JPS61284686A - Gps navigation device - Google Patents

Abstract

PURPOSE:To perform precise position measurement by reading an optimum arrangement satellite number out of a memory and selecting a satellite which is optimum in current position, altitude, and time immediately. CONSTITUTION:The optimum arrangement satellite number is calculated previously on the basis of parameters of a position, altitude, and time, and the result is stored in a memory 13 for the optimum arrangement satellite number. A satellite radio wave received by an antenna 10 is processed by a reception arithmetic processing part 11 to measure the current position, altitude, and time of a vehicle. Then, the satellite number which is measurable with the optimum measurement precision at the current position, altitude, and time is read out of the memory 13 and compared with a satellite number which is received currently to change satellites when necessary, thereby measuring the position with the best measurement precision.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a GPS navigation device that receives signals from satellites, calculates and displays a user's position.

(Conventional technology) For users who move from time to time, such as ships and aircraft,
In recent years, GPSff
The usefulness of the L11 device is attracting attention.

This GPS positioning device.

■ Can be used continuously all over the world at any time.

■ Extremely high accuracy in measuring position and speed.

■ There is no limit to the number of users.

From this perspective, GP
The object that uses the S positioning device is a ship.

This is not limited to aircraft (it should also apply to vehicles such as cars).

In particular, if it can be used to avoid traffic congestion in urban areas, confirm one's current location in a short time, and find a detour to a destination, one hour can have a huge economic effect. Let's be.

However, in order to obtain the best positioning accuracy, conventional GPS navigation devices always calculate the GDOP (accuracy degradation due to satellite geometry) value using a combination of four satellites from the currently visible satellites.

(Problem to be Solved by the Invention) Therefore, in order to find the best combination of satellites for the above-mentioned GDOP value, it is necessary to calculate the GDOP value using 126 combinations, for example, assuming that there are 9 visible satellites. The drawback was that it took a long time to find the best combination. Also, to shorten the time required for this calculation.

This method requires a high-speed, high-performance calculator, which has the disadvantage of increasing the price of the GPS navigation device.

(Means for Solving the Problem) In order to solve this drawback, the present invention calculates the optimum satellite number for placement in advance using the parameters of position, altitude, and time, and uses this result as the position.

By installing a memory stored in the GPS navigation device to make it easier to explore based on the altitude and time, and reading out the optimum placement satellite number from the memory as needed, it is possible to determine the optimum position and altitude at the time. It instantly selects a satellite and constantly performs highly accurate position measurements and provides them to the user.

(Embodiment) The figure is a block diagram of an embodiment of the device of the present invention. In the figure, 10 is an antenna, 11 is a reception calculation processing section, and 12
1 is a display unit, and 13 is a memory for optimally placed satellite numbers.

Next, the operation will be explained.

As is well known, when measuring the traveling speed, direction, and current location of a moving object such as a ship, vehicle, or aircraft using a GPS satellite, the amplitude of the transmitted GPS radio waves is interpreted as a change in voltage. Therefore, from among the transmitted radio waves of a plurality of artificial satellites, an artificial satellite is selected from which a voltage related to the transmitted radio waves of a predetermined level or higher can be obtained.

That is, in the reception arithmetic processing section 11, the frequency of the GPS satellite transmission radio wave modulated by the PN code is converted by a frequency converter, and this is amplified. In other words, since the radio waves transmitted from the GPS satellite are spread spectrum by the PN code, they are despread by the signal from the PN code generator and then synchronized. Detection is performed. This synchronous detection signal is reintroduced to the PN code generator, and the signal generation control of the PN code generator is performed so that despreading is always performed with the radio waves containing the PN code that are transmitted. - The signals related to the received radio waves obtained in this way are counted based on the clock frequency sent from the reference oscillator to obtain pseudorange data.

In other words, since there is a time offset between the clock device mounted on the moving object and the atomic clock mounted on the artificial satellite, pseudorange data is obtained here as distance data that includes this time offset. .

By the way, as described above, when the reception calculation processing unit 11 obtains the pseudoranges to four satellites from the satellite radio waves received by the satellite reception antenna 10 through the above process, this pseudorange data.

A positioning navigation equation is created using the satellite positions of the four satellites derived from the navigation message data that has already been received, and this is solved (thereby, the current position and altitude of the vehicle are determined. This is output to the display unit 12.The reception calculation processing unit 11 determines the optimal satellite number based on the measured position and altitude2 time.
□ Read the number of the satellite that can measure the position with the best measurement accuracy at the current position and altitude 2 time from the bone memory 3, compare it with the satellite number currently being received, and replace it if there is a satellite that needs to be changed. It is possible to perform positioning with the best measurement accuracy and always provide the user with a highly accurate position.

(Effect of the invention〕 As mentioned above, the present invention uses information such as current location and altitude.

Since the optimal satellite number can be searched for in a short time using time, if the present invention is applied to an object moving at high speed, the position with the best measurement accuracy can always be calculated. Furthermore, there is an advantage that the cost of the pGPs navigation system can be reduced by replacing the high-speed, high-performance calculator necessary for calculating the GDOP value with an inexpensive calculator.

[Brief explanation of drawings]

The figure is a layout diagram of a GPS navigation device according to the present invention. DESCRIPTION OF SYMBOLS 10... Antenna, 11... Reception calculation processing part, 12
...Display section, 13...Memory for optimally placed satellite number.

Claims (1)

[Claims] An antenna that receives radio waves from the artificial satellites that make up the GPS, and the altitude of the current location from the received signal from the antenna.
A reception calculation processing unit that detects a signal for calculating the time and calculates the altitude and time of the current position based on this signal, a display unit that outputs the position etc. calculated by the reception calculation processing unit, and the area to be navigated from now on. 1. A GPS navigation device comprising: a memory for an optimally placed satellite number storing a GPS optimally placed satellite number calculated in advance based on the positional altitude and time of the GPS navigation device.