CN106597492A - Satellite navigation receiver and near-far effect resisting method and indoor positioning method thereof - Google Patents

Abstract

The invention is applicable to the field of satellite navigation, and in particular relates to a satellite navigation receiver, a method for resisting near-far effect and an indoor positioning method. The satellite navigation receiver includes an antenna unit, a radio frequency unit, a baseband signal processing unit, a control and information processing unit and a human-computer interaction unit connected in sequence, the baseband signal processing unit has a near-far effect suppression unit, and the near-far effect suppression unit includes a signal Reconstruction module, weak satellite signal tracking module and at least one strong satellite signal tracking module, strong satellite signal tracking module includes first autocorrelation module, first cross-correlation module, first subtractor and second subtractor, weak satellite signal tracking The modules include a second autocorrelation module, a second cross-correlation module, a third subtractor and a fourth subtractor. The invention can enhance the anti-far-near effect ability of the satellite navigation receiver.

Description

Satellite navigation receiver and its anti-near effect method and indoor positioning method

technical field

The invention belongs to the field of satellite navigation, and in particular relates to a satellite navigation receiver, a method for resisting near-far effect and an indoor positioning method.

Background technique

The current GNSS (Global Navigation Satellite System, Global Satellite Navigation System) mainly includes: GPS (Global Positioning System, Global Positioning System) of the United States, GLONASS (Glonass Satellite Navigation System) of Russia, BD (Beidou Satellite Navigation System) of China System) and European Galileo (Galileo Satellite Positioning System), GNSS is a radio positioning system, by estimating the propagation delay of radio waves from the satellite to the satellite navigation receiver, the linear distance from the satellite navigation receiver to the satellite is obtained, which is A method of ranging using time of arrival.

Due to the limitations of the indoor pseudo-satellite system itself, such as low satellite deployment height, large elevation changes, small and complex indoor environment, etc., the received pseudo-satellite signal will change significantly when the satellite navigation receiver is moving indoors. Every time the distance doubles, the power attenuation can reach 6dB. When the satellite navigation receiver is close to one or two pseudolites at the same time, the signal power of the closer pseudolite will increase significantly, which will increase the noise floor power at the antenna end of the satellite navigation receiver, that is, the near-far effect will occur, making the distance closer The capture and tracking of distant pseudolite signals is affected, and even the satellite is lost, which in turn affects the positioning of the satellite navigation receiver.

Since the CA code is not strictly orthogonal, its isolation is about 24dB. Therefore, when the power difference between the two pseudolite signals exceeds the threshold, the cross-correlation power between the strong satellite signal and the weak satellite signal will increase significantly, thus affecting the weak As a result of the autocorrelation of satellite signals, weak satellite signals are eventually drowned in noise. The key to suppressing cross-correlation interference is to obtain the parameters of strong satellite signals to accurately reproduce strong satellite signals. Signal parameters include carrier frequency, carrier phase, code phase, amplitude and message bits. The effectiveness of cross-correlation suppression depends directly on the accuracy of locally reproduced strong satellite signals. The satellite navigation receiver can track the strong satellite signal stably for a certain period of time, and its carrier loop and code loop can accurately track the strong satellite signal, so the carrier frequency, carrier phase and code phase can be directly extracted from the loop. The message bits can be given by a message predictor. The performance of cross-correlation suppression then directly depends on the estimation accuracy of the magnitude.

Contents of the invention

The object of the present invention is to provide a satellite navigation receiver capable of resisting the near-far effect, a method for resisting the near-far effect and an indoor positioning method.

