JPH11125666A - Gps receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a GPS receiver capable of quickly and properly performing position measuring calculation even in spite of poor reception environment. SOLUTION: This receiver is provided with a navigation data memory 18 storing whole demodulated navigation data, a clock part 26 outputting count signals indicating the present time and a satellite transmission time predictor 20 which compares a part of demodulated navigation data from a currently receiving satellite signals with a navigation data demodulator 16, detects the pit position of the currently receiving one and predicts the time data in the navigation data updated at every 6 seconds from the currently received one by using the pit position and the count signals and calculates the satellite prediction time when the stored navigation data in hot start (in the case track data in two hours is held) has not passed for two hours and is not updated. A position measuring operation part 22 obtains the position data of the user position by using the satellite prediction time in position measuring calculation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
(Global Positioning System
m) GPS for receiving and processing satellite signals transmitted from satellites
More specifically, the present invention relates to a GPS receiver that performs positioning calculation without demodulating time data of navigation data by utilizing that navigation data of a satellite signal is updated almost every two hours.

[0002]

2. Description of the Related Art Conventionally, as this kind of GPS receiver,
For example, one having a configuration as shown in FIG.
The GPS receiver includes an antenna 10 for receiving a plurality of satellite signals respectively transmitted from a plurality of GPS satellites, a frequency converter 12 for amplifying these satellite signals and converting them to an intermediate frequency signal having a predetermined frequency. A pseudo-range measuring unit 14 that measures a pseudo-range to a user position based on a plurality of frequency-converted satellite signals, and a pseudo-range measurement unit 14 that is updated at a predetermined cycle (usually a 6-second cycle) included in the frequency-converted satellite signals. A navigation data demodulation unit 16 for demodulating navigation data including time data and orbit data (ephemeris data) updated every predetermined time (usually every two hours), and pseudo-range and orbit data for each of a plurality of GPS satellites. Positioning calculation unit 22 that outputs the result of positioning calculation as user position data, and a plurality of GPS units based on the position data and the orbit data. It is made and a reception control arithmetic unit 24 for controlling the reception state of the pseudo-range measuring unit 14 and the navigation data demodulation unit 16 according to the result of determining the combinations of the predetermined number appropriate for the current positioning of the star.

In the case of this GPS receiver, first, at the time of a hot start (when the GPS receiver holds orbit data within two hours), the reception control arithmetic unit 24 controls the reception state to obtain the current position data, Time data,
And a predetermined number of GPS to search based on orbit data
Select a satellite (satellite signal).

[0004] Next, after capturing satellite signals from a predetermined number of GPS satellites selected by the control of the reception state of the reception control calculation section 24, the pseudorange measurement section 14 measures the pseudorange.

[0005] Further, the satellite transmission time is obtained by demodulating the Z count as time data in the navigation data by the navigation data demodulation unit 16, and thereafter, the positioning calculation unit 22 calculates the positioning based on the pseudo distance and the orbit data. And outputs the result as position data of the user position.

In this GPS receiver, it is necessary to obtain time data necessary for positioning calculation from the navigation data demodulation unit 16, but since this time data is transmitted in the navigation data at a period of 6 seconds, the data is not transmitted normally. Assuming that the demodulation has been successfully performed, it takes at least 6 seconds to obtain time data smoothly.

[0007]

In the case of the above-mentioned GPS receiver, a data demodulation time (shortest at 6 seconds, at most) for demodulating the Z count (time data) in the navigation data at the time of positioning calculation at the time of hot start. 12 seconds), it takes a time corresponding to the data demodulation time until the positioning calculation is actually performed.

In the case of the existing GPS receiver described above,
For example, in a place where the reception environment is bad, such as a building street, the Z count (time data) is not easily demodulated, so that there is a problem that positioning calculation is not performed depending on the reception environment.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a technical problem of the present invention is to provide a GPS receiver capable of performing quick and accurate positioning calculation even if the reception environment is not excellent. Is to do.

[0010]

