrying out the present invention will be described based on the following embodiments with reference to the drawings.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

<First embodiment>
<System>
A global navigation satellite system (GNSS) according to this embodiment includes a GNSS satellite that orbits the earth and a GNSS receiver 100 that is located on the earth and can move on the earth. In this embodiment, GPS will be described as an example of GNSS. You may apply to GNSS other than GPS.

  GNSS satellites always broadcast navigation messages (satellite signals) to the earth. The navigation message includes satellite orbit information (ephemeris and almanac) for the corresponding GNSS satellite, clock correction values, and ionospheric correction coefficients. The navigation message is spread by the C / A code, placed on the L1 band carrier (frequency: 1575.42 MHz), and constantly broadcast toward the earth. In addition, the navigation message is spread by the P code, and is always broadcast to the earth on the L2 band carrier (frequency: 1227.6 MHz).

  The L1 band carrier wave is a combined wave of a sine wave modulated with a C / A code and a Cos wave modulated with a P code (Precision Code), and is orthogonally modulated. The L2 band carrier wave is a Cos wave modulated with a P code and is orthogonally modulated. The C / A code and the P code are pseudo noise codes, and are code strings in which -1 and 1 are arranged irregularly and periodically.

  Currently, about 30 GNSS satellites orbit the earth at an altitude of about 20,000 km, and there are six orbiting planes inclined by 55 degrees, each with four or more GNSS satellites. Are evenly arranged. Therefore, at least 5 or more GNSS satellites can be observed at any time anywhere on the earth as long as the sky is open.

<GNSS receiver>
The GNSS receiver 100 is mounted on a mobile object, for example. The mobile body includes a vehicle, a motorcycle, a train, a ship, an aircraft, a robot, and the like, and an information terminal such as a portable terminal that moves as a person moves. In the present embodiment, a case where it is mounted on a vehicle will be described as an example of a moving body.

  The GNSS receiver 100 synchronizes with a delay synchronization circuit (hereinafter referred to as a “DLL (L1-C / A) circuit”) that synchronizes with an L1 band C / A code and an L1 band P code. A delay synchronization circuit (hereinafter referred to as `` DLL (L1-P) circuit '') and a delay synchronization circuit (hereinafter referred to as `` DLL (L2-P) circuit '') that synchronizes with the P code in the L2 band; Have

  The GNSS receiver 100 includes a C / A code phase calculated by a DLL (L1-C / A) circuit, and a P code phase calculated by a DLL (L1-P) circuit and a DLL (L2-P) circuit. The smoothing process is performed using In the smoothing process, a pseudo distance calculated based on the C / A code phase (hereinafter referred to as “C / A code phase distance”) and a pseudo distance calculated based on the P code phase (hereinafter referred to as “ (Referred to as “P code phase distance”), and both pseudo distances are smoothed, in other words, moving averaged. The weighting is performed so that the distribution (weighting) of the P code phase increases as the vehicle speed decreases (so that the distribution of the C / A code phase decreases), and the C / A code phase increases as the vehicle speed increases. The distribution is set to be large (so that the distribution (weighting) of the P code phase is small).

  P-codes are often used to reduce ionospheric errors and the like. In the present GNSS receiver 100, a P code is used in order to reduce errors due to multipath. Positioning accuracy can be improved simply by receiving a P code and performing positioning based on the P code. However, the P code is hidden by the military code and cannot be used normally. Therefore, decoding is performed by a technique such as cross-correlation, but the P code decoded by such a technique has a weak signal strength as a side effect. Since the signal strength is weak, whether the P code can be used for positioning depends on the radio wave environment. Therefore, when the vehicle speed is high, fluctuations in the radio wave environment increase, and it is not preferable to perform positioning based on the P code. Accordingly, the higher the speed, the larger the C / A code phase distribution is set. On the other hand, since the radio wave environment is stable when the vehicle speed is low, it is preferable to perform positioning based on the P code. Also, the slower the vehicle speed, the greater the error in the C / A code phase under multipath. Therefore, the lower the speed, the larger the P code phase distribution is set.

  When the vehicle speed is lower than a predetermined speed, the smoothing process is performed using only the P code phase. For example, the weighting is set so that the smoothing process is performed using only the P code phase. For example, the predetermined speed may be a speed that provides a bandwidth capable of demodulating the C / A code. The bandwidth capable of demodulating the C / A code may be the Nyquist frequency of the modulation band of the C / A code. Hereinafter, the predetermined speed is referred to as “speed A”. By performing smoothing processing using only the P code phase when the vehicle speed is lower than the speed A, the influence of multipath is reduced even when the vehicle speed is lower than the speed A. The satellite pseudorange can be obtained.

  FIG. 2 shows an example of a GNSS receiver according to the present embodiment.

  The GNSS receiver 100 includes a high frequency circuit 102. The high frequency circuit 102 converts radio waves from the GNSS satellite received by the antenna into baseband signals. The baseband signal is input to the multiplier 104.

  The GNSS receiver 100 includes a multiplier 104. The multiplier 104 is connected to the high frequency circuit 102. The multiplier 104 multiplies the baseband signal input by the high-frequency circuit 102 and the replica signal of the carrier wave (L1 band), and removes the carrier wave (L1 band). The baseband signal from which the carrier wave has been removed is input to a delay locked loop (DLL (L1-C / A)) circuit 106.

  The GNSS receiver 100 includes a DLL (L1-C / A) circuit 106. The DLL (L1-C / A) circuit 106 is connected to the multiplier 104. The DLL (L1-C / A) circuit 106 removes the C / A code from the signal input by the multiplier 104. The DLL (L1-C / A) circuit 106 performs C / A code synchronization by shifting the phase of the C / A code replica signal with respect to the L1 band C / A code. The C / A code synchronization is to synchronize the phase of the C / A code replica signal with the phase of the received C / A code. The C / A code replica signal is a code in which the sequences of +1 and −1 are the same as the C / A code put on the satellite signal from the GNSS satellite. The C / A code has a 1-bit length of 1 μs, and a length corresponding to 1 bit is about 300 m. The C / A code phase and the navigation message are obtained by removing the C / A code from the signal input to the DLL (L1-C / A) circuit 106. The DLL (L1-C / A) circuit 106 inputs the C / A code phase to the smoothing processing unit 108. Details of the DLL (L1-C / A) circuit 106 will be described later.