In a first aspect, the present invention provides a satellite navigation receiver, comprising an antenna unit, a radio frequency unit, a baseband signal processing unit, a control and information processing unit, and a human-computer interaction unit connected in sequence, and the baseband signal processing unit has a near-far effect Suppression unit, the near-far effect suppression unit includes a signal reconstruction module, a weak satellite signal tracking module and at least one strong satellite signal tracking module, the strong satellite signal tracking module includes a first autocorrelation module, a first cross-correlation module, a first subtraction and the second subtractor, the weak satellite signal tracking module includes a second autocorrelation module, a second cross-correlation module, a third subtractor and a fourth subtractor, wherein the input terminal of the first autocorrelation module and the second autocorrelation The input terminals of the modules are respectively connected to the output terminals of the radio frequency unit, the input signal of the first cross-correlation module is 0, the first output terminal of the first auto-correlation module and the first output terminal of the first cross-correlation module are respectively connected with the first subtraction The two input terminals of the device are connected, the second output terminal of the first autocorrelation module and the second output terminal of the first cross-correlation module are respectively connected with the two input terminals of the second subtractor, and the reconstruction signal of the first autocorrelation module The output terminal is connected to the input terminal of the signal reconstruction module, the amplitude control terminal of the signal reconstruction module is connected to the control and information processing unit, and the amplitude control is provided by the control and information processing unit, and the output terminal of the signal reconstruction module is connected to the second cross-correlation The input terminal of the module is connected, the first output terminal of the second autocorrelation module and the first output terminal of the second cross-correlation module are connected with the two input terminals of the third subtractor respectively, and the second output terminal of the second autocorrelation module The second output terminal of the second cross-correlation module is respectively connected to the two input terminals of the fourth subtractor, the enable terminal of the first autocorrelation module is connected to the control and information processing unit, and the control and information processing unit provides the enable Control, the amplitude control terminal of the second cross-correlation module is connected with the control and information processing unit, the amplitude control is provided by the control and information processing unit, the output of the first subtractor, the second subtractor, the third subtractor and the fourth subtractor The terminal is connected with the control and information processing unit for tracking control by the control and information processing unit.

In a second aspect, the present invention provides a method for resisting the near-far effect of a satellite navigation receiver, wherein the satellite navigation receiver is the above-mentioned satellite navigation receiver, and the method includes:

When the carrier-to-noise ratio of a satellite signal is lower than the low threshold among the tracked satellite signals, the satellite navigation receiver searches whether there is a signal with a carrier-to-noise ratio higher than the high threshold among all the tracked satellite signals;

If the satellite signal carrier-to-noise ratio of at least one channel is higher than the high threshold, it is determined that the near-far effect has occurred, and the satellite navigation receiver enables the first autocorrelation module of the strong satellite signal tracking module to output the reconstruction signal, and enables the signal reconstruction The reconstruction module outputs the reconstructed signal, and sends the reconstructed signal to the second cross-correlation module of the weak satellite signal tracking module; in the next tracking interruption, the satellite navigation receiver reduces the cross-correlation in the weak satellite signal tracking module The integration result is used as the input of the phase detector.

In a third aspect, the present invention provides an indoor positioning method for a satellite navigation receiver, where the satellite navigation receiver is the above-mentioned satellite navigation receiver, and the method includes:

The satellite navigation receiver is turned on or reset from a known position, and the signals of each pseudolite are captured by means of code phase parallel and frequency serial;

After the satellite navigation receiver completes the capture and towing of each pseudolite at the known position, it turns to tracking and demodulates the navigation message; when the satellite navigation receiver obtains the coordinates of the satellite from the navigation message of the pseudolite, The carrier integer ambiguity will be statically initialized. When all the pseudolites have completed the initialization of the carrier integer ambiguity, the satellite navigation receiver will complete the static initialization;

After the satellite navigation receiver completes the static initialization, the satellite navigation receiver moves freely and extracts the carrier phase measurement value of the pseudolite in real time;

According to the carrier phase measurement value of the pseudolite, the CHAN algorithm is used as the positioning calculation algorithm to realize the indoor positioning of the satellite navigation receiver;

Send the positioning results and the coordinate parameters of each pseudolite to the host computer for display.

In the present invention, since the near-far effect suppression unit includes a signal reconstruction module, a weak satellite signal tracking module and at least one strong satellite signal tracking module, the strong satellite signal tracking module includes a first autocorrelation module, a first cross-correlation module, a first Subtractor and the second subtractor, the weak satellite signal tracking module includes the second autocorrelation module, the second cross-correlation module, the third subtractor and the fourth subtractor, the reconstruction signal output terminal of the first autocorrelation module and the signal reconstruction The input terminal of the module is connected, the amplitude control terminal of the signal reconstruction module is connected with the control and information processing unit, and the amplitude control is provided by the control and information processing unit, and the output terminal of the signal reconstruction module is connected with the input terminal of the second cross-correlation module. Therefore, it can significantly improve the satellite navigation receiver's ability to track weak satellite signals in the case of strong interference, greatly improve the maximum power value difference between different pseudolites that are allowed to arrive at the same time, and significantly enhance the satellite navigation receiver's ability to resist near-far effects. Expand the effective positioning area of the satellite navigation receiver in the indoor pseudolite system.

