JP2018009938A - Radio positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio positioning device capable of improving positioning accuracy by using electric field intensity of a plurality of radio signals while suppressing complication of a configuration for measuring electric field intensity.SOLUTION: A radio positioning device 100 is mounted on a vehicle A, and comprises: a positioning control part 20; an electric field intensity measurement part 30; and a positioning processing part 50. The positioning control part 20 acquires a reference track indicating a correspondence relation between the position of the vehicle A and electric field intensity. The electric field intensity measurement part 30 receives radio waves of a plurality of channels, and converts the received radio waves into the information of a frequency area, and calculates the electric field intensity of each channel from the converted information of the frequency area. Thus, the electric field intensity of the radio signals of the plurality of channels is measured. The poisoning processing part 50 estimates the position of the vehicle A on the basis of the reference track and the calculated electric field intensity of the plurality of channels.SELECTED DRAWING: Figure 1

Description

  The disclosure according to this specification relates to a wireless positioning device that is mounted on a moving body such as a vehicle and measures the position of the moving body.

  Conventionally, for example, Patent Literature 1 discloses a wireless positioning system that measures the current position of a vehicle by measuring the electric field strength of a wireless signal transmitted from a reference station installed in the vicinity of a road. In this wireless positioning system, reference trajectory information indicating the correspondence between the position of the vehicle and the acquired electric field strength when the vehicle is driven along a road is stored in advance. The wireless positioning system can measure the current position of the vehicle by using the current electric field strength of the wireless signal and a reference trajectory prepared in advance.

  On the other hand, for example, Patent Document 2 discloses a field strength measuring device capable of measuring the field strength of wireless signals having different frequencies as a technique related to reception of a wireless signal. This electric field strength measuring apparatus includes a plurality of RF units tuned to the frequency of each channel, and measures the electric field strength for each channel in real time using each RF unit.

JP 2013-257306 A JP 2014-3453 A

  Now, if it is the structure which calculates the electric field strength of the radio signal of a several channel, the improvement of the precision which measures a position will be attained. Therefore, the inventor of the present disclosure has studied a specific configuration of a wireless positioning device that can calculate the electric field strength of a plurality of channels of wireless signals. As an example, a wireless positioning device is conceived that employs a configuration such as the electric field strength device of Patent Document 2 in order to measure the electric field strength of radio signals of a plurality of channels. However, in the configuration disclosed in Patent Document 2, a large number of RF circuits and the like corresponding to the frequency of each channel are provided. For this reason, even if the positioning accuracy is improved, there is a concern that the configuration for measuring the electric field strength may be complicated.

  The present disclosure has been made in view of the above problems, and its purpose is to improve positioning accuracy by using electric field strengths of a plurality of radio signals while suppressing complication of a configuration for measuring electric field strengths. Is to provide a simple wireless positioning device.

  In order to achieve the above object, a disclosed first aspect is a wireless positioning device that is mounted on a mobile object (A) and measures the position of the mobile object, and an electric field of a radio signal received by the mobile object An intensity measuring unit (30, 230, 330) for measuring the intensity, an information acquiring unit (20) for acquiring reference information indicating the correspondence between the position of the moving object and the acquired electric field strength, and an intensity measuring unit And a positioning processing unit (50) for estimating the position of the moving body based on the measured electric field strength and the reference information, and the strength measuring unit receives radio waves in a specific band including radio signals of a plurality of channels. Receiver (41), an area converter (47) for converting radio waves in a specific band received by the receiver into frequency domain information, and each channel from the frequency domain information converted by the area converter Calculator for calculating the electric field strength of (48 Has, positioning processor estimates the position of the moving body using the electric field strength of a plurality of channels calculated in the calculator.

  According to this aspect, radio waves in a specific band including radio signals of a plurality of channels are converted into frequency domain information, so that the electric field strength of each channel can be calculated individually. With the above configuration, the electric field strength of a radio signal of a plurality of channels can be calculated without providing a large number of RF circuits or the like corresponding to the frequency of each channel. Therefore, a wireless positioning device that can improve the positioning accuracy by using the field strengths of a plurality of wireless signals while suppressing the complexity of the configuration of the field strength measuring unit is realized.

  Note that the reference numbers in the parentheses merely show an example of a correspondence relationship with a specific configuration in an embodiment described later, and do not limit the technical scope at all.