  The GNSS receiver 100 includes a multiplier 112. The multiplier 112 is connected to the high frequency circuit 102. The multiplier 112 multiplies the baseband signal input by the high-frequency circuit 102 and the replica signal of the carrier wave (L1 band), and removes the carrier wave (L1 band). The baseband signal from which the carrier wave has been removed is input to a delay locked loop (DLL (L1-P)) circuit 114.

  The GNSS receiver 100 includes a DLL (L1-P) circuit 114. The DLL (L1-P) circuit 114 is connected to the multiplier 112. The DLL (L1-P) circuit 114 acquires the P code phase. The P code is concealed by the W code, which is a military code. The P code concealed by the W code is called a Y code. In order to acquire the P code phase, it is necessary to acquire the P code phase by a method such as using two frequency bands of the L1 band and the L2 band. In the present embodiment, as an example of a method for acquiring a P code, a method using two frequency bands of the L1 band and the L2 band is shown. The P code phase may be acquired by other methods.

  The DLL (L1-P) circuit 114 obtains a correlation value between the signal input by the multiplier 112 and the P-code replica signal. The DLL (L1-P) circuit 114 performs P code synchronization by shifting the phase of the P code replica signal with respect to the L1 band P code. The initial phase of the P code replica signal is notified by the C / A code generator 1070 of the DLL (L1-C / A) circuit 106. The P code synchronization is to synchronize the phase of the P code replica signal with the phase of the received P code. The DLL (L1-P) circuit 114 accumulates the correlation values. At the stage where the correlation values are accumulated, the P code is concealed by the W code. The P code phase is obtained by removing the W code from the signal obtained by integrating the correlation values. Details of the DLL (L1-P) circuit 114 will be described later.

  The GNSS receiver 100 includes a high frequency circuit 116. The high frequency circuit 116 converts radio waves from the GNSS satellite received by the antenna into baseband signals. The baseband signal is input to the multiplier 118.

  The GNSS receiver 100 includes a multiplier 118. The multiplier 118 is connected to the high frequency circuit 116. The multiplier 118 multiplies the baseband signal input by the high-frequency circuit 116 and the replica signal of the carrier wave (L2 band), and removes the carrier wave (L2 band). The baseband signal from which the carrier wave has been removed is input to a delay locked loop (DLL (L2-P)) circuit 120.

  The GNSS receiver 100 has a DLL (L2-P) circuit 120. The DLL (L2-P) circuit 120 is connected to the multiplier 118. The DLL (L2-P) circuit 120 acquires the P code phase. The DLL (L2-P) circuit 120 obtains a correlation value between the signal input by the multiplier 118 and the P-code replica signal. The DLL (L2-P) circuit 120 performs P code synchronization by shifting the phase of the P code replica signal with respect to the L2 band P code. The initial phase of the P code replica signal is notified by the C / A code generator 1070 of the DLL (L1-C / A) circuit 106. The P code synchronization is to synchronize the phase of the P code replica signal with the phase of the received P code. The DLL (L2-P) circuit 120 integrates the correlation values. At the stage where the correlation values are accumulated, the P code is concealed by the W code. The P code phase is obtained by removing the W code from the signal obtained by integrating the correlation values. Details of the DLL (L2-P) circuit 120 will be described later.

<DLL (L1-C / A) circuit>
The DLL (L1-C / A) circuit 106 will be described in detail.

  The DLL (L1-C / A) circuit 106 includes a multiplier 1062, an integrator 1064, an LPF 1066, a numerically controlled oscillator 1068, and a C / A code generator 1070. Multiplier 1062, integrator 1064, LPF 1066, numerically controlled oscillator 1068, and C / A code generator 1070 perform processing on EARLY, LATE, and PROMPT. One or two of EARLY, LATE, and PROMPT may be processed, or four or more may be processed.

  Multiplier 1062 is connected to multiplier 104. The multiplier 1062 multiplies the signal input from the multiplier 104 by the C / A code replica signal input from the C / A code generator 1070 to remove the C / A code. The signal from which the C / A code has been removed by the multiplier 1062 is input to the integrator 1064.

  The integrator 1064 is connected to the multiplier 1062. The integrator 1064 integrates the signal (code residual) from which the C / A code has been removed by the multiplier 1062. The integrator 1064 inputs an integrated value (C / A code phase) of a residual to an LPF (Low-pass filter) 1066 and a smoothing processing unit 108.

  The LPF 1066 is connected to the integrator 1064. The LPF 1066 filters the C / A code phase input by the integrator 1064 and outputs a phase residual. For example, the C / A code phase that fluctuates due to the phase change of the reflected wave due to multipath is filtered. Multipath errors can be reduced by filtering the C / A code phase. The phase residual output by the LPF 1066 is input to the numerically controlled oscillator 1068.

  The numerically controlled oscillator 1068 is connected to the LPF 1066. The numerically controlled oscillator 1068 converts the phase residual input by the LPF 1066 into a frequency residual. The numerically controlled oscillator 1068 inputs the frequency residual to the C / A code generator 1070. In other words, the frequency residual is applied to the C / A code generator 1070.

  The C / A code generator 1070 is connected to the numerically controlled oscillator 1068. The C / A code generator 1070 adjusts the oscillation period based on the frequency residual applied by the numerically controlled oscillator 1068 and generates a C / A code replica signal. The C / A code generator 1070 inputs the C / A code replica signal to the multiplier 1062. The C / A code generator 1070 calculates the C / A code phase by the DLL (L1-C / A) circuit 106 and then inputs the C / A code phase to the DLL (L1-P) circuit 114. .

<DLL (L1-P) circuit>
The DLL (L1-P) circuit 114 will be described in detail.

  The DLL (L1-P) circuit 114 includes a multiplier 1142, an integrator 1144, a W code removal unit 1146, an LPF 1148, a numerically controlled oscillator 1150, and a P code generator 1152. The multiplier 1142, the integrator 1144, the W code removal unit 1146, the LPF 1148, the numerically controlled oscillator 1150, and the P code generator 1152 perform processing on EARLY, LATE, and PROMPT. Among EARLY, LATE, and PROMPT, processing may be performed for 1 or 2, or processing may be performed for four or more.

