JP2000056007A - Gps receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a GPS receiver shortening the time from power-on to position calculation in the environment having many radio wave interruptions. SOLUTION: This GPS receiver is provided with a GPS antenna 1 receiving the signal from a GPS satellite, a signal demodulation section 2 demodulating and converting the signal into data of a bit train, a data analysis section 3 extracting the orbit information of the GPS satellite via a data analysis, and a position calculation section 4 calculating the position of the receiver, based on the orbit information of the GPS satellite and the reception time of the signal. The data analysis section 3 is provided with a judgment control means judging whether the data are collected in a word unit so that data can be intermittently collected even when data cannot be continuously received by radio wave interruptions. The time required for collecting the orbit information is shortened, and the time from power-on to position calculation is shortened.

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 an on-vehicle navigation system and the like, and particularly to a GPS receiver configured to shorten the time from power-on to position calculation in an environment where radio waves are frequently interrupted.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional GPS receiver. In FIG. 5, the GPS receiver is a GPS receiver.
GPS antenna 1 for receiving signals from satellites (not shown)
A signal demodulation unit 2 for synchronizing signals with a plurality of GPS satellites (not shown) and demodulating data, a data analyzing unit 7 for analyzing data and extracting orbit information of the GPS satellites, A position calculating unit 4 that calculates the position of the receiver using the orbit information of the GPS satellites and the reception time of the signal.

Next, the operation of the above-mentioned conventional GPS receiver will be described. GPS (Global Positioning System)
In the case of using a satellite, the signal demodulation unit 2 includes a GPS antenna 1
Performs a frequency conversion and a despreading process of multiplying the received signal by a code specific to each GPS satellite.
A signal is demodulated by multiplying the frequency shift of the carrier generated by the relative speed between the receiver and the GPS satellite by a sine wave of the same frequency to extract bit string data.

[0004] Data transmitted from a GPS satellite is called a navigation message, and its structure has a format as shown in FIG.

The data analysis unit 7 finds the beginning of the data from the bit string data by the processing procedure shown in FIG.
The orbit information of the S satellite is extracted.

[0006] That is, in FIG.
Then, the preamble at the head of each subframe having the format configuration as shown in FIG. 7B is detected, and in step 62, 30 bits are collected from the head. Note that 30
The bits constitute a word as shown in FIG.

Next, in step 63, a parity check is performed every time 30 bits are collected. If there is an error, the process returns to step 61 to detect the preamble again. If there is no error in the parity, the process proceeds to step 64, and this is repeated until all the subframes 1 to 3 are collected. When all of subframes 1 to 3 can be collected, the process proceeds to step 66, where each variable of the GPS satellite orbit information is extracted.

[0008] The position calculator 4 obtains the position of the GPS receiver using the reception time of the signal from the signal demodulator 2 and the orbit information of each GPS satellite from the data analyzer 7.

[0009]

However, in the above-mentioned conventional GPS receiver, there must be no parity error until all of the sub-frames 1 to 3 can be collected. Therefore, it is necessary to collect orbit information in an environment where radio waves are frequently interrupted. There has been a problem that the time from the power-on to the position calculation may be long.

[0010]

According to a first aspect of the present invention, there is provided a GPS antenna for receiving a signal from a GPS satellite, a demodulation of the signal, and a bit stream of data. A signal demodulator for converting the data into a data, a data analyzer for analyzing data to extract orbit information of the GPS satellite, and a position calculator for calculating the position of the receiver using the orbit information of the GPS satellite and the reception time of the signal. The data analysis unit is provided with a judgment management means of whether or not data can be collected in word units, so that data can be intermittently collected in word units even when data cannot be continuously received due to radio wave interruption. It was done.

