JPH0829515A - Gps receiver - Google Patents

Abstract

PURPOSE:To enhance the positioning accuracy of receiving position being calculated based on the phase of a pseudo noise code by enhancing the phase locking accuracy thereof. CONSTITUTION:Based on a designated number and a phase, a pseudo noise code generator 21 generates a pseudo noise code which is fed to a despread spectrum processing section 22 and multiplied by an intermediate frequency signal. An LPF 23 removes high frequency components from I signal and Q signal produced through the despread spectrum processing. A phase control section 26 scans the phase and detects such phase as a signal passed through the LPF 23 has an amplitude higher than a predetermined value before making a transition to phase lock processing. During the phase lock processing, the phase control section 26 swings the phase from a central phase and a section 24 calculates the phase difference of pseudo noise code based on the relationship between the phase difference from the central phase and the amplitude of single passed through the LPF 23. The control gain is multiplied by the phase difference at the phase control section 26 depending on the average level of I and Q signals determined at an average signal level calculating section 25 and a central phase signal thus obtained is inputted to the pseudo noise code generator 21 in order to calculate a pseudo distance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS receiver which performs phase synchronization control by obtaining a phase difference from the relationship between the phase difference from the center phase and the signal amplitude.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a schematic configuration of a conventional GPS receiver. In FIG. 2, the GPS receiving apparatus includes an antenna 1 for receiving radio waves from three or four GPS satellites flying in the sky, a high-frequency amplification for a received signal from the antenna 1, and a frequency conversion. The reception processing unit 2 that outputs the intermediate frequency signal S1 is provided. Further, the intermediate frequency signal S from the reception processing unit 2
1 and the pseudo noise code number signal S2 are input, and the pseudo noise code phase synchronization control unit 3 for outputting the pseudo noise code phase signal S3 according to the received signal level and changing the phase synchronization control gain is provided. There is.

A data demodulation unit 4 for demodulating a navigation message and GPS satellite time from a signal S4 output from the pseudo noise code phase synchronization control unit 3, demodulated data from the data demodulation unit 4 and a pseudo noise code phase signal S3. Is input and outputs position information obtained by calculating a reception position (for example, two-dimensional information of latitude and longitude), and a display unit for displaying the position information from the position calculation unit 5 on a screen or the like. 6
Are provided.

FIG. 3 is a block diagram showing the configuration of the pseudo noise code phase synchronization control unit 3 shown in FIG. In FIG.
The pseudo noise code phase synchronization control unit 3 receives the pseudo noise code number signal S2 and generates a pseudo noise code signal, and an intermediate frequency signal from the reception processing unit 2 in FIG. Spectrum despreading unit 1 for multiplying S1 and the pseudo noise code from the pseudo noise code generator 11
2 are provided. Further, a low-pass filter (LPF) 13 that outputs a signal S4 that is an I signal and a Q signal from which a high-frequency component of the pseudo-noise code signal from the spectrum despreading processing unit 12 is removed, and the low-pass filter 13 Based on the phase difference calculation unit 14 for calculating the phase difference of the pseudo noise code signal and the phase difference signal from the phase difference calculation unit 14, the phase of the pseudo noise code signal generated by the pseudo noise code generator 11 is controlled, A phase control unit 16 for outputting the pseudo noise code phase signal S3 to the position calculation unit 5 in FIG. 2 is provided.

The operation of the pseudo noise code phase synchronization control unit 3 configured as described above will be described below.

The pseudo noise code generator 11 generates a pseudo noise code having a number and a phase designated by the pseudo noise code number signal S2. The pseudo noise code signal generated by the pseudo noise code generator 11 is the spectrum despreading processing unit 12
To the intermediate frequency signal S1 which is simultaneously input. After this, the high frequency component generated by the multiplication in the spectrum despreading processing unit 12 is passed through the low pass filter 13
The signal S4 removed in step S6 is output. In this case, as the phase pull-in process, the phase control unit 16 detects a phase in which the amplitude of the signal passed through the low-pass filter 13 becomes a certain value or more while scanning the phase, and shifts to the phase synchronization process.

During the phase synchronization processing, the phase controller 16 shifts the phase within a range of ± 1 chip from the central phase, and the phase difference calculator calculates the phase difference from the central phase and the amplitude of the signal passed through the low pass filter 13. At 14, the phase difference of the pseudo noise code is obtained. The phase controller 16 multiplies the phase difference obtained by the phase difference calculator 14 by the control gain to obtain the central phase.
The phase obtained by the phase controller 16 is fed back to the pseudo noise code generator 11 and used for calculating a pseudo distance between the GPS satellite for calculating the reception position and the reception position.