  The multiplier 1142 is connected to the multiplier 112. Multiplier 1142 multiplies the signal input from multiplier 112 by the P-code replica signal input from P-code generator 1152, and removes the P-code. The signal from which the P code has been removed by the multiplier 1142 is input to the integrator 1144.

  The integrator 1144 is connected to the multiplier 1142. The integrator 1144 integrates the signal (code residual) from which the P code has been removed by the multiplier 1142. The integrator 1144 inputs the residual integrated value to the W code removal unit 1146 and the DLL (L2-P) circuit 120. At this stage, the P code is concealed by the W code.

  W code removal unit 1146 is connected to integrator 1144. The W code removal unit 1146 removes the W code by canceling each other based on the P code phase input by the integrator 1144 and the P code phase input by the DLL (L2-P) circuit 120. The P code phase from which the W code has been removed by the W code removal unit 1146 is input to the smoothing processing unit 108 and also input to the LPF 1148.

  The LPF 1148 is connected to the W code removal unit 1146. The LPF 1148 filters the P code phase input by the W code removal unit 1146 and outputs a phase residual. The phase residual output by the LPF 1148 is input to the numerically controlled oscillator 1150.

  The numerically controlled oscillator 1150 is connected to the LPF 1148. The numerically controlled oscillator 1150 converts the phase residual input by the LPF 1148 into a frequency residual. The numerically controlled oscillator 1150 inputs the frequency residual to the P code generator 1152. In other words, the frequency residual is applied to the P code generator 1152.

  P code generator 1152 is connected to C / A code generator 1070, numerically controlled oscillator 1150, and multiplier 1142. Information indicating the C / A code phase is input to the P code generator 1152 from the C / A code generator 1070. The P code generator 1152 sets the initial phase of the P code based on the information indicating the C / A code phase. After setting the initial phase of the P code, the P code generator 1152 adjusts the oscillation period based on the frequency residual applied by the numerically controlled oscillator 1150 and generates a P code replica signal. The P code generator 1152 inputs the P code replica signal to the multiplier 1142.

<DLL (L2-P) circuit>
The DLL (L2-P) circuit 120 will be described in detail.

  The DLL (L2-P) circuit 120 includes a multiplier 1202, an integrator 1204, and a W code removal unit 1206. Multiplier 1202, integrator 1204, and W code removal section 1206 perform processing on EARLY, LATE, and PROMPT. Among EARLY, LATE, and PROMPT, processing may be performed for 1 or 2, or processing may be performed for four or more.

  Multiplier 1202 is connected to multiplier 118 and P code generator 1152. Multiplier 1202 multiplies the signal input from multiplier 118 by the P-code replica signal input from P-code generator 1152, and removes the P-code. The signal from which the P code has been removed by the multiplier 1202 is input to the integrator 1204.

  The integrator 1204 is connected to the multiplier 1202. The integrator 1204 integrates the signal from which the P code is removed by the multiplier 1202 (code residual). The integrator 1204 inputs the accumulated residual value to the W code removal unit 1206 and the W code removal unit 1146 of the DLL (L1-P) circuit 114. At this stage, the P code is concealed by the W code.

  W code removal unit 1206 is connected to integrator 1204. The W code removal unit 1206 removes the W code by canceling each other based on the P code phase input by the integrator 1204 and the P code phase input by the DLL (L1-P) circuit 114. The P code phase from which the W code has been removed by the W code removal unit 1206 is input to the smoothing processing unit 108 and also input to the LPF 1148.

  LPF 1148 is connected to W code removal section 1206. The LPF 1148 filters the P code phase input by the W code removal unit 1206 and outputs a phase residual. The phase residual output by the LPF 1148 is input to the numerically controlled oscillator 1150.

  The numerically controlled oscillator 1150 converts the phase residual input by the LPF 1148 into a frequency residual. The numerically controlled oscillator 1150 inputs the frequency residual to the P code generator 1152. In other words, the frequency residual is applied to the P code generator 1152.

  The P code generator 1152 receives information indicating the C / A code phase from the C / A code generator 1070. The P code generator 1152 sets the initial phase of the P code based on the information indicating the C / A code phase. After setting the initial phase of the P code, the P code generator 1152 adjusts the oscillation period based on the frequency residual applied by the numerically controlled oscillator 1150 and generates a P code replica signal. The P code generator 1152 inputs a P code replica signal to the multipliers 1142 and 1202.

<Smoothing processing unit>
The GNSS receiver 100 includes a smoothing processing unit 108. The smoothing processing unit 108 is connected to the integrator 1064 and the W code removal units 1146 and 1206. The smoothing processing unit 108 obtains a pseudorange based on the C / A code phase input by the DLL (L1-C / A) 106, and obtains the DLL (L1-P) 114 and / or DLL (L2-P) 120. The pseudo distance is obtained based on the P code phase inputted by the above and a smoothing process is performed by weighting both pseudo distances.

  FIG. 3 shows details of the smoothing processing unit 108.

  The smoothing processing unit 108 includes a weight coefficient setting unit 1082 and a satellite pseudorange calculation unit 1084.

  The weighting factor setting unit 1082 sets the weighting factor M when performing the smoothing process. The weighting factor M may be set to zero immediately after capturing the satellite, gradually increase with time, and fixed when reaching a certain value. You may make it change the maximum value of this weighting coefficient with the speed of a vehicle. The weighting factor M may be for the pseudorange obtained by the C / A code phase. This is because if the weight for the pseudo distance obtained by the C / A code phase is set, the weight for the pseudo distance obtained by the P code phase is also uniquely set. Conversely, the weighting factor M may be for the pseudorange obtained by the P code phase. This is because if the weight for the pseudo distance obtained by the P code phase is set, the weight for the pseudo distance obtained by the C / A code phase is also uniquely set. For example, the sum of the weighting for the pseudorange obtained by the P code phase and the weighting for the pseudorange obtained by the C / A code phase may be 1.

  FIG. 4 shows an example of the maximum value of the weighting factor M set by the weighting factor setting unit 1082. The weighting factor setting unit 1082 increases the maximum value of the weighting factor of the carrier phase as the speed decreases. The weighting factor setting unit 1082 sets the maximum value of the weighting factor to infinity when the vehicle speed is equal to or lower than the speed A.

