JP6702051B2 - Wireless positioning device - Google Patents

Description

  The disclosure of 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.

  BACKGROUND ART Conventionally, for example, Patent Document 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 near a road. In this wireless positioning system, reference locus information indicating the correspondence between the position of the vehicle and the acquired electric field strength when the vehicle is run along the 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 the reference trajectory prepared in advance.

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

JP, 2013-257306, A JP, 2014-3453, A

  Now, with the configuration of calculating the electric field strengths of wireless signals of a plurality of channels, it is possible to improve the accuracy of positioning the position. Therefore, the inventor of the present disclosure has examined a specific configuration of a wireless positioning device capable of calculating the electric field strengths of wireless signals of a plurality of channels. As an example thereof, a radio positioning device that employs a configuration like the electric field intensity device of Patent Document 2 is conceived in order to measure the electric field intensity of radio signals of a plurality of channels. However, the configuration disclosed in Patent Document 2 is provided with a large number of RF circuits corresponding to the frequencies of the individual channels. Therefore, even if the positioning accuracy is improved, the configuration for measuring the electric field strength may be complicated.

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

In order to achieve the above object, a first aspect disclosed is a wireless positioning device that is mounted on a mobile body (A) and measures the position of the mobile body, which is an electric field of a radio signal received by the mobile body. The strength measuring unit (30, 230, 330) for measuring the strength, the information acquiring unit (20) for acquiring the reference information indicating the correspondence between the position of the moving body and the acquired electric field strength, and the strength measuring unit. A positioning processing unit (50) for estimating the position of the moving body based on the electric field strength measured by the above and reference information, and the strength measuring unit receives radio waves of a specific band including radio signals of a plurality of channels. A receiver (41), a modulator (43) for reducing the frequency of the radio wave received by the receiver, a domain converter (47) for converting the radio wave of a specific band received by the receiver into frequency domain information, From the AD converter (46) that converts the analog signal of the radio wave whose frequency has been reduced by the modulator into a digital signal that is processed by the domain converter, information on the frequency domain converted by the domain converter. A modulator (48) for calculating the electric field strength for each channel, wherein the modulator adjusts to the frequency of the channel received by the receiver based on the channel information indicating the channel receivable by the receiver. , The magnitude of the frequency to be lowered is changed, the AD converter increases or decreases the sampling frequency used for signal conversion in accordance with the frequency of the channel received by the receiver based on the channel information, and the positioning processing unit calculates The position of the moving body is estimated using the electric field intensities of the plurality of channels calculated by the instrument .
A second aspect disclosed is a wireless positioning device which is mounted on a mobile body (A) and measures the position of the mobile body, the strength measurement measuring electric field strength of a radio signal received by the mobile body. Section (30, 230, 330), an information acquisition section (20) for acquiring reference information indicating the correspondence between the position of the moving body and the acquired electric field strength, and the electric field strength measured by the strength measuring section. And a positioning processing unit (50) for estimating the position of the moving body based on the reference information and the reference information.
A receiver (41) that receives radio waves of a specific band including radio signals of a plurality of channels, a domain converter (47) that converts radio waves of a specific band received by the receiver into frequency domain information, and a domain converter. A calculator (48) that calculates the electric field strength for each channel from the converted frequency domain information, a modulator (43) that reduces the frequency of the radio wave received by the receiver, and a frequency that is reduced by the modulator An AD converter (46) for converting the analog signal of the radio wave into a digital signal, and an amplifier (344) for adjusting the amplification amount of the analog signal input to the AD converter are received by the receiver. Of the three or more channels, the high intensity channel is adjusted by adjusting at least one of the magnitude of the frequency lowered by the modulator and the sampling frequency of the AD converter so that the high intensity channel with the highest electric field intensity is removed. The amplification amount of the amplifier is adjusted so that the amplitude of the analog signal of the channels other than the above matches the input range of the AD converter, and the positioning processing unit uses the electric field strengths of the plurality of channels calculated by the calculator. Estimate the position of.

According to an aspect of these radio wave of a specific band including the radio signals of a plurality of channels, by being converted into frequency domain information, the field strength of the individual channels, it is possible to calculate separately. With the above configuration, it is possible to calculate the electric field strength of radio signals of a plurality of channels without providing a large number of RF circuits or the like corresponding to the frequencies of the individual channels. Therefore, it is possible to realize a wireless positioning device that can improve the positioning accuracy by using the electric field strengths of a plurality of wireless signals while suppressing the complication of the configuration of the electric field strength measurement unit.

