JP2004286495A - Gps receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GPS receiver for avoiding a decrease in position measurement precision when a vehicle moves and for reducing loss in reception channels. <P>SOLUTION: The peripheral condition of vehicles is determined by a condition determining section 25, based on a navigation apparatus 100 or/and a vehicle sensor 32, and it is predicted whether the reception by a GPS satellite is acceptable according to the condition of vehicles by a GPS satellite prediction section 26 according to the navigation apparatus 100 or/and vehicle sensor 32 and information from the elevation angle of each GPS satellite stored in a memory 6. Then, the GPS receiver has a search control section 27 for changing the search priority of each GPS satellite according to the prediction result and searching for the GPS satellite by a GPS reception section 20a according to the search priority. Additionally, the GPS receiver has a reception limiting section 30 for stopping the reception of the GPS satellite by the GPS reception section 20a when a tunnel or underground is determined as the peripheral condition of vehicles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a GPS receiver. The GPS receiver according to the present invention is applied to, for example, a navigation device mounted on a vehicle.
[0002]
[Prior art]
The GPS (Global Positioning System) receives navigation information transmitted by a plurality of GPS satellites orbiting the satellite at an altitude of 20000 km or more from the earth, for example, in a mobile body moving on the earth. The information included in the route information is used for highly accurate positioning of the current position of a moving object such as an automobile, an aircraft or a ship as data such as latitude, longitude and altitude on a map.
[0003]
At the time of positioning, the GPS receiver searches and captures currently receivable GPS satellites from all the GPS satellite candidates in order to receive navigation information from more than the number of GPS satellites necessary for positioning. Here, in order to shorten the positioning time by the GPS, it is necessary to search for a GPS satellite that can be received at present earlier. In order to search for a GPS satellite faster, there is a conventional technique as disclosed in Patent Document 1, for example.
[0004]
FIG. 12 is a block diagram relating to the search method described in Patent Document 1. First, information such as the satellite number, reception time, and reception level of a GPS satellite that has received a signal by the GPS reception unit is stored in the reception history storage unit. Next, when a search becomes necessary, the reception control calculation unit determines the search order and frequency at the time of search based on the reception history stored in the reception history storage unit, and operates the GPS reception unit. Is controlled.
[0005]
[Patent Document 1]
JP 2000-356671 A
[0006]
[Problems to be solved by the invention]
However, when the mobile body moves after the positioning, the GPS satellite having a relatively low elevation angle may be blocked by a building or the like, and there is a problem that the positioning accuracy is deteriorated. In the case of a limited reception channel, if interruption occurs, it is necessary to re-acquire the GPS satellites, hold the reception channel until the GPS satellites can be re-received, and further allocate other GPS satellites. However, there is a problem that a reception channel loss occurs.
[0007]
In view of the above, the present invention provides a GPS receiver capable of shortening a search time and suppressing a loss or a decrease in positioning accuracy due to a reception channel holding state or the like due to communication interruption when a moving object moves. It is intended to do so.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the GPS receiver according to claim 1 predicts whether or not each GPS satellite can be received based on the surrounding conditions of the moving object and navigation information such as the elevation angle of each GPS satellite, and according to the prediction result. A search control means for changing the search priority of each GPS satellite in accordance with the search priority and searching for the GPS satellite according to the search priority. As a result, a search can be performed from an appropriate GPS satellite according to the surrounding situation of the moving object, and the search time can be reduced.
[0009]
A GPS receiver according to a second aspect of the present invention is characterized in that a GPS satellite that has been successfully received as a result of a search for a GPS satellite by a receiving unit according to a search priority is assigned to each reception channel. As a result, receivable GPS satellites can be allocated to a plurality of reception channels in accordance with the surroundings of the moving object. Therefore, it is possible to suppress a loss due to a holding state of the reception channel or the like and a reduction in positioning accuracy due to a communication interruption when the moving body moves.