  The speed A may be set based on the speed of the vehicle and the orbit information of the GNSS satellite. The speed A information may be included in the GNSS receiver 100 as map information, or may be calculated based on orbit information received from a GNSS satellite in the GNSS receiver 100. Further, the speed A may be set to a constant value in advance.

  The satellite pseudorange calculation unit 1084 is connected to the weight coefficient setting unit 1082. The satellite pseudorange calculation unit 1084 receives the C / A code phase from the delay locked loop circuit 106, receives the weighting factor M from the weighting factor setting unit 1082, and receives the DLL (L1-P) circuit 114 and the DLL (L2-L2). P) The P code phase is input by the circuit 120.

The satellite pseudorange calculation unit 1084 obtains a pseudorange based on the C / A code phase input by the DLL (L1-C / A) circuit 106. The pseudorange is referred to as C / A code phase distance ρ ₁ (t _i ). The subscript “i” indicates an epoch. In general, the pseudorange ρ can be obtained as ρ = N × 300 when the GNSS satellite receives the Nth bit of the C / A code on the assumption that the C / A code is the 0th bit. . That is, the pseudorange ρ can be calculated by measuring the difference between the code phase time of the GNSS satellite of the received C / A code and the time of the GNSS receiver. The satellite pseudorange calculation unit 1084 obtains a pseudorange based on the input P code phase. The pseudorange is referred to as P code phase distance ρ ₂ (t _i ). The subscript “i” indicates an epoch. The pseudorange ρ can be obtained as ρ = N × 300 when the GNSS satellite is receiving the Nth bit of the P code assuming that the P code is the 0th bit. That is, the pseudorange ρ can be calculated by measuring the difference between the code phase time of the received GNSS satellite of the P code and the time of the GNSS receiver.

The satellite pseudorange calculation unit 1084 obtains the satellite pseudorange based on the C / A code phase distance ρ ₁ (t _i ), the P code phase distance ρ ₂ (t _i ), and the weighting factor M. For example, the satellite pseudorange calculation unit 1084 obtains the satellite pseudorange by Equation (1).

衛星擬似距離演算部１０８４は、衛星擬似距離を測位演算部１１０に入力する。

The satellite pseudorange calculation unit 1084 inputs the satellite pseudorange to the positioning calculation unit 110.

  The GNSS receiver 100 includes a positioning calculation unit 110. The positioning calculation unit 110 is connected to the smoothing processing unit 108. The positioning calculation unit 110 calculates the current position of the GNSS satellite in the world coordinate system based on the satellite orbit information included in the navigation message. Since the GNSS satellite is one of artificial satellites, its movement is limited to a certain plane (orbital plane) including the center of gravity of the earth. The orbit of the GNSS satellite is an elliptical motion with the earth's center of gravity as one focal point, and the position of the GNSS satellite on the orbital plane can be calculated by sequentially calculating the Kepler equation. In addition, the position of the GNSS satellite shall be converted to a three-dimensional rotational coordinate from the position of the GNSS satellite on the orbital plane in consideration of the rotational relationship between the orbital plane of the GNSS satellite and the equatorial plane of the world coordinate system. It is obtained with. The world coordinate system is defined by an X axis and a Y axis that are orthogonal to each other within the equator plane, and a Z axis that is orthogonal to both axes with the center of gravity of the earth as the origin.

  The positioning calculation unit 110 measures the position of the GNSS receiver 100 based on the calculation result of the satellite position and the calculation result of the satellite pseudorange input by the smoothing processing unit 108. The position of the GNSS receiver 100 may be derived on the principle of triangulation using the respective satellite pseudoranges and satellite positions obtained for the three GNSS satellites 100. In this case, since the satellite pseudorange includes a clock error, the clock error component is removed using the satellite pseudorange and the satellite position obtained for the fourth GNSS satellite. The positioning calculation unit 110 outputs the (current) position.

  The positioning method of the position of the GNSS satellite is not limited to such independent positioning, but may be interference positioning (a method in which received data at a fixed station installed at a known point is used in combination). In the case of interference positioning, the position of the GNSS receiver 100 is measured using a single phase difference, a double phase difference, or the like of pseudoranges obtained by the fixed station and the GNSS receiver 100, respectively.

<Operation of this GNSS receiver>
FIG. 5 is a flowchart showing the operation of the GNSS receiver 100.

  The GNSS receiver 100 obtains the C / A code phase (step S502). For example, the DLL (L1-C / A) circuit 106 obtains the C / A code phase by synchronizing the positioning signal from the GNSS satellite with the C / A code replica signal.

  The GNSS receiver 100 obtains the P code phase (step S504). For example, the DLL (L1-P) circuit 114 has a P code phase concealed by the W code by synchronizing a signal obtained by removing the L1 band carrier from the positioning signal from the GNSS satellite and a replica signal of the P code. Ask for. Here, the initial phase of the P code is input by the DLL (L1-C / A) circuit 106. The DLL (L2-P) circuit 120 obtains the P code phase concealed by the W code by synchronizing the signal obtained by removing the L2 band carrier from the positioning signal from the GNSS satellite and the P code replica signal. . The DLL (L1-P) circuit 114 cancels the P code phase obtained by the DLL (L1-P) circuit 114 and the P code phase obtained by the DLL (L2-P) circuit 120 by canceling each other. Remove code and determine P-code phase. The DLL (L2-P) circuit 120 cancels the P code phase obtained by the DLL (L2-P) circuit 120 and the P code phase obtained by the DLL (L1-P) circuit 114 by canceling each other. Remove code and determine P-code phase.

  The GNSS receiver 100 sets a weighting factor for the pseudorange obtained from the C / A code phase based on the vehicle speed (step S506). For example, the weighting factor setting unit 1082 obtains a weighting factor for the pseudo distance obtained from the C / A code phase input by the DLL (L1-C / A) 106.

The GNSS receiver 100 obtains the pseudo distance between the GNSS satellite and the GNSS receiver 100 (step S508). For example, the smoothing processing unit 108 determines the C / A code phase distance ρ ₁ (t _i ) and the P code phase distance ρ based on the weighting factor for the pseudo distance obtained from the C / A code phase set in step S506. ₂ (t _i ) is weighted to determine the satellite pseudorange.

