JP3576268B2 - Positioning device, positioning system and positioning method - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a positioning system that receives radio waves transmitted from a positioning satellite and performs positioning between a base station and a mobile station, a positioning device that applies to the system and performs positioning of the mobile station, and a base station and a mobile station. The present invention relates to a positioning method in which positioning is performed by using a method.
[0002]
[Prior art]
Conventionally, in a positioning system such as a GPS, for example, information for observing the distance from each positioning satellite to a receiving point and information for calculating the position of each positioning satellite are transmitted from each positioning satellite. The distance from each positioning satellite to the receiving point and the position of each positioning satellite are obtained using the signals from the number of positioning satellites required for three-dimensional positioning by extracting from the positioning signals, and from these information I want the position of the receiving point.
[0003]
Radio waves transmitted from such positioning satellites should be less susceptible to noise, and even if all satellites transmit signals using the same carrier, only radio waves from the desired satellite can be identified. Spread spectrum modulation is performed using a pseudo-noise code (C / A code) at the time of transmission from a satellite in order to enable reception. Therefore, a signal from a desired satellite is searched for and received by generating a C / A code corresponding to the number of the satellite to be received and changing its phase and Doppler frequency.
[0004]
[Problems to be solved by the invention]
Therefore, to receive a positioning signal from a desired positioning satellite, a certain search time is required for each satellite, and a time from when the power is turned on until the first positioning result is obtained (in general, TTFF: Time To First Fix). ) Is determined by the time required to complete the search of all required satellites (at least four in the case of three-dimensional positioning) and the time required for positioning calculation.
[0005]
By the way, when searching for a signal from each satellite, the satellites are selected so as to search for a signal from a satellite predicted to be present in the field of view, but whether each satellite is in the field of view or out of the field of view is selected. Is estimated from the orbit information of each satellite, the estimated position of the receiving point, and the current time. Therefore, if the orbit information of each satellite or the estimated position of the receiving point held by the receiver is uncertain or the receiver's clock contains a large error, the estimation of the inside and outside of the field of view of each satellite may be incorrect. Become. For example, if a satellite estimated to be in the field of view is actually outside the field of view, such as on the back of the earth, the search will fail, and the search time will be wasted. After all, the time required to complete the search for the required number of satellites is greatly affected by the accuracy of the orbital information of each satellite held by the receiver, the accuracy of the estimated position of the receiving point, and the error of the clock of the receiver. change.
[0006]
In addition, when the receiver has not yet collected the orbit information of each satellite, the relative motion state of each satellite to be received with respect to the receiving point is not clear, so that it is not included in the signal transmitted from that satellite. Since the Doppler frequency in question cannot be predicted, the Doppler frequency must be searched over a wide range. Therefore, in this case, the time required to search for a signal from each satellite becomes longer.
[0007]
Here, taking a general 8-channel GPS positioning device as an example, FIG. 18 shows the relationship between the power-on state and the TTFF value. For example, as shown in "warm start", the deviation from the final positioning position to the actual position when the power is turned on is within 1 degree in latitude and longitude, the deviation of the clock of the positioning device with respect to the GPS time is within 10 minutes, and If almanac data four months ago and ephemeris data four hours ago were backed up, TTFF would be about 45 seconds. Also, for example, as shown in "Cold start 1", the deviation from the final positioning position to the actual position when the power is turned on is within 1 degree in latitude and longitude, and the deviation of the clock of the positioning device with respect to the GPS time is within 30 minutes. The almanac data one month ago is backed up, but if there is no ephemeris data, the TTFF is about 75 seconds. In addition, for example, as shown in "Autonomous start", the position of the receiving point is indefinite (when the value is far from the actual position), and the value of the clock is also indefinite (the deviation from the current time is very large). ), And if neither the almanac data nor the ephemeris data is backed up, the TTFF is about 15 minutes. In addition, as shown in FIG. 18 as “cold start 2”, when the position of the receiving point is indefinite, the value of the clock is also indefinite, and only the almanac data of one year ago is actually backed up, Although the position of the receiving point and the clock are incorrect, in order to preferentially receive signals from positioning satellites that are predicted to be receivable from the incorrect information and severely shifted almanac data, In practice, reception is attempted from a positioning satellite that cannot be received, and the search fails. Therefore, it takes, for example, one hour before the satellites to be received are sequentially switched and the search is actually successful and the first positioning result is obtained.
