JPH0727845A - GPS receiver - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to demodulate navigation data by preventing transition of navigation data during addition processing of correlation detection output and enabling demodulation of navigation data without performing intermediate value processing. Keep it simple. A GPS receiver that receives radio waves from a plurality of satellites and measures the position, speed, and time of a reception point from the information contained in the received radio waves. A signal tracking unit 30 including a plurality of signal tracking means 32a to 32n for extracting information required for measurement.
And a control unit 60 that controls the signal tracking means 32a to 32n and measures the reception position. The plurality of signal tracking means 32a to 32n are each synchronized with the repetition cycle of the GPS satellite signal to be tracked. A PN code generator 34 is provided, and each of the PN code generators 34 shifts the PN code frequency and phase of the satellite to be searched on a predetermined time axis, searches for a specific GPS satellite signal, and performs the search. Is configured to capture and track the GPS satellite signals of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS receiver used in a global positioning system (abbreviated as GPS), and more particularly to a plurality of GPS satellites (GPS satellites). GP that receives a radio wave transmitted from a satellite), processes the information superimposed on the received radio wave, and measures the position of the reception point.
The present invention relates to an S receiver.

[0002]

2. Description of the Related Art GP in a global satellite navigation system
The S receiver receives GPS radio waves transmitted from a plurality of satellites, and based on a pseudo noise signal (hereinafter referred to as a PN code) superimposed on the radio waves and 50 bits / second navigation data, The position of the receiving device is measured.

As is well known, the PN code is a code string composed of a chip rate of 1.023 MHz and 1023 chips in one cycle, and has a code string unique to each satellite. Then, as shown in FIG. 3A, the repetition cycle of the PN code (hereinafter, the repetition cycle is referred to as an epoch).
Is 1 msec. And is synchronized with GPS navigation data.

As is well known, the measurement of the position of the receiving point in the GPS receiver is performed by receiving GPS radio waves from three or more satellites and measuring the distance between each satellite and the receiving point. For the measurement of, the PN code peculiar to each satellite superimposed on each radio wave is tracked, the navigation data is received, the time difference between the time when the navigation data is transmitted and the time when the navigation data is received is detected, and the navigation data is demodulated, You need to decrypt it.

Usually, in a GPS receiving device, the correlation between the PN code of the received signal from the satellite and the PN code generated in the receiving device is determined by the repetition period of the PN code of 1 ms.
ec. Each epoch signal is compared at the same time, and the satellite signal is captured and tracked by obtaining the correlation of all chips (1023 chips) of the PN code. Based on the correlation result, the navigation data is demodulated and decoded to obtain the navigation data. The time difference from the time of satellite transmission to the time of satellite reception is detected.

The conventional GPS receiver 2 is constructed as shown in FIG. 3B, and as a means for obtaining the correlation of all chips of the PN code, addition processing is generally performed. That is, in FIG. 3B, the navigation data and the PN code, which are the received signals from the satellites, are input to the correlation unit 4 that performs the correlation processing. On the other hand, in the GPS receiver 2, based on the reference signal generated by the reference signal generator 6, the timing generator 8 generates a timing signal that substantially matches the epoch signal.

GPS generated by the timing generator 8
The addition unit 12 is controlled via the addition control unit 10 based on the timing signal on the receiving device 2 side, and the addition processing of the signals detected by the correlation unit 4 is performed. The control unit 14 controls the correlation processing of the correlation unit 4 and the generation of the timing signal of the timing generator 8.

[0008]

FIG. 4 is a time chart for explaining the addition processing in the conventional GPS receiver 2 shown in FIG. 3, in which (a) is the navigation data of satellite A,
(B) is the PN code epoch signal of satellite A, (c) is the navigation data of satellite B, (d) is the PN code epoch signal of satellite B, and (e) is generated by the timing generator 8 of GPS receiver 2. 3 shows a receiver timing signal according to the present invention. Further, (f) shows the added value of the receiving channel A (satellite A side), (g) shows the demodulated signal thereof, (h) shows the added value of the receiving channel B (satellite B side), and (i) shows the demodulated signal. Shows the signal.