In addition, because the present invention uses the CHAN algorithm as the positioning solution algorithm to realize the indoor positioning of the satellite navigation receiver according to the carrier phase measurement value of the pseudolite, it can effectively eliminate the need for time synchronization in the pseudolite system. The influence of the clock drift of the pseudolite system of the constant temperature crystal on the ranging results, and can achieve high-precision positioning before the satellite navigation receiver and the pseudolite system have not completed time synchronization, and is applicable to all kinds of indoor pseudolite systems. In addition, the calculation amount of CHAN is smaller than that of the least square method commonly used by satellite navigation receivers, which is beneficial to the satellite navigation receivers to realize real-time positioning.

Description of drawings

FIG. 1 is a schematic structural diagram of a satellite navigation receiver provided by Embodiment 1 of the present invention.

FIG. 2 is a circuit block diagram of a near-far effect suppression unit in a satellite navigation receiver provided by Embodiment 1 of the present invention.

Fig. 3 is a circuit block diagram of a first autocorrelation module and a second autocorrelation module in the near-far effect suppression unit of the satellite navigation receiver provided by Embodiment 1 of the present invention.

Fig. 4 is a circuit block diagram of the first cross-correlation module in the near-far effect suppression unit of the satellite navigation receiver provided by Embodiment 1 of the present invention.

Fig. 5 is a circuit block diagram of a second cross-correlation module in the near-far effect suppression unit of the satellite navigation receiver provided by Embodiment 1 of the present invention.

Fig. 6 is a circuit block diagram of a signal reconstruction module in the near-far effect suppression unit of the satellite navigation receiver provided by Embodiment 1 of the present invention.

detailed description

In order to make the object, technical solution and beneficial effects of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In order to illustrate the technical solutions of the present invention, specific examples are used below to illustrate.

Embodiment one:

Please refer to Fig. 1, the satellite navigation receiver that embodiment one of the present invention provides, it can be used for receiving the satellite navigation signal of indoor pseudolite system, and satellite navigation receiver comprises antenna unit 11, radio frequency unit 12, baseband signal processing that are connected successively unit 13 , a control and information processing unit 14 and a human-computer interaction unit 15 , wherein the baseband signal processing unit 13 has a near-far effect suppression unit 131 .

Referring to Fig. 2, the near-far effect suppression unit includes a signal reconstruction module 1311, a weak satellite signal tracking module 1313 and at least one strong satellite signal tracking module 1312, and the strong satellite signal tracking module 1312 includes a first autocorrelation module 13121, a first cross-correlation Module 13122, a first subtractor 13123 and a second subtractor 13124, the weak satellite signal tracking module 1313 includes a second autocorrelation module 13131, a second cross-correlation module 13132, a third subtractor 13133 and a fourth subtractor 13134, wherein, The input end of the first autocorrelation module 13121 and the input end of the second autocorrelation module 13131 are respectively connected to the output end of the radio frequency unit, the input signal of the first cross-correlation module 13122 is 0, and the first output of the first autocorrelation module 13121 terminal and the first output end of the first cross-correlation module 13122 are respectively connected with two input ends of the first subtractor 13123, and the second output end of the first auto-correlation module 13121 is connected with the second output end of the first cross-correlation module 13122 respectively It is connected to the two input terminals of the second subtractor 13124, the reconstruction signal output terminal of the first autocorrelation module 13121 is connected to the input terminal of the signal reconstruction module 1311, and the amplitude control terminal of the signal reconstruction module 1311 is connected to the control and information processing unit , the amplitude control is provided by the control and information processing unit, the output of the signal reconstruction module 1311 is connected to the input of the second cross-correlation module 13132, the first output of the second auto-correlation module 13131 is connected to the second cross-correlation module 13132 The first output terminal is respectively connected to the two input terminals of the third subtractor 13133, and the second output terminal of the second autocorrelation module 13131 and the second output terminal of the second cross-correlation module 13132 are respectively connected to the two input terminals of the fourth subtractor 13134. The enabling terminal of the first autocorrelation module 13121 is connected to the control and information processing unit, and the enabling control is provided by the control and information processing unit, and the amplitude control terminal of the second cross-correlation module 13132 is connected to the control and information processing unit. Amplitude control is provided by the Control and Information Processing Unit. The output terminals of the first subtractor 13123 , the second subtractor 13124 , the third subtractor 13133 and the fourth subtractor 13134 are connected to the control and information processing unit for tracking control by the control and information processing unit.