According to a second aspect of the present invention, in addition to the parity check, judgment management based on signal amplitude is also performed as judgment management means for judging whether data has been collected in word units, thereby collecting data. This is to improve the reliability of all judgment management.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a GPS receiver comprising a GPS antenna, a signal demodulation unit, a data analysis unit, and a position calculation unit, wherein the data analysis unit Is provided with means for determining and managing whether or not data has been collected in word units, so that even if data cannot be continuously received due to radio wave interruption, data can be intermittently collected in word units.

According to a second aspect of the present invention, in addition to the parity check, judgment management based on signal amplitude is performed as judgment management means for judging whether or not data has been collected in word units, thereby collecting data. This has the effect of increasing the reliability of all judgment management.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a diagram showing the configuration of a GPS receiver according to a first embodiment of the present invention. In FIG. 1, the GPS receiver transmits a signal from a GPS satellite. GPS antenna 1 for receiving and a plurality of GPS satellites
(Not shown) a signal demodulation unit 2 for synchronizing a signal with respect to a signal and demodulating data,
It comprises a data analysis unit 3 for extracting the orbit information of the satellite, and a position calculation unit 4 for calculating the position of the receiver using the orbit information of the GPS satellite and the reception time of the signal.

Next, the operation of the first embodiment will be described. The signal demodulation unit 2 converts the frequency of the signal received by the GPS antenna 1 and converts each signal into GPS satellites (not shown).
A despreading process of multiplying by a unique code is performed.
The signal is demodulated by multiplying the frequency shift of the carrier generated by the relative speed between the PS receiver and the GPS satellite by a sine wave of the same frequency to extract bit string data.

The data transmitted from the GPS satellite is called a navigation message, and has a structure as shown in FIG. 7A.

The data analysis unit 3 finds the head of the data from the bit string data and extracts the orbit information of the GPS satellite by the processing procedure shown in FIG. At this time, a word collection flag for managing whether or not each word of subframes 1 to 3 has been collected is used.

That is, in FIG.
Then, the preamble at the head of each subframe having the format configuration as shown in FIG. 7B is detected, and then, in step 22, all bits of the word collection flag are cleared. Then, in step 23, 30 bits are collected. The 30 bits make up a word as shown in FIG. 7 (c).

Next, in step 24, a parity check is performed every 30 bits. If there is no error, it is determined that the word has been collected, and in step 25, the corresponding bit of the word collection flag is turned on. If there is an error in the parity check, step
Proceed to 26. Then, the steps of 30-bit collection and parity check are repeated until all the words necessary for position calculation, such as the orbit information of the GPS satellites included in the subframes 1 to 3 in the format as shown in FIG. If all necessary words can be collected in step 26, each variable of the GPS satellite orbit information is extracted in step 27.

Although words unnecessary for position calculation such as words containing only reserved data included in subframes 1 to 3 need not be collected, in order to simplify management of data collection, subframes 1 to 3 are used. All three words may be collected.

The position calculator 4 obtains the position of the GPS receiver using the reception time of the signal from the signal demodulator 2 and the orbit information of each GPS satellite from the data analyzer 3.

(Second Embodiment) FIG. 3 is a diagram showing a configuration of a GPS receiver according to a second embodiment of the present invention. In FIG. 3, the GPS receiver transmits a signal from a GPS satellite. GPS antenna 1 for receiving and a plurality of GPS satellites
(Not shown) A signal demodulation unit 5 for synchronizing a signal with respect to a signal and demodulating data,
It comprises a data analysis unit 6 for extracting the orbit information of the satellite, and a position calculation unit 4 for calculating the position of the receiver using the orbit information of the GPS satellite and the reception time of the signal.

Next, the operation of the second embodiment will be described. The signal demodulation unit 5 performs a frequency conversion and a despreading process of multiplying a signal received by the GPS antenna 1 by a code unique to each GPS satellite (not shown), and further performs a relative spreading between the GPS receiver and the GPS satellite. The signal is demodulated by multiplying the frequency shift of the carrier generated by the speed by a sine wave of the same frequency to extract bit string data. Further, the signal amplitude is passed to the data analyzer 6.