Normally, when the GPS receiver 2 receives a plurality of GPS satellite signals, the epoch signals of the PN codes of the satellites A and B and the navigation data are as shown in (a) to (d) of FIG. It is asynchronous at the receiving point. This is the same for other satellites, and the description will be given here using satellite A and satellite B as an example.

Therefore, the PN code generated inside the GPS receiver 2 and its epoch signal may be asynchronous with the epoch signal of any of a plurality of satellites, and the navigation data of the asynchronous satellite is also asynchronous. Become. GPS
Unique timing signal (e) generated in the receiver 2
By 1 msec. When detecting the correlation of the PN code for each interval, as shown in (f) and (g) of the receiving channel A and (h) and (i) of the receiving channel B in FIG. The correlation output is constant, and the added value shows two values, the maximum value when the navigation data is "1" and the minimum value when the navigation data is "0". It is possible to demodulate the navigation data by observing the state of the added value indicating this binary value.

However, the navigation data (a) and (c)
In the section where the transition of the value occurs, since the transition occurs in the middle of the addition processing section, the correlation output is reversed, and the added value does not show the maximum value or the minimum value, but takes the intermediate value. For this reason, in the conventional GPS receiving apparatus 2, there is a disadvantage that an accurate demodulated signal of the navigation data cannot be obtained unless the intermediate value processing means for deriving the transition of the navigation data from the intermediate value is used.

The present invention has been made to solve the above-mentioned inconvenience, and simplifies the navigation data demodulation process in the GPS receiver, that is, synchronizes with the epoch signals of a plurality of satellites. It is an object of the present invention to provide a GPS receiving device capable of demodulating navigation data without performing the intermediate value process by adding the correlation outputs of GPS satellite signals using a plurality of timing signals.

[0013]

In order to achieve the above object, the present invention receives radio waves from a plurality of GPS satellites, and based on the information contained in the received radio waves, the position of the reception point,
In a GPS receiver that measures speed and time, a. An antenna for receiving radio waves from the GPS satellites; b. High frequency processing means for deriving a high frequency signal having a predetermined frequency and amplitude from the antenna output signal; c. Analog / digital conversion means for converting the analog output signal of the high frequency processing means into a digital signal; d. A signal tracking section having a plurality of signal tracking means for extracting information required for tracking GPS satellite signals and measuring position from the digital output signal of the analog / digital converting means; e. And control means for controlling the signal tracking means and measuring the reception position, f. Each of the plurality of signal tracking means has a GP to be tracked.
It has a signal tracking control means for synchronizing with the repetition period of the S satellite signal, and each of the signal tracking control means shifts the PN code frequency and phase of the GPS satellite to be searched for on a predetermined time axis, and a specific GPS It is characterized in that the satellite signal is searched for, and the specific GPS satellite signal is captured and tracked.

According to the present invention, in the GPS receiving apparatus, each of the plurality of signal tracking means includes a PN code received from a GPS satellite to be tracked and a PN code generated in the signal tracking means. It is characterized by including a comparing means for comparing, and performing tracking of a specific GPS satellite signal by comparing the received PN code with the PN code generated in the signal tracking means.

Further, according to the present invention, in the GPS receiving apparatus, each of the plurality of signal tracking means further includes a carrier comparison means, and an addition unit for adding the PN code comparison result and the carrier comparison result, It is characterized by comprising an addition control section for controlling the addition section based on an epoch signal generated from the signal tracking control means.

[0016]

In the GPS receiver according to the present invention, 1.023
A clock signal of MHz is generated from the reference signal generator and supplied to the PN code generator in the plurality of signal tracking means. The PN code generator functions as a signal tracking control unit, generates a desired PN code to be tracked at a predetermined frequency and phase based on a reference signal (clock signal) from the reference signal generation unit, and also generates a PN code. Of 1 msec. Generates an epoch signal for each
The frequency and phase of the PN code and the epoch signal are adjusted by the control from the control unit, and signal tracking and control are performed.