[0008]
As described above, in the conventional positioning device, if the orbit information of each satellite held by the receiver, the estimated position of the reception point, or the content of the clock of the receiver is uncertain, the TTFF must be long.
[0009]
An object of the present invention is to make it possible to appropriately select a satellite to be searched even if the orbit information of each satellite of the receiver, the estimated position of the receiving point, or the content of the clock of the receiver is uncertain, so that the power is turned on. It is another object of the present invention to provide a positioning system, a positioning device, and a positioning method that can reduce a time (TTFF) until a position of a reception point is first obtained.
[0011]
[Means for Solving the Problems]
Further, the positioning system of the present invention enables the satellite to be searched to be properly selected even if the orbit information of each satellite of the receiver, the estimated position of the receiving point or the content of the clock of the receiver is uncertain. In order to reduce the time (TTFF) until the position of the receiving point is first obtained after the power is turned on, Claim 1 As described in, satellite signal receiving means for selectively receiving signals transmitted from a plurality of positioning satellites, and a satellite for broadcasting identification information of a plurality of positioning satellites in the field of view received by the satellite signal receiving means A base station comprising identification information broadcasting means;
A plurality of satellite signal receiving means for selectively receiving signals transmitted from the respective satellites based on the identification information of the positioning satellites; and information from the orbit information of each positioning satellite, the estimated position information of the mobile station, and the current time information. In-field satellite estimating means for estimating a positioning satellite in the field of view; and Positioning satellite Satellite identification information receiving means for receiving identification information; and positioning information received by the satellite identification information receiving means as identification information of a positioning satellite to be received by the satellite signal receiving means. Of the positioning satellite Identification information , Assigned to the satellite signal receiving means in preference to the positioning satellite identification information estimated by the in-field satellite estimating means And, the closer the distance between the base station and the mobile station is, the more the number of satellite identification information received by the satellite identification information receiving means to the plurality of satellite signal receiving means is increased. Reception allocating means And Mobile station.
[0013]
Furthermore, the positioning system of the present invention is transmitted from a satellite even if the receiver does not have the orbit information of each satellite and the motion state of each satellite to be received relative to the receiving point is not clear. To obtain information on the Doppler frequency contained in the signal and eliminate the need for extensive Doppler frequency searches, Claim 2 As described in, satellite signal receiving means for receiving signals transmitted from a plurality of positioning satellites, and satellite identification information broadcasting for broadcasting identification information of positioning satellites within the field of view received by the satellite signal receiving means Means, a base station comprising Doppler frequency information broadcasting means for broadcasting Doppler frequency information of the signal from the satellite,
A satellite identification information receiving unit and a Doppler frequency information receiving unit that receive the satellite identification information and the Doppler frequency information from the base station; and a satellite transmitted from a positioning satellite indicated by the satellite identification information received by the satellite identification information receiving unit. And a means for searching for and receiving an incoming signal based on the Doppler frequency information received by the Doppler frequency information receiving means.
[0014]
The positioning device of the present invention is applied to the above positioning system so that the position of the reception point can be obtained in a short time after power-on, Claim 3 As described in above, satellite identification information receiving means for receiving satellite identification information from a base station, and means for receiving a signal transmitted from a positioning satellite indicated by the satellite identification information received by the satellite identification information receiving means And
[0016]
[Action]
Of the present invention Claim 1 In the positioning system according to the above, signals transmitted from a plurality of positioning satellites are received by the base station, and the identification information of these satellites is broadcast as the identification information of the satellites within the field of view. One mobile station receives the satellite identification information in the field of view broadcast from the base station, and receives the positioning satellite indicated by the satellite identification information.