It is a figure which shows typically the whole image of the wireless positioning system by 1st embodiment, and each block provided in a wireless positioning device. It is a figure which shows the detailed structure of an electric field strength measurement part. It is an image figure which shows typically the spectrum at the time of receiving the AM broadcast wave of multiple channels, Comprising: It is a figure which shows the case where AD conversion of the whole frequency band of AM broadcast is carried out. It is a figure for demonstrating adjusting the acquisition bandwidth of AD conversion according to the frequency of the AM broadcast currently received. It is a figure which shows typically the information Fourier-transformed to the frequency domain by the fast Fourier transformer. It is a figure which shows typically a mode that a present position is measured by matching with a reference locus | trajectory and electric field strength. It is a flowchart which shows the detail of the positioning process implemented in a positioning process part. It is a figure which shows typically the whole image of the wireless positioning system by 2nd embodiment, and each block provided in a wireless positioning apparatus. It is a figure which shows the detailed structure of the electric field strength measurement part by 3rd embodiment. It is a figure for demonstrating possibility that positioning accuracy deteriorates with a high intensity | strength channel. It is a figure which shows typically the case where the signal of a high intensity | strength channel is removed from the analog signal input into AD converter.

  Hereinafter, a plurality of embodiments of the present disclosure will be described based on the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. Moreover, not only the combination of the configurations explicitly described in the description of each embodiment, but also the configuration of a plurality of embodiments can be partially combined even if they are not explicitly described, as long as there is no problem in the combination. And the combination where the structure described in several embodiment and the modification is not specified shall also be disclosed by the following description.

(First embodiment)
As shown in FIG. 1, the wireless positioning device 100 according to the first embodiment of the present disclosure is a mobile terminal that is mounted on a vehicle A as a moving body and can move together with the vehicle A. The wireless positioning device 100 constitutes a wireless positioning system together with the information providing device 110, the plurality of broadcasting stations 121 to 123, and the like. The wireless positioning system is a positioning system that complements positioning by GNSS (Global Navigation Satellite System). The wireless positioning system enables, for example, high-precision positioning that is difficult with GNSS and positioning when it is difficult to receive satellite signals from GNSS positioning satellites.

  The information providing apparatus 110 is installed in a traffic management center or the like outside the vehicle A. The information providing apparatus 110 can communicate with the wireless positioning apparatus 100 and transmits / receives information to / from the wireless positioning apparatus 100. The information providing apparatus 110 includes a wide area wireless device 112 and an antenna 113 for communication, a server 111 for data processing, and the like.

  The information providing apparatus 110 receives a request for providing information such as a reference trajectory, which will be described later, from the radio positioning apparatus 100 mounted on a large number of vehicles A by the wide area radio 112 and the antenna 113. The server 111 is provided with a processing circuit that processes a request from each wireless positioning device 100 and a large-capacity storage medium such as a hard disk drive. In the storage medium of the server 111, reference trajectories at various locations in the service providing area of the wireless positioning system are accumulated. The information providing apparatus 110 selects a reference trajectory necessary for each vehicle A, and transmits the selected reference trajectory toward each wireless positioning device 100.

  As an example, each of the broadcasting stations 121 to 123 is a broadcasting station that transmits a radio AM broadcast by wireless communication. Each of the broadcast stations 121 to 123 transmits AM broadcasts of different channels. For example, in Japan, a frequency band of 526 to 1632 kHz is allocated to AM broadcasting. The frequency of the radio signal transmitted by each of the broadcast stations 121 to 123 is set in advance to a frequency different from each other in the AM broadcast frequency band. In AM broadcasting, audio information is transmitted by amplitude modulation. A radio signal of AM broadcasting includes a carrier wave component and a sideband component (see FIG. 3). In addition, the radio signal by each broadcasting station 121-123 may be transmitted from the same point, or may be transmitted from different points.

  Next, a detailed configuration of the wireless positioning device 100 will be described. The wireless positioning device 100 is mounted on the vehicle A to measure the current position of the vehicle A. The wireless positioning device 100 specifies the current position of the vehicle A by comparing the current RSSI (Received Signal Strength Indicator, hereinafter referred to as “electric field strength”) of each of the broadcasting stations 121 to 123 and the reference locus. The reference trajectory is reference information indicating the correspondence between the position where the vehicle A is traveling and the acquired electric field strength for each of the broadcasting stations 121 to 123. In order to realize such wireless positioning, the wireless positioning device 100 includes a GNSS receiving unit 21, a wide area radio 22 and an antenna 23, a storage unit 24, a positioning control unit 20, an electric field strength measuring unit 30, and a positioning processing unit 50. Yes.

  The GNSS receiver 21 receives satellite signals from GNSS positioning satellites. The GNSS receiving unit 21 is connected to the positioning control unit 20 and sequentially provides the received satellite signals to the positioning control unit 20.

