JP2002124902A - Satellite communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a satellite communication terminal which can reduce GPS satellite capturing time and positioning calculation time. SOLUTION: This satellite communication terminal is an orbicom satellite communication terminal having a radio communication circuit 7 for radio communication with the orbicom satellite, central computing equipment 1 for controlling the whole and a positioning calculation part 9 for calculating a self position by using GPS satellites. The central computing equipment 1 is provided with a reference position selecting means 102 for selecting the position of a base station with which the equipment 1 links via the orbicom satellite, as the reference position of GPS satellite retrieval when GPS satellite capturing is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a satellite communication terminal capable of performing radio communication with a base station connected to a terrestrial communication network via a satellite.

[0002]

2. Description of the Related Art In recent years, since self-location confirmation means using a GPS satellite or the like has become easily available, reporting of location information has been widely used in car navigation, emergency calls, monitoring of mobile bodies, and the like. . However, in order to report the user's location information, the radio and the base station that receives radio waves from the radio must be adjacent to each other, and the base stations are too far apart in the sea or in mountainous areas. , It was difficult to report its location. In recent years, global mobile communication terminals using satellites orbiting the earth such as the Orbitcom satellite have come into practical use. As a result, information can be transmitted and received on a global scale regardless of the area where the satellite communication terminal is used, and reporting of position information is also being used in various fields.

FIG. 1A is a block diagram showing a general orbitcom satellite communication terminal.

In FIG. 1A, 1 is a central processing unit for controlling transmission / reception processing, 2 is a program storage unit storing a program for defining the operation of the central processing unit 1, and 3 is a flag for recording a flag being processed. A rewritable memory, 4 is a transmission message storage memory for storing created uplink transmission messages, 5 is a reception message storage memory for storing received downlink reception messages, and 6 is Orbicom which transmits and receives communication radio waves to and from Orbicom satellites. Antenna, 7 is a wireless communication circuit that performs wireless communication with Orbicom satellite, 8 is GP
GPS antenna for receiving radio waves from S satellite, 9 is GP
It is a positioning calculation unit that processes received information from the S satellite and performs positioning calculation.

The conventional operation of the orbitcom satellite communication terminal configured as described above will be described with reference to FIGS. FIG. 5 is an explanatory diagram showing a conventional GPS satellite search method, and FIG. 6 is an explanatory diagram showing a GPS satellite search method when the reference position is located directly opposite to the current position.

5 and 6, reference numeral 10 denotes a GPS satellite,
P1 is a previous positioning position as a reference position, and P2 is a current positioning position.

As shown in FIG. 5, the occurrence of a positioning request event causes the Obicom satellite communication terminal to operate the GPS satellite 10
First, the reference position is determined in order to perform the positioning calculation using. Normally, the previous positioning position P1 is used as the reference position,
If there is no previous positioning position, a default reference position corresponding to a geodetic system specified in advance is used. Then, a plurality of GPS satellites 10 flying above the reference position are acquired by referring to almanac which is orbit information of the GPS satellites 10. After capturing the GPS satellites 10 required for positioning, positioning calculation is performed using the reference position as an initial position for positioning calculation, and the position of the orbitcom satellite communication terminal is determined. The positioning information thus obtained is transmitted to the base station via an Orbicom satellite (not shown) as an uplink message.

[0008]

However, in the conventional orbitcom satellite communication terminal, as shown in FIG.
When the relationship between the reference position P1 and the actual positioning position P2 is exactly opposite to the earth, there is a problem that it takes time to capture a GPS satellite. For example, if the last measured position P1 is in Japan and the next measured position P2 is in South America, which is the exact opposite of the earth, the Obicom satellite communication terminal is located in the area completely opposite to Japan. Since the last measured position is Japan, that is, the reference position is Japan, an attempt is made to capture a GPS satellite flying over Japan. Although GPS satellites are flying over Japan, the GPS that Orbicom satellite communication terminals are looking for
Since the satellite number and the actually flying GPS satellite number are completely different, it takes time to capture the GPS satellites, and as a result, it takes much time to obtain the positioning result.