The transmission power from each GPS satellite is constant, and the electric field strength (reception signal level) received by the GPS receiver is inversely proportional to the square of the distance between the GPS satellite and the reception position. The electric field strength (received signal level) of the GPS satellite located directly above and the GPS satellite located near the horizon is about 3: 2. Therefore, the phase gain used by the phase control unit 16 is set to a value with which phase synchronization can be achieved for signals in this range.

As described above, in the pseudo noise code phase synchronization control unit 3 of the conventional GPS receiver, the phase difference is obtained from the relationship between the phase difference from the central phase and the signal amplitude passed through the low pass filter 13. Control of phase synchronization can be performed.

[0010]

However, in the GPS receiver of the conventional example, all G signals having different reception signal levels are used.
Since the same phase synchronization control gain is used for PS satellites, this phase synchronization control gain cannot be optimized.
Therefore, the phase synchronization accuracy of the pseudo noise code is poor, and the positioning accuracy of the reception position performed through the phase of the pseudo noise code is deteriorated.

The present invention solves such a conventional problem, and improves the phase synchronization accuracy of the pseudo noise code, and improves the positioning accuracy of the reception position calculated through the phase of the pseudo noise code. It is intended to provide a receiving device.

[0012]

In order to achieve the above object, a GPS receiving apparatus according to a first aspect of the present invention has a receiving means for outputting a reception signal of a radio wave of a GPS satellite, and a designated number and phase. Pseudo-noise code generating means for generating a pseudo-noise code, and spectrum despreading processing for outputting a spectrum despreading I signal and Q signal obtained by multiplying a received signal from the receiving means and a pseudo-noise code from the pseudo-noise code generating means. Means, phase difference calculation means for detecting the phase difference between the signals from the spectrum despreading processing means, average signal level calculation means for calculating the average signal level of the signal from the spectrum despreading processing means, and phase at the time of phase pull-in , And the phase difference from the phase difference calculation means is multiplied by the control gain based on the average level from the average signal level calculation means during phase synchronization. It has a configuration and a phase control means for outputting the diacritics generating means.

In the GPS receiving apparatus according to the second aspect, the average signal level calculating means squares the I signal and the Q signal, respectively, and calculates the square root value of the added value, or the I signal and the Q signal.
The average signal level is set to either the sum of the absolute values of the signals or the absolute value of only the I signal.

[0014]

With such a structure, the G according to claims 1 and 2
The PS receiver detects the phase difference of the signal of the spectrum despread which is obtained by multiplying the received signal and the pseudo noise code from the pseudo noise code generating means, and further calculates the average signal level,
During phase synchronization, the phase difference is multiplied by a control gain based on the average level to control the phase in the pseudo noise code generation means. That is, the phase synchronization control is performed using the optimized phase synchronization control gain of the pseudo noise code corresponding to the received signal level. Therefore, the phase synchronization accuracy of the pseudo noise code is improved, and the positioning accuracy of the reception position calculated through the phase of the pseudo noise code is improved.

[0015]

Embodiments of the GPS receiving apparatus of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a pseudo noise code phase synchronization control unit provided in the GPS receiver of the present invention. Since the configuration of this GPS receiver is the same as the configuration shown in FIG. 2 previously, the description will be given here by using FIG. 2 redundantly. In FIG. 1, the pseudo-noise code phase synchronization control unit 3 shown in FIG.
2 is input to multiply the pseudo noise code generator 21 for generating a pseudo noise code signal, the intermediate frequency signal S1 from the reception processing unit 2 shown in FIG. 1 and the pseudo noise code from the pseudo noise code generator 21. A spectrum despreading processing unit 22 is provided.

Further, the signal S4 from which the high frequency component of the pseudo noise code signal from the spectrum despreading processing unit 22 is removed
There is provided a low pass filter (LPF) 23 for outputting and a phase difference calculator 24 for calculating the phase difference of the pseudo noise code signal from the low pass filter 23. Also, an average signal level calculator 25 for averaging the pseudo noise code signals (I signal and Q signal) from the low pass filter 23,
The phase of the pseudo noise code signal generated by the pseudo noise code generator 21 is controlled based on the phase difference signal from the phase difference calculation section 24, and the pseudo noise code phase signal S3 is output to the position calculation section 5 shown in FIG. The phase control unit 26 is provided.