  The wide area wireless device 22 and the antenna 23 transmit and receive information by wireless communication between the wide area wireless device 112 and the antenna 113 of the information providing apparatus 110. The wide area radio 22 and the antenna 23 are connected to the positioning control unit 20, and transmission / reception of information is controlled by the positioning control unit 20.

  The storage unit 24 includes a storage medium that stores a reference locus, channel information described later, and the like. The storage medium may have a configuration such as a hard disk drive or a flash memory built in the wireless positioning device 100, or is provided in the form of a memory card or the like and is inserted into a card slot provided in the wireless positioning device 100. It may be a configuration. The storage unit 24 is connected to the positioning control unit 20. The positioning control unit 20 can read and rewrite information stored in the storage unit 24.

  The positioning control unit 20 controls acquisition of information necessary for wireless positioning in cooperation with the GNSS receiving unit 21, the wide-area radio device 22, the antenna 23, and the storage unit 24. Specifically, the positioning control unit 20 performs rough current position acquisition processing based on satellite signals, reference trajectory acquisition and output processing, channel information acquisition and output processing, and the like.

  The positioning control unit 20 measures the current rough position of the vehicle A from the satellite signal acquired from the GNSS receiving unit 21. The positioning control unit 20 acquires a reference trajectory for each of the receivable broadcasting stations 121 to 123 for the road on which the vehicle A is traveling and the road on which the vehicle A is scheduled to travel based on the positioning result based on the satellite signal. The positioning control unit 20 can acquire a necessary reference locus from the information providing apparatus 110 in response to a request for information provision to the information providing apparatus 110. In addition, the positioning control unit 20 can acquire a necessary reference locus from the storage unit 24 when the reference locus around the current position is stored in the storage unit 24. The positioning control unit 20 outputs the acquired reference trajectory toward the positioning processing unit 50.

  In addition, the positioning control unit 20 acquires channel information indicating the frequency of a receivable channel at the current position measured by the satellite signal. The channel information may be acquired from the information providing apparatus 110 in response to a request for information provision to the information providing apparatus 110, or may be read from the storage unit 24, similarly to the reference trajectory. Or the channel information memorize | stored in the radio receiver (for example, audio equipment) mounted in the vehicle A may be acquired by the positioning control part 20. FIG. The positioning control unit 20 outputs the acquired channel information to the electric field strength measurement unit 30.

  The electric field strength measuring unit 30 shown in FIGS. 1 and 2 measures the electric field strength of a radio signal received by the vehicle A. The electric field strength measuring unit 30 of the first embodiment receives AM broadcast waves broadcast by the respective broadcast stations 121 to 123 as radio signals, and measures the electric field strength of each AM broadcast wave. The electric field strength measuring unit 30 is connected to the positioning control unit 20 and the positioning processing unit 50. The electric field strength measurement unit 30 acquires channel information from the positioning control unit 20. The electric field strength measuring unit 30 outputs the measured electric field strengths of the broadcasting stations 121 to 123 to the positioning processing unit 50. The electric field strength measurement unit 30 includes a receiver 41, a modulator 43, a variable low-pass filter 45, an AD converter 46, a fast Fourier transformer 47, and a power calculator 48.

  The receiver 41 is a radio signal transmitted from each of the broadcasting stations 121 to 123 and receives an AM broadcast wave broadcast by amplitude modulation. The specific band receivable by the receiver 41 is set wider than the frequency band assigned to the AM broadcast so as to include radio signals of a plurality of channels of AM broadcast. The receiver 41 includes an AM broadcast antenna 41a and a low noise amplifier (hereinafter referred to as “LNA”) 41b. The receiver 41 amplifies the radio wave analog signal received by the AM broadcast antenna 41 a by the LNA 41 b and outputs the amplified signal to the modulator 43.

  The modulator 43 lowers the frequency of the radio wave analog signal received by the receiver 41. By reducing the frequency, the signal processing of the AD converter 46 and the like is facilitated. The modulator 43 includes a local oscillator 43b and a mixer 43a. The local oscillator 43b is provided with a PLL (Phase Locked Loop) circuit 43c.

  The PLL circuit 43c can generate a signal having an arbitrary frequency. As an example, the PLL circuit 43c outputs a center value of a frequency band assigned to AM broadcasting, specifically, a signal of 1079 kHz (see FIG. 3). As another example, the PLL circuit 43c can change the output frequency according to the frequency of the channel received by the receiver 41 based on the channel information. Specifically, among the receivable channels, the broadcasting station 121 with the lowest frequency transmits an AM broadcast wave of 600 kHz, and the broadcasting station 123 with the highest frequency transmits an AM broadcast wave of 1200 kHz ( (See FIG. 4). In this case, the center value of the frequency of the two broadcasting stations 121 and 123, specifically, a signal of 900 kHz is output.

