TWI434524B - Satellite signal tracking device and method thereof - Google Patents

Description

Satellite signal tracking device and method

The present invention relates to a satellite signal tracking process, and more particularly to a signal tracking device and method applicable between different satellite systems.

The Global Navigation Satellite System (GNSS) provides services such as satellite positioning and signal transmission, which brings great convenience to human life. In the process of transmitting signals, the positioning accuracy and signal stability of satellite signals It is closely related to the number of available satellites. When the number of available satellites is larger, the transmission strength and coordinate calculation of the signal will be better and more stable and accurate.

At present, there are more than one type of GNSS installed in the world, such as the satellite navigation system GPS in the United States or the Galileo satellite navigation system in Europe. Each of the satellite navigation systems has different signal bands, and the receiving end can simultaneously Receiving carriers in different signal bands and transforming the carrier into an identifiable transmission signal, which can simultaneously utilize satellites of different systems, and enhance the accuracy of positioning and signal stability by increasing the total number of available satellites. . The signal modulation mode between the satellite systems is more commonly used by a double-offset carrier (Binary Offset Carrier (BOC) modulation method. However, due to the multi-peak autocorrelation phenomenon, the BOC signal produces a secondary peak. This peak value may cause the receiver to mistakenly use the secondary peak as the primary peak during the process of locking the peak, causing false tracking, which causes the navigation to be misjudged.

Please refer to FIG. 1 , which is a patent application method and device for "Double Offset Carrier Signal Acquisition and Tracking" in the Republic of China Announcement No. I337027, and discloses a BOC signal acquisition and tracking method and apparatus. The pre-case includes one The code unit 91, a code delay estimator 92 and a controller 93. The code unit 91 generates a BOC, a BOC subcarrier, and a pseudo-random noise (PRN), and inputs the BOC, BOC subcarrier and PRN into the code delay estimator 92 to generate a merge correlation. The value is input to the controller 93, so that the controller 93 controls the BOC, BOC subcarrier, and PRN output by the code unit 91. The code delay estimator 92 uses a merge correlation function to remove the secondary peak in the process of generating the combined correlation value to avoid the peak lock error. The merge correlation function utilized in the previous case is as follows:

R _combi =R ² _BOC/BOC (τ)-α×R ² _BOC/PRN (τ)

among them

R _combi : merge the relevant values,

R _BOC/BOC : BOC related power to BOC,

R _BOC / _PR N: BOC vs. PRN related power.

In the code delay estimator 92, the R _BOC/BOC and the R _BOC/PRN are respectively _subjected to a square and subtraction operation by a combining unit 921 to generate a combined correlation value.

It can be seen that the signal generated by the code unit 91 and the processing of the signal affect the signal processing complexity of the subsequent code delay estimator 92 and the controller 93. In the architecture of the code unit 91 of the previous case, the code delay estimator 92 must have a merging unit 921, and the merging unit 921 needs to perform a squaring operation, so that the complexity of the code delay estimator 92 is increased, resulting in The cost of hardware implementation of the signal tracking system has increased.

The main object of the present invention is to provide a signal tracking apparatus and method, which can be applied to tracking different satellite signals.

A secondary object of the present invention is to provide a signal tracking apparatus and method that has a lower complexity.

In order to achieve the foregoing object, the technical means for the present invention comprises: a satellite signal tracking device, comprising: a code generator, generating a BOC code and a PRN code; a shift register unit, connecting the code a generator, the shift temporary storage unit receives the BOC code and the PRN code, and shifts the BOC code to generate a BOC leading code, a BOC backward code and a PRN alignment code; a hybrid operation unit, connecting The shifting temporary storage unit performs a mixing operation of the BOC leading code, the BOC backward code and the PRN alignment code with a satellite signal CBOC, and obtains a leading correlation value, a backward correlation value and a Aligning the correlation value; a discriminator, connecting the hybrid operation unit, the discriminator receiving the leading correlation value, the backward correlation value, and the alignment correlation value, and outputting a correction signal through a correlation function calculation; and a control And connecting the discriminator and the shift register unit, the controller receives the correction signal and outputs a control signal to the shift register unit.

The satellite signal tracking device of the present invention, wherein the discriminator's correlation function is:

D _coh ( τ ) = N _coh [D _CB ( τ ) -α D _CP ( τ )] ,

D _CB ( τ ) = R _CB ( τ+ (d/2)) - R _CB ( τ- (d/2)) ;

D _CP ( τ ) = R _CP ( τ ) ;

D _coh ( τ ) is the correction signal, R _CB ( τ+ (d/2)) is the backward correlation value of CBOC for BOC interaction, and R _CB ( τ- (d/2)) is CBOC for BOC interaction operation. Leading correlation value, R _CP ( τ ) is the alignment correlation value of CBOC for PRN interaction operation, N _coh is an adjustable parameter, and α is an adjustment factor.