[0010]
Further, the GPS receiver according to the third aspect is characterized in that if there is no receivable satellite in the prediction result by the GPS satellite prediction means, the reception by the reception means is stopped. This can reduce the loss of the receiving unit such as continuing reacquisition of GPS satellites in a place where signals from GPS satellites do not reach the destination, such as a tunnel or underground.
[0011]
Further, in the GPS receiver according to the fourth aspect, the surrounding situation of the moving destination of the moving body is determined by at least one of a navigation device, a steering angle detection sensor, a direction indicating device, an illuminance detection sensor, and an illumination switch. It is assumed that. This can suppress an increase in cost due to the provision of a separate device.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, an example in which the present invention is applied to a GPS receiver connected to a navigation device will be described.
[0013]
FIG. 1 is a block diagram illustrating a schematic configuration of a navigation device according to the present embodiment. As shown in FIG. 1, a navigation device 100 according to the present embodiment includes a position detection device 1, a map data input device 5, a memory 6, an operation device 7, a display device 9, an audio output device 10, a remote control sensor 11, and a VICS receiver. 13 and a control circuit 8 connected thereto.
[0014]
The navigation device 100 according to the present embodiment executes a navigation function such as displaying a road map of the surrounding area on the display device 9 together with the current position, and displaying a guide route to the destination on the display device 9. As for the guide route, when the position of the destination is designated by the operation device 7 or the remote control sensor 11 and the remote control 12, the optimum route to the destination starting from the current position detected by the position detection device 1 is automatically determined. To form a guidance route and display it on the display device 9. As a method of automatically setting the optimum route, for example, a known Dijkstra method is used. These functions are mainly executed by the control circuit 8 performing various arithmetic processing.
[0015]
The position detecting device 1 includes a well-known geomagnetic sensor 2, a gyroscope 3, a distance sensor 4, and the like. These are configured to be used while being complemented by a plurality of sensors, since each has an error having a different property. Depending on the accuracy of each sensor, the position detection device 1 may be constituted by a part of the above-described components, and furthermore, a rotation sensor of the steering wheel, a vehicle speed sensor of each rolling wheel, or the like may be used. The position detecting device 1 also uses positioning information from a GPS receiver 20 for a GPS (Global Positioning System) that detects the position of a vehicle based on route information from a GPS satellite.
[0016]
The map data input device 5 outputs various data such as map data, landmark data, and background data from the memory 6 in response to a request from the control circuit 8. As the memory 6 for storing these various data, a CD-ROM or a DVD-ROM is generally used due to the amount of data. In the present embodiment, a writable storage medium such as a memory card or a hard disk is used. The memory 6 also stores navigation route information and search priority information of GPS satellites, which will be described later.
[0017]
The VICS receiver 13 is a device that receives information such as road traffic information distributed from the VICS center via beacons laid on roads and FM broadcast stations in various places. The road traffic information includes, for example, traffic congestion information on each road, regulation information such as closing roads due to accidents and construction, and closing entrances and exits on expressways and the like. The traffic congestion information is represented in a plurality of evaluation stages (for example, traffic congestion, congestion, vacancy, etc.). The received road traffic information is processed by the control circuit 8, and, for example, traffic congestion information, regulation information, and the like are displayed on a map displayed on the screen of the display device 9.
[0018]
The control circuit 8 is configured as a normal computer, and includes a well-known CPU, ROM, RAM, I / O, and a bus line connecting these components. A program to be executed by the navigation device 100 is written in the ROM, and the CPU and the like execute predetermined arithmetic processing according to the program. This program can be obtained from the outside via the memory 6.
[0019]
Next, the GPS receiver 20 will be described with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration including the GPS receiver 20 according to the embodiment of the present invention. In FIG. 2, the GPS receiver 20 includes a GPS receiver 20a and a GPS controller 20b. The GPS control unit 20b is configured by connecting the navigation device 100, the vehicle sensor 32, and the memory 6.