On the other hand, the PN code comparison unit compares the PN code in the received signal from the satellite input via the analog / digital conversion means with the PN code generated by the PN code generator, Correlate the PN code. If all chips of the PN code match on the time axis by the PN code comparison unit, the correlation result is PN.
By despreading the code, a signal obtained by removing the PN code from the input signal is obtained.

Similarly, in the carrier comparison unit, the carrier signal in the received signal from the satellite and the carrier detection signal generated by the carrier detection signal generator are phase-compared, and the carrier signal is converted from the input signal. The component (carrier component) is also removed, and the navigation data, that is, GPS
Information required for tracking satellite signals and measuring positions is extracted.

The addition unit adds the comparison results of the PN code comparison unit and the carrier comparison unit to compare all chips of the PN code. At this time, the addition unit is controlled by the addition control unit that receives the PN code epoch signal generated from the PN code generator as an input, and at the same period as the PN code epoch signal generated from the PN code generator. ,
The PN code comparison result and the carrier comparison result are added.

The frequency and phase of the PN code generated from the PN code generator of each signal tracking means are adjusted according to the frequency and phase of the PN code received from the satellite to be tracked for each reception channel. PN code 1
The period of the epoch signal (timing signal for addition control of the addition unit) generated for each period is also adjusted, and synchronization with the reception navigation data is established for each reception channel.

As a result, in the addition section of each reception channel, the addition value of the comparison result by the PN code comparison section and the carrier comparison section shows a binary value of the maximum value and the minimum value corresponding to the content of the received navigation data. , The intermediate value is not taken, and a plurality of specific Gs are independently provided for each reception channel.
The correlation output output from the addition unit obtained by tracking and capturing the PS satellite signal is sent as it is to the control unit as a demodulation signal of navigation data, and the control unit measures the reception point.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A GPS receiver according to the present invention will be described below in detail with reference to the accompanying drawings, with reference to a preferred embodiment. FIG. 1 is a diagram showing a schematic configuration of a GPS receiving device according to the present invention.

In FIG. 1, the GPS receiver 20 includes an antenna 22, a high frequency converter 24, an analog / digital converter 26, a reference signal generator 28, a signal tracking unit 30,
It is composed of a control unit 60, an output unit 70, and the like. Radio waves from the satellite are received from the antenna 22, and the high frequency converting means 24 derives a high frequency signal having a predetermined frequency and amplitude. The analog output signal of the high frequency converting means 24 is converted from an analog signal to a digital signal by the analog / digital converting means 26 and input to the signal tracking section 30.

The reference signal generating means 28 generates a reference signal and inputs it to the high frequency converting means 24 and the signal tracking section 30. The reference signal generating means 28 can be composed of, for example, a frequency divider that receives a clock signal having an integer multiple frequency of 1.023 MHz of the chip plate, and a clock of 1.023 MHz which is the output of the frequency divider. Use the signal as a reference signal. The control unit 60 includes the signal tracking unit 30.
Is controlled, the data obtained from the signal tracking unit 30 is processed, and, for example, position data is measured and output to the outside via the output means 70.

The signal tracking section 30 is composed of signal tracking means 32a, 32b, ..., 32n (reception channels A to N) for individually tracking and capturing a plurality of GPS satellite signals. Each signal tracking means 32a, 32b,
.., 32n have the same configuration, the following description will be given using the signal tracking means 32a (reception channel A) as a typical example.

The signal tracking means 32a includes a PN code generator 34, a PN code comparison unit 36, a carrier detection signal generator 38, a carrier comparison unit 40, an addition unit 42, and an addition control unit 4.
The PN code generator 34 generates a desired PN code to be tracked at a predetermined frequency and phase on the basis of the reference signal (clock signal) from the reference signal generating means 28. 1 msec, which is the code repetition period. Each epoch signal is generated, and these signals are tracked by the signal tracking means 32a to 32a as described later.
Used for signal tracking control in 2n. In this sense
The PN code generator 34 functions as a signal tracking control means.