[0017]
By broadcasting the information of the satellites within the field of view from the base station and using the information at the mobile station, the mobile station may not know the estimated position of the receiving point in the initial state, Even if there is no information or the information on the current time is incorrect, only the satellites within the field of view are reliably searched, so that the positioning result can be obtained immediately after the power is turned on.
[0018]
Also ,each The positioning satellite in the field of view is estimated from the orbit information of the positioning satellite, the estimated position information of the mobile station, and the information of the current time, but the identification information of the positioning satellite to be received by the satellite signal receiving means is transmitted from the base station. Since the received satellite identification information is assigned with higher priority than the identification information of the positioning satellite estimated, if satellite identification information cannot be received from the base station, a signal from the estimated satellite is received and the satellite identification information is transmitted from the base station. When the information can be received, a signal from the satellite indicated by the satellite identification information is received. For example, when the power is turned on in an underground parking lot and the vehicle goes outside after a while, the satellite signal receiving means first receives a signal from the positioning satellite based on the identification information of the positioning satellite. After that, the satellite identification information is received from the base station, and the satellite signal receiving means is allocated so that the signal from the satellite indicated by the satellite identification information is received. As a result, the satellite search is started immediately after the power is turned on, and the satellite to be searched is properly selected, and the positioning result can be obtained immediately after the power is turned on.
[0019]
Moreover The shorter the distance between the base station and the mobile station, the more the number of satellite identification information received from the base station to a plurality of satellite signal receiving means increases. Conversely, as the distance between the base station and the mobile station increases, the number of assignments of the satellite identification information received from the base station decreases. In other words, as the distance between the base station and the mobile station increases, the probability that the satellites that are visible in the field of view from the base station will be out of the field of view from the mobile station increases. By changing the number of assigned satellite identification information received from the base station to a plurality of satellite signal receiving means according to the distance, the satellite to be searched can be properly determined regardless of the distance between the base station and the mobile station. The probability of selection is increased, and TTFF is shortened.
[0020]
Claim 2 In the positioning system according to the identification information of the positioning satellite in the field of view, Doppler frequency information of the signal from the satellite is broadcast from the base station, the mobile station receives its satellite identification information and Doppler frequency information, A signal transmitted from the positioning satellite indicated by the received satellite identification information is searched for and received based on the Doppler frequency information. Accordingly, even if the receiver does not have the orbit information of each satellite and the relative motion state of each satellite to be received with respect to the receiving point is not clear, it is included in the signal transmitted from the satellite. By obtaining information on the Doppler frequency, it is not necessary to search for a wide range of Doppler frequencies, and the time required for searching each satellite is reduced.
[0021]
Claim 3 In the positioning device according to the present invention, the satellite identification information in the field of view broadcast from the base station is received, and the positioning satellite indicated by the satellite identification information is received. Signal sent from Is received, and a positioning operation is performed based on signals from the plurality of positioning satellites.
[0022]
By using the information on the satellites in the field of view broadcast from the base station in the positioning device, the positioning device does not have the orbit information of each satellite in the initial state, or the information of the current time is incorrect. However, the positioning result can be obtained immediately after the power is turned on.
[0024]
【Example】
First, a configuration of a positioning device according to a first embodiment of the present invention will be described below with reference to FIGS. The first embodiment is a positioning device corresponding to a differential GPS receiver that receives differential correction data wirelessly transmitted from a base station.