  After the satellite pseudorange is determined, the (current) position is determined based on the satellite pseudorange.

  According to the present embodiment, in the smoothing process, the pseudo distance obtained from the C / A code phase and the pseudo distance obtained from the P code phase are weighted. The weighting is set such that the lower the vehicle speed, the larger the pseudorange distribution (weighting) obtained by the P code phase and the smaller the pseudorange distribution (weighting) obtained by the C / A code phase. . Since the P code phase has a smaller multipath error than the C / A code phase, the positioning accuracy can be improved by obtaining the satellite distance from the P code phase.

  When the vehicle speed is lower than a predetermined speed, the smoothing process is performed using only the P code phase. By performing the smoothing process using only the P code phase, the influence of multipath can be reduced and the satellite distance can be obtained even when the vehicle speed is lower than a predetermined speed.

  Also, as the vehicle speed increases, the pseudo distance distribution by the C / A code phase is increased and the pseudo distance distribution by the P code phase is decreased. In comparison with the C / A code, the P code phase may have lower reception sensitivity in the GNSS receiver 100. In particular, the change in the state of the received radio wave becomes more severe as the vehicle speed increases. When the pseudo distance based on the P code phase is switched to the pseudo distance based on the C / A code at a certain speed, the pseudo distance before and after the switching becomes discontinuous. Therefore, the GNSS receiver 100 obtains a pseudo distance using a C / A code and a pseudo distance using a P code. This GNSS receiver 100 increases the pseudorange weight based on the C / A code phase in the high-speed range and decreases the pseudorange weight based on the P code phase. The GNSS receiving apparatus 100 increases the pseudorange weight based on the P code phase and decreases the pseudorange weight based on the C / A code phase in the low speed range.

<Second embodiment>
<System>
The GNSS according to this embodiment is the same as that of the first embodiment.

<GNSS receiver>
FIG. 6 shows a GNSS receiver 100 according to the present embodiment. It differs from the GNSS receiver 100 shown in the first embodiment in that it has a loop bandwidth setting unit 122.

  The loop bandwidth setting unit 122 is connected to the LPF 1066. Vehicle speed information is input to the loop bandwidth setting unit 122.

  FIG. 7 shows the characteristics of the C / A code phase output by the integrator 1064.

  When the vehicle speed is high, the C / A code phase fluctuation period becomes shorter with respect to time. When the vehicle speed is slow, contrary to when the vehicle speed is fast, the C / A code phase fluctuation period becomes longer with respect to time.

  Therefore, in order to eliminate the C / A code phase fluctuation, the loop bandwidth in the DLL 106 is set to a large value when the vehicle speed is high, and the loop bandwidth in the DLL 106 is set when the vehicle speed is low. It is preferable to set a small value.

  The loop bandwidth setting unit 122 changes the loop bandwidth of the DLL based on the vehicle speed information.

  FIG. 8 shows an example of setting the DLL loop bandwidth. As shown in FIG. 8, for example, as the vehicle speed decreases, the loop bandwidth of the DLL is reduced. By narrowing the DLL loop bandwidth, positioning errors can be reduced.

  In addition, when the vehicle speed is lower than the predetermined speed A, the loop bandwidth setting unit 122 sets the loop bandwidth of the DLL as a bandwidth capable of demodulating the C / A code. The predetermined speed A is preferably set to a speed at which the moving speed of the GPS receiving device has a bandwidth capable of demodulating the C / A code. By making the loop bandwidth of the DLL a bandwidth that can demodulate the C / A code, it is possible to prevent the GPS satellite signal from being decoded. The bandwidth capable of demodulating the C / A code may be the Nyquist frequency of the modulation band of the C / A code.

The loop bandwidth setting unit 122 inputs the set value of the loop bandwidth of the DLL to the LPF 1066.
The LPF 1066 filters the C / A code phase according to the loop bandwidth set by the loop bandwidth setting unit 122 and outputs a phase residual.

<Operation of this GNSS receiver>
FIG. 9 is a flowchart showing the operation of the GNSS receiver 100. FIG. 9 mainly shows processing included in step S502 in the flowchart described with reference to FIG.

  The GNSS receiver 100 sets the loop bandwidth based on the vehicle speed (step S902). For example, the loop bandwidth setting unit 122 sets the loop bandwidth based on the vehicle speed information. For example, the loop bandwidth setting unit 122 narrows the loop bandwidth of the DLL as the vehicle speed decreases. Further, the loop bandwidth setting unit 114 sets the DLL loop bandwidth to C / C when the speed of the vehicle is lower than the speed at which the moving speed of the GPS receiver is a bandwidth capable of demodulating the C / A code. Let A code be a demodulatable bandwidth. The loop bandwidth is input to the LPF 1066.

  The GNSS receiver 100 filters the C / A code phase according to the loop bandwidth set in step 902 (step S904). For example, the LPF 1066 filters the C / A code phase with the loop bandwidth set by the loop bandwidth setting unit 122.

  According to the present embodiment, the positioning error can be reduced by changing the loop bandwidth of the DLL (L1-C / A) circuit based on the speed of the vehicle. The loop bandwidth of the DLL (L1-C / A) circuit is narrowed as the vehicle speed decreases. Also, when the moving speed is lower than the predetermined speed that can demodulate the C / A code, the C / A code can be demodulated using the loop bandwidth of the DLL (L1-C / A) circuit. Bandwidth. By making the loop bandwidth of the DLL (L1-C / A) circuit a bandwidth capable of demodulating the C / A code, it is possible to prevent the signal from the GPS satellite from being unable to be decoded.

  In this embodiment, the loop bandwidth of the DLL (L1-P) circuit may be changed based on the speed of the vehicle. Specifically, it is narrowed as the vehicle speed decreases. However, the P-code DLL bandwidth is wide enough that it is preferable to limit it only at very low speeds.

<Third embodiment>
<System>
The GNSS according to this embodiment is the same as that of the first embodiment.

<GNSS receiver>
The GNSS receiver 100 according to the present embodiment has a P code phase distance estimation unit 124 in addition to the GNSS receiver 100 shown in the first and second embodiments.