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

It is a figure which shows typically the whole image of the radio positioning system by 1st embodiment, and each block provided in a radio 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 broadcasting wave of a plurality of channels, and is a figure showing the case where the whole frequency band of AM broadcasting is AD-converted. It is a figure for demonstrating adjusting the acquisition bandwidth of AD conversion according to the frequency of the AM broadcast being received. It is a figure which shows typically the information Fourier-transformed into 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 a reference locus and an electric field strength. It is a flowchart which shows the detail of the positioning process implemented in the positioning processing part. It is a figure which shows typically the whole image of the radio positioning system by 2nd embodiment, and each block provided in a radio positioning device. 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 the possibility that positioning accuracy may deteriorate with a high intensity channel. It is a figure which shows typically the case where the signal of a high intensity channel is removed from the analog signal input into an AD converter.

  Hereinafter, a plurality of embodiments of the present disclosure will be described with reference to the drawings. In addition, in each of the embodiments, the corresponding components may be denoted by the same reference numerals, and redundant description may be omitted. When only a part of the configuration is described in each embodiment, the configurations of the other embodiments described above can be applied to the other part of the configuration. Further, not only the combination of the configurations explicitly described in the description of each embodiment, but also if the combination does not cause any trouble, the configurations of the plurality of embodiments can be partially combined even if they are not explicitly described. Further, unspecified combinations of the configurations described in the plurality of embodiments and the modified examples are also 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 is movable together with the vehicle A. The wireless positioning device 100 constitutes a wireless positioning system together with the information providing device 110 and a plurality of broadcasting stations 121 to 123. The wireless positioning system is a positioning system that complements positioning by a GNSS (Global Navigation Satellite System). The wireless positioning system enables, for example, high-accuracy positioning that is difficult with GNSS and positioning when satellite signals from GNSS positioning satellites are difficult to receive.

  The information providing device 110 is installed in a traffic management center or the like outside the vehicle A. The information providing device 110 can communicate with the wireless positioning device 100, and exchanges information with the wireless positioning device 100. The information providing device 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 device 110 receives a request for providing information such as a reference trajectory described later from the wireless positioning device 100 mounted on many vehicles A by the wide area wireless device 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. Reference trajectories at various places in the service area of the wireless positioning system are stored in the storage medium of the server 111. The information providing apparatus 110 selects a reference trajectory required for each vehicle A, and transmits the selected reference trajectory to each wireless positioning apparatus 100.

  Each of the broadcasting stations 121 to 123 is, for example, a broadcasting station that transmits AM radio broadcasting by radio communication. Each of the broadcasting stations 121 to 123 transmits AM broadcasts of different channels. For example, in Japan, the frequency band of 526 to 1632 kHz is assigned to AM broadcasting. The frequencies of the radio signals transmitted by the broadcast stations 121 to 123 are preset to different frequencies in the AM broadcast frequency band. In AM broadcasting, audio information is transmitted by amplitude modulation. The radio signal of AM broadcasting includes a carrier component and a sideband component (see FIG. 3). The radio signals from the broadcasting stations 121 to 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 radio positioning device 100 specifies the current position of the vehicle A by collating the current RSSI (Received Signal Strength Indicator, hereinafter, “electric field strength”) of each broadcasting station 121 to 123 and the reference locus. The reference locus is reference information indicating a correspondence relationship 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 wireless device 22, 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. There is.

  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 with the wide area wireless device 112 and the antenna 113 of the information providing apparatus 110. The wide area wireless device 22 and the antenna 23 are connected to the positioning control unit 20, and the positioning control unit 20 controls transmission and reception of information.

  The storage unit 24 has a storage medium that stores a reference trajectory, 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 may be provided in the form of a memory card or the like and inserted into a card slot provided in the wireless positioning device 100. The configuration may be different. The storage unit 24 is connected to the positioning control unit 20. The positioning control unit 20 can read and rewrite the information stored in the storage unit 24.