  The mixer 43a outputs a signal having a difference between the two frequencies as a calculation result by an operation of multiplying signals having different frequencies. The analog signal output from the receiver 41 and the modulation signal generated by the local oscillator 43b are input to the mixer 43a. The modulator 43 lowers the frequency of the analog signal of the AM broadcast using the modulation signal by the mixer 43 a and outputs it to the variable low-pass filter 45. The modulator 43 can change the magnitude of the frequency to be lowered by increasing or decreasing the frequency of the signal generated by the PLL circuit 43c.

  The variable low-pass filter 45 has a configuration in which a component having a frequency higher than the cut-off frequency is gradually reduced so as not to pass substantially. The cutoff frequency is set to ½ of the sampling rate of the AD converter 46 based on the sampling theorem. The variable low-pass filter 45 removes a frequency component outside the AM broadcast band from the analog signal modulated by the modulator 43 and outputs it to the AD converter 46.

  The AD converter 46 converts the analog signal of the AM broadcast that has passed through the variable low-pass filter 45 into a digital signal that can be processed by the fast Fourier transformer 47. The AD converter 46 can arbitrarily change the sampling rate when performing AD conversion. As an example, when the entire frequency band assigned to AM broadcasting is to be subjected to AD conversion (see FIG. 3), the AD converter 46 sets the sampling rate to 1106 kHz. As described above, the acquisition bandwidth is ensured wider than the frequency band of AM broadcasting.

  As another example, the AD converter 46 increases or decreases the sampling rate used for signal conversion in accordance with the frequency of the channel received by the receiver 41 based on the channel information. Specifically, when the broadcast station 121 transmits an AM broadcast wave of 600 kHz and the broadcast station 123 transmits an AM broadcast wave of 1200 kHz (see FIG. 4), the sampling rate is set to 600 kHz. The AD converter 46 outputs the radio wave information of the AM broadcast band converted into a digital signal to the fast Fourier transformer 47.

  The fast Fourier transformer 47 Fourier-transforms the radio wave information in the AM broadcast band converted into a digital signal by the AD converter 46 from information in the time domain to information in the frequency domain. Spectral information indicating the correlation between the frequency of the radio signal in the AM broadcast band and the electric field strength of each frequency is acquired by Fourier transform by the fast Fourier transformer 47 (see FIG. 5).

  The power calculator 48 calculates the electric field strength for each channel from the spectrum information in the frequency domain converted by the fast Fourier transformer 47. As described above, in AM broadcasting in which amplitude modulation is performed, the power of the sideband components above and below the carrier wave component varies with changes in the audio information that is the broadcast content. On the other hand, the power of the carrier component is not related to audio information. Therefore, the power calculator 48 extracts the carrier component from the radio signal included in one channel, and calculates the electric field strength of the carrier component. The carrier wave component is set in a range of 500 Hz before and after the center frequency of each of the broadcasting stations 121 to 123 set by the channel information. That is, the bandwidth of 1 kHz centered on the center frequency is used as the carrier component, and the electric field strength of one channel is calculated based on the energy of 1 kHz (see FIG. 5).

  As described above, the power calculator 48 can measure the electric field strength without being affected by the fluctuation caused by the voice information. The power calculator 48 extracts the carrier component and calculates the electric field strength of the carrier component for a plurality of receivable channels. The power calculator 48 sequentially outputs the electric field strengths of the broadcasting stations 121 to 123 toward the positioning processing unit 50.

  The positioning processing unit 50 acquires the reference trajectory for each channel provided from the positioning control unit 20 at regular intervals. In addition, the positioning processing unit 50 starts the positioning process for estimating the current position of the vehicle A when the power of the wireless positioning device 100 is turned on, and is repeatedly performed until the power is turned off. In the positioning process, the positioning processing unit 50 repeatedly acquires the electric field strength for each channel measured by the electric field strength measuring unit 30 (S101 in FIG. 7). Then, the electric field strength measurement unit 30 compares the transition along the time series of the electric field strength of each channel and the reference trajectory of the corresponding channel (S102 in FIG. 7). As shown in FIG. 6, the electric field strength measuring unit 30 estimates a detailed current position of the vehicle A by searching for a position where the degree of coincidence between the transition of the electric field strength and the reference locus is maximized (see FIG. 6). 7 S103). By the above matching process, for example, a lane (for example, Lane 1) in which the vehicle A is currently traveling can be specified among a plurality of lanes. The positioning processing unit 50 can provide the estimated position information of the vehicle A to various in-vehicle devices mounted on the vehicle A.