Referring to Fig. 3, the first autocorrelation module and the second autocorrelation module all include carrier digitally controlled oscillator 21, pseudocode generator 22, first integrator 23 and second integrator 24, and carrier digitally controlled oscillator 21 produces The two-way orthogonal carrier is multiplied by the digital intermediate frequency signal output by the radio frequency unit, respectively to obtain the digital baseband signal of the stripped carrier; the pseudo code generator 22 is multiplied by the digital baseband signal of the stripped carrier respectively, and the multiplied results are respectively used as the first integral The input of the device 23 and the second integrator 24, the output terminals of the first integrator 23 and the second integrator 24 serve as the first output terminal and the second output terminal of the first autocorrelation module and the second autocorrelation module respectively.

The first autocorrelation module also includes a message predictor 25, and the non-inverting branch of the carrier digital control oscillator 21 is multiplied by the pseudo code generator 22, the message predictor 25, and the enable signal provided by the control and information processing unit to obtain a reconstruction signal.

Please refer to Fig. 4, the first cross-correlation module comprises carrier digitally controlled oscillator 31, pseudo code generator 32, the 3rd integrator 33 and the 4th integrator 34, and carrier digitally controlled oscillator 31 produces two-way quadrature carrier and input Signal 0 is multiplied to obtain the digital baseband signal of the stripped carrier respectively; the pseudocode generator 32 is multiplied with the digital baseband signal stripped of the carrier respectively, and the multiplied result is used as the input of the third integrator 33 and the fourth integrator 34 respectively, The output terminals of the third integrator 33 and the fourth integrator 34 serve as the first output terminal and the second output terminal of the first cross-correlation module respectively. The carrier digitally controlled oscillator and pseudo code generator of the first cross-correlation module may be shared with the carrier digitally controlled oscillator and pseudo code generator of the first autocorrelation module.

Referring to Fig. 5, the second cross-correlation module includes a carrier digitally controlled oscillator 41, a pseudocode generator 42, a fifth integrator 43 and a sixth integrator 44, and the carrier digitally controlled oscillator 41 produces two-way quadrature carrier and signal The reconstructed signal outputted by the reconstruction module is multiplied to obtain the digital baseband signal stripping the carrier respectively; the pseudocode generator 42 is multiplied with the digital baseband signal stripping the carrier respectively, and the multiplied results are used as the fifth integrator 43 and the sixth integrator respectively. The input of the integrator 44, the output signals of the fifth integrator 43 and the sixth integrator 44 are respectively multiplied by the amplitude control signal provided by the control and information processing unit, and the two multiplied output terminals are respectively used as the second cross-correlation module The first output terminal and the second output terminal. The carrier digitally controlled oscillator and pseudo code generator of the second cross-correlation module may be shared with the carrier digitally controlled oscillator and pseudo code generator of the second autocorrelation module.

Referring to FIG. 6 , the signal reconstruction module includes N multipliers 51 and one N-input adder 52 sequentially connected, and N is a natural number greater than or equal to 1. The output signal of the first autocorrelation module of each strong satellite signal tracking module of every road is sent in the N input adder 52 after the multiplier 51 controls the amplitude; If enabled, output a reconstructed signal composed of N channels of reconstructed signals to the second cross-correlation module of the weak satellite signal tracking module at each moment.

Embodiment two:

The method for anti-far-near effect of the satellite navigation receiver provided by the second embodiment of the present invention, the satellite navigation receiver is the satellite navigation receiver provided by the first embodiment of the present invention, and the method includes the following steps:

When the carrier-to-noise ratio of a satellite signal is lower than the low threshold among the tracked satellite signals, the satellite navigation receiver searches whether there is a signal with a carrier-to-noise ratio higher than the high threshold among all the tracked satellite signals;

If the satellite signal carrier-to-noise ratio of at least one channel is higher than the high threshold, it is determined that the near-far effect has occurred, and the satellite navigation receiver enables the first autocorrelation module of the strong satellite signal tracking module to output the reconstruction signal, and enables the signal reconstruction The reconstruction module outputs the reconstructed signal, and sends the reconstructed signal to the second cross-correlation module of the weak satellite signal tracking module; in the next tracking interruption, the satellite navigation receiver reduces the cross-correlation in the weak satellite signal tracking module The integration result is used as the input of the phase detector;

If the carrier-to-noise ratio of satellite signals without channels is higher than the high threshold, it is determined that there is no near-far effect, and the satellite navigation receiver extends the coherent integration time of the weak satellite signal tracking module.