Next, the operation of this embodiment will be described. The pseudo noise code generator 21 generates a pseudo noise code having a number and a phase designated by the pseudo noise code number signal S2. The pseudo noise code signal generated by the pseudo noise code generator 21 is input to the spectrum despreading processing unit 22 and is multiplied by the intermediate frequency signal S1 input at the same time.
After that, the high-frequency component generated by multiplication in the spectrum despreading processing unit 22 is removed by the low-pass filter 23, and the signal S4 which is the I signal and Q signal thereof is output.
The number of the pseudo noise code is designated by the pseudo noise code number signal S2 from the position calculation unit 5 shown in FIG. 2, and the phase of the pseudo noise code is designated by the phase control unit 26.

In this case, the phase control unit 26 performs the phase pull-in process while scanning the phase and the low-pass filter 23.
A phase in which the amplitude of the signal passing through is equal to or greater than a certain value is detected, and the process proceeds to phase synchronization processing. During the phase synchronization processing, the phase control unit 26 shifts the phase within a range of ± 1 chip from the center phase, and the phase difference from the center phase and the low pass filter 2
The phase difference of the pseudo noise code is obtained by the phase difference calculation unit 24 from the relationship of the signal amplitudes passing through 3. Further, the average signal level calculation unit 25 obtains the average signal level of the signal S4 that is the I signal and the Q signal that has passed through the low pass filter 23. This averaging level is obtained by the following [Equation 1] [Equation 2] [Equation 3], respectively.

[0020]

[Equation 1]

[0021]

[Equation 2]

[0022]

(Equation 3) [Equation 2] and [Equation 3] simplify the calculation, and the approximated average level is obtained. The reason why only the I signal in [Equation 3] is set to the average level is that the factors are concentrated on the I signal. The phase control unit 26 calculates the center phase by multiplying the phase difference calculated by the phase difference calculation unit 24 by the control gain according to the average signal level calculated by the average signal level calculation unit 25. The phase obtained by the phase control unit 26 is fed back to the pseudo noise code generator 21 and used for calculating the pseudo distance between the GPS satellite for calculating the reception position and the reception position.

[0023]

As is apparent from the above description, according to the GPS receivers of claims 1 and 2, the optimized phase synchronization control gain is used for the pseudo noise code corresponding to the received signal level. Since the phase synchronization control is performed by using the pseudo noise code, the phase synchronization accuracy of the pseudo noise code is improved, and the positioning accuracy of the reception position calculated through the phase of the pseudo noise code is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a pseudo noise code phase synchronization control unit provided in a GPS receiving device of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a GPS receiving device.

3 is a block diagram showing a configuration of a pseudo noise code phase synchronization control unit 3 shown in FIG.

[Explanation of symbols]

 2 reception processing unit 3 pseudo-noise code phase synchronization control unit 5 position calculation unit 21 pseudo-noise code generator 22 spectrum despreading processing unit 23 low-pass filter 24 phase difference calculation unit 25 average signal level calculation unit 26 phase control unit S1 intermediate Frequency signal S2 Pseudo-noise code number signal S3 Pseudo-noise code phase signal S4 signal

Claims (2)

[Claims] 1. A receiving means for outputting a received signal which receives a radio wave of a GPS satellite, a pseudo noise code generating means for generating a pseudo noise code having a designated number and phase, a received signal from the receiving means and the A spectrum despreading means for outputting a spectrum despreading I signal and a Q signal multiplied by the pseudonoise code from the pseudonoise code generation means, and a phase difference for detecting a phase difference between the signals from the spectrum despreading means. A calculation means, an average signal level calculation means for calculating an average signal level of the signal from the spectrum despreading processing means, a phase is scanned at the time of phase pull-in, and the average of the phase differences from the phase difference calculation means at the time of phase synchronization is obtained. A phase control means for multiplying the control gain based on the average level from the signal level calculation means and outputting it to the pseudo noise code generation means. PS receiver. 2. The average signal level calculating means squares the I signal and the Q signal, respectively, and calculates the square root value of the added value, or the added value of the absolute values of the I signal and the Q signal, or the I signal. The GPS receiving apparatus according to claim 1, wherein any one of the absolute values of the two is used as the average signal level.