[0025]
FIG. 1 is a block diagram showing the configuration of the positioning device. In the figure, an analog signal processing circuit 2a converts a signal from a GPS satellite received by the receiving antenna 1 into an intermediate frequency, and an AD converter 2b converts the signal into digital data. The signal processing gate array 3 receives digital data from the AD converter 2b, receives C / A code pattern data, C / A code phase data, carrier phase data, and the like from the CPU 5, generates a C / A code pattern, and outputs a C / A code pattern. A correlation operation with the A code is performed. The clock circuit 4 has a reference oscillator, and divides the reference oscillation signal to measure the current time. The CPU 5 executes a program previously written in the ROM 6, reads correlation data from the signal processing gate array 3, performs a predetermined loop filter operation, and performs C / A code pattern data, C / A By giving the A code phase data and the carrier phase data, the C / A code phase and the carrier phase are synchronized, and further, the navigation message data is extracted. Further, the CPU 5 extracts ephemeris (orbit information of the satellite) from the navigation message data, obtains position information of each satellite, obtains a pseudo distance to each satellite, and calculates the position of the receiving point. Further, the CPU 5 outputs the positioning result via the data transmission interface 8. The RAM 7 is used as a working area when performing these processes. The receiving circuit 10 receives a radio wave transmitted from the base station via the antenna 9 and obtains it as serial digital data. The CPU 5 reads the data (differential correction data) via the interface 11.
[0026]
FIG. 2 shows an example of some differential correction data of the standard standard RTCM SC-104 for the purpose of error correction by SA (selective availability) of a GPS system created by the U.S. Maritime Radio Technology Commission. In the figure, the TYPE 1 or TYPE 9 message is data comprising satellite identification information (satellite number), a pseudo distance correction value, and a distance change rate correction value. The correction value and its change rate (change distance per unit time) are transmitted. The TYPE2 message is data including satellite identification information, a delta pseudo-range correction value, and a delta distance change rate correction value. When the orbit information from the satellite is updated, the base station receives new orbit information before the mobile station. In this case, the mobile station performs correction based on the difference (delta correction value) between the correction data based on the new track information and the correction data based on the old track information. The TYPE 3 message is position information of the base station, and is indicated by X, Y, Z coordinates in the earth fixed center of the earth (ECEF) coordinates. The TYPE 5 message includes identification information of each satellite and health data indicating its health status. As will be described later, among these messages, a message including satellite identification information such as TYPE1, TYPE2, TYPE5, and TYPE9 uses the satellite identification information as satellite identification information in the field of view. It is used when considering the distance between the mobile station and the base station as described later.
[0027]
Each of the above messages is broadcast in various forms by "Road Traffic Information and Communication System: VICS" jointly operated by the Ministry of Construction, the National Police Agency, and the Ministry of Posts and Telecommunications. The receiving circuit shown in FIG. 1 is a circuit for receiving, for example, FM multiplex broadcasting.
[0028]
FIG. 3 is a flowchart showing a processing procedure from power-on to assignment of a satellite to each channel. First, it is determined whether correction data has been received from the base station (n1). If a TYPE 3 message is received, the process of receiving a signal from the base station is performed in parallel by another process. The position of the base station is obtained as latitude, longitude, and height information (n2 → n3). . If the first positioning result has already been obtained at this point, the distance from the own station (mobile station) to the base station is determined here (n4 → n5). If the distance is a short distance within a predetermined distance, the number employed when assigning a satellite number to a reception channel based on the satellite identification information received from the base station is maximized. That is, the state is set so that a satellite number based on the satellite identification information received from the base station is assigned as much as possible to a plurality of (eight) reception channels (n5 → n7). If the distance is longer than a predetermined distance, the number of satellites assigned to the receiving channel based on the satellite identification information received from the base station is set to four. That is, the state is set so that the satellites indicated by the satellite identification information received from the base station are allocated to four of the eight reception channels (n5 → n6). If the first positioning result has not been obtained yet, the state is set so that a satellite based on the satellite identification information received from the base station is allocated as much as possible to a plurality of (eight) reception channels (n4 → n7). ). Thereafter, when a message including satellite identification information such as TYPE 1, 2, 5, 9 or the like is received from the base station, the satellite identification information included in the message is stored (updated) as the satellite number of the satellite in the field of view (n8). ). Then, the satellite number is assigned to each channel within a range not exceeding the number of adoptions (n9). Note that the default value (initial value) of the adopted number is the maximum, and if no TYPE 3 message has been received yet, a satellite number based on the satellite identification information received from the base station can be assigned to eight reception channels. Assign as long as you can. As described above, the number of the above-mentioned adopted numbers is maximized until the first positioning result is obtained after the power is turned on. Therefore, even if the own station (mobile station) is far from the base station, the satellite identification information received from the base station is obtained. Increases the probability of receiving signals from four or more satellites, and shortens the TTFF.