  In the first embodiment described so far, radio waves in a specific AM broadcast band including radio signals of a plurality of channels are converted into information in the frequency domain by the fast Fourier transformer 47. Therefore, the power calculator 48 can individually calculate the electric field strength of each channel. With the above configuration, the electric field strength of a radio signal of a plurality of channels can be calculated without providing a large number of RF circuits or the like corresponding to the frequency of each channel. Therefore, the wireless positioning device 100 that can improve the positioning accuracy by using the field strengths of a plurality of wireless signals while suppressing the complexity of the configuration of the field strength measuring unit 30 is realized.

  In addition, the electric field intensity measurement unit 30 of the first embodiment can use AM broadcast waves from all the received broadcast stations for estimation of the current position of the vehicle A even when the number of receivable broadcast stations increases. . Therefore, the wireless positioning device 100 can acquire high positioning accuracy by flexibly responding to an increase or decrease in the number of broadcasting stations.

  In addition, in the first embodiment, the magnitude of the frequency to be lowered by the modulator 43 is adjusted based on the channel information in accordance with the frequency of the channel that can be received by the receiver 41. In addition, the sampling rate (sampling frequency) of the AD converter 46 is increased or decreased in accordance with the frequency of the receivable channel (see FIG. 4). As described above, even if the receivable channel differs depending on the current position of the vehicle A, the electric field strength measuring unit 30 optimizes the acquisition bandwidth of the AD converter 46 in accordance with the frequency distribution of the currently receivable channel. Can be If the sampling rate of the AD converter 46 is suppressed in this way, it is possible to reduce the signal processing load, and hence the power consumed by the electric field strength measuring unit 30.

  Moreover, if it is the structure using the radio wave of AM broadcast transmitted from the existing broadcasting stations 121-123 like 1st embodiment, a radio positioning system will not require maintenance of special infrastructure. Can perform high-precision wireless positioning over a wide area.

  Furthermore, in the first embodiment, since positioning is performed using AM broadcast in which broadcast is transmitted by amplitude modulation, the power calculator 48 does not use the sideband component in the radio signal of one channel, and the carrier component Only calculate the intensity. According to the above, since the fluctuation of the electric field strength due to the traveling position is distinguished from the electric field strength due to the change of the voice information, the positioning accuracy is not lowered due to the change of the voice information. Thus, the power calculator 48 can calculate the electric field strength suitable for positioning that does not vary depending on the broadcast content.

  In the first embodiment, the positioning control unit 20 corresponds to the “information acquisition unit”, the electric field strength measurement unit 30 corresponds to the “strength measurement unit”, and the fast Fourier transformer 47 corresponds to the “region converter”. The power calculator 48 corresponds to a “calculator” and the vehicle A corresponds to a “moving object”.

(Second embodiment)
The second embodiment of the present invention shown in FIG. 8 is a modification of the first embodiment. In the wireless positioning system according to the second embodiment, FM broadcast stations 131 to 133 are used in addition to the AM broadcast stations 121 to 123 that are substantially the same as those of the first embodiment. Radio FM broadcasts by the FM broadcast stations 131 to 133 transmit audio information using frequency-modulated radio signals. The frequencies of the FM broadcast stations 131 to 133 are set in advance to different frequencies in the frequency band (76 to 90 MHz) of the FM broadcast.

  The wireless positioning device 200 of the second embodiment includes two electric field strength measuring units 30 and 230. One electric field strength measurement unit 30 has substantially the same configuration as that of the first embodiment, and calculates the electric field strength of the AM broadcast wave of each channel received from the AM broadcast stations 121 to 123. The other electric field strength measurement unit 230 calculates the electric field strength of the FM broadcast wave of each channel received from the FM broadcast stations 131 to 133.

  Similar to the electric field strength measurement unit 30, the electric field strength measurement unit 230 includes a receiver 41, a modulator 43, a variable low-pass filter 45, an AD converter 46, a fast Fourier transformer 47, and a power calculator 48. (See FIG. 2). The receiver 41 has an FM broadcast antenna, and provides an analog signal obtained by amplifying the FM broadcast wave to the modulator 43. In FIG. 8, the FM broadcast antenna is provided in the electric field strength measurement unit 230 separately from the AM broadcast antenna. However, the electric field strength measurement units 30 and 230 are antennas shared by AM broadcast and FM broadcast. The wireless signal received by may be received.

  The power calculator 48 (see FIG. 2) acquires FM broadcast wave channel information from the positioning control unit 20 and extracts the entire radio signal included in one channel. As an example, the power calculator 48 calculates the total electric power within the range of the occupied frequency width (± 0.1 MHz) allocated to one channel as the electric field strength of the channel. The power calculator 48 calculates the electric field strength of each channel that can be received at the current position, and sequentially outputs the calculation result to the positioning processing unit 50.