The PN code generator 34 is also controlled by the control unit 60 to generate the frequency of the PN code,
The phase can be adjusted at any time. Similarly, the carrier detection signal in the GPS receiver 20 is also generated by the carrier detection signal generator 38, and its frequency and phase can be adjusted at any time under the control of the control unit 60.

On the other hand, the PN code comparing section 36 compares the PN code in the received signal from the satellite input through the analog / digital converting means 26 with the PN code generated by the PN code generator 34. Then, the correlation processing of both PN codes is performed. The PN code comparison unit 36
If all chips of the N code match on the time axis, the correlation result is a signal well known in the GPS receiver 20, and a signal in which the PN code is removed from the input signal is obtained by despreading the PN code.

Similarly, the carrier comparison unit 40 also compares the phase of the carrier signal in the received signal from the satellite with the carrier detection signal generated by the carrier detection signal generator 38, and compares it with the input signal. The carrier signal component (carrier component) is also removed, and the navigation data, that is,
Information required for tracking the GPS satellite signal and measuring the position is extracted.

The adding section 42 adds the comparison results of the PN code comparing section 36 and the carrier comparing section 40 in order to compare all chips of the PN code. At this time, the addition unit 42
Is controlled by the addition controller 44 which receives the PN code epoch signal generated from the PN code generator 34 as input, and at the same period as the PN code epoch signal generated from the PN code generator 34. The PN code comparison result and the carrier comparison result are added.

At the tracking stage of the GPS satellite signal, the PN code received from the GPS satellite signal and the GPS receiving device 20 for all the 1023 chips of the PN code.
When the frequency, phase, etc. of the PN code generated within the same match on the time axis, it can be determined that tracking or acquisition of a specific satellite has been performed.

For this comparison, the GPS receiving apparatus 20 of the present invention controls the addition unit 42 by the addition control unit 44 which receives the epoch signal of the PN code generated from the PN code generator 34 as described above. It is configured to perform addition processing of the PN code comparison result and the carrier comparison result at intervals of the same period as the epoch signal. For example, a counter is used as the addition unit 42 and the addition control unit 44 Is configured to perform operation control such as reset or hold on the adder 42 based on the epoch signal.

Next, the process of adding the correlation outputs of GPS satellite signals in the GPS receiver 20 according to the present invention will be described. FIG. 2 is a time chart for explaining the addition processing in the GPS receiving device 20, and in FIG.
(A) is the navigation data of satellite A, (b) is the PN code epoch signal of satellite A, (c) is the navigation data of satellite B,
(D) shows the PN code epoch signal of satellite B. Further, (f) shows the added value of the receiving channel A (satellite A side), (g) shows the demodulated signal thereof, (h) shows the added value of the receiving channel B (satellite B side), and (i) shows the demodulated signal. Shows the signal.

(E1) and (e2) are reception channels A and B
Is a reception timing signal in the signal tracking means 32.
The epoch signal generated by the PN code generator 34 of a or 32b is added to the addition controller 44 as a reception timing signal.
Is input to.

Here, in the PN code generator 34 and the carrier detection signal generator 38, as described above, the frequency and phase of the generated PN code and the carrier detection signal are adjusted as needed under the control of the control unit 60. The control unit 60 performs the signal tracking means 32a to 32n (reception channels A to N) so that each of them tracks and captures another specific GPS satellite signal. The frequencies and phases of the PN code and the carrier detection signal generated from the PN code generator 34 and the carrier detection signal generator 38 of 32a to 32n are adjusted as needed.

Therefore, according to the frequency and phase of the PN code received from the satellite to be tracked for each reception channel,
PN code generator 3 of each signal tracking means 32a to 32n
The frequency and phase of the PN code generated from 4 are adjusted,
Along with this, as shown in (e1) and (e2) of FIG. 2, the cycle of the epoch signal (timing signal for addition control of the adding section 42) generated for each cycle of the PN code is also adjusted, and Synchronization with the reception navigation data is established for each reception channel.

