JPH06100644B2 - Receiving method of GPS navigation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention switches radio waves from GPS (Global Positioning System) satellites for each of a plurality of satellites one by one, and receives the radio waves, for example, aircraft, ships, vehicles, etc. The method of receiving a GPS navigation device that measures the distance between a mobile body and each satellite to determine the position of the mobile body.

(Prior Art) Conventionally, as a reception system by this type of GPS navigation device, a one-channel sequential reception system in which satellites required for positioning are sequentially switched and received is known. This is as shown in FIG.
After collecting each orbital data (D _{1 to} D ₄ ) of ₄ satellites, switch at 1 second intervals and pseudo range from receiving point to each satellite (R ₁ to D ₄ ).
R ₄ ) is measured and the position of the receiving point is calculated to obtain (C).

The data transmitted from the GPS satellites consist of 5 subframes each of which has a length of 30 seconds and a length of 6 seconds. The first one subframe is clock correction and propagation correction data for pseudorange measurement, and the following two subframes are trajectory data.

Here, supplementing the explanation with respect to FIG. 6, FIG. 6 shows a conventional sequential time sequence. In FIG. 6, R _{1 to} R ₄ are pseudorange measurements, and D _{1 to} D ₄ are orbits. Data demodulation, C indicates positioning calculation, 1 for pseudorange measurement
It takes 18 seconds to collect each second and orbital data. It takes 1 second to measure the pseudorange because the PN transmitted from the satellite
This is because it usually takes a little less than 1 second to synchronize the phase (frequency) of the code (pseudo-noise code) with the PN code generated by the receiver.

(Problems to be Solved by the Invention) In such a conventional receiving system, it is normally 1-2 in order to perform switching for measuring the pseudorange to each satellite.
Since it takes seconds, when the moving body (reception point) is operating at high speed, the GPS navigation device and the satellite do not follow well,
There is a drawback that positioning cannot be performed when updating orbit data or changing satellite combinations.

(Means for Solving Problems) According to the present invention, at least a signal for measuring pseudoranges of a plurality of satellites used for positioning calculation is used during a period of 1 bit (20 mS) of orbit data from the satellite. The reception of signals from one satellite and the reception of 1-bit orbit data of satellites that need to collect orbit data are performed sequentially, and the orbit data of all the satellites used for positioning and the measured pseudo data are acquired. The positioning calculation is performed using the distance data to eliminate the unpositionable time when updating the orbit data or changing the combination of satellites used for positioning, which will be described in detail below with reference to the drawings.

(Example) FIG. 1 and FIG. 2 and FIG. 3 are diagrams for explaining the method of the present invention, where R _{1 to} R ₄ are pseudorange measurements from satellite 1 to satellite 4 used for positioning calculation. , D ₁ represents demodulation of orbital data of satellite number i, and C represents positioning calculation.

Orbital data (Ephemeris) at a speed of 50 baud from the satellite
It will be sent for 18 seconds. Therefore, all the orbital data can be continuously received by sampling and receiving every 20 mS of 1-bit data for a time of several mS over 18 seconds. During the remaining time of this 20 mS period, the signals for pseudo range measurement are sequentially received by other satellites.

As described above, at the beginning of receiving a signal from the satellite, it takes less than 1 second until the phase and frequency of the PN code on the receiver side are synchronized. As in the present invention, if several satellites are sequentially received by several mS each, it takes more time (1 second × the number of satellites (seconds)), but once synchronized, all the receiving satellites are close to each other almost at the same time. Since it will be in a state, the time to track to the synchronization state is very small, after that,
Enables high-speed sequential reception.

The illustration of Fig. 1 shows that the positioning calculation can be performed by measuring the pseudo distances to the satellites required for positioning calculation for four satellites in synchronization with the 1-bit (20mS) period of the orbital data. Or satellites that need orbital data collection for the remaining period (for example, satellites that are currently in the sky but are not used for positioning, or satellites that are used for positioning that require updating of orbital data, or Orbit data of satellites for collecting rough orbit data (almanac) of all satellites is demodulated.

This speeds up the positioning time interval to 20 mS, allowing users to use high-speed moving objects. In addition, when the orbit data of the satellite used for positioning is updated, or when the optimum combination of satellites used for positioning changes, positioning will no longer become impossible due to the collection of orbit data for the newly selected satellite. .

In the illustration of Fig. 2, half of the 20mS period is divided into pseudo-range measurement of one satellite, half is divided into orbit data collection, and the positioning time interval is set to 80mS. Although it is inferior to the example of, the S / N of orbit data demodulation can be improved by 4 dB.

In this way, the pseudo-range measurement of four satellites is sequentially performed at a cycle of an integral multiple of 20 mS or an arbitrary repetition cycle according to the purpose, and the orbital data is demodulated one bit at a time every 20 mS. Can be achieved.