  The positioning control unit 20 cooperates with the GNSS receiving unit 21, the wide area wireless device 22 and the antenna 23, and the storage unit 24 to control acquisition of information necessary for wireless positioning. Specifically, the positioning control unit 20 performs a rough current position acquisition process based on a satellite signal, a reference trajectory acquisition and output process, a channel information acquisition and output process, 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 the receivable reference loci of each of the 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 by the satellite signal. The positioning control unit 20 can acquire the required reference locus from the information providing apparatus 110 in response to the information providing request to the information providing apparatus 110. Further, when the reference locus around the current position is stored in the storage unit 24, the positioning control unit 20 can acquire the necessary reference locus from the storage unit 24. The positioning control unit 20 outputs the acquired reference trajectory to the positioning processing unit 50.

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

  The electric field strength measurement unit 30 shown in FIGS. 1 and 2 measures the electric field strength of the radio signal received by the vehicle A. The electric field strength measuring unit 30 of the first embodiment receives the AM broadcast wave broadcast by each broadcasting station 121 to 123 as a radio signal and measures the electric field strength of each AM broadcast wave. The electric field strength measurement 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 measurement unit 30 outputs the measured electric field strength of each broadcasting station 121 to 123 to the positioning processing unit 50. The electric field strength measuring unit 30 has 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 receives an AM broadcast wave that is a radio signal transmitted from each of the broadcasting stations 121 to 123 and is 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 the AM broadcast. The receiver 41 has an AM broadcasting antenna 41a and a low noise amplifier (hereinafter, "LNA") 41b. The receiver 41 amplifies the analog signal of the radio wave received by the AM broadcasting antenna 41a by the LNA 41b and outputs it to the modulator 43.

  The modulator 43 lowers the frequency of the analog signal of the radio wave received by the receiver 41. By reducing the frequency, the above-described signal processing of the AD converter 46 and the like becomes easy. The modulator 43 has 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 signal at the center value of the 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 channel frequency received by the receiver 41 based on the channel information. Specifically, among the receivable channels, the broadcasting station 121 having the lowest frequency transmits the AM broadcasting wave of 600 kHz, and the broadcasting station 123 having the highest frequency transmits the AM broadcasting wave of 1200 kHz ( (See FIG. 4). In this case, the center value of the frequencies 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 two frequencies as an operation result by performing 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 AM broadcast by using the signal for modulation by the mixer 43a, 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 cutoff frequency is gradually reduced and substantially not passed. The cutoff frequency is set to 1/2 of the sampling rate of the AD converter 46 based on the sampling theorem. The variable low-pass filter 45 removes the frequency component outside the band of AM broadcasting from the analog signal modulated by the modulator 43, and outputs it to the AD converter 46.

  The AD converter 46 converts the AM broadcast analog signal 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 targeted for AD conversion (see FIG. 3 ), the AD converter 46 sets the sampling rate to 1106 kHz. As described above, the acquisition bandwidth is ensured to be 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 broadcasting station 121 transmits an AM broadcasting wave of 600 kHz and the broadcasting station 123 transmits an AM broadcasting wave of 1200 kHz (see FIG. 4 ), the sampling rate is set to 600 kHz. The AD converter 46 outputs the radio wave information in the AM broadcast band, which has been converted into a digital signal, to the fast Fourier converter 47.

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

  The power calculator 48 calculates the electric field intensity 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 sideband components above and below the carrier component varies with changes in the audio information that is the content of the broadcast. On the other hand, the power of the carrier component is not related to voice information. Therefore, the power calculator 48 extracts the carrier wave component from the radio signal included in one channel, and calculates the electric field strength of the carrier wave component. The carrier wave component is set within a range of 500 Hz around the center frequency of each broadcasting station 121 to 123 set in the channel information. That is, the bandwidth of 1 kHz around 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 due to 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 to 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 processing for estimating the current position of the vehicle A when the power of the wireless positioning device 100 is turned on, and repeatedly performs the positioning processing 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 measuring unit 30 compares the time-series transition of the electric field strength of each channel with the reference locus of the corresponding channel (S102 in FIG. 7). As shown in FIG. 6, the electric field strength measurement unit 30 estimates the 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 becomes maximum (FIG. 6). 7 S103). By the above matching processing, for example, the lane in which the vehicle A is currently traveling (for example, Lane 1) can be specified from the 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 frequency domain information 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, it is possible to calculate the electric field strength of radio signals of a plurality of channels without providing a large number of RF circuits or the like corresponding to the frequencies of the individual channels. Therefore, it is possible to realize the radio positioning device 100 that can improve the positioning accuracy by using the electric field strengths of a plurality of radio signals while suppressing the complication of the configuration of the electric field strength measurement unit 30.