  FIG. 10 shows the P code phase distance estimation unit 124.

  The P code phase distance estimation unit 124 includes a satellite tracking determination unit 1242, a carrier phase distance difference value calculation unit 1244, and a P code phase distance calculation unit 1248. The carrier phase distance difference value calculation unit 1244 has a memory 1246, and the P code phase distance calculation unit 1248 also has a memory 1250.

  The P code phase distance estimation unit 124 is connected to the DLL (L1-P) circuit 114, the DLL (L2-P) circuit 120, and the smoothing processing unit 108. The P code phase distance estimation unit 124 calculates the difference value of the phase distance using the carrier phase integrated value. The P code phase distance estimation unit 124 determines whether the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120 has lost the GNSS satellite. When it is determined that the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120 has lost the GNSS satellite, the P code phase distance estimation unit 124 calculates the relative value obtained from the carrier phase integrated value. Estimate P-code phase distance by distance change. The P code phase distance estimation unit 124 inputs the P code phase distance to the smoothing processing unit 108. When the P code phase distance is input from the P code phase distance estimation unit 124, the smoothing processing unit 108 obtains a satellite pseudorange using the P code phase distance. On the other hand, if it is not determined that the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120 has lost the GNSS satellite, the P code phase distance estimation unit 124 sends a DLL to the smoothing processing unit 108. The P code phase input by the (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120 is input. Further, the P code phase distance estimation unit 124 calculates and stores the P code phase distance based on the P code phase.

  The satellite tracking determination unit 1242 is connected to the DLL (L1-P) circuit 114, the DLL (L2-P) circuit 120, and the smoothing processing unit 108. The satellite tracking determination unit 1242 determines whether or not the GNSS receiver 100 has lost the GNSS satellite. In other words, it is determined whether the GNSS satellite can be tracked by the GNSS receiver 100. For example, the radio wave status information is input to the satellite tracking determination unit 1242. The satellite tracking determination unit 1242 may determine that the GNSS satellite is not tracked based on the radio wave state information when the radio wave state information does not satisfy a predetermined radio wave state.

  The satellite tracking determination unit 1242 may observe a correlation peak between the received signal and the P-code replica signal in the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120. Good. The satellite tracking determination unit 1242 may determine that tracking has not been performed when the peak value of the correlation peak decreases below the correlation peak threshold value. The correlation peak threshold value may be changed based on the elevation angle of the GNSS satellite.

  Further, the satellite tracking determination unit 1242 may determine whether the radio wave from the GNSS satellite is blocked by an obstacle such as a high-rise building or trees based on the map information. If it is determined that the radio wave is blocked, the satellite tracking determination unit 1242 may determine that the GNSS satellite cannot be tracked.

  When the satellite tracking determination unit 1242 determines that the GNSS satellite can be tracked, the satellite tracking determination unit 1242 smoothes the P code phase input by the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120. Unit 108 and P code phase distance calculation unit 1248. In addition, when the satellite tracking determination unit 1242 determines that the GNSS satellite cannot be tracked, the P code phase input by the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120 is It is determined that it is incorrect, and the P code phase is not input to the smoothing processing unit. When the satellite tracking determination unit 1242 determines that the P code phase input by the DLL (L1-P) circuit 114 and / or the DLL (L2-P) circuit 120 is incorrect, the satellite tracking determination unit 1242 Command to output P code phase distance.

The carrier wave phase difference difference calculation unit 1244 receives the carrier wave phase integrated value. The carrier phase integrated value is input by a phase locked loop (PLL) (not shown). The carrier phase integrated value may be calculated from the Doppler frequency for each epoch. For example, the Doppler frequency is integrated. The carrier phase distance difference value calculation unit 1244 obtains a pseudo distance from the carrier phase integrated value. The pseudorange is also called a carrier phase distance Φ. The carrier phase distance difference value calculation unit 1244 stores the carrier phase distance Φ in the memory 1246. After the carrier phase distance Φ is stored in the memory 1246, the carrier phase distance difference value calculation unit 1244 obtains the carrier phase distance from the carrier phase integrated value input in the next epoch. The carrier phase distance difference value calculation unit 1244 is a difference (Φ _i -Φ _i-1 ) between the carrier phase distance and the carrier pseudo distance one epoch before stored in the memory 1246 (where i represents an epoch). Is stored in the memory 1246 and input to the P code phase distance calculation unit 1248.

The P code phase distance calculation unit 1248 is connected to the satellite tracking determination unit 1242, the carrier phase distance difference value calculation unit 1244, and the smoothing processing unit 108. A carrier phase distance difference value (Φ _i −Φ _i−1 ) is input to the P code phase distance calculator 1248 by the carrier phase distance difference value calculator 1244. Further, the P code phase distance calculation unit 1248 receives the P code phase from the satellite tracking determination unit 1242. In addition, the P code phase distance calculation unit 1248 receives a command for outputting the P code phase distance by the satellite tracking determination unit 1242 in a predetermined case.

The P code phase distance calculation unit 1248 obtains the P code phase distance from the P code phase input by the satellite tracking determination unit 1242. The P code phase distance is stored in the memory 1250. The P code phase distance calculation unit 1248 obtains the P code phase distance based on the difference value (Φ _i -Φ _i-1 ) of the carrier phase distance input by the carrier phase distance difference value calculation unit 1244. For example, the P code phase distance calculation unit 1248 obtains the P code phase distance using Equation (2).

式（２）において、ρ₂（ｔ_i-1）は、メモリ１２５０に記憶された値を用いる。Pコード位相距離演算部１２４８は、新たに求めたPコード位相距離をメモリ１２５０に記憶する。Pコード位相距離演算部１２４８は、衛星追尾判定部１２４２により入力されるPコード位相距離を出力する命令に従って、スムージング処理部１０８に、Pコード位相距離を入力する。

In equation (2), ρ ₂ (t _i-1 ) uses a value stored in the memory 1250. The P code phase distance calculation unit 1248 stores the newly obtained P code phase distance in the memory 1250. The P code phase distance calculation unit 1248 inputs the P code phase distance to the smoothing processing unit 108 in accordance with a command for outputting the P code phase distance input by the satellite tracking determination unit 1242.