The satellite signal tracking device of the present invention, wherein the code generator has a primary carrier generator, a PRN generator and a mixing unit, and an output of the secondary carrier generator and an output of the PRN generator are connected to the mixing unit The input.

In the satellite signal tracking device of the present invention, the hybrid operation unit has a plurality of mixing units and a plurality of integral correlation operation units for performing the mixing operation. .

The satellite signal tracking device of the present invention, wherein the mixing unit is a multiplication unit.

The satellite signal tracking device of the present invention, wherein the controller has a loop filter and a numerically controlled oscillator, the loop filter is coupled to the discriminator, and the numerical control oscillator is coupled to the loop filter and the shift register unit.

The above and other objects, features, and advantages of the present invention will become more apparent from the aspects of the invention. Some components of a conventional GNSS signal receiver, such as a GPS receiver, etc., are used to receive a satellite signal.

Referring to FIG. 2, the satellite signal tracking device of the present invention comprises a code generator 1, a shift register unit 2, a hybrid operation unit 3, a discriminator 4 and a controller 5. The code generator 1 inputs the generated code into the shift temporary storage unit 2, and the shift register unit 2 shifts the code to a chip rate, and then inputs the code to the hybrid operation unit 3. Performing an operation with a satellite signal, and then sending the operation result to the discriminator 4 to obtain a correction signal, and finally transmitting the correction signal to the controller 5, and controlling the shift register unit 2 through the controller 5 Shift code rate.

The code generator 1 mainly generates a BOC code and a PRN code. The code generator 1 can be provided with a primary carrier generator 11 and a PRN generator 12 as in the embodiment. The PRN generator 12 is directly generated. a PRN code; the secondary carrier generator 11 can generate a primary carrier code, and mix the secondary carrier code with the PRN code through a mixing unit 13, thereby outputting a BOC code. The mixing unit 13 can be any conventional mixing calculation, or a multiplication unit as in this embodiment, and is not limited herein.

The shift register unit 2 is connected to the code generator 1 and receives the BOC code generated by the code generator 1 and the PRN code. After entering the shift register unit 2, the PRN code is directly output as one. PRN alignment code: After the BOC code enters the shift register unit 2, the BOC code is first shifted in the code rate forward and backward, and then a BOC leading (Early) code is output, and a BOC is behind (Late )Telegraphic code. The shift register unit 2 can have a shift register 21 and a register 22, and the shift register 21 can perform temporary storage and code on the received BOC code. The rate shifts to output the BOC leading code and the BOC backward code; the register 22 temporarily stores the received PRN code and triggers the output of the PRN alignment code at an appropriate time. The lead code rate and the backward code rate are freely adjustable, and are generally between 0 and 1. For example, the embodiment is set at a 1/2 code rate.

The hybrid operation unit 3 is connected to the shift temporary storage unit 2, and receives the BOC leading code, BOC backward code, PRN alignment code and a satellite signal CBOC code, and obtains a leading correlation value through an interaction operation. Correlation values and an alignment correlation value. The satellite signal CBOC code can be a carrier or signal transmitted by the satellite system. In this embodiment, the hybrid operation unit 3 obtains a plurality of correlation calculation values by transmitting the BOC leading code, the BOC backward code, and the PRN alignment code to the satellite signal CBOC code through the plurality of mixing units 31, and then A plurality of correlation operation values are input to the plurality of integral correlation operation units 32 to obtain the leading correlation value, the backward correlation value, and the alignment correlation value. The number mixing unit 31 and the integral correlation operation unit 32 may be any related operation manners, which are not limited herein, or as in this embodiment, the number mixing unit 31 is a multiplication unit.

The discriminator 4 is connected to the hybrid operation unit 3 to receive the lead correlation value, the backward correlation value, and the alignment correlation value, and output a correction signal. Since the BOC code may have a secondary peak after being output by the shift register unit 2, in order to eliminate the secondary peak, a correlation function must be used to remove the secondary peak, so that the signal is correctly locked. The correlation function is set in the discriminator 4 and is expressed by a formula as follows:

D _coh ( τ ) = N _coh [-D _CB ( τ )- α D _CP ( τ )] (1)

among them

D _CB ( τ ) = R _CB ( τ+ (d/2)) - R _CB ( τ -(d/2)) ,

D _CP ( τ ) = R _CP ( τ ) ,

D _coh ( τ ) : correction signal,

N _coh : adjustable parameters,

α: adjustment factor,

R _CB ( τ+ (d/2)) : the backward correlation value of CBOC for BOC interaction

,

R _CB ( τ- (d/2)) : the leading correlation value of CBOC for BOC interaction,

R _CP ( τ ) : the alignment correlation value of the CBOC for the PRN interaction operation,

The discriminator 4 inputs the leading correlation value, the backward correlation value and the alignment correlation value into the above formula, wherein the adjustable parameter N _coh is determined according to the received signal power intensity and the signal sampling rate; the adjustment factor α The value can be changed as appropriate, whereby the size of the function distribution of the discriminator 4 is finely adjusted to eliminate the residual signal peak, and finally the correction signal D _coh ( τ ) is transmitted.