  Further, the electric field strength measuring unit 30 of the first embodiment can use the AM broadcast waves from all the receiving broadcasting stations to estimate the current position of the vehicle A, even if the number of receivable broadcasting stations increases. .. Therefore, the wireless positioning device 100 can acquire high positioning accuracy by flexibly responding to the 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 according to the frequency of the channel receivable by the receiver 41 based on the channel information. After that, the sampling rate (sampling frequency) of the AD converter 46 is increased or decreased according to 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 measurement unit 30 optimizes the acquisition bandwidth of the AD converter 46 in accordance with the frequency distribution of the currently receivable channel. Can be converted. If the sampling rate of the AD converter 46 is suppressed in this way, it is possible to reduce the load of signal processing, and thus the power consumed by the electric field strength measuring unit 30.

  Further, as in the first embodiment, if the configuration uses the radio waves of the AM broadcasting transmitted from the existing broadcasting stations 121 to 123, the radio positioning system does not require special infrastructure maintenance. , High-accuracy wireless positioning can be implemented in a wide area.

  Furthermore, in the first embodiment, since positioning is performed using AM broadcasting in which broadcasting is transmitted by amplitude modulation, the power calculator 48 does not use the sideband component but the carrier component in the radio signal of one channel. Calculate the intensity of chisel. According to the above, the variation of the electric field strength due to the traveling position and the electric field strength due to the change of the voice information are distinguished from each other, so that the positioning accuracy does not deteriorate due to the change of the voice information. In this way, the power calculator 48 can calculate the electric field strength suitable for positioning that does not change 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”. However, the electric power calculator 48 corresponds to a “calculator”, and the vehicle A corresponds to a “moving body”.

(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 broadcasting stations 131 to 133 are used in addition to the AM broadcasting stations 121 to 123 that are substantially the same as those in the first embodiment. In FM broadcast of radio by the FM broadcast stations 131 to 133, audio information is transmitted by a frequency-modulated radio signal. The frequencies of the FM broadcasting stations 131 to 133 are preset to different frequencies within the frequency band (76 to 90 MHz) of FM broadcasting.

  The wireless positioning device 200 according to the second embodiment includes two electric field strength measuring units 30 and 230. One electric field strength measuring 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 measuring unit 230 calculates the electric field strength of the FM broadcast wave of each channel received from the FM broadcast stations 131 to 133.

  The electric field strength measuring unit 230 has 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, like the electric field strength measuring unit 30. (See Figure 2). The receiver 41 has an antenna for FM broadcasting and provides the modulator 43 with an analog signal obtained by amplifying the FM broadcasting wave. In FIG. 8, the antenna for FM broadcasting is provided in the electric field strength measuring unit 230 separately from the antenna for AM broadcasting. However, the electric field strength measuring units 30 and 230 are common antennas for AM broadcasting and FM broadcasting. The wireless signal received by may be received.

  The power calculator 48 (see FIG. 2) acquires the channel information of the FM broadcast wave from the positioning control unit 20, and extracts the entire wireless signal included in one channel. As an example, the power calculator 48 calculates the sum of powers within the range of the occupied frequency width (±0.1 MHz) assigned to one channel as the electric field strength of the channel. The power calculator 48 calculates the electric field strength of each channel receivable 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 AM broadcasting measured by the electric field strength measuring unit 30 and the electric field strength for each channel of FM broadcasting measured by the electric field strength measuring unit 230, and performs positioning. The reference locus provided by the control unit 20 is compared with the reference locus for each channel. The positioning processing unit 50 searches for a position where the degree of coincidence between the transition of the electric field strength of each channel in time series and the reference locus of the corresponding channel is maximized, and estimates the detailed current position of the vehicle A. To do.

  For example, when the reception sensitivity of FM broadcasting is good, the positioning processing unit 50 performs processing of estimating the current position by weighting the electric field strength of FM broadcasting among the electric field strengths of AM broadcasting and FM broadcasting. May be. Further, when the reception sensitivity of FM broadcasting is poor, the positioning processing unit 50 performs a process of estimating the current position by weighting the electric field strength of AM broadcasting among the electric field strengths of AM broadcasting and FM broadcasting. Good.