[0020]
The GPS receiver 20a includes an antenna 21, an LNA (low noise amplifier) 22, an RF / IF unit 23, a reception channel unit 24, and the like. The route information received by the antenna 21 is amplified by the LNA 22, frequency-converted by the RF / IF unit 23, and data-demodulated by the reception channel unit 24. The reception channel unit 24 is provided with eight channels 24a to 24h, thereby enabling radio waves from a maximum of eight GPS satellites to be demodulated in parallel. Note that the number of channels is not limited to the above.
[0021]
The GPS control unit 20b includes a situation determination unit 25, a GPS satellite prediction unit 26, a search control unit 27, a GPS satellite allocation unit 28, a reception limit unit 29, a route information acquisition unit 30, and a positioning unit 31.
[0022]
The situation determination unit 25 determines the surrounding situation of the vehicle using the navigation device 100 and / or the vehicle sensor 32. The vehicle sensor 32 includes a steering angle sensor that detects a steering direction of the vehicle, a direction supporter that indicates a moving direction of the vehicle, an illuminance sensor that detects illuminance around the vehicle, an illumination switch that indicates ON / OFF of illumination of the vehicle, and the like. It is provided with.
[0023]
The GPS satellite prediction unit 26 predicts whether or not each GPS satellite can be received in the vehicle's surrounding state based on the vehicle's surrounding state by the state determination unit 25 and the orbit, current position, and elevation angle of each GPS satellite stored in the memory 6. It is.
[0024]
The search control unit 27 determines a search priority according to the reception possibility of each GPS satellite predicted by the GPS satellite prediction unit 26, and causes the GPS reception unit 20a to perform a search process based on the search priority. is there. Further, information on whether or not the route information from the searched GPS satellites has been received is acquired from the GPS receiving unit 20a, and when the navigation route information has been received, the GPS satellite allocating unit 28 transmits the GPS satellites to predetermined reception channels 24a to 24h. Request to be assigned.
[0025]
The reception restricting unit 29 stops the reception of the navigation information by the GPS receiving unit 20a when there is no GPS satellite that can be received in the surrounding situation of the vehicle determined by the situation determining unit 25 described above. .
[0026]
The route information acquiring unit 30 acquires route information (C / A code, orbit information, etc.) transmitted from a GPS satellite. In addition, the positioning unit 31 measures the position of the vehicle based on the route information acquired by the route information acquiring unit 30 described above, and inputs the position to the navigation device 100. Further, the positioning unit 31 calculates the elevation angle of each GPS satellite from the RTC time (not shown), the route information, and the last position measured and stored in the memory 6 when the GPS receiver 20 was previously activated. calculate. When available route information is stored in the memory 6, the elevation angle can be calculated without the route information acquired by the route information acquisition unit 30.
[0027]
Here, the positioning processing by the GPS will be described based on the schematic flowchart of the positioning processing by the GPS shown in FIG. First, in the satellite search process S1, usually, when there is an accurate RTC time and available route information in the memory 6, the GPS satellites above the GPS receiver 20 are searched in descending order of the elevation angle. If there is no available route information in the time and memory 6, all satellites are searched, and receivable GPS satellites are allocated to each of the receiving channels 24a to 24h. At this time, a C / A code, which is a different code for each GPS satellite, is received by the reception channel unit 24, and a pseudo distance is calculated based on the received C / A code. Next, in the satellite route information receiving process S2, the orbit information (ephemeris, almanac, etc.) of the satellite is received. The current position of the GPS satellite is calculated from the orbit information. Next, in the positioning process S3, the current position of the vehicle is measured based on the pseudorange calculated in the satellite search process S1 and the current position of the GPS satellite calculated in the satellite route information receiving process S2.
[0028]
Here, the satellite search processing will be described in detail. FIG. 4 is a flowchart of satellite supplementary search processing. FIG. 5 is a flowchart of the C / A code synchronous phase search. FIG. 6 is a graph showing an example of the correlation value obtained as a result of the C / A code search.
