JPH0782085B2 - Satellite navigation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a satellite that is mounted on a vehicle such as an automobile and receives signals from a satellite to calculate and display the current position and speed of the vehicle. It relates to navigation equipment.

[Conventional technology]

BACKGROUND ART Conventionally, there is a GPS (Global Positioning System) navigation device as a satellite navigation device mounted on a vehicle such as an automobile.

To obtain the user's position three-dimensionally with the GPS navigation device,
Find three unknowns of three components (X, Y, Z) in the earth center and the earth fixed coordinate system. The relational expression between this unknown and latitude, longitude, and height is well known. Since the calculation is performed by the signal obtained by one-way propagation of the radio wave from the satellite to the user, the transmitter (satellite) and the receiver (user) should have highly accurate and well-matched clocks. Therefore, it is necessary to take a method of directly measuring the propagation time of the radio wave with the two clocks. However, it is not practical to equip each user with such a highly accurate timepiece. Therefore, the user receives the radio waves from a plurality of satellites at the same time, and calculates the position of the user from the pseudo-range data including the no time offset between each satellite and the user and the position data of each satellite. That is, it is necessary to add the time T that matches the satellite clock as another unknown number, and solve the four unknown numbers (X, Y, Z, T) in addition to the three unknown numbers related to the position. For that purpose, it is necessary to receive radio signals from four satellites scattered in the sky. Since there is little change in height in a moving body such as an automobile, even if there is a slight error in height, the two-dimensional position of latitude and longitude is rarely misaligned. for that reason,
Height contains known numbers, 3 unknowns latitude from 3 satellites,
Two-dimensional positioning is performed by solving the longitude and time.

Such a GPS navigation device has the advantage that it has higher positioning accuracy than other navigation devices, such as a dead reckoning device that calculates an estimated position from the measurement data of an azimuth sensor and a rangefinder, so it has received particular attention recently. There is.

[Problems to be solved by the invention]

However, when traveling in an area where there are many radio wave obstacles such as buildings such as an urban area such as an automobile, it is often impossible to receive the direct wave from the satellite in a normal state. On the other hand, it often receives various abnormal radio waves such as reflected waves from buildings, combined waves of reflected waves and direct waves, and direct waves attenuated by forests and overpasses. When the GPS navigation device receives this radio wave and calculates the position, there is a problem that an incorrect result is obtained.

The present invention has been made to solve such a problem, and is a satellite navigation device capable of calculating an accurate position even when an automobile or the like is traveling in an area with many radio interference such as an urban area. Is provided.

[Means for solving problems]

As a result of repeating a number of positioning tests with the conventional GPS navigation device, the present inventors attenuated the intensity of the reflected wave from a building or the like, or the radio wave affected by an overpass or the like, or a composite wave. Grows stronger. Therefore, it was found that the signal level was out of the range when the signal was received directly (in the case of normal reception). It was also found that the pseudo range data measured by receiving the reflected wave is extremely different from the pseudo range data measured by receiving the reflected wave, and has poor continuity.

In order to solve the above problems, a satellite navigation device to which the present invention is applied based on such knowledge will be described with reference to the block diagram of FIG. As shown in the figure, the satellite navigation device of the present invention has an antenna unit 11 for receiving a plurality of satellite radio waves.
A receiving unit 12 that demodulates the navigation data of the received satellite radio waves to measure a pseudo distance, a positioning calculation unit 13 that calculates the position of the operating body from the navigation data and the pseudo distance, and a display unit that displays the position of the operating body. 14 and a determination circuit 15. Judgment circuit
15, in order to determine whether the propagation of satellite radio waves being received is normal, in order to determine whether the signal level during reception is obtained from the receiving unit, the signal level is compared with preset upper limit signal level and lower limit signal level. Means for determining whether or not the signal level falls between an upper limit signal level and a lower limit signal level, and a pseudorange measured for the satellite being received is obtained from the receiving unit, and the pseudorange and the same satellite as before. Between the upper limit signal level and the lower limit signal level, and a means for determining whether or not the difference between the pseudo distances measured and stored in step 1 is within a preset limit value. And a means for outputting a calculation stop signal to the positioning calculation section when the difference between the pseudo distances is not within the limit value.

[Action]

Antenna section 11, receiving section 12, positioning calculation section 13 and display section 14
The position of the operating body is calculated and displayed according to the conventional method.
The judging circuit 15 compares the received satellite signal level (strength) with the reference signal level and compares the pseudo distances of the respective satellites in time series to make a judgment. If the satellite signal level deviates from the reference signal level, or if the measured pseudorange discontinuously differs greatly from the pseudorange for each satellite, it is considered that an abnormal radio wave is being received. So
The determination circuit 15 issues an instruction to stop the calculation to the positioning calculation unit 13.
As a result, the display unit 14 does not display an incorrect position.

〔Example〕

Hereinafter, embodiments of the satellite navigation device to which the present invention is applied will be described in detail.