Figure 3 shows the pseudorange measurements (R ₁ and R ₂ and R ₃ and R ₃ and
R ₄ ) and orbit data collection for two satellites (in other words, it corresponds to demodulation, like D _i and D _k ), the time required for orbit data collection is
It has the advantage of requiring only half as compared to the case of Figs. First
It is needless to say that in the figures, FIG. 2 and FIG. 3, the order of R _{1 to} R ₄ , D _i and D _k and the distance to the receiving point may be taken into consideration in order to arrange them in a convenient order for reception.

FIG. 4 is a block diagram of an apparatus for carrying out the method of the present invention in FIGS. 1, 2 and 3.

In FIG. 4, a receiving antenna 1 for receiving a signal radio wave from a satellite
The signal captured in 1 is tracked by the receiving unit 2 and supplied to the data switching unit 3. In this case, the satellites are switched by the satellite switching unit 6 driven by the timing of the satellites created in the receiving unit 2, and the pseudo-range data and the orbit data are changed, for example, as shown in FIG. (FIG. 3 and FIG. 3 are different in the order of switching).

The orbit information is supplied to the orbit data demodulation unit 4, and the pseudo distance information is supplied to the pseudo distance measurement unit 5. Therefore, the trajectory data demodulation unit 4 and the pseudo distance measurement unit 5 provide the trajectory data and the pseudo distance data, respectively. The orbit data and the pseudo distance data are supplied to the positioning calculation section 7, and the positioning calculation section 7 performs positioning calculation. For this positioning calculation, the positioning calculation unit normally applied to the GPS navigation device can be used. The operating position information of the moving body at the time of the measurement, which corresponds to the output signal from the positioning calculation unit 7, is displayed on the display unit 8.

It is necessary to understand the above-described operation of FIG. 4 as the orbital data of the first selected satellites 1 to 4 has already been collected.

Figure 5 shows the flow chart of the program.
If the positioning calculation section is operated in accordance with this procedure, this positioning calculation section is simplified from the configuration of the positioning calculation section 7 described above. In the figure, when the positioning calculation is started, the number of collected orbital data bits of satellite number i is B _i = 0, the number of satellites in the sky before the sequence is n _o = 0, and the current ( The number of satellites in the sky (at the time of positioning start) n ₁ = 0, i = 1, and the total number of satellites n ₁ is obtained as in (a), and n ₁ ≠ n ₀ is determined. If YES, n ₀ = n ₁ , i =
1, with B _i = 0, select the optimum satellite of C from 1 to 4.

Next, the pseudo distances R ₁ , R
₂ , R ₃ and R ₄ are obtained, and this is combined with the orbit data collected in advance for the satellites 1 to 4 to perform the positioning calculation of KU. Next, it is checked whether or not B _i has finished the planned 900 bits, for example, and if YES, the process moves to the next step. Furthermore, as to whether or not the data of all satellites in the sky were collected, YE
If S, the positioning calculation result is displayed through the steps of K and S. If the total number of satellites in the sky has changed in the next stage of step a, if NO, go to step c. Also
If it is not B _i = 900 bits, NO, so go to step S. If the data of all satellites in the sky are collected, and if NO, then go to step S.

(Effect of the invention) As described above, since the 1 bit of the orbit data is collected within the 1 bit (20 mS) period of the orbit data and the pseudo range of 4 satellites is measured at arbitrary time intervals, the orbit data Positioning is possible even while collecting the orbit data, and bit information of the orbit data can be continuously collected, so the orbit data collection can be completed within one frame of the transmission data from the GPS satellites, and the mobile body moving at high speed. The user can also use the GPS navigation device according to the method of the present invention, which has a remarkable effect that it is useful for expanding the application range of the GPS navigation device.

[Brief description of drawings]

FIGS. 1, 2 and 3 are diagrams for explaining the method of the present invention, FIG. 4 is a block diagram of an apparatus for carrying out the method of the present invention, FIG. 5 is a diagram showing a flow chart of a program, and FIG. The figure is a figure for demonstrating the conventional method. 1 ... Antenna, 2 ... Receiving section, 3 ... Data switching section,
4 ... Orbit data demodulation unit, 5 ... Pseudo distance measurement unit, 6 ...
... Satellite switching unit, 7 ... Positioning calculation unit, 8 ... Display unit.

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Claims (1)

[Claims] 1. A method of receiving a GPS navigation device, wherein a receiver of 1 channel sequentially receives signal radio waves from a plurality of satellites to measure the operation position of a mobile body. From the satellite, the reception of the signal from at least one satellite of the signals for pseudorange measurement to the point and the reception of at least one 1-bit of the orbital data requiring the collection of the orbital data are transmitted. Performs positioning within a period (20 mS) equivalent to 1 bit of orbital data, performs positioning calculation using the orbital data of all the satellites used for positioning and the measured pseudo-range data, A method for receiving a GPS navigation device, which is characterized by positioning the operating position of a vehicle without regret.