[0029]
First, when this processing is started, an initial setting of the GPS satellite frequency is performed in S10. In this case, a carrier reception frequency (hereinafter, simply referred to as a reception frequency) f0 is calculated for a GPS satellite to be captured. When the reception frequency f0 is set, the process proceeds to S11, where a C / A code synchronous phase search is performed. The route information from the GPS satellite is transmitted as a spread spectrum signal, and the C / A code is one of the codes used for modulating the route information, and “1” and “0” are arranged in a predetermined arrangement. 1023 pieces are arranged (each of "1" and "0" is called a chip). In order to extract the route information, it is necessary to detect at what phase the C / A code is carried on the carrier. This involves generating a C / A code of the same format as the C / A code of the satellite to be captured in the reception channel unit 24, changing the phase of the C / A code, and generating a C / A code with the received spread spectrum signal. This is performed by measuring a correlation value. The contents of this processing are shown in the flowchart of FIG.
[0030]
That is, in the synchronous phase search of the C / A code, first, in S20, the initial phase (normally, 0 chip) of the C / A code is set. Then, in S21, the correlation value between the received C / A code and the C / A code of the same format generated in the reception channel unit 24 is measured (S21). If the set reception frequency is incorrect or the C / A code is not synchronized with the C / A code of the received spread spectrum signal, the correlation value will be close to zero, but the reception frequency and C / A If both codes are appropriate, the correlation value indicates a predetermined value. In S22, the peak correlation value up to that time is stored, and in S23, it is determined whether or not the C / A code has been generated in all phases (here, 1022.5 chips). If not, the process proceeds to S24, where the phase of the C / A code is changed by 0.5 chip. By repeating the processing of S21 to S24, correlation values for 1023 chips are measured, and a peak correlation value during this period is obtained.
[0031]
FIG. 6 shows an example of this state. FIG. 6 is a graph with the C / A code phase on the horizontal axis and the correlation value on the vertical axis. In the case of the figure, since the peak correlation value Cp is obtained as the correlation value, it is understood that the demodulation should be performed at this phase. In addition, it can be understood at the same time that the setting of the reception frequency was appropriate.
[0032]
In subsequent S25, the peak correlation value Cp is compared with a predetermined threshold value. If the peak correlation value Cp is equal to or larger than the threshold value, the process proceeds to S26, and it is considered that synchronization has been achieved. If the peak correlation value Cp does not satisfy the threshold value, the process proceeds to S27 and it is considered that synchronization has not been achieved.
[0033]
Now return to FIG. As a result of the processing in S11, it is determined whether or not synchronization has been achieved. S12. If the synchronization has been achieved, this processing ends. If the processing has been asynchronous, the processing proceeds to S13, where the reception frequency is changed. The process of S13 changes the frequency, assuming that the reception frequency set in S10 is incorrect. As a mode of changing the frequency in S13, the frequency is initially set to a frequency f1 slightly higher (for example, 1 kHz) than the reception frequency f0 set in S10. The frequency f2 may be slightly lower, and if synchronization is still not achieved, the frequency f3 may be higher than the frequency f1. However, when the value becomes somewhat different from the frequency f0, the value may be returned to f0 again and the search may be performed periodically.
[0034]
That is, in the satellite search process, the reception frequency of each satellite is estimated, the synchronous phase search of the C / A code is performed for each of the estimated frequencies, and if the synchronization is not achieved, the reception frequency is changed to search for the carrier frequency. The synchronous phase search of the C / A code is performed in parallel.
[0035]
Even if a GPS search is assigned to each of the reception channels 24a to 24h by performing a satellite search in this manner, the surroundings of the vehicle change with the movement of the vehicle, and some of the GPS satellites assigned to the reception channels 24a to 24h include: GPS satellites that cannot be received or can be received appear. In some cases, all the GPS satellites assigned to the reception channels 24a to 24h cannot be received. Therefore, in the present invention, a search is performed by assigning a variable search priority to each GPS satellite according to the surrounding situation of the vehicle when performing the throne by the GPS satellite.