[0029]
If a signal from the base station has not been received, the approximate position of each satellite is calculated, and satellites within the field of view where the elevation angle of each satellite as viewed from the receiving point is positive are allocated to unused channels that have not been allocated yet. (N10 → n11). By repeating the above processing, satellites are allocated to a plurality of reception channels according to either the satellite number extracted from the differential correction data or the satellite number in the field of view obtained by calculation. The plurality of channels correspond to a plurality of satellite signal receiving means according to claim 2 of the present invention.
[0030]
In the satellite allocation in step n9, a satellite having a small correction value based on the differential correction data is preferentially allocated. For example, PR is a pseudo distance after correction based on the message of TYPE1, and PRm is a pseudo distance measured at time t. _t If the correction value of the pseudo distance is PRC, the correction value of the distance change rate is RRC, and the previous correction time is to, the corrected pseudo distance PR is
PR = PRm _t + PRC + RRC · (t-to). Since the correction using the correction value RRC of the distance change rate is a first-order approximation, when the cycle of receiving the TYPE 1 message becomes longer, the correction amount based on the correction value RRC of the distance change rate is calculated. Accuracy decreases. Therefore, the smaller the distance change rate correction value is, the higher the priority is assigned to the channel.
[0031]
FIG. 4 shows the contents of the navigation message extraction process. In this process, almanac data and ephemeris data are extracted from a navigation message included in a received signal from each satellite, and these are edited as orbit information of each satellite.
[0032]
FIG. 5 is a flowchart showing the procedure for calculating the satellite position of each satellite, and corresponds to the processing in step n9 in FIG. First, the orbit information, the current time, and the estimated position information of the receiving point of each satellite are read, and the position of each satellite is calculated based on these information.
[0033]
FIG. 6 is a flowchart showing the procedure of the positioning calculation process. First, the pseudo distance from the receiving point to each satellite is corrected using differential correction data. After that, the position of the receiving point is determined from the position information of each satellite and the corrected pseudorange of each satellite.
[0034]
FIGS. 7 to 9 show examples of satellite assignment to each channel. In each figure, the “satellite numbers extracted by the differential correction data” are arranged in ascending order of the distance change rate correction value. The “satellite numbers in the field of view obtained by calculation” are arranged in ascending order of elevation.
[0035]
FIG. 7 shows an example in which all satellite numbers included in the differential correction data are assigned. Thus, first, the seven satellite numbers 3,4,8,10,14,17,18 included in the differential correction data are converted into seven channels of channel numbers 0,1,2,3,4,5,6. When the satellite numbers obtained by the calculation are assigned to the vacant channel 7 after that, the satellite numbers 3 and 8 are already assigned to the channel numbers 0 and 2, so the next satellite number 11 is assigned to the vacant channel 7. When assigning a satellite number in the field of view obtained by calculation to an empty channel as described above, a satellite having a large elevation angle (around 90 °) is preferentially assigned. Thereby, even if the almanac data of each satellite is old and the estimated position of each satellite is shifted, the satellite having the highest probability of being in the field of view is assigned.