In the second embodiment of the present invention, the parameters of the strong satellite signal include: navigation message symbol D _i , CA code phase τ _i , carrier Doppler f _di , carrier phase and the signal amplitude A _i . Then the normalized magnitude is expressed as The reconstructed signal output by the signal reconstruction module is:

Among them, A is the amplitude used for reference in normalization, which is taken from any strong satellite signal channel; t is time; CA _i is the pseudo code variable of strong signal; f _IF is the intermediate frequency.

Parameters of weak satellite signals include: Doppler f _dw , carrier phase and code phase τ _w . The result of the cross-correlation calculation between the weak satellite signal and the reconstructed signal is:

Among them, CA _w is the pseudocode variable of the weak signal, the output of the second cross-correlation module of the weak satellite signal tracking module is _Ic and _Qc , and the output of the second autocorrelation module is I and Q, so the _Iw after the cross-correlation is reduced , Q _w way integration result is:

_Iw = IA· _Ic

_Qw = QA· _Qc

Since the algorithm uses a reference strong signal amplitude to normalize all strong signal amplitudes, only one estimation channel is used to estimate the cross-correlation interference of all strong signals, which reduces hardware overhead and is more conducive to hardware implementation.

Embodiment three:

The indoor positioning method of the satellite navigation receiver provided by the third embodiment of the present invention, the satellite navigation receiver is the satellite navigation receiver provided by the first embodiment of the present invention, and the method includes the following steps:

The satellite navigation receiver is turned on or reset from a known position, and the signal of each pseudolite is captured by means of code phase parallel and frequency serial; on the premise that the pseudolite system realizes clock synchronization in the network, The pseudolites should have the same carrier Doppler value, otherwise the satellite navigation receiver will recapture each pseudolites signal;

After the satellite navigation receiver completes the capture and towing of each pseudolite at the known position, it turns to tracking and demodulates the navigation message; when the satellite navigation receiver obtains the coordinates of the satellite from the navigation message of the pseudolite, The carrier integer ambiguity will be statically initialized. When all the pseudolites have completed the initialization of the carrier integer ambiguity, the satellite navigation receiver will complete the static initialization;

After the satellite navigation receiver completes the static initialization, the satellite navigation receiver moves freely and extracts the carrier phase measurement value of the pseudolite in real time;

According to the carrier phase measurement value of the pseudolite, the CHAN algorithm is used as the positioning solution algorithm to realize the indoor positioning of the satellite navigation receiver; The method of anti-far-near effect of satellite navigation receiver to suppress the far-near effect;

Send the positioning results and the coordinate parameters of each pseudolite to the host computer for display.

The Chan algorithm is a positioning algorithm based on TDOA positioning technology and has an analytical expression solution. It has good performance when the TDOA error obeys the ideal Gaussian distribution. TDOA positioning technology is a method of positioning using time difference.

In the third embodiment of the present invention, the satellite navigation receiver needs to be initialized from a known position, assuming that the initial coordinates of the satellite navigation receiver are (x, y), and the coordinates of the i-th pseudolite are ( _xi , y _i ), The expression of the carrier integer ambiguity at the initial position is:

Among them, [·] represents the rounding operation, N _i0 represents the integer ambiguity of the i-th pseudolite or the base station, and λ is the carrier wavelength. Then the carrier phase measurement value of the i-th pseudolite, that is, the distance between the satellite navigation receiver and the base station, can be expressed as:

The initial coordinates can be sent by the host computer through the serial port, or obtained by other wireless communication methods. in, yes the fractional part of is the change value of the carrier phase after initialization, which can be obtained by the code loop NCO of the satellite navigation receiver.

Described according to the carrier phase measurement value of pseudolite, adopting CHAN algorithm to realize the indoor positioning of the satellite navigation receiver as a positioning solution algorithm may specifically include the following steps:

Assuming that in a two-dimensional plane area, the signal is transmitted from the i-th base station ( _xi , y _i ) to the satellite navigation receiver (x, y), then the square of the distance R _i from the satellite navigation receiver to the base station is

in, We record the distance difference from the i-th base station to the first base station as R _i,1 , then

where c is the speed of light in vacuum, and t _i,1 is the time difference of TDOA measurement.

also because

When i=1,

Subtract formula (2-4) from formula (2-3) to get

Wherein, x _i,1 = _xi -x ₁ , y _i,1 =y _i -y ₁ . Treating x, y, R ₁ as unknowns, then formula (2-5) becomes a system of linear equations.