[0036]
The GPS satellite search method of the present invention will be described with reference to the drawings. First, when the vehicle moves, as shown in the flowchart of FIG. 7 for predicting the surroundings of the vehicle, the surroundings determination processing of the surroundings of the vehicle is performed by the surroundings determining process. If it is determined in S101 that the surrounding area of the vehicle is the building street / under the overpass, the process proceeds to satellite determination processing. If it is determined in S201 that the surroundings of the vehicle are a tunnel or an underground, the process proceeds to reception restriction processing. In other cases, the satellite currently being received is received.
[0037]
FIG. 8 is a flowchart of the satellite determination process. Here, the GPS satellite prediction unit 26 predicts whether or not each GPS satellite can be received in the situation around the vehicle, and determines the search priority according to the prediction result.
[0038]
First, in the GPS satellite prediction process in S102, the reception possibility of each GPS satellite is predicted according to the situation around the vehicle. In the search satellite priority determination in S103, if the prediction result of the GPS satellite prediction processing in S102 shows no change in the prediction of whether or not each GPS satellite can be received, the satellite currently being received is received, and the reception of each GPS satellite is performed. If the prediction of the propriety is changed, the search satellite priority is changed and the process proceeds to S104 to switch the search satellite.
[0039]
Next, in the surrounding situation determination processing, when it is determined that the surrounding situation is a tunnel or an underground, reception restriction processing is performed. FIG. 9 is a flowchart of the reception restriction process. Here, in S202, the reception of the GPS satellite by the GPS receiving unit 20a is stopped, and the process proceeds to S203. After a predetermined time elapses after moving to the tunnel and underground in S203, the reception state with the GPS satellite is determined. If reception is not possible, the process returns to S202 and the determination of the reception state is repeated in S203. If reception with the GPS satellites becomes possible in S203, the process returns to the surrounding situation determination.
[0040]
Here, the actual operation will be described with reference to the drawings. FIG. 10A is a diagram illustrating an image when a vehicle moves in a building street, and FIG. 10B is a diagram illustrating an image when moving under an elevated road. FIG. 11 is a diagram showing the correspondence between the reception channels 24a to 24h and the GPS satellites after (a) the surrounding conditions of the vehicle change and (b) after the surrounding conditions of the vehicle change. In FIG. 11, regarding ◎, ，, and ×, ◎ indicates that the signal is receivable and has a good reception state, ○ indicates that the signal can be received, but the reception state is worse than that of the の GPS satellite, and × indicates that the signal cannot be received. Shall be.
[0041]
First, as shown in FIG. 11A, before the surroundings of the vehicle change, GPS satellites that can be received on the reception channels 24a to 24h and have a high search priority (search priority 1 to search priority 8). 1, GPS satellites 8, GPS satellites 31, GPS satellites 18, GPS satellites 15, GPS satellites 32, GPS satellites 10, and GPS satellites 25 are assigned. Thereafter, as shown in FIG. 11B, after the surrounding conditions of the vehicle change, the GPS satellites 31 assigned to the reception channel 24c and the GPS satellites 15 assigned to the reception channel 24e and the reception channel 24h are assigned. It is assumed that the GPS satellite prediction unit 26 predicts that the received GPS satellite 25 cannot be received. Also, at this time, it is assumed that the GPS satellite prediction unit 26 predicts that the GPS satellites 7, the GPS satellites 16, and the GPS satellites 24 among the satellites not allocated to the reception channel can be received.
[0042]
Specifically, as shown in FIG. 10A, when the vehicle is at the location 301, the GPS satellites 31, the GPS satellites 1, the GPS satellites 8 and the like can be received, and the reception channels 24a to 24h Will be assigned. At that time, the GPS satellites 7, 16 and 24 cannot be received by buildings A to D in the vicinity. Next, when the vehicle moves to the location 302, if the GPS satellites 7, 16 and 24 become receivable based on the relationship between the orbits, the current position, and the elevation of the buildings A to D around the vehicle and the GPS satellites. It is predicted that the GPS satellite 31, the GPS satellite 15, and the GPS satellite 25 cannot be received. Note that FIG. 10 shows only the GPS satellites 7, the GPS satellites 31, and the GPS satellites 1.