The data sent from the GPS satellite is called a navigation message, and its structure has a format as shown in FIG.

The data analysis unit 6 finds the head of the data from the bit string data and extracts the orbit information of the GPS satellite by the processing procedure as shown in FIG. At this time, a word collection flag for managing whether or not each word of subframes 1 to 3 has been collected is used.

That is, in FIG.
At 41, the preamble at the head of each subframe having the format configuration as shown in FIG. 7B is detected, and then at step 42, all bits of the word collection flag are cleared. Then, in step 43, 30 bits are collected. The 30 bits make up a word as shown in FIG. 7 (c).

In step 44, it is checked whether the signal amplitude is larger than the threshold value every 30 bits are collected. If the signal amplitude is not larger than the threshold value, it is determined in step 44 that the radio wave has been interrupted, and the process returns to step 43. Perform 30-bit acquisition.

If it is determined in step 44 that the value is larger than the threshold value, the flow advances to step 45, where a parity check is performed. To If there is an error in the parity check in step 45, it is determined that the preamble is not erroneously detected but the radio wave is not interrupted, and the process returns to step 41 and returns to the preamble detection again.

In step 47, subframes 1 to 3
The 30-bit collection in step 43 and the parity check in step 45 are repeated until all the words necessary for position calculation, such as the orbit information of the GPS satellites included in the data, can be collected. Go ahead, G
Each variable of the orbit information of the PS satellite is extracted.

Although unnecessary words for position calculation such as words of only reserved data included in subframes 1 to 3 need not be collected, in order to simplify the management of data collection, subframes 1 to 3 are used. All three words may be collected.

The position calculator 4 obtains the position of the GPS receiver using the reception time of the signal from the signal demodulator 5 and the orbit information of each GPS satellite from the data analyzer 6.

[0033]

As described above, according to the first aspect of the present invention, since the data analysis unit is provided with the judgment management means for determining whether or not data has been collected in word units, Even if data cannot be received continuously due to interception, data can be intermittently collected in word units, so in environments where radio waves are frequently interrupted, the time required to collect orbit information can be reduced, and the time from power-on to position calculation can be reduced. It has the effect that it can be shortened.

According to the second aspect of the present invention, in addition to the parity check, the judgment management based on the signal amplitude is performed as the judgment management means for judging whether or not data has been collected in word units. The reliability of determination management by collecting data can be improved, the time required to collect orbit information in the case of a preamble erroneous detection can be reduced, and the time from power-on to position calculation can be reduced. Has an effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a GPS receiver according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a processing flow of a data analysis unit according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a configuration of a GPS receiver according to a second embodiment of the present invention;

FIG. 4 is a diagram showing a processing flow of a data analysis unit according to the second embodiment of the present invention;

FIG. 5 is a diagram showing a configuration of a conventional GPS receiver.

FIG. 6 is a diagram showing a processing flow of a data analysis unit in a conventional GPS receiver.

FIG. 7 is a diagram showing a data format configuration from a GPS satellite.

[Explanation of symbols]

 1 GPS antenna 2, 5 signal demodulation unit 3, 6, 7 data analysis unit 4 position calculation unit

Claims (2)

[Claims] 1. A GPS for receiving a signal from a GPS satellite
An antenna, a signal demodulation unit that demodulates a signal to convert the data into bit string data, and a GPS that analyzes data.
A data analyzing unit for extracting the orbit information of the satellite; and a position calculating unit for calculating the position of the receiver using the orbit information of the GPS satellite and the reception time of the signal. The data analyzing unit can collect data in word units. G is provided so that data can be intermittently collected in word units even when data cannot be received continuously due to radio wave interruption.
PS receiver. 2. As a means for managing whether or not data has been collected in word units, in addition to parity check,
The GPS receiver according to claim 1, wherein the reliability of determination management by collecting data is enhanced by performing determination management based on signal amplitude.