As a result, in the addition section 42 of each reception channel, the addition value of the comparison result by the PN code comparison section 36 and the carrier comparison section 40 is 2 of the maximum value and the minimum value corresponding to the content of the received navigation data. It shows a value and never takes an intermediate value. This is because in the navigation data (a) and (c), the synchronization with the received navigation data is established by the timing signals (e1) and (e2) for each satellite, and the section where the transition of the value occurs is added. This is because it does not occur in the middle of the processing section.

Normally, in the GPS receiver 20, 3
The position of the reception point is measured by processing the reception signals from more than one satellite. In the GPS receiver 20 of the present invention, the reception channel is independently operated for each reception channel as described above. The correlation output output from the adding unit 42 obtained by tracking and capturing a plurality of specific GPS satellite signals is sent as it is to the control unit 60 as a demodulation signal of navigation data, and the control unit 60 measures the position of the reception point. The position data can be output from the output means 70.

[0039]

According to the GPS receiver of the present invention,
The following effects can be obtained. That is, in the present invention,
In order to obtain synchronization by adjusting the PN code of the GPS satellite signal to be tracked and captured, the frequency and phase of the epoch signal, etc. for each of a plurality of reception channels, and in order to achieve synchronization, the addition result is the result of the addition of the received navigation. The maximum value and the minimum value are shown in correspondence with the contents of the data, the intermediate value is not taken, and the correlation output output from the adder can be used as it is as the demodulation signal of the navigation data. As described above, intermediate value processing in the addition processing of navigation data is not required. Therefore, the demodulation process of the navigation data can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a GPS receiver according to the present invention.

FIG. 2 is a time chart showing a process of adding correlation outputs of a PN code and a PN code received from a satellite in the GPS receiving apparatus according to the present invention.

FIG. 3 is a diagram showing a configuration of a GPS receiver according to a conventional example.

FIG. 4 is a time chart showing a process of adding a correlation output between a PN code and a PN code received from a satellite in a GPS receiving apparatus according to a conventional example.

[Explanation of symbols]

20 ... GPS receiver 22 ... Antenna 24 ... High frequency conversion means 26 ... Analog / digital conversion means 28 ... Reference signal generation means 30 ... Signal tracking part 32a-32n ... Signal tracking means 34 ... PN code generator 36 ... PN code comparison part 38 ... Carrier detection signal generator 40 ... Carrier comparison unit 42 ... Addition unit 44 ... Addition control unit 60 ... Control unit 70 ... Output means

Claims (3)

[Claims] 1. Receiving radio waves from a plurality of GPS satellites,
A GPS receiving device that measures the position, speed, and time of a receiving point from the information included in the received radio wave, comprising: a. An antenna for receiving radio waves from the GPS satellites; b. High frequency processing means for deriving a high frequency signal having a predetermined frequency and amplitude from the antenna output signal; c. Analog / digital conversion means for converting the analog output signal of the high frequency processing means into a digital signal; d. A signal tracking section having a plurality of signal tracking means for extracting information required for tracking GPS satellite signals and measuring position from the digital output signal of the analog / digital converting means; e. And control means for controlling the signal tracking means and measuring the reception position, f. Each of the plurality of signal tracking means has a GP to be tracked.
It has a signal tracking control means for synchronizing with the repetition period of the S satellite signal, and each of the signal tracking control means shifts the PN code frequency and phase of the GPS satellite to be searched for on a predetermined time axis, and a specific GPS A GPS receiver configured to search for a satellite signal and capture and track the specific GPS satellite signal. 2. The GPS receiver according to claim 1, wherein
Each of the plurality of signal tracking means includes a comparison means for comparing a PN code received from a GPS satellite to be tracked with a PN code generated in the signal tracking means, and the received PN code and the signal tracking means. A GPS receiver characterized by performing tracking of a specific GPS satellite signal by comparing with a PN code generated in the GPS receiver. 3. The GPS receiver according to claim 2, wherein
Each of the plurality of signal tracking means further includes a carrier comparison means, and adds based on an epoch signal generated from the signal tracking control means and an addition unit that adds the comparison result of the PN code and the comparison result of the carrier. GPS comprising an addition control unit for controlling the unit
Receiver.