<Operation of this GNSS receiver>
FIG. 11 is a flowchart showing the operation of the GNSS receiver 100.

  In FIG. 11, steps S1102-S1104 and S1112-S1114 are the same as S502-S508 described with reference to FIG. Therefore, it demonstrates from step S1106.

  The GNSS receiver 100 determines whether or not the GNSS satellite is lost (step S1106). For example, the satellite tracking determination unit 1242 may determine whether the GNSS satellite is lost based on the radio wave state information.

  When it is determined that the GNSS satellite has been lost (step S1106: YES), the GNSS receiver 100 obtains the P code phase distance based on the difference value of the carrier phase distance (step S1108). For example, the carrier phase distance difference value calculation unit 1244 obtains a difference in carrier phase distance. The P code phase distance calculation unit 1248 obtains the P code phase distance based on the difference value of the carrier phase distance obtained by the carrier phase distance difference value computation unit 1244.

  When it is not determined that the GNSS satellite is lost (step S1106: NO), the GNSS receiver 100 obtains a P code phase distance based on the P code phase (step S1110). For example, the satellite pseudorange calculation unit 1084 of the smoothing processing unit 108 obtains the P code phase distance based on the P code phase.

  According to the present embodiment, it can be determined whether or not the GNSS satellite is lost. Even when the GNSS satellite is lost, the satellite distance can be obtained from the carrier phase.

  According to the above-described embodiment, there is provided a GNSS receiver that performs a positioning calculation based on a positioning signal transmitted from a GNSS satellite.

The GNSS receiver is
Generate a C / A code replica signal and synchronize the C / A code replica signal with the positioning signal from the GNSS satellite to obtain the phase of the C / A code, DLL (L1-C / A) a first delay locked loop circuit as a circuit;
A DLL (L1-P) circuit, a DLL (L2-P2) circuit that generates a P-code replica signal and obtains the phase of the P-code by synchronizing the P-code replica signal with the positioning signal from the GNSS satellite. P) a second delay locked loop circuit as a circuit;
Based on the moving speed of the GNSS receiver, a weight setting unit that sets a weight for the pseudorange obtained by the phase of the C / A code;
Based on the weight set by the weight setting unit, the phase of the C / A code determined by the first delay locked loop circuit, and the phase of the P code determined by the second delay locked loop circuit A pseudo distance calculation unit as the smoothing processing unit 108 for obtaining a pseudo distance;
A positioning calculation unit that performs positioning based on the pseudo distance obtained by the pseudo distance calculation unit.

  In the smoothing process, when weighting the pseudo distance obtained by the C / A code phase and the pseudo distance obtained by the P code phase, the weight is changed based on the speed of the vehicle. For example, the lower the vehicle speed, the smaller the pseudorange distribution (weighting) obtained by the C / A code phase is set. As a result, the distribution (weighting) of the pseudo distance obtained by the P code phase increases. Since the P code phase has a smaller multipath error than the C / A code phase, the positioning accuracy can be improved by obtaining the satellite distance from the P code phase.

further,
A loop bandwidth setting unit that sets a loop bandwidth of the first delay locked loop circuit based on a moving speed of the GNSS receiver;
The first delay locked loop circuit obtains the phase of the C / A code based on the loop bandwidth set by the loop bandwidth setting unit.

  The positioning error can be reduced by changing the loop bandwidth of the DLL (L1-C / A) circuit based on the vehicle speed. That is, the multipath error can be reduced by changing the loop bandwidth and the weighting coefficient of the C / A code phase and the P code phase according to the speed of the vehicle. Multipath errors can be reduced by using the P-code phase even in a low-speed region that is equal to or less than the modulation band of the C / A code. That is, multipath errors can be reduced in the entire speed range.

further,
The loop bandwidth setting unit sets the loop bandwidth to a narrower value as the speed of the GNSS receiver becomes lower.

  By narrowing the loop bandwidth of the DLL (L1-C / A) circuit as the vehicle speed decreases, the positioning accuracy can be improved.

further,
The loop bandwidth setting unit, when the speed of the GNSS receiver is equal to or lower than a predetermined speed that is a bandwidth capable of demodulating the C / A code in the first delay locked loop circuit, Is set to a bandwidth that can be demodulated.

  By making the loop bandwidth of the DLL (L1-C / A) circuit a bandwidth capable of demodulating the C / A code, it is possible to prevent the signal from the GPS satellite from being unable to be decoded.

further,
The weighting setting unit sets the weighting to a smaller value as the speed of the GNSS receiver becomes lower.

  The smaller the C / A code phase weight, the greater the P code phase weight. By increasing the weighting of the P code phase, the satellite distance can be obtained by reducing the influence of multipath even when the vehicle speed is low.

further,
The weight setting unit sets the weight for the pseudo distance obtained from the phase of the P code based on the moving speed of the GNSS receiver to a larger value as the speed of the GNSS receiver decreases.

  The greater the P code phase weight, the smaller the C / A code phase weight. By increasing the weighting of the P code phase, the satellite distance can be obtained by reducing the influence of multipath even when the vehicle speed is low.

further,
The weighting setting unit sets the weighting to a minimum value when the speed of the GNSS receiving apparatus is equal to or lower than a predetermined speed.

  By performing the smoothing process using only the P code phase, the influence of multipath can be reduced and the satellite distance can be obtained even when the vehicle speed is lower than a predetermined speed.

further,
A satellite tracking determination unit that determines whether a GNSS satellite can be tracked;
A differential value calculation unit as a carrier phase distance difference value calculation unit that calculates a pseudo distance based on the carrier phase and calculates a difference at a predetermined time of the pseudo distance;
A pseudo-range estimation unit as a P-code phase distance calculation unit that estimates a pseudo-range calculated from the P-code phase based on the difference obtained by the difference value calculation unit;
When the satellite tracking determination unit determines that the GNSS satellite has not been tracked, the pseudo distance calculation unit, based on the pseudo distance estimated by the pseudo distance estimation unit, between the GNSS satellite and the GNSS receiver. Find the pseudo distance between.

  According to the present embodiment, the satellite distance can be obtained even when the GNSS satellite is lost. Even when the P code cannot be tracked instantaneously due to noise or the like, the change amount of the P code phase can be taken over by calculating the carrier phase (carrier phase) using the PLL. Even when the P code cannot be tracked instantaneously due to noise or the like, the P code phase can continue to be used.