Considering the case of only three base stations, the coordinates (x, y) of the satellite navigation receiver in formula (2-5) can be solved as

Substitute formula (2-6) into In , a quadratic equation about R ₁ can be obtained, and the positive root of the equation is the position estimate of the satellite navigation receiver. When there are two positive roots in the equation, the false roots can be eliminated according to the size of the positioning area, the navigation message and other information.

When four or more base stations participate in positioning, the CHAN algorithm makes full use of the redundant TDOA measurement values provided by the base stations to optimize the positioning results. Assume is the unknown vector, z _p =[x,y] ^T is the position of the undetermined target, and the error vector can be obtained from formula (2-5):

in,

{*} ⁰ is a noise-free measurement value, {*} refers to all expressions, n _{i, 1} indicates measurement noise, then there are So the error vector can be expressed as

in, is the Schur product, and n is the measurement noise matrix. Practical applications, The error vector can be regarded as a random vector approximately obeying a normal distribution, and its covariance is

Ψ＝E[ψψ ^T ]＝c ² BQB (2-9)

where Q is the covariance matrix of the TDOA measurement noise. The approximate solution of the weighted least squares (WLS) method of equation (2-9) is

If the target to be determined is far away from the base station, define the distance R ⁰ and It is relatively close, then, B≈R ⁰ I, I is the identity matrix. Then the above formula can be replaced by

If the undetermined target is close to the base station, an initial solution can be obtained from formula (2-11) to calculate B, and then obtain the position of the satellite navigation receiver by formula (2-10), the above is the first WLS calculation.

Next, to continue the WLS calculation, it is necessary to first obtain the covariance matrix of the estimated position of the satellite navigation receiver. Considering the noise,

and h=h ⁰ +Δh, since Formula (2-7) can be transformed into

make Substitute into formula (2-10) to get

Only keep the linear perturbation part of formula (2-14), combine formula (2-8) and formula (2-16), get ΔZ _a and its covariance matrix as

When the TDOA measurement error is small, the deviation is negligible, Z _a is a vector whose mean is the actual value, and the elements of Z _a can be expressed as

Among them, e ₁ , e ₂ , e ₃ are the estimation errors of each component respectively. Subtract the first two elements of Z _a from x ₁ and y ₁ respectively, and then square each element to get

The above formula is abbreviated as

ψ′=h′-G _a ′Z _a ′ (2-19)

The above formula is approximately true only when the error is relatively small. The covariance matrix of ψ′ is

ψ′ and ψ follow the same Gaussian distribution, then the second step WLS estimation is

The matrix ψ′ contains the real coordinates of the satellite navigation receiver, B′ can be calculated from Z _a , Can be approximately replaced by G _a . Substituting the result of formula (2-21) into formula (2-9) instead of matrix B, if the satellite navigation receiver is far away from the base station, the covariance matrix of Z _a can be expressed as

At this point, formula (2-21) can be simplified as

Therefore, the final estimate of the position of the satellite navigation receiver is

Among them, Z _a ′ is the error correction amount obtained by WLS estimation in the second step. Determine the final position of the satellite navigation receiver according to the size of the positioning area, the navigation message and other information.

The CHAN algorithm can also be extended to the situation of three-dimensional positioning, which will not be repeated here. The CHAN algorithm is a variant of the least squares method, but it has a small amount of calculation and a small hardware overhead. And it uses the first-order difference result of the carrier phase measurement value between the satellites as the input, which can realize the positioning calculation before the satellite navigation receiver and the pseudolite have not completed clock synchronization, and is not affected by the pseudolite and satellite navigation receiver. The impact of its own clock bias and clock drift, but the premise is that the pseudolite system has completed the time synchronization in the network.

In the present invention, since the near-far effect suppression unit includes a signal reconstruction module, a weak satellite signal tracking module and at least one strong satellite signal tracking module, the strong satellite signal tracking module includes a first autocorrelation module, a first cross-correlation module, a first Subtractor and the second subtractor, the weak satellite signal tracking module includes the second autocorrelation module, the second cross-correlation module, the third subtractor and the fourth subtractor, the reconstruction signal output terminal of the first autocorrelation module and the signal reconstruction The input terminal of the module is connected, the amplitude control terminal of the signal reconstruction module is connected with the control and information processing unit, and the amplitude control is provided by the control and information processing unit, and the output terminal of the signal reconstruction module is connected with the input terminal of the second cross-correlation module. Therefore, it can significantly improve the satellite navigation receiver's ability to track weak satellite signals in the case of strong interference, greatly improve the maximum power value difference between different pseudolites that are allowed to arrive at the same time, and significantly enhance the satellite navigation receiver's ability to resist near-far effects. Expand the effective positioning area of the satellite navigation receiver in the indoor pseudolite system.