[0043]
In such a case, the GPS satellites 31 (search priority 3 → search priority 12), the GPS satellites 15 (search priority 5 → search priority 14) and the GPS satellites 25 (search priority 8 → search priority 18) And the GPS satellites 7 (search priority 9 → search priority 3), the GPS satellites 16 (search priority 25 → search priority 5), and the GPS satellites 24 (search priority 30 → search priority). The search priority is increased as in priority 8). Then, for the three empty reception channels predicted to be unreceivable among the reception channels 24a to 24h, a GPS satellite 7 (search priority 3) having a higher search priority is selected from satellites not allocated to the reception channels. The GPS receiver 20a is controlled to search for the GPS satellites 16 (search priority 5) and the GPS satellites 24 (search priority 8).
[0044]
As a result of the search, if all of the newly searched GPS satellites 7, 16 and 24 become receivable, a reception success signal is sent from the reception channel unit 24 to the search control 27, The reception search control unit 27 controls the GPS satellite allocation unit to allocate the GPS satellites to the reception channels 24c, e, and h.
[0045]
If any one of the GPS satellites 7, 16 and 24 cannot be received, a search is made for a GPS satellite having the next highest search priority among satellites not assigned to a reception channel. The search is performed in order from the one with the highest search priority among the satellites not allocated to the reception channel until the available reception channel is filled.
[0046]
In addition, in the prediction of whether or not a GPS satellite can be received by the GPS satellite prediction unit 26, the presence or absence of a building around the vehicle, the height information of the building, the orbit of the GPS satellite stored in the memory 6, This is predicted by the position and the elevation angle. For example, referring to FIG. 10A as an example, a building D exists between the vehicle and the satellite 1, but the height of the building D does not affect the reception of the route information from the satellite 1. In the case of the height, when the vehicle moves to the place 302, it is predicted that reception is possible even if the building C exists. In the case of the satellite 31, when the vehicle moves to the location 302 because the height of the building C existing between the vehicle and the satellite 31 affects the reception of the route information from the satellite 31. Is predicted to be unreceivable.
[0047]
In addition, as shown in FIG. 10B, when the vehicle is under an overpass as a situation around the vehicle, for example, even if the elevation angle of the GPS satellite 7 is high, reception of navigation information is hindered by the overpass, so that search priority is given. Decrease the degree. In such a case, the search priority of the GPS satellites such that the elevation does not hinder the reception of the navigation information even when the elevation angle is low like the GPS satellites 1 is set to be high. Further, although not shown, even in the case of a mountainous area, the search priority of a GPS satellite is set to be high so that the reception of navigation information is not hindered by surrounding mountains and the like.
[0048]
Next, as shown in FIG. 11A, before the surroundings of the vehicle change, GPS satellites that can be received on the reception channels 24a to 24h and have a high search priority (search priority 1 to search priority 8). 1, GPS satellites 8, GPS satellites 31, GPS satellites 18, GPS satellites 15, GPS satellites 32, GPS satellites 10, and GPS satellites 25 are assigned. Thereafter, when the situation determining unit 25 determines that the surrounding situation of the vehicle is a place where the route information from the GPS satellite such as a tunnel or an underground is cut off, the reception restricting unit 29 determines whether or not the vehicle is in the GPS receiving section 20a. Stop receiving the route information. Further, after that, when the situation determination unit 25 determines that the surrounding situation of the vehicle is receivable, the GPS satellite prediction unit 26 calculates the receivable state, the position estimated by a gyro, etc., the satellite position and the surrounding situation. Determine the satellite search priority and search. Here, when there is a GPS satellite which becomes unreceivable, the search is performed in order from the GPS satellites having the higher search priority among the unassigned satellites, and the search is performed until the reception channels 24a to 24h are filled.
[0049]
As a result, it is possible to search from an appropriate GPS satellite according to the surrounding situation of the vehicle, and it is possible to shorten the search time. Furthermore, since GPS satellites that can be received according to the surrounding conditions of the vehicle can be assigned to a plurality of reception channels, loss due to the state of holding the reception channel due to communication interruption when the vehicle moves and a decrease in positioning accuracy are suppressed. can do. Further, in a situation where navigation information from a GPS satellite such as a tunnel or underground cannot be received, the reception in the reception channel unit 24 is stopped to reduce a loss such as continuing to reacquire the GPS satellite in the reception channel unit 24. can do.