[0036]
FIG. 8 shows an example in which the distance between the base station and the mobile station is longer than a certain distance, and only four satellites are employed among a plurality of satellite numbers extracted from the differential correction data. (As described later, it is determined how many satellites among a plurality of satellite numbers extracted from the differential correction data are to be adopted according to the distance between the base station and the mobile station.) That is, the satellite numbers are extracted from the differential correction data. Satellite numbers 3, 4, 8, and 10 are assigned to channel numbers 0, 1, 2, and 3, respectively. Of the satellite numbers in the field of view obtained by the calculation, the satellite numbers other than the satellite numbers extracted from the differential correction data are used as free channels. Assign to That is, since the satellite numbers 3, 8, and 4 are already assigned to the channel numbers 0, 2, and 1, the satellite numbers 11, 14, 9, and 21 of the other high-elevation satellites are assigned to the vacant channels 4, 5, and 6, respectively. , 7.
[0037]
FIG. 9 shows a case where the satellite number in the field of view is estimated by calculation before the differential correction data is received, the satellite number is allocated to the channel first, and then, when the differential correction data is received, the satellite number is allocated. This is an example. That is, first, satellite numbers 3, 8, 11, 4, 14, 9, and 21 are temporarily assigned to channel numbers 0, 1, 2, 3, 4, 5, and 6, and then satellite numbers are extracted from differential correction data. The satellite number is assigned to an empty channel, and the satellite number extracted from the differential correction data is preferentially replaced and assigned. In the example shown in the figure, the satellite numbers 3, 4, 8, and 14 extracted from the differential correction data are already assigned to the channels 0, 3, 1, and 4, respectively. Assign to 7. Since the satellite numbers 9 and 21 do not exist in the satellite numbers extracted from the differential correction data, the satellite numbers 17 and 18 are reset for the channel numbers 6 and 5, respectively.
[0038]
In the example described above, an example is shown in which a message is received in a format standardized by the RTCM SC-104 and satellite identification information is extracted, but the combination information of a plurality of satellites used for positioning and the combination of the satellites is used. The base station transmits the information of the positional deviation included in the result of the positioning operation as a pair, and the receiving station performs the positioning operation with the same combination of satellites and corrects the position deviation for the result. The present invention can be similarly applied to a differential GPS system of a type which performs the above operation. For example, as shown in FIG. 10, the base station transmits information on a plurality of combinations of satellites and error information Δφ, Δλ, Δh of latitude, longitude, and height from the base station. When the mobile station receives the information, A plurality of satellite numbers included in the satellite combination information are used as the satellite numbers of the satellites within the field of view, and satellites are allocated to channels in the same manner as described above.
[0039]
In the example described above, a state occurs in which a plurality of satellite numbers extracted from the differential correction data are assigned to all eight channels. For example, the number of adopted satellite numbers extracted from the differential correction data is set to the maximum. In this case, if this is allocated to seven channels and the remaining one channel is allocated a satellite number in the field of view obtained by calculation, even if the base station becomes abnormal and broadcasts abnormal data, The mobile station can receive signals from satellites within the field of view on the one channel. If it is determined from this that the broadcast content of the base station cannot be relied on, the number of channels to which satellite numbers in the field of view obtained by calculation may be increased thereafter.
[0040]
Next, a configuration of a positioning system according to a second embodiment of the present invention will be described below with reference to FIGS. In the second embodiment, a message is transmitted from a base station in a unique format using, for example, TYPE numbers 64-128 of RTCM SC-104, and the mobile station receives the message.
[0041]
FIG. 11 is a block diagram showing a configuration of the base station. In the figure, the configurations of an analog signal processing circuit 22a, an AD converter 22b, a signal processing gate array 23, a clock circuit 24, and a CPU 25 are the same as those of each section of the positioning device shown in FIG. The same applies to the use of the RAM 27. The transmission circuit 30 wirelessly transmits the message data signal output from the interface 31 to the mobile station via the antenna 29. The CPU 25 outputs message data to the interface 31. The configuration of the mobile station used in the second embodiment is the same as that of the positioning device shown in FIG.