In addition, because the present invention uses the CHAN algorithm as the positioning solution algorithm to realize the indoor positioning of the satellite navigation receiver according to the carrier phase measurement value of the pseudolite, it can effectively eliminate the need for time synchronization in the pseudolite system. The influence of the clock drift of the pseudolite system of the constant temperature crystal on the ranging results, and can achieve high-precision positioning before the satellite navigation receiver and the pseudolite system have not completed time synchronization, and is applicable to all kinds of indoor pseudolite systems. In addition, the calculation amount of CHAN is smaller than that of the least square method commonly used by satellite navigation receivers, which is beneficial to the satellite navigation receivers to realize real-time positioning.

Those of ordinary skill in the art can understand that all or part of the steps in the method of the above-mentioned embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage Media such as ROM/RAM, magnetic disk, optical disk, etc.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. A satellite navigation receiver, comprising an antenna unit, a radio frequency unit, a baseband signal processing unit, a control and an information processing unit and a human-computer interaction unit connected successively, is characterized in that the baseband signal processing unit has a near-far effect suppression unit , the near-far effect suppression unit includes a signal reconstruction module, a weak satellite signal tracking module and at least one strong satellite signal tracking module, and the strong satellite signal tracking module includes a first autocorrelation module, a first cross-correlation module, a first subtractor and The second subtractor, the weak satellite signal tracking module includes the second autocorrelation module, the second cross-correlation module, the third subtractor and the fourth subtractor, wherein, the input terminal of the first autocorrelation module and the second autocorrelation module The input ends are respectively connected to the output ends of the radio frequency unit, the input signal of the first cross-correlation module is 0, the first output end of the first auto-correlation module and the first output end of the first cross-correlation module are respectively connected with the first subtractor The two input terminals are connected, the second output terminal of the first autocorrelation module and the second output terminal of the first cross-correlation module are respectively connected with the two input terminals of the second subtractor, and the reconstruction signal output terminal of the first autocorrelation module It is connected with the input terminal of the signal reconstruction module, the amplitude control terminal of the signal reconstruction module is connected with the control and information processing unit, and the amplitude control is provided by the control and information processing unit, and the output terminal of the signal reconstruction module is connected with the second cross-correlation module The input end is connected, and the first output end of the second autocorrelation module and the first output end of the second cross-correlation module are respectively connected with the two input ends of the third subtractor, and the second output end of the second autocorrelation module is connected with the first output end of the second cross-correlation module. The second output terminals of the two cross-correlation modules are respectively connected to the two input terminals of the fourth subtractor, the enabling terminal of the first autocorrelation module is connected to the control and information processing unit, and the enabling control is provided by the control and information processing unit, The amplitude control terminal of the second cross-correlation module is connected with the control and information processing unit, and the amplitude control is provided by the control and information processing unit, and the output terminals of the first subtractor, the second subtractor, the third subtractor and the fourth subtractor are connected with the The control and information processing unit is connected for tracking control by the control and information processing unit. 2. satellite navigation receiver as claimed in claim 1, is characterized in that, the first autocorrelation module and the second autocorrelation module all comprise carrier digitally controlled oscillator, pseudocode generator, first integrator and the second integrator The carrier digitally controlled oscillator generates two orthogonal carriers and multiplies the digital intermediate frequency signal output by the radio frequency unit to obtain the digital baseband signal stripped from the carrier respectively; the pseudo code generator multiplies the digital baseband signal stripped from the carrier respectively The results of are used as the input of the first integrator and the second integrator respectively, and the output terminals of the first integrator and the second integrator are respectively used as the first output terminal and the second output of the first autocorrelation module and the second autocorrelation module end. 3. satellite navigation receiver as claimed in claim 2, it is characterized in that, the first autocorrelation module also comprises message predictor, the in-phase branch of carrier digital control oscillator and pseudo code generator, message predictor and control and The enabling signal provided by the information processing unit is multiplied to obtain the reconstructed signal. 