[0050]
The situation determination unit 25 predicts the destination of the vehicle using the route guidance of the navigation device 100 or the direction indicator of the vehicle sensor 32, and predicts whether or not the GPS satellite can be received by the GPS satellite prediction unit 26 based on the result. You may make it. By doing so, it is possible to predict whether or not a GPS satellite can be received more quickly by predicting the situation of the destination, and to search from an appropriate GPS satellite according to the surrounding conditions of the vehicle, thereby shortening the search time. be able to.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a navigation device 100 according to a first embodiment.
FIG. 2 is a block diagram showing a schematic configuration of a GPS receiver 20 according to the embodiment of the present invention.
FIG. 3 is a flowchart of a positioning process according to the embodiment of the present invention.
FIG. 4 is a flowchart of a satellite supplementary search process according to the embodiment of the present invention.
FIG. 5 is a flowchart of a C / A code synchronous phase search process according to the embodiment of the present invention.
FIG. 6 is a graph showing an example of a correlation value obtained as a result of a C / A code search according to the embodiment of the present invention.
FIG. 7 is a flowchart of a peripheral situation determination process according to the embodiment of the present invention.
FIG. 8 is a flowchart of a satellite determination process according to the embodiment of the present invention.
FIG. 9 is a flowchart of a reception restriction process according to the embodiment of the present invention.
10A is a diagram illustrating an image when a vehicle moves to a building street according to the embodiment of the present invention, and FIG. 10B is a diagram illustrating an image when moving under an overpass according to the embodiment of the present invention. It is a figure which shows the image of.
11A is a diagram showing the correspondence between the reception channels 24a to 24h and the GPS satellites before the surroundings of the vehicle change according to the embodiment of the present invention, and FIG. 11B is a diagram showing the embodiment of the present invention. FIG. 9 is a diagram showing the correspondence between the reception channels 24a to 24h and the GPS satellites after the surrounding conditions of the vehicle have changed.
FIG. 12 is a block diagram related to a search method according to the related art.
[Explanation of symbols]
Reference Signs List 20 GPS receiver, 20a GPS receiver, 20b GPS controller, 24 reception channel unit, 25 situation determination unit, 26 GPS satellite prediction unit, 27 search control unit, 28 GPS satellite allocation unit, 29 reception limit unit, 30 route information Acquisition unit, 31 Positioning unit, 32 Vehicle sensor, 100 Navigation device

Claims (4)

Situation determining means for determining the surrounding situation of the moving object;
Satellite route information storage means for storing route information for each of a plurality of GPS satellites;
Receiving means comprising a plurality of receiving channels for receiving signals transmitted from each GPS satellite in one-to-one correspondence with the plurality of GPS satellites and variably corresponding thereto;
GPS satellite prediction means for predicting whether each of the GPS satellites can be received based on the determination information of the situation determination means and the satellite information of the satellite route information storage means,
A GPS receiver comprising: a search control unit that changes a search priority of each of the GPS satellites according to a prediction result of the GPS satellite prediction unit, and searches the reception unit for a GPS satellite according to the search priority. 2. The GPS receiver according to claim 1, wherein the search control unit allocates the received GPS satellite to each of the reception channels as a result of searching for a GPS satellite by the receiving unit according to the search priority. 3. 3. The GPS reception device according to claim 1, further comprising a reception restriction unit that stops reception by the reception unit when there is no receivable satellite in the prediction result by the GPS satellite prediction unit. 4. Machine. The GPS receiver is mounted on a vehicle, and the situation determining means includes a navigation device, a steering angle detection sensor, a direction indicating device, an illuminance detection sensor, and an illumination switch. The GPS receiver according to any one of claims 1 to 4, wherein a surrounding situation is determined.

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