  According to the present embodiment, there is provided a method in a GNSS receiver that performs a positioning calculation based on a positioning signal transmitted from a GNSS satellite.

The method
Generating a C / A code replica signal;
Obtaining the phase of the C / A code by synchronizing the replica signal of the C / A code and the positioning signal from the GNSS satellite;
Generating a P-code replica signal; and
Obtaining the phase of the P code by synchronizing the replica signal of the P code and the positioning signal from the GNSS satellite;
Based on the moving speed of the GNSS receiver, a weight setting step for setting a weight for the pseudorange obtained by the phase of the C / A code;
The weight set in the weight setting step, the phase of the C / A code obtained by the step of obtaining the phase of the C / A code, and the phase of the P code obtained by the step of obtaining the phase of the P code. A pseudo-range calculation step for obtaining a pseudo-range based on:
A positioning calculation step for performing positioning based on the pseudo distance obtained by the pseudo distance calculation step.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be implemented in hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

1 High-frequency circuit 2 Multiplier 3 Integrator 4 Low-pass filter (LPF)
5 Numerical Control Oscillator 6 C / A Code Generator 7 Distance Calculation Unit 10 Delay-Locked Loop (DLL) Circuit 100 GNSS Receiver 102 High Frequency Circuit 104 Multiplier 106 Delay Locked Loop Circuit (DLL (L1-C / A) Circuit)
1062 Multiplier 1064 Integrator 1066 Low-pass filter 1068 Numerically controlled oscillator 1070 C / A code generator 108 Smoothing processing unit 1082 Weight coefficient setting unit 1084 Satellite pseudorange calculation unit 110 Positioning calculation unit 112 Multiplying unit 114 Delay synchronous loop circuit ( DLL (L1-P) circuit)
1142 Multiplier 1144 Integrator 1146 W Code Eliminator 1148 Low-Pass Filter 1150 Numerical Control Oscillator 1152 P Code Generator 116 High Frequency Circuit 118 Multiplier 120 Delay Delayed Loop Circuit (DLL (L2-P))
1202 Multiplying unit 1204 Integrator 1206 W code removal unit 122 Loop bandwidth setting unit 124 P code phase distance estimation unit 1242 Satellite tracking determination unit 1244 Carrier phase distance difference value calculation unit 1246 Memory 1248 P code phase distance calculation unit 1250 Memory

Claims (9)

A GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first delay locked loop circuit that generates a C / A code replica signal and obtains the phase of the C / A code by synchronizing the C / A code replica signal with the positioning signal from the GNSS satellite. When,
A second delay locked loop circuit for generating a P code replica signal, and obtaining a phase of the P code by synchronizing the P code replica signal with the positioning signal from the GNSS satellite;
Based on the moving speed of the GNSS receiver, a weight setting unit that sets a weight for the pseudorange obtained by the phase of the C / A code;
Based on the weight set by the weight setting unit, the phase of the C / A code determined by the first delay locked loop circuit, and the phase of the P code determined by the second delay locked loop circuit , A pseudo distance calculation unit for obtaining a pseudo distance;
A positioning calculation unit that performs positioning based on the pseudo distance obtained by the pseudo distance calculation unit. In the GNSS receiver according to claim 1,
A loop bandwidth setting unit that sets a loop bandwidth of the first delay locked loop circuit based on a moving speed of the GNSS receiver;
The first delay locked loop circuit is a GNSS receiver that obtains a phase of a C / A code based on a loop bandwidth set by the loop bandwidth setting unit. The GNSS receiver according to claim 2,
The loop bandwidth setting unit is a GNSS receiver that sets the loop bandwidth to a narrower value as the speed of the GNSS receiver decreases. In the GNSS receiver according to claim 2 or 3,
The loop bandwidth setting unit, when the speed of the GNSS receiver is equal to or lower than a predetermined speed that is a bandwidth capable of demodulating the C / A code in the first delay locked loop circuit, A GNSS receiver that sets the loop bandwidth to a bandwidth that can be demodulated. In the GNSS receiver according to any one of claims 1 to 4,
The weighting setting unit is a GNSS receiving apparatus that sets the weighting to a smaller value as the speed of the GNSS receiving apparatus becomes lower. In the GNSS receiver according to any one of claims 1 to 4,
The weighting setting unit is a GNSS receiving device that sets the weighting for the pseudo distance obtained from the phase of the P code based on the moving speed of the GNSS receiving device to a larger value as the speed of the GNSS receiving device becomes lower. In the GNSS receiver according to claim 5,
The weighting setting unit is a GNSS receiving apparatus that sets the weighting to a minimum value when the speed of the GNSS receiving apparatus is equal to or lower than a predetermined speed. In the GNSS receiver according to any one of claims 1 to 7,
A satellite tracking determination unit that determines whether a GNSS satellite can be tracked;
A difference value calculation unit for obtaining a pseudo distance based on a carrier phase and obtaining a difference at a predetermined time of the pseudo distance;
A pseudo-range estimation unit that estimates a pseudo-range obtained from the P-code phase based on the difference obtained by the difference value computation unit;
When the satellite tracking determination unit determines that the GNSS satellite has not been tracked, the pseudo distance calculation unit, based on the pseudo distance estimated by the pseudo distance estimation unit, between the GNSS satellite and the GNSS receiver. A GNSS receiver that calculates the pseudo distance between the two. A method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
Generating a C / A code replica signal;
Obtaining the phase of the C / A code by synchronizing the replica signal of the C / A code and the positioning signal from the GNSS satellite;
Generating a P-code replica signal; and
Obtaining the phase of the P code by synchronizing the replica signal of the P code and the positioning signal from the GNSS satellite;
Based on the moving speed of the GNSS receiver, a weight setting step for setting a weight for the pseudorange obtained by the phase of the C / A code;
The weight set in the weight setting step, the phase of the C / A code obtained by the step of obtaining the phase of the C / A code, and the phase of the P code obtained by the step of obtaining the phase of the P code. A pseudo-range calculation step for obtaining a pseudo-range based on:
A positioning calculation step of performing positioning based on the pseudo distance obtained by the pseudo distance calculation step.

Images