[0042]
FIG. 12 is a flowchart showing the procedure of the receiving process in the base station. In this process, C / A code pattern data is set according to the satellite number to be received, and C / A code phase and carrier phase are synchronized by providing C / A code phase data and carrier phase data. And further extract the navigation message data. At the same time, the Doppler frequency of the satellite is extracted.
[0043]
FIG. 13 shows the contents of the navigation message extraction processing in the base station. In this process, almanac data and ephemeris data are extracted from a navigation message included in a received signal from a satellite, and these are edited as orbit information of each satellite.
[0044]
FIG. 14 is a flowchart showing the procedure of calculating the satellite position of each satellite in the base station. First, the orbit information of each satellite, the current time, and the position information of a known reception point are read, and the position of each satellite is calculated based on these information. Subsequently, satellites existing in the field of view viewed from the receiving point (base station) are extracted.
[0045]
FIG. 15 is a flowchart showing a procedure for broadcasting a message including satellite identification information. First, information on the satellite number and Doppler frequency of each satellite in the field of view is broadcast sequentially for all satellites in the field of view, followed by information on the broadcastable distance. Then, this process is repeated.
[0046]
FIG. 16 shows the format of the message. For example, this content
03, -3
06, + 1
09, +0
12, +2
1000
Then, the Doppler frequency of the signal from the satellite number 3 is -3 kHz, the Doppler frequency of the signal from the satellite number 6 is +1 kHz, the Doppler frequency of the signal from the satellite number 9 is 0 kHz, and the satellite number 12 Indicates that the Doppler frequency of the signal from the satellite is +2 kHz and the broadcastable distance is 1000 km.
[0047]
FIG. 17 is a flowchart showing a procedure of a process of receiving a signal from the base station in the mobile station. First, information on each satellite number, Doppler frequency, and broadcastable distance of the satellites within the field of view is received, and the satellites within the field of view obtained by this are assigned to each channel. At the time of reception processing in each channel, a search for a Doppler frequency is performed around the Doppler frequency within the upper limit and the lower limit of the Doppler frequency determined according to the broadcastable distance. That is, the maximum search range of the Doppler frequency of the satellite to be received is determined based on the information on the broadcastable distance. For example, as the distance between the base station and the mobile station is shorter, the difference between the Doppler frequency included in the signal from a certain satellite as viewed from the base station and the Doppler frequency included in the signal from the certain satellite as viewed from the mobile station is smaller. Conversely, as the distance between the base station and the mobile station increases, the difference between the Doppler frequency included in the signal from a certain satellite viewed from the base station and the Doppler frequency included in the signal from the satellite viewed from the mobile station increases. growing. The range of the deviation eventually depends on the distance between the base station and the mobile station, and the maximum search range of the Doppler frequency is determined by setting the broadcastable distance to the maximum expected distance from the mobile station to the base station. As described above, in the mobile station, the range in which the Doppler frequency of the signal to be received can be determined in advance from the information on the Doppler frequency of each satellite and the broadcastable distance, the width in which the Doppler frequency should change is limited, and the Doppler frequency is limited. Is reduced, and the time from when the power is turned on to when the first positioning result is obtained is reduced.
[0048]
【The invention's effect】
Of the present invention Claim 1 Positioning system To According to this, since information on satellites within the field of view is broadcast from the base station and used by the mobile station, each mobile station does not have the orbit information of each satellite in the initial state, and the estimated position of the reception point is also determined. Even if the information is incorrect, or even if the current time information is incorrect, only the satellites within the field of view are surely searched, so that the positioning result can be obtained immediately after the power is turned on.
[0049]
Also In accordance with the distance between the base station and the mobile station, the number of allocations of the satellite identification information received from the base station to the plurality of satellite signal receiving means changes, regardless of the distance between the base station and the mobile station. Therefore, the probability that the satellite to be searched can be properly selected increases, and the TTFF is shortened.