  The positioning processing unit 50 acquires the electric field strength for each channel of the AM broadcast measured by the electric field strength measurement unit 30 and the electric field strength for each channel of the FM broadcast measured by the electric field strength measurement unit 230, and performs positioning. This is collated with a reference trajectory for each channel provided from the control unit 20. The positioning processing unit 50 searches for a position where the degree of coincidence between the transition along the time series of the electric field strength of each channel and the reference trajectory of the corresponding channel is maximized, and estimates the detailed current position of the vehicle A. To do.

  For example, when the FM broadcast reception sensitivity is good, the positioning processing unit 50 performs a process of estimating the current position by placing a specific gravity on the FM broadcast electric field strength among the electric field strengths of AM broadcast and FM broadcast. May be. In addition, when the FM broadcast reception sensitivity is poor, the positioning processing unit 50 performs a process of estimating the current position by placing a specific gravity on the AM broadcast field strength among the AM broadcast and FM broadcast field strengths. Also good.

  Also in the second embodiment described so far, radio waves in each band of AM broadcast and FM broadcast are converted into frequency domain information, and the electric field strength of each channel is calculated. As described above, the wireless positioning apparatus 200 does not require a large number of RF circuits corresponding to the frequency of each channel. Therefore, the radio positioning device 200 can improve the positioning accuracy by using the radio waves of each channel of the AM broadcast wave and the FM broadcast wave without complicating the configuration of the electric field strength measuring units 30 and 230.

  In addition, the wireless positioning device 200 of the second embodiment can use both AM broadcast waves and FM broadcast waves. AM broadcast waves easily reach places such as valleys of buildings and indoors. Therefore, wireless positioning using an AM broadcast wave enables acquisition of the current position in a scene where positioning by GNSS is difficult. On the other hand, positioning using FM broadcast waves is more accurate than positioning using AM broadcast waves, and is effective for estimating the lane of travel. As described above, the wireless positioning device 200 that can use both AM broadcast waves and FM broadcast waves can perform wireless positioning that effectively complements GNSS. In the second embodiment, in addition to the electric field intensity measuring unit 30, the electric field intensity measuring unit 230 corresponds to an “intensity measuring unit”.

(Third embodiment)
The third embodiment of the present invention shown in FIGS. 9 to 11 is another modification of the first embodiment. In the wireless positioning device 300 according to the third embodiment, as shown in FIG. 9, the configuration of the electric field strength measuring unit 330 is different from that of the first embodiment. The electric field strength measurement unit 330 is similar to the electric field strength measurement unit 30 (see FIG. 2) of the first embodiment. have. In addition, the electric field strength measurement unit 330 includes a variable gain amplifier 344 and a variable low-pass filter 345.

  The variable gain amplifier 344 is disposed between the modulator 43 and the variable low-pass filter 345. The variable gain amplifier 344 amplifies the analog signal input from the modulator 43 and outputs it to the variable low-pass filter 345. The variable gain amplifier 344 is configured to be able to adjust the amplification amount (rate) of the analog signal and can change the amplitude of the analog signal input to the AD converter 46.

  The variable low-pass filter 345 has a configuration corresponding to the variable low-pass filter 45 (see FIG. 2) of the first embodiment, and gradually decreases a frequency component higher than the cutoff frequency. The variable low-pass filter 345 is configured to adjust the cutoff frequency. The cutoff frequency of the variable low-pass filter 345 is adjusted based on the channel information.

  The function of the electric field strength measuring unit 330 configured as described above will be described. As shown in FIG. 10, when there is a channel having a significantly higher electric field strength than the other channels (hereinafter referred to as “high intensity channel”), the power input to the AD converter 46 (see FIG. 9) is Adjusted to the power of the high intensity channel. In this way, if the frequencies of all broadcasting stations are tried to fall within the acquisition bandwidth, the change in the electric field strength of other channels may be difficult to detect due to insufficient resolution of the AD converter 46. As a result, in spite of receiving three or more channels, it is possible to obtain only the positioning accuracy substantially equivalent to the case where the positioning is performed based only on the electric field strength of the high-intensity channel.

  Therefore, as shown in FIGS. 9 and 10, the electric field strength measurement unit 330 removes the high-strength channel frequency component when the receiver 41 receives three or more channels. The high-intensity channel is a channel having the highest electric field strength among a plurality of channels, for example, a channel having electric field strength twice or more higher than the electric field strength of a broadcasting station having the second highest radio field strength. The electric field intensity measurement unit 330 adjusts the magnitude of the frequency lowered by the modulator 43, the cutoff frequency of the variable low-pass filter 45, and the sampling rate of the AD converter 46 so that the high-intensity channel is removed.