  Also in the second embodiment described so far, radio waves in each band of AM broadcast and FM broadcast are converted into information in the frequency domain, and the electric field strength of each channel is calculated. As described above, the radio positioning device 200 does not need a large number of RF circuits corresponding to the frequencies of the respective channels. 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 configurations of the electric field strength measurement 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 AM broadcast waves 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 easier to ensure accuracy than positioning using AM broadcast waves, and is effective in estimating the driving lane. As described above, the radio positioning device 200 that can use both AM broadcast waves and FM broadcast waves can perform radio positioning that effectively complements GNSS. In addition, in the second embodiment, in addition to the electric field intensity measuring unit 30, the electric field intensity measuring unit 230 also corresponds to the “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 measurement unit 330 is different from that of the first embodiment. The electric field strength measuring unit 330 is similar to the electric field strength measuring unit 30 (see FIG. 2) of the first embodiment, the receiver 41, the modulator 43, the AD converter 46, the fast Fourier transformer 47, and the power calculator 48. have. In addition, the electric field strength measurement unit 330 has a variable gain amplifier 344 and a variable low pass filter 345.

  The variable gain amplifier 344 is arranged 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 has a configuration capable of adjusting the amplification amount (ratio) 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 reduces the frequency component higher than the cutoff frequency. The variable low-pass filter 345 has a configuration in which the cutoff frequency can be adjusted. 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 having the above configuration will be described. As shown in FIG. 10, when there is a channel (hereinafter, “high-strength channel”) whose electric field strength is remarkably higher than those of other channels, 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 to be kept within the acquisition bandwidth, the change in the electric field strength of other channels may be difficult to detect due to lack of resolution of the AD converter 46. As a result, even though three or more channels are received, substantially only positioning accuracy equivalent to that when positioning is performed based on the electric field strength of the high-strength channel is obtained.

  Therefore, as shown in FIGS. 9 and 10, the electric field intensity measuring unit 330 removes the high intensity channel frequency component when the receiver 41 receives three or more channels. The high-strength channel is a channel having the highest electric field strength among a plurality of channels, and is, for example, a channel whose electric field strength is twice or more higher than that of a broadcasting station having the second highest radio wave strength. The electric field strength 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-strength channel is removed.

  Specifically, the electric field strength measurement unit 330 adjusts the frequency output from the PLL circuit 43c of the local oscillator 43b and the cutoff frequency of the variable low-pass filter 345 to adjust the frequency component of the high-strength channel to the AD converter 46. Do not enter. In addition, the electric field strength measurement unit 330 adjusts the sampling rate of the AD converter 46 according to 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 high-strength channel (broadcasting station 3) has a frequency of 1200 kHz, and the channels other than the high-strength channel (broadcasting stations 1 and 2) have frequencies of 600 kHz and 800 kHz, respectively. Suppose 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, the analog signals of the radio waves of the other channels are allowed to pass through the variable low pass filter 345. On the other hand, the variable low-pass filter 345 blocks the analog signal of the radio wave of the high-strength channel. Furthermore, the acquisition bandwidth of the AD converter 46, that is, the sampling rate is changed according to 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 another channel matches the input range of the AD converter 46. As a result, the amplitude of each analog signal of the other channel is adjusted to a size such that the input range of the AD converter 46 can be effectively used. As described above, if the signal accuracy is ensured by avoiding the lack of resolution, even a slight change in the electric field strength of other channels is reflected in the digitized information after AD conversion.

  The third embodiment described up to this point also has the same effects as the first embodiment. In addition, as in the third embodiment, the radio positioning device 300 capable of removing remarkable high-strength channels can perform high-precision positioning by using the electric field strengths of broadcast waves of a plurality of channels. Further, if the electric field strength measuring unit 330 has a configuration that integrally controls the PLL circuit 43c and the variable low-pass filter 345, 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 strength measurement unit 330 can appropriately remove the high-strength channel according to the reception status of the receiver 41. In the third embodiment, the variable gain amplifier 344 corresponds to “amplifier”.

(Other embodiments)
Although a plurality of embodiments according to the present disclosure have been described above, the present disclosure should not be construed as being limited to the above embodiments and applied to various embodiments and combinations without departing from the scope 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 wireless positioning device according to the first modification, the frequency of the signal output by 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 band of AM broadcasting can be contained within the acquisition bandwidth.