[0050]
Claim 2 According to the positioning system according to the above, even if the receiver does not have the orbit information of each satellite and the relative motion state of each satellite to be received with respect to the receiving point is not clear, the signal transmitted from the satellite The information of the Doppler frequency included in the information is obtained, so that the search of the Doppler frequency over a wide range becomes unnecessary, and the time required for searching each satellite is reduced.
[0051]
In addition, the present invention Claim 3 According to the positioning device according to the present invention, by using the information of the satellites within the field of view broadcast from the base station, even if the satellite does not have the orbit information in the initial state, or even if the current time information is incorrect, It is possible to reliably search only the satellites within the satellite and obtain a positioning result immediately after the power is turned on.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a positioning device according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a message broadcast from a base station in the first embodiment.
FIG. 3 is a flowchart illustrating a processing procedure of the positioning device.
FIG. 4 is a flowchart illustrating a processing procedure of the positioning device.
FIG. 5 is a flowchart illustrating a processing procedure of the positioning device.
FIG. 6 is a flowchart illustrating a processing procedure of the positioning device.
FIG. 7 is a diagram showing an example of assigning a satellite number to each channel.
FIG. 8 is a diagram showing an example of assigning a satellite number to each channel.
FIG. 9 is a diagram showing an example of assigning a satellite number to each channel.
FIG. 10 is a diagram illustrating another example of the differential correction data transmitted from the base station.
FIG. 11 is a block diagram illustrating a configuration of a base station in the positioning system according to the second embodiment.
FIG. 12 is a flowchart showing a processing procedure in the base station.
FIG. 13 is a flowchart showing a processing procedure in the base station.
FIG. 14 is a flowchart showing a processing procedure in the base station.
FIG. 15 is a flowchart showing a processing procedure in the base station.
FIG. 16 is a diagram illustrating an example of a message broadcast from a base station.
FIG. 17 is a flowchart showing a processing procedure in the mobile station.
FIG. 18 is a diagram illustrating an example of a state at power-on and a time until a first fix.

Claims (3)

Satellite signal receiving means for receiving signals transmitted from a plurality of positioning satellites, and satellite identification information broadcasting means for broadcasting identification information of a plurality of positioning satellites within the field of view received by the satellite signal receiving means. A base station to be provided,
A plurality of satellite signal receiving means for selectively receiving signals transmitted from the respective satellites based on the identification information of the positioning satellites; and information from the orbit information of each positioning satellite, the estimated position information of the mobile station, and the current time information. A satellite-in-view estimating means for estimating a positioning satellite in a visual field, a satellite identification information receiving means for receiving identification information of the positioning satellite from the base station, and a positioning satellite to be received by the satellite signal receiving means. assigned as identification information, the identification information of the positioning satellite received by the satellite identification information receiving means, in preference to identification information of the positioning satellite that is estimated by the in-field satellite estimating means to the satellite signal receiving means , more and close the distance between the mobile station and the base station, to the plurality of satellite signal receiving means, increasing the number of allocated satellite identification information received by the satellite identification information receiving means Positioning system comprising a mobile station and a signal allocating unit. Satellite signal receiving means for receiving signals transmitted from a plurality of positioning satellites, satellite identification information broadcasting means for broadcasting identification information of positioning satellites within the field of view received by the satellite signal receiving means, A base station comprising Doppler frequency information broadcasting means for broadcasting Doppler frequency information of a signal from
A satellite identification information receiving unit and a Doppler frequency information receiving unit that receive the satellite identification information and the Doppler frequency information from the base station; and a satellite transmitted from a positioning satellite indicated by the satellite identification information received by the satellite identification information receiving unit. And a means for searching for and receiving an incoming signal based on the Doppler frequency information received by the Doppler frequency information receiving means. In the positioning system according to claim 1 or 2, and the satellite identification information receiving means for receiving identification information of the positioning satellite from said base station, the positioning indicated by the identification information received by the satellite identification information receiving means Means for receiving a signal transmitted from a satellite for use in a mobile station .

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