[0009] In this Orbicom satellite communication terminal, GPS
It is required to reduce the GPS satellite acquisition time and the positioning calculation time by selecting an appropriate reference position at the time of satellite acquisition and positioning calculation.

[0010] The present invention satisfies this demand by using GPS.
An object of the present invention is to provide a satellite communication terminal capable of shortening a satellite acquisition time and a positioning calculation time.

[0011]

SUMMARY OF THE INVENTION In order to solve this problem, a satellite communication terminal according to the present invention comprises a wireless communication circuit for performing wireless communication with a satellite, a central processing unit for controlling the whole, and a GPS.
A satellite communication terminal having a positioning operation unit that calculates its own position using a satellite, wherein the central processing unit operates at the time of starting GPS satellite acquisition to determine the position of the base station linked via the satellite. Is provided as a reference position selecting means for selecting as a reference position for GPS satellite search.

As a result, a satellite communication terminal capable of shortening the GPS satellite acquisition time and the positioning calculation time can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A satellite communication terminal according to a first aspect of the present invention includes a wireless communication circuit for performing wireless communication with a satellite,
A satellite communication terminal having a central processing unit that controls the entire system and a positioning operation unit that calculates its own position using a GPS satellite, wherein the central processing unit controls the satellite when it starts capturing GPS satellites. Reference position selecting means for selecting a position of a base station linked via the terminal as a reference position of a GPS satellite search.

According to this configuration, almost all GPS satellites flying over the base station linked via the satellites can be captured, so that the time required for capturing GPS satellites required for positioning can be reduced. Therefore, there is an effect that the positioning calculation time can be reduced.

According to a second aspect of the present invention, there is provided a satellite communication terminal according to the first aspect, wherein the reference position selecting means is provided when the satellite is not linked to the base station at the start of the GPS satellite acquisition. The position of the reference station linked last and the positioning position obtained last time are referred to, and the position updated most recently among the two is selected as the reference position for the GPS satellite search.

According to this configuration, even when the satellite is not linked to the base station, it is possible to obtain the reference position for the GPS satellite search.

According to a third aspect of the present invention, there is provided the satellite communication terminal according to the first or second aspect, wherein the reference position selecting means selects a position when performing a positioning operation after capturing a GPS satellite required for positioning. The determined reference position is set as the initial position of the positioning calculation.

With this configuration, the speed of the positioning calculation can be increased, and the positioning calculation time can be shortened.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) The configuration of an orbitcom satellite communication terminal according to Embodiment 1 of the present invention is the same as that of the conventional one, as shown in FIG. The difference of this embodiment from the conventional one is mainly the operation of the central processing unit.

FIG. 1 (b) is a functional block diagram showing a central processing unit 1 constituting an orbitcom satellite communication terminal according to the first embodiment of the present invention.

In FIG. 1B, reference numeral 101 denotes determination means for performing various determinations, and reference numeral 102 denotes a reference position selection means for selecting a reference position.

The operation of the orbitcom satellite communication terminal configured as described above will be described with reference to FIGS. FIG. 2 is an explanatory diagram showing a case where a linked reference station is used as a reference position for a GPS satellite search, and FIG. 3 is an explanatory diagram showing a positional relationship between an orbitcom satellite and a GPS satellite. 2 and 3, reference numeral 10 denotes a GPS satellite, 11
Is an Orbicom satellite, and 12 is a base station.