According to the present invention, receiving means for receiving a plurality of satellite signals respectively transmitted from a plurality of GPS satellites, and measuring a pseudo distance to a user position based on the plurality of satellite signals Pseudo-range measuring means, and navigation data demodulating means for demodulating navigation data including time data updated at a predetermined cycle for each of a plurality of GPS satellites included in a plurality of satellite signals and orbit data updated at a predetermined time interval. Positioning calculation means for outputting a position calculation result based on pseudo-range and orbit data of each of a plurality of GPS satellites as position data of a user position, and a current position of a plurality of GPS satellites based on the position data and the orbit data. A reception control calculator that controls the reception state of the pseudo distance measuring means and the navigation data demodulating means according to the result of determining a suitable combination of predetermined numbers. In GPS receiver with bets,
Navigation data storage means for storing all of the demodulated navigation data, counting means for outputting the result of counting the current time as a count signal, and the stored navigation data being updated during a hot start without lapse of a predetermined time. While there is no navigation data demodulation means, a part of the navigation data demodulated from the satellite currently being received as a predetermined number of satellite signals is compared with the stored navigation data to detect the bit position of the currently received one. Satellite transmission time estimating means for calculating a satellite predicted time value by using a value predicted from the bit position and the count signal as time data, wherein the positioning operation means uses the satellite predicted time value at the time of positioning calculation. Is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is described below with reference to Examples.
The PS receiver will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a basic configuration of a GPS receiver according to one embodiment of the present invention. This GPS
In the case of the receiver, the same configuration as that of the conventional device shown in FIG. 3, that is, an antenna 10 for receiving a plurality of satellite signals respectively transmitted from a plurality of GPS satellites, and amplifying these satellite signals to obtain a predetermined signal A frequency conversion unit 12 for converting an intermediate frequency signal having a frequency, a pseudo distance measurement unit 14 for measuring a pseudo distance to a user position based on a plurality of frequency-converted satellite signals, and a plurality of frequency-converted satellite signals And a navigation data demodulation unit 16 for demodulating navigation data including time data updated in a 6-second cycle and orbit data updated every two hours, and pseudo-range and orbit data for each of a plurality of GPS satellites. A positioning calculation unit 22 that outputs the result of positioning calculation as position data of the user position, and is suitable for the current positioning of a plurality of GPS satellites based on the position data and the orbit data. And a reception control arithmetic unit 24 for controlling the reception state of the pseudo-range measuring unit 14 and the navigation data demodulation unit 16 according to the result of determining the combinations of the predetermined number.

However, in the case of this GPS receiver, a navigation data storage unit 18 for storing all of the navigation data newly demodulated by the navigation data demodulation unit 16 and a count signal (real-time time) And a clock unit 26 serving as a counting means for outputting the data as a predetermined number of satellite signals in the navigation data demodulation unit 16 while the stored navigation data is not updated within two hours during hot start. A part of the navigation data demodulated from the satellite in the middle is checked against the stored navigation data to detect the bit position of the currently received one, and the satellite prediction is performed using the value predicted from the bit position and the count signal as time data. A satellite transmission time estimating unit 20 for calculating a time value, and the positioning operation unit 22 uses the satellite estimated time value at the time of positioning calculation to calculate the position of the user position. Which is to obtain the data.

In this GPS receiver, a plurality of satellite signals respectively transmitted from a plurality of GPS satellites are received by an antenna 10, and these satellite signals are amplified by a frequency converter 12, and an intermediate signal having a predetermined frequency is transmitted. It is converted to a frequency signal. The satellite signal converted into the intermediate frequency signal is transmitted to the pseudo distance measuring unit 14 and the navigation data demodulating unit 16.

The pseudo-range measuring unit 14 measures the pseudo-range to the user position for the satellite signal of each of the predetermined number of GPS satellites selected by the reception control calculating unit 24. Here, the time required for transmission from the GPS satellite corresponding to the specific satellite signal to the user position is measured, and this time is converted into a distance. The distance obtained in this manner is called a pseudo distance because it includes an influence of an error of a clock mounted at the user position. This pseudo distance is transmitted to the positioning calculation unit 22.

The navigation data demodulation unit 16 demodulates the navigation data of the corresponding GPS satellite from the satellite signal for each of the predetermined number of GPS satellites selected by the reception control calculation unit 24. The navigation data includes time data indicating the transmission time of the GPS satellite that transmitted the satellite signal, orbit data, and data indicating a schematic orbit of each GPS satellite constituting the GPS. The navigation data demodulated here is stored in the navigation data storage 1
8, transmitted to the reception control calculation unit 24, the positioning calculation unit 22, and the satellite transmission time prediction unit 20. Incidentally, in the navigation data demodulation unit 16, when demodulating the navigation data from the satellite signals for each of the predetermined number of GPS satellites selected by the reception control calculation unit 24, it takes at least 6 seconds to demodulate the time data. In order to demodulate the orbit data, a minimum of 18 seconds is required.

The navigation data storage unit 18 stores all the demodulated navigation data as data of 12.5 minutes per cycle, and stores pages 1 to 25 of subframes 1 to 5, and stores the navigation data in a binary data sequence. Is transmitted to the satellite transmission time prediction unit 20.

The satellite transmission time estimating section 20 outputs a predetermined number of satellite signals from the satellite currently being received by the navigation data demodulating section 16 while the stored navigation data is not updated within two hours at the time of the hot start. The bit position of the currently received data is detected by searching and collating a part of the demodulated navigation data with the same string as the binary bit string of the stored navigation data stored in the navigation data storage unit 18.

For example, as shown in FIG. 2, the collation is performed from a buffer in the navigation data storage unit 18 here.
Assume that 00 bits are taken out, and if a part of the navigation data demodulated from the currently received satellite signal is 60 bits, a part of the 60-bit navigation data is converted into a bit with respect to the stored navigation data of 1500 bits. While comparing the data length, and detects the bit position of the currently received satellite signal.