  Specifically, the electric field intensity measurement unit 330 adjusts the frequency output from the PLL circuit 43c of the local oscillator 43b and adjusts the cutoff frequency of the variable low-pass filter 345, so that the frequency component of the high-intensity channel is sent to the AD converter 46. Prevent input. In addition, the electric field strength measurement unit 330 adjusts the sampling rate of the AD converter 46 in accordance with the bandwidth of the analog signal that has passed through the variable low-pass filter 345.

  For example, as shown in FIGS. 9 and 10, the frequency of the high-intensity channel (broadcasting station 3) is 1200 kHz, and the frequencies of the other channels (broadcasting stations 1 and 2) excluding the high-intensity channel are 600 kHz and 800 kHz, respectively. Suppose there was. In this case, the electric field strength measurement unit 330 sets the frequency of the signal input from the local oscillator 43b to the mixer 43a to 700 kHz, and sets the cutoff frequency of the variable low-pass filter 345 to 200 kHz. As described above, analog signals generated by radio waves of other channels are allowed to pass through the variable low-pass filter 345. On the other hand, an analog signal generated by radio waves of a high intensity channel is blocked by the variable low-pass filter 345. Further, the acquisition bandwidth of the AD converter 46, that is, the sampling rate is changed in accordance with the band passing through the variable low-pass filter 345.

  In addition, the electric field strength measurement unit 330 adjusts the amplification amount of the variable gain amplifier 344 so that the amplitude of the analog signal of the other channel matches the input range of the AD converter 46. Thereby, the amplitude of each analog signal of the other channel is adjusted to such a size that the input range of the AD converter 46 can be used effectively. As described above, if signal accuracy is ensured by avoiding lack of resolution, slight changes in the electric field strength of other channels are also reflected in the digitized information after AD conversion.

  The third embodiment described so far has the same effect as the first embodiment. In addition, as in the third embodiment, the wireless positioning apparatus 300 capable of removing a significant high-intensity channel can perform high-precision positioning using the electric field strength of broadcast waves of a plurality of channels. Furthermore, if the electric field strength measuring unit 330 is configured to control the PLL circuit 43c and the variable low-pass filter 345 in an integrated manner, the frequency band that passes through the variable low-pass filter 345 and is input to the AD converter 46 is flexible. It can be changed. Therefore, the electric field intensity measurement unit 330 can appropriately remove the high intensity channel in accordance with the reception status of the receiver 41. In the third embodiment, the variable gain amplifier 344 corresponds to an “amplifier”.

(Other embodiments)
Although a plurality of embodiments according to the present disclosure have been described above, the present disclosure is not construed as being limited to the above embodiments, and can be applied to various embodiments and combinations without departing from the gist of the present disclosure. can do.

  In the above embodiment, the frequency of the signal output from the local oscillator and the sampling rate of the AD converter are adjusted based on the channel information. However, in the radio positioning device according to the first modification, the frequency of the signal output from the local oscillator is fixed at the center of the entire band of AM broadcasting, for example. Similarly, the sampling rate of the AD converter is set to a high value in advance so that, for example, the entire AM broadcast band can be accommodated within the acquisition bandwidth.

  In the said embodiment, the channel information acquired based on the positioning information by GNSS was provided from the positioning control part to the electric field strength measurement part. However, the electric field strength measurement unit may acquire receivable channel information by scanning a currently received broadcast wave, for example.

  In the above-described embodiment, a mode in which radio positioning is performed using AM broadcast waves and FM broadcast waves has been described. However, radio signals that can be used for radio positioning are not limited to AM broadcast waves and FM broadcast waves. For example, a television broadcast wave may be used for wireless positioning. Furthermore, the roadside unit for road-to-vehicle communication may be used as a reference station, and the electric field strength of the V2X communication wave transmitted from the roadside unit may be used for wireless positioning. Note that the number, frequency, band, and the like of each broadcast wave and V2X communication wave may be changed as appropriate depending on the country and region.

  The information providing apparatus of the above embodiment provides the same reference trajectory to all vehicles that request information provision without changing the content of the reference trajectory for each channel. However, the information providing apparatus may change the content of the reference locus for each channel, for example, for each vehicle type. Alternatively, the wireless positioning device may adjust the content of the acquired reference locus according to the reception characteristics of the wireless signal in the host vehicle.