When the positioning request event occurs, the Obicom communication terminal first captures a plurality of GPS satellites 10 necessary for positioning, as shown in FIG.
Investigate the base station linked via 1. When the base station is determined, the base station / base station position correspondence table registered in advance in the Obicom satellite communication terminal is searched, and the latitude / longitude of the base station is treated as a reference position for GPS satellite search. The reference position for the GPS satellite search is selected by the reference position selecting means 102 of the central processing unit 1. As described above, by using the position of the base station 12 linked via the Orbikom satellite 11 as the search reference position of the GPS satellite 10, the previous positioning position is set to Japan, and then to the conventional positioning position. Even if the selected area is in South America, which is the exact opposite of the Earth, the Orbicom satellite communication terminal will fly not the GPS satellite flying over Japan, but the location (South America) where the current Obicom satellite communication terminal exists. GPS satellites can be acquired.

As shown in FIG. 3, the GPS satellite 10 is flying in a circular orbit of about 20,000 km from the surface of the earth, while the orbitcom satellite 11 is 800 km.
Is a low-Earth orbit satellite. Therefore, the GPS satellites 10 flying above the base station 12 to which the Obicom satellite communication terminal is linked via the Obicom satellite 11 can be almost always captured from the Obicom satellite communication terminal. Can be sufficiently used as the reference position for capturing the GPS satellite 10, and the time required for capturing the GPS satellite 10 can be reduced.

As described above, according to the present embodiment, at the start of GPS satellite acquisition, central processing unit 1 determines the position of the base station which is linked via the Obicom satellite by the reference position for GPS satellite search. Since the GPS satellites flying over the base station linked via the Orbicom satellite can be almost captured by having the reference position selecting means 102 for selecting
The satellite acquisition time can be reduced, and therefore the positioning calculation time can be reduced.

(Embodiment 2) The configuration of an orbitcom satellite communication terminal according to Embodiment 2 of the present invention is the same as that of Embodiment 1. This embodiment is different from the first embodiment in the operation of the reference position selecting means 102 of the central processing unit 1 described in the first embodiment.

The operation of the orbitcom satellite communication terminal thus configured will be described.

In low orbit satellites such as Orbicom satellites,
When the Obicom satellite communication terminal is located in the Pacific Ocean, it may not be possible to link to a terrestrial base station. In such a case, the position of the base station cannot be used as the reference position. As a countermeasure, the orbitcom satellite communication terminal simultaneously stores the time when the link with the base station was last disconnected and the position of the base station. Further, when the positioning result is obtained, the position and the time at which the positioning result was obtained are similarly stored. At this time, both (the position of the base station and the positioning time,
By storing both the positioning position and the positioning acquisition time in the non-volatile memory, it is possible to be a candidate for a reference position for positioning even after the power is turned off. Thus, when it is not possible to link with any base station, the two times are compared, and the latest position information is selected, whereby an appropriate reference position for satellite search is obtained. Through these processes, even if the Obicom terminal cannot link to the base station via the Obicom satellite, the acquisition reference position of the GPS satellite can be obtained.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the operation of the central processing unit 1.

In FIG. 4, first, the determining means 101 determines whether or not there is a positioning request (S1). Next, the determination means 101 determines whether or not the Orbicom satellite is linked to the base station (S2). If it is determined that the orbit is linked, the reference position selection means 102 acquires the position of the base station. The position is selected as a reference position, and the process proceeds to step S8 (S3, S4). When it is determined in step S2 that the base station is not linked, the reference position selecting means 102 acquires the position A of the base station linked last (S5), and acquires the positioning position B acquired last (S5).
6), the position whose position was last updated in both A and B is selected as a reference position, and the process proceeds to step S8 (S8).
7). In step S8, the reference position selecting means 102
The selected reference position is set as the reference position for the GPS satellite search. Next, a GPS satellite required for positioning is captured (S9), positioning is performed using the reference position as an initial positioning position (initial position) (S10), and a positioning result is obtained (S1).
1).