The satellite transmission time prediction unit 20 uses the bit position and the count signal from the clock unit 26 (for example, a real-time clock having an accuracy within ± 2 seconds) to grasp the current accurate time and receive the current accurate time. Exists in the navigation data
The satellite prediction time value is calculated by predicting the Z count (time data) updated in the second cycle, and the satellite prediction time value is output to the positioning calculation unit 22.

As a method of calculating the prediction of the Z count, first, the clock section 26 outputs the current time as a count signal to the UT.
The day of the week, hour, minute, and second are acquired by C, and the GPS time is obtained by adding a leap second according to the unit of second, that is, GP.
A relationship of S time = UTC (second) + leap second is obtained, and from this, for example, the elapsed time ztime from midnight on Sunday
(Second) = (current time−reference time) / [7 (day) × 24
(Time) x 60 (minutes) x 60 (seconds)]
Next, the calculation of Z count = ztime / 6 + 1 may be performed.

Incidentally, here, +1 indicates the time of the next subframe in the Z count, and the Z count is GP.
This is a counter that counts up every 1.5 seconds with the start of the week at S time as 0. In the navigation data, the counter value is counted up every six seconds obtained by dividing this value by four.

Therefore, the positioning calculation unit 22 obtains position data using the satellite predicted time value from the satellite transmission time prediction unit 20 at the time of positioning calculation, and demodulates the Z count (time data) in the navigation data. The positioning calculation is performed without (without waiting for the demodulation).

In short, the GPS receiver has the navigation data storage unit 18 for storing all navigation data, so that the satellite transmission is not performed when the stored navigation data is not updated within two hours at the time of hot start. The time estimating unit 20 demodulates a part (for example, 60 bits) of the navigation data from the received satellite signal, and compares the demodulated data with the navigation data stored in the navigation data storage unit 18 to obtain the currently received satellite signal. After detecting the bit position, using the bit position and the count signal from the clock unit 26, the time data (Z
Count) to calculate a satellite predicted time value, and the positioning operation unit 22 functions to obtain position data of the user position using the satellite predicted time value. As a result, the pseudo distance and the position of the GPS satellite can be measured after the satellite transmission time is obtained without demodulating the time data in the navigation data, and the time until the positioning calculation is shortened.

[0025]

As described above, the GPS of the present invention
According to the receiver, the navigation data is entirely stored in the navigation data storage unit, and during the hot start, while the stored navigation data is not updated without the lapse of the predetermined time, the satellite transmission time estimation unit receives the navigation data from the received satellite signal. After detecting the bit position of the currently received satellite signal by comparing the demodulated part of the navigation data with the navigation data stored in the navigation data storage unit, the bit position and the count signal from the clock unit are detected. The predetermined period (6
Since the satellite prediction time value is calculated by predicting the time data (Z count) updated in the second cycle), the positioning calculation unit obtains the position data of the user position by using the satellite prediction time value. It is possible to measure the pseudo-range and position of GPS satellites by determining the satellite transmission time without demodulating the time data in the data. As a result, even if the reception environment is somewhat unsatisfactory, quick and accurate positioning calculation Can be performed. For example, compared to a conventional GPS receiver, the TTFF (time until the first positioning) can be reduced by about 6 to 12 seconds.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a GPS receiver according to one embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining verification of navigation data in a satellite transmission time prediction unit provided in the GPS receiver shown in FIG. 1;

FIG. 3 is a block diagram showing a basic configuration of a conventional GPS receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Antenna 12 Frequency conversion part 14 Pseudorange measurement part 16 Navigation data demodulation part 18 Navigation data storage part 20 Satellite transmission time prediction part 22 Positioning calculation part 24 Reception control calculation part 26 Clock part

Claims (1)

[Claims] 1. A receiving means for receiving a plurality of satellite signals respectively transmitted from a plurality of GPS satellites; a pseudo distance measuring means for measuring a pseudo distance to a user position based on the plurality of satellite signals; Navigation data demodulating means for demodulating navigation data including time data updated at a predetermined cycle for each of the plurality of GPS satellites and orbital data updated at a predetermined time included in the satellite signals;
Positioning calculation means for outputting a result of positioning calculation based on the pseudorange and the orbit data for each PS satellite as position data of the user position; and a current position of the plurality of GPS satellites based on the position data and the orbit data. A reception control calculating means for controlling a reception state of the pseudo-range measuring means and the navigation data demodulating means in accordance with a result of determining a predetermined number of combinations suitable for positioning.
In the S receiver, navigation data storage means for storing all of the demodulated navigation data, counting means for outputting the result of counting the current time as a count signal, While the navigation data is not updated without passing, a part of the navigation data demodulated from the currently received satellite as the predetermined number of satellite signals in the navigation data demodulation means is compared with the stored navigation data and Satellite transmission time estimation means for detecting a bit position of a currently received signal and calculating a satellite prediction time value using the bit position and a value predicted from the count signal as the time data, Is a GPS receiver for obtaining the position data by using the satellite predicted time value at the time of the positioning calculation.