FIG. 1 is a block diagram of an embodiment of the satellite navigation device of the present invention. In the figure, 11 is an antenna unit that receives satellite radio waves, 12 is a receiving unit that demodulates navigation data and measures pseudoranges, 13 is a positioning calculation unit that solves a known navigation equation, and 14 is a display that includes a cathode ray tube display, etc. Reference numeral 15 is a determination circuit. FIG. 2 is a flowchart showing the operation of the decision circuit 15. The determination circuit 15 compares the received signal level with the lower limit signal level and the upper limit signal level and outputs a determination signal when the signal level is lower than the lower limit signal level or higher than the upper limit signal level, and in the previous measurement. Means to store the pseudo range of each satellite, to find the difference from the corresponding pseudo range of each satellite in this measurement, and to compare with a preset limit value And means for outputting a computation stop signal to the positioning computation unit when the discrimination signal of the pseudo level difference is outputted together with the discrimination signal of the signal level.

Next, the operation will be described.

The satellite signal received from the antenna unit 11 enters the receiving unit 12 where the navigation data is demodulated and the pseudorange is measured. Receiver 12
Sends the navigation message data of the satellite and the pseudo range data of the satellite to the positioning calculation unit 13. The positioning calculation unit 13 calculates the position of the vehicle by solving a navigation equation combining these data. The position is output to the display unit 14.

While operating according to the ordinary method as described above, the decision circuit 15
Operates in the procedure shown in the flowchart of FIG. The signal level of each satellite is detected from the receiving unit 12 (step 101), and this signal level is compared with preset lower limit signal level and upper limit signal level and the signal level is below the lower limit signal level (step 102) or upper limit signal level. In the above case (step 103), the discrimination signal is output. Further, the pseudo range x of each satellite is obtained from the receiving unit 12 (step 10
4) Find the difference Δx from the previous pseudo distance x ₀ (step 1
05). The difference Δx is compared with a preset limit value, and when the difference is equal to or larger than the limit value, a discrimination signal is signaled (step 106).
If neither of the discrimination signal obtained in step 102 or step 103 and the discrimination signal obtained in step 106 is output, it means that the reception is normal, and the position of the vehicle is determined by the operation of the satellite navigation device described above. ,
The position is displayed. When both of these discrimination signals are output (step 108), since abnormal radio waves are being received, the positioning calculation unit 13 is instructed to perform calculation (step 109).

〔The invention's effect〕

As described above, the satellite navigation device to which the present invention is applied is not normal in a reflected wave, a synthetic wave, an attenuated direct wave, or the like when a vehicle equipped with the device travels in an area with many radio interference such as an urban area. When the radio wave is being received, the positioning is stopped, so that the wrong position is not displayed.

Therefore, it is most suitable for application to automobiles and the like that travel in areas where there are many radio interference.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a satellite navigation device to which the present invention is applied, and FIG. 2 is a flow chart showing an operation procedure of a decision circuit. 11 …… antenna section, 12 …… reception section, 13 …… positioning calculation section, 14 …… display section, 15 …… determination circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Harumasa Hojo 5-1-1 Shimorenjaku, Mitaka-shi, Tokyo Japan Radio Co., Ltd. (72) 5-1-1 1-1 Shimorenjaku, Mitaka-shi, Tokyo (72) Inventor Noboru Yamaoka 5-1-1, Shimorenjaku, Mitaka-shi, Tokyo Within Japan Radio Co., Ltd. (72) Inventor, Mikio Nakamura 5-1-1, Shimorenjaku, Mitaka-shi, Tokyo Within Japan Radio Co., Ltd. ( 72) Inventor Yasuyuki Uekusa, Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Hisao Kishi, 2 Takaramachi, Kanagawa-ku, Yokohama, Kanagawa Prefecture, Nissan Motor Co., Ltd. (72) Hideo Takai Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (56) Reference JP 61-137009 (JP, A) JP 6 0-15573 (JP, A) JP 61-70698 (JP, A) JP 56-162924 (JP, A) JP 60-108778 (JP, A)

Claims (1)

[Claims] 1. An antenna unit for receiving a plurality of satellite radio waves,
A receiving unit that demodulates the navigation data of the received satellite radio waves to measure a pseudo distance, a positioning calculation unit that calculates the position of the operating body from the navigation data and the pseudo distance, and a display unit that displays the position of the operating body. In the satellite navigation device, the signal level of the satellite radio wave being received is obtained from the receiving unit, and the signal level is compared with preset upper limit signal level and lower limit signal level. Means for determining whether or not the level is within the level, and the pseudo range measured for the satellite being received is obtained from the receiving unit, and the pseudo range and the pseudo range previously measured by the same satellite and stored. Means for comparing to determine whether the difference between the pseudo distances is within a preset limit value; and the signal level is not between the upper limit signal level and the lower limit signal level, and Satellite navigation device, characterized in that the difference between the serial pseudoranges with a decision circuit and means for outputting a signal of the operational discontinuation in the measurement position calculation unit when not within the limits.