As described above, according to the present embodiment, the reference position selecting means 102 determines whether or not the Obicom satellite is linked to the base station at the start of the GPS satellite acquisition.
By referring to the position of the last linked reference station and the previously obtained positioning position, and selecting the most recently updated position of both as the reference position for GPS satellite search,
Even when the Orbicom satellite is not linked to the base station, it is possible to obtain the reference position for the GPS satellite search. In addition, the reference position selecting means 102 determines the G required for positioning.
When the positioning operation is performed after capturing the PS satellite, the selected reference position is used as the initial position of the positioning operation, whereby the speed of the positioning operation can be increased, and the positioning operation time can be shortened.

[0033]

As described above, according to the Obicom satellite communication terminal according to the first aspect of the present invention, a radio communication circuit for performing radio communication with an Obicom satellite, a central processing unit for controlling the whole, and a GPS An orbitcom satellite communication terminal having a positioning operation unit that calculates its own position using a satellite, wherein the central processing unit is a base station to which itself is linked via an orbicom satellite at the start of GPS satellite acquisition. Has a reference position selecting means for selecting the position of the GPS satellite as a reference position of the GPS satellite search, so that the GP flying above the base station linked via the Orbicom satellite
Since the S satellite can be captured almost, G required for positioning
An advantageous effect is obtained in that the time required for capturing PS satellites can be reduced, and therefore the time required for positioning calculation can be reduced.

According to the Obicom satellite communication terminal of the second aspect, in the Obicom satellite communication terminal of the first aspect, the reference position selecting means links the Obicom satellite to the base station at the start of GPS satellite acquisition. If there is not, by referring to the position of the last linked reference station and the previously obtained positioning position, and selecting the most updated position of both as the reference position of the GPS satellite search, the Obicom satellite Has an advantageous effect of being able to acquire a reference position for a GPS satellite search even when is not linked to a base station.

According to the third aspect of the present invention, in the first or second aspect of the present invention, the reference position selecting means includes a GP which is necessary for positioning.
When the positioning operation is performed after capturing the S satellite, the selected reference position is set as the initial position of the positioning operation, whereby the speed of the positioning operation can be increased, and the positioning operation time can be advantageously reduced. The effect is obtained.

[Brief description of the drawings]

FIG. 1A is a block diagram showing a general orbitcom satellite communication terminal. FIG. 1B is a functional block diagram showing a central processing unit constituting the orbitcom satellite communication terminal according to the first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a case where a linked reference station is used as a reference position for GPS satellite search.

FIG. 3 is an explanatory diagram showing a positional relationship between an orbitcom satellite and a GPS satellite.

FIG. 4 is a flowchart showing the operation of the central processing unit.

FIG. 5 is an explanatory diagram showing a conventional GPS satellite search method.

FIG. 6 shows a GP in a case where the reference position is directly opposite to the current position.
Explanatory diagram showing the S satellite search method

[Explanation of symbols]

 Reference Signs List 1 central processing unit 2 program storage unit 3 rewritable memory 4 transmission message storage memory 5 reception message storage memory 6 orbicom antenna 7 wireless transmission circuit 8 GPS antenna 9 positioning operation unit 10 GPS satellite 11 orbicom satellite 12 base station

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasushi Yokomitsu 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. FF20 HH08

Claims (3)

[Claims] A wireless communication circuit for performing wireless communication with a satellite;
A satellite communication terminal having a central processing unit that controls the entire system and a positioning operation unit that calculates its own position using a GPS satellite, wherein the central processing unit is configured to start capturing GPS satellites.
GP the location of the base station to which it is linked via satellite
A satellite communication terminal having a reference position selecting means for selecting as a reference position for S satellite search. 2. When the satellite is not linked to the base station at the start of GPS satellite acquisition, the reference position selecting means refers to the position of the last linked reference station and the previously obtained positioning position, 2. The satellite communication terminal according to claim 1, wherein the last updated position is selected as a reference position for the GPS satellite search. 3. 3. The reference position selecting means according to claim 1, wherein said reference position selecting means selects a G value required for positioning.
3. The satellite communication terminal according to claim 1, wherein when performing a positioning operation after capturing a PS satellite, the selected reference position is set as an initial position of the positioning operation. 4.