The controller 5 is connected to the discriminator 4 and the shift register unit 2 to receive the correction signal output by the discriminator 4, and adjust the shift code rate of the shift register unit 2 by the correction signal. . The controller 5 can have a loop filter 51 and a number control oscillator 52 as in this embodiment. The loop filter 51 is connected to the discriminator 4 to receive the correction signal and perform signal Filtering, and then outputting the filtered correction signal, the value control oscillator 52 is connected to the loop filter 51 and the shift register unit 2 to receive the filtered correction signal, and output a control signal to the shift The temporary storage unit 2 adjusts the shift code rate of the BOC leading code and the BOC backward code in the shift temporary storage unit 2, so that the tracking of the signal is better and more accurate.

Referring to FIG. 2 and FIG. 3, the satellite signal tracking method of the present invention includes a code generating step S1, a code shifting step S2, a correlation value generating step S3, a modified signal generating step S4, and a code shifting adjustment. Step S5.

The code generating step S1 is to generate a BOC code and a PRN code by using the code generator 1. In this embodiment, the PRN generator 12 directly generates a PRN code; and the secondary carrier generator 11 is used to generate the PRN code. The carrier code is mixed with the subcarrier code and the PRN code through a mixing unit 13, and the BOC code is output.

The code shifting step S2 is to shift and temporarily store the BOC code and the PRN code, and output the PRN alignment code, the BOC leading code and the BOC backward code, which may be utilized in the embodiment. The register 21 receives the BOC code, and outputs the BOC leading code and the BOC backward code; the temporary memory 22 temporarily stores the PRN code, and then outputs the PRN alignment code.

The correlation value is generated in step S3, and the satellite signal is received, and the satellite signal is correlated with the BOC leading code, the BOC backward code and the PRN alignment code to obtain the leading correlation value, the backward correlation value and the alignment. Relevant value. In this embodiment, the BOC leading code, the BOC backward code, and the PRN alignment code are respectively received by the frequency mixing unit 31, and the satellite signal is transmitted to each of the mixing units 31 for mixing operation, and then each The mixing result is separately transmitted to the number integral correlation operation unit 32 to obtain the leading correlation value, the backward correlation value, and the alignment correlation value.

The correction signal generating step S4 generates the correction signal by passing the leading correlation value, the backward correlation value and the alignment correlation value through a correlation function. The correlation function is as follows:

D _coh ( τ ) = N _coh [D _CB ( τ ) -α D _CP ( τ )]

A detailed description of the correlation function has been mentioned in the description of the discriminator 4 and will not be described again.

The code shift adjustment step S5 receives the correction signal and outputs the control signal to control the code rate of the code shift. In this embodiment, the correction signal first filters the correction signal through the loop filter 51, and the control signal 52 outputs the control signal to the shift register unit 2 through the value control, and adjusts the shift register unit. The BOC leads the code and the shift rate of the backward code of the BOC.

In this embodiment, the BOC leading code, the BOC backward code and the PRN alignment code generated by the shift temporary storage unit 2 are respectively correlated with the satellite signal to output the leading correlation value and the backward correlation. Value and alignment related values. And the leading correlation value, the backward correlation value and the alignment correlation value do not need to go through a merging unit to obtain a combined correlation value, but are directly sent to the discriminator 4, and the correlation function of the discriminator 4 is obtained. The correction signal, the correlation function does not need to square the leading correlation value, the backward correlation value, and the alignment correlation value, thereby reducing the complexity of the hardware implementation.

The satellite signal tracking device and method of the invention can eliminate the secondary peak of the signal carrier when the signals of different satellite systems are transmitted, and has the functions suitable for different satellite systems.

The satellite signal tracking device and method of the present invention have low hardware complexity and have the effect of reducing hardware cost.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

[this invention]

1. . . Code generator

11. . . Secondary carrier generator

12. . . PRN generator

13. . . Mixing unit

2. . . Shift register unit

twenty one. . . Shift register

twenty two. . . Register

3. . . Hybrid arithmetic unit

31. . . Mixing unit

32. . . Integral correlation unit

4. . . Discriminator

5. . . Controller

51. . . Loop filter

52. . . Numerically controlled oscillator

[知知]

91. . . Code unit

92. . . Code delay estimator

921. . . Merging unit

93. . . Controller

Figure 1: A conventional satellite signal tracking device.