  The fast Fourier transformer 47 of the first embodiment performs Fourier transform at a sampling rate of 1200 kHz and 2048 FFT points, for example (see FIG. 5). Such settings of the fast Fourier transformer 47 may be changed as appropriate according to the content of data to be subjected to Fourier transform.

  In the third embodiment, all of the modulation frequency of the local oscillator 43b, the cutoff frequency of the variable low-pass filter 345, and the sampling rate of the AD converter 46 are adjusted in order to remove the high-intensity channel. However, if the high-intensity channel can be removed, the parameter adjusted by the electric field intensity measurement unit may be one of a modulation frequency, a cutoff frequency, and a sampling rate.

  Functional units such as a positioning control unit and a positioning processing unit in the wireless positioning device of the above embodiment may be provided by various hardware and software, or a combination thereof. Further, the wireless positioning device may be provided as a part of another in-vehicle device mounted on the vehicle, for example, a locator.

  In the above embodiment, an example in which a wireless positioning device, which is a mobile terminal, is mounted on a vehicle as a moving body has been described. The vehicle on which the wireless positioning device is mounted is not limited to a general passenger car, and may be a truck (truck), a bus, a motorcycle, or the like. Furthermore, the mobile body on which the wireless positioning device is mounted is not limited to a vehicle, and may be a tractor, a construction machine, an agricultural machine, a ship, an aircraft, a train, a streetcar, or the like.

20 Positioning control unit (information acquisition unit), 30, 230, 330 Electric field strength measurement unit (strength measurement unit), 41 Receiver, 43 Modulator, 344 Variable gain amplifier (amplifier), 45, 345 Variable low-pass filter (variable filter) ), 46 AD converter, 47 fast Fourier transformer (regional converter), 48 power calculator (calculator), 50 positioning processing unit, 100, 200, 300 wireless positioning device, A vehicle (moving body) fast Fourier transform Vessel 47

Claims (7)

A wireless positioning device mounted on a moving body (A) for positioning the position of the moving body,
An intensity measuring unit (30, 230, 330) for measuring an electric field intensity of a radio signal received by the mobile body;
An information acquisition unit (20) for acquiring reference information indicating a correspondence relationship between the position of the moving object and the acquired electric field intensity;
A positioning processing unit (50) for estimating the position of the moving body based on the electric field strength measured by the strength measuring unit and the reference information,
The intensity measuring unit is
A receiver (41) for receiving radio waves of a specific band including radio signals of a plurality of channels;
An area converter (47) for converting the radio waves in the specific band received by the receiver into frequency domain information;
A calculator (48) for calculating the electric field strength for each channel from the frequency domain information converted by the domain converter;
The positioning processing unit is a wireless positioning device that estimates the position of the moving body using electric field strengths of a plurality of channels calculated by the calculator.   The wireless positioning device according to claim 1, wherein the intensity measurement unit acquires channel information indicating channels that can be received by the receiver. The intensity measuring unit includes a modulator (43) that lowers the frequency of the radio wave received by the receiver, and a digital signal in which the analog signal of the radio wave that has been lowered by the modulator is processed by the area converter. An AD converter (46) for converting the signal into a signal;
Based on the channel information, the modulator changes the magnitude of the frequency to be lowered according to the frequency of the channel received by the receiver,
The radio positioning apparatus according to claim 2, wherein the AD converter increases or decreases a sampling frequency used for signal conversion in accordance with a frequency of a channel received by the receiver based on the channel information. The intensity measuring unit is
A modulator (43) for lowering the frequency of the radio wave received by the receiver;
An AD converter (46) for converting an analog signal of a radio wave whose frequency is lowered by the modulator into a digital signal;
An amplifier (344) for adjusting the amplification amount of the analog signal input to the AD converter;
Of the three or more channels received by the receiver, the magnitude of the frequency lowered by the modulator and the sampling frequency of the AD converter so that the high-intensity channel having the highest electric field strength is removed. Adjust at least one of the
The radio positioning device according to claim 1 or 2, wherein an amplification amount of the amplifier is adjusted so that an amplitude of an analog signal of a channel excluding the high-intensity channel matches an input range of the AD converter.   The wireless positioning device according to claim 1, wherein the receiver receives a wireless signal transmitted from a broadcasting station. The receiver receives a radio signal that transmits a broadcast by amplitude modulation;
The radio positioning apparatus according to claim 5, wherein the calculator extracts a carrier wave component from a radio signal included in one channel and calculates an electric field strength of the carrier wave component. The receiver receives a radio signal that transmits a broadcast by frequency modulation,
The radio positioning device according to claim 5 or 6, wherein the calculator extracts the entire radio signal included in one channel and calculates the entire electric field strength.

Images