4. satellite navigation receiver as claimed in claim 1, is characterized in that, the first cross-correlation module comprises carrier digital control oscillator, pseudo code generator, the 3rd integrator and the 4th integrator, carrier digital control oscillator Generate two quadrature carriers and multiply the input signal 0 to obtain the digital baseband signal stripped off the carrier respectively; the pseudo code generator is multiplied by the digital baseband signal stripped off the carrier respectively, and the multiplied results are respectively used as the third integrator and the fourth integrator The input of the integrator, the output terminals of the third integrator and the fourth integrator serve as the first output terminal and the second output terminal of the first cross-correlation module respectively. 5. satellite navigation receiver as claimed in claim 1, is characterized in that, the second cross-correlation module comprises carrier digital control oscillator, pseudo code generator, the 5th integrator and the 6th integrator, carrier digital control oscillator The two-way orthogonal carrier is multiplied by the reconstructed signal output by the signal reconstruction module to obtain the digital baseband signal stripped from the carrier respectively; The input of the fifth integrator and the sixth integrator, the output signals of the fifth integrator and the sixth integrator are respectively multiplied by the amplitude control signal provided by the control and information processing unit, and the two output terminals after multiplication are respectively used as the second The first output terminal and the second output terminal of the cross-correlation module. 6. satellite navigation receiver as claimed in claim 1, is characterized in that, signal reconstruction module comprises N road multipliers and 1 road N input adders are connected in sequence, N is a natural number greater than or equal to 1, each road strong satellite The output signal of the first autocorrelation module of the signal tracking module is sent to the N input adder after the multiplier controls the amplitude; the N input adder is enabled when the satellite navigation receiver determines that there is near-far effect interference, and at each moment Output a reconstructed signal composed of N channels of reconstructed signals to the second cross-correlation module of the weak satellite signal tracking module. 7. A method for satellite navigation receiver anti-near-far effect, characterized in that, said satellite navigation receiver is the satellite navigation receiver described in any one of claims 1 to 6, said method comprising: When the carrier-to-noise ratio of a satellite signal is lower than the low threshold among the tracked satellite signals, the satellite navigation receiver searches whether there is a signal with a carrier-to-noise ratio higher than the high threshold among all the tracked satellite signals; If the satellite signal carrier-to-noise ratio of at least one channel is higher than the high threshold, it is determined that the near-far effect has occurred, and the satellite navigation receiver enables the first autocorrelation module of the strong satellite signal tracking module to output the reconstruction signal, and enables the signal reconstruction The reconstruction module outputs the reconstructed signal, and sends the reconstructed signal to the second cross-correlation module of the weak satellite signal tracking module; in the next tracking interruption, the satellite navigation receiver reduces the cross-correlation in the weak satellite signal tracking module The integration result is used as the input of the phase detector. 8. The method according to claim 7, wherein after the satellite navigation receiver searches all tracked satellite signals whether there is a signal with a carrier-to-noise ratio higher than the high threshold, the method further comprises: if there is no If the carrier-to-noise ratio of the satellite signal of the channel is higher than the high threshold, it is determined that there is no near-far effect, and the satellite navigation receiver extends the coherent integration time of the weak satellite signal tracking module. 9. An indoor positioning method of a satellite navigation receiver, characterized in that, the satellite navigation receiver is the satellite navigation receiver according to any one of claims 1 to 6, and the method comprises: The satellite navigation receiver is turned on or reset from a known position, and the signals of each pseudolite are captured by means of code phase parallel and frequency serial; After the satellite navigation receiver completes the capture and towing of each pseudolite at the known position, it turns to tracking and demodulates the navigation message; when the satellite navigation receiver obtains the coordinates of the satellite from the navigation message of the pseudolite, The carrier integer ambiguity will be statically initialized. When all the pseudolites have completed the initialization of the carrier integer ambiguity, the satellite navigation receiver will complete the static initialization; After the satellite navigation receiver completes the static initialization, the satellite navigation receiver moves freely and extracts the carrier phase measurement value of the pseudolite in real time; According to the carrier phase measurement value of the pseudolite, the CHAN algorithm is used as the positioning calculation algorithm to realize the indoor positioning of the satellite navigation receiver; Send the positioning results and the coordinate parameters of each pseudolite to the host computer for display. 10. The method according to claim 9, wherein when the near-far effect occurs in the moving process, the satellite navigation receiver enables the first autocorrelation module of the strong satellite signal tracking module to output the reconstruction signal, and enables the signal The reconstruction module outputs the reconstruction signal, and sends the reconstruction signal to the second cross-correlation module of the weak satellite signal tracking module; in the next tracking interruption, the satellite navigation receiver reduces the cross-correlation in the weak satellite signal tracking module The integration result of is used as the input of the phase detector.