Figure 2: Satellite signal tracking device of the present invention.

Figure 3: Satellite signal tracking step of the present invention.

1. . . Code generator

11. . . Secondary carrier generator

12. . . PRN generator

13. . . Mixing unit

2. . . Shift register unit

twenty one. . . Shift register

twenty two. . . Register

3. . . Hybrid arithmetic unit

31. . . Number mixing unit

32. . . Number integral correlation unit

4. . . Discriminator

5. . . Controller

51. . . Loop filter

52. . . Numerically controlled oscillator

Claims (9)

A satellite signal tracking device comprises: a code generator, which generates a BOC code and a PRN code; a shift register unit connected to the code generator, the shift register unit receives the BOC code and the PRN The code, and shifting the BOC code to generate a BOC leading code, a BOC backward code and a PRN alignment code; a hybrid operation unit connecting the shift register unit, the hybrid operation unit is leading the BOC The code, the BOC backward code and the PRN alignment code are respectively mixed with a satellite signal CBOC, and a leading correlation value, a backward correlation value and an alignment correlation value are obtained; a discriminator is connected to the hybrid operation unit, The discriminator receives the leading correlation value, the backward correlation value, and the alignment correlation value, and outputs a correction signal through a correlation function calculation; and a controller that connects the discriminator and the shift temporary storage unit, the control The device receives the correction signal and outputs a control signal to the shift temporary storage unit; wherein the correlation function of the discriminator is: D _coh ( τ ) = N _coh [D _CB ( τ ) -α R _CP ( τ )] , D _CB ( τ ) = R _CB ( τ+ (d/2)) - R _CB ( τ- (d/2)) ; and D _CP ( τ ) = R _CP ( τ ) ; D _coh ( τ For the correction signal, R _CB ( τ+ (d/2)) is the backward correlation value of the CBOC interaction with the BOC, and R _CB ( τ- (d/2)) is the leading correlation value of the CBOC interaction with the BOC. R _CP ( τ ) is the alignment correlation value of CBOC for PRN interaction operation, N _coh is an adjustable parameter, and α is an adjustment factor. The satellite signal tracking device according to claim 1, wherein the code generator has a primary carrier generator, a PRN generator and a mixing unit, and the output of the secondary carrier generator and the output of the PRN generator The terminal is connected to the input of the mixing unit. The satellite signal tracking device according to claim 1, wherein the hybrid operation unit has a plurality of mixing units and a plurality of integral correlation operation units to perform the mixing operation. The satellite signal tracking device according to claim 2, wherein the mixing unit is a multiplication unit. The satellite signal tracking device according to claim 1, wherein the controller has a loop filter and a numerically controlled oscillator, the loop filter is connected to the discriminator, and the numerical control oscillator is connected to the loop filter and The shift register unit. A satellite signal tracking method includes: a code generation step of generating a BOC code and a PRN code by using a code generator; and a code shifting step of transmitting the BOC code and the PRN code through a shift register unit Performing rate shifting and temporary storage processing, and outputting a PRN alignment code, a BOC leading code and a BOC backward code; a correlation value generating step of receiving a satellite signal and respectively respectively, the satellite signal CBOC BOC leading code, BOC backward code and PRN alignment code are mixed to obtain a leading correlation value, a backward correlation value and an alignment correlation value; a correction signal generation step is to correlate the leading correlation value and the backward correlation The value and the alignment correlation value are input to a correlation function to generate a correction signal; and a code shift adjustment step is to receive the correction signal by using a controller, and output a control signal to control the code rate of the code shift; Where the correlation function is: D _coh ( τ ) = N _coh [D _CB ( τ )- α D _CP ( τ )] , D _CB ( τ ) = R _CB ( τ+ (d/2)) - R _CB ( τ -(d/2)) ; and D _CP ( τ ) = R _{C P} ( τ ) ; D _coh ( τ ) is the correction signal, R _CB ( τ+ (d/2)) is the backward correlation value of CBOC for BOC interaction, and R _CB ( τ- (d/2)) is CBOC For the leading correlation value of BOC interaction operation, R _CP ( τ ) is the alignment correlation value of CBOC for PRN interaction operation, N _coh is an adjustable parameter, and α is an adjustment factor. The satellite signal tracking method according to claim 6, wherein the hybrid operation of the correlation value generating step comprises a mixing operation and an integral correlation operation. According to the satellite signal tracking method of claim 6, wherein the code generation step performs a mixing operation with the PRN code using a primary carrier code to obtain the BOC code. The satellite signal tracking method according to claim 7 or 8, wherein the mixing operation is a multiplication operation.