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

  In the above embodiment, the mode in which the radio positioning is performed using the AM broadcast wave and the FM broadcast wave has been described. However, the radio signals that can be used for radio positioning are not limited to AM broadcast waves and FM broadcast waves. For example, television broadcast waves may be used for wireless positioning. Furthermore, the roadside device 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 device may be used for wireless positioning. Note that the number of channels, frequency, band, etc. of each broadcast wave and V2X communication wave may be appropriately changed depending on the country and region.

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

  The fast Fourier transformer 47 of the first embodiment performs the Fourier transform at a sampling rate of 1200 kHz and an FFT score of 2048 points (see FIG. 5). The setting of such a fast Fourier transformer 47 may be appropriately changed according to the content of the data to be subjected to the 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-strength channel can be removed, the parameter adjusted by the electric field strength measurement unit may be one of the modulation frequency, the cutoff frequency, and the sampling rate.

  The functional units such as the positioning control unit and the 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 vehicle-mounted device mounted on the vehicle, for example, a locator.

  In the above-described embodiment, an example in which the wireless positioning device, which is a mobile terminal, is installed in a vehicle as a moving body has been shown. The vehicle equipped with the wireless positioning device is not limited to a general passenger car, but may be a lorry (truck), a bus, a two-wheeled vehicle, or the like. Furthermore, the moving body equipped with the wireless positioning device is not limited to a vehicle, and may be a tractor, a construction machine, an agricultural machine, a ship, an aircraft, a train, a tram, or the like.

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

Claims (6)

A wireless positioning device mounted on a mobile body (A) for positioning the position of the mobile body, comprising:
An intensity measuring unit (30, 230, 330) for measuring the 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 body and the acquired electric field strength;
A positioning processing section (50) for estimating the position of the moving body based on the electric field strength measured by the strength measuring section and the reference information;
The strength measurement unit,
A receiver (41) for receiving radio waves in a specific band including radio signals of a plurality of channels,
A modulator (43) for reducing the frequency of the radio wave received by the receiver,
A domain converter (47) for converting the radio waves of the specific band received by the receiver into information of a frequency domain,
An AD converter (46) for converting an analog signal of a radio wave whose frequency is reduced by the modulator into a digital signal processed by the area converter,
A calculator (48) for calculating the electric field strength for each channel from the information of the frequency domain converted by the domain converter,
The modulator, based on channel information indicating a channel that can be received by the receiver, in accordance with the frequency of the channel received by the receiver, to change the magnitude of the frequency to be lowered,
The AD converter increases or decreases the sampling frequency used for signal conversion in accordance with the frequency of the channel received by the receiver based on the channel information,
The positioning processing unit is a wireless positioning device that estimates the position of the moving body using the electric field intensities of a plurality of channels calculated by the calculator. A wireless positioning device mounted on a mobile body (A) for positioning the position of the mobile body, comprising:
An intensity measuring unit (30, 230, 330) for measuring the 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 body and the acquired electric field strength;
A positioning processing section (50) for estimating the position of the moving body based on the electric field strength measured by the strength measuring section and the reference information;
The strength measuring unit,
A receiver (41) for receiving radio waves in a specific band including radio signals of a plurality of channels,
A domain converter (47) for converting the radio waves of the specific band received by the receiver into information of a frequency domain,
A calculator (48) for calculating the electric field strength for each channel from the information of the frequency domain converted by the domain converter,
A modulator (43) for reducing 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 an amplification amount of an 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 with the highest electric field strength is removed. Adjust at least one of
The amplification amount of the amplifier is adjusted so that the amplitude of the analog signals of the channels other than the high-intensity channel matches the input range of the AD converter,
The positioning processing unit is a wireless positioning device that estimates the position of the moving body using the electric field intensities of a plurality of channels calculated by the calculator. The radio positioning device according to claim 2 , wherein the intensity measurement unit acquires channel information indicating a channel receivable by the receiver. The receiver, radio positioning apparatus according to any one of claims 1 to 3 for receiving a radio signal transmitted from a broadcasting station. The receiver receives a radio signal transmitting a broadcast by amplitude modulation,
The radio positioning device according to claim 4 , wherein the calculator extracts a carrier component from a radio signal included in one channel and calculates an electric field strength of the carrier component. The receiver receives a radio signal transmitting a broadcast by frequency modulation,
The calculator extracts the whole of radio signals contained in one channel, the wireless positioning apparatus according to claim 4 or 5 for calculating the field strength of the entire.

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