JP2015080078A - Transmitting/receiving system, transmitter, transmitting method, and transmission program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitting/receiving system including a plurality of transmitters and a receiver and capable of reducing demodulation (capture) load of a transmitted signal.SOLUTION: IMES100 includes a plurality of transmitters 10' and a receiver 20. Each of the plurality of transmitters 10' comprises a transmission unit 14 which transmits an IMES signal which can be demodulated by a GPS receiver, a reception unit 15 which receives the IMES signal transmitted from other transmitter 10' as a received signal, a demodulation unit 16 which demodulates the received signal, and a phase control unit 13 which determines a phase of the IMES signal transmitted by the transmission unit 14 according to a phase of the received signal demodulated by the demodulation unit 16. The receiver 20 comprises a reception unit 21 which receives the IMES signal transmitted from the transmitter 10' as a received signal and a demodulation unit 22 which demodulates the received signal by performing correlation operation between a replica signal and the received signal while shifting a phase of the replica signal.

Description

  The present invention relates to a transmission / reception system for transmitting a position information signal from a transmitter to a receiver.

  Conventionally, GPS (Global Positioning System) is known as a positioning system. In recent years, by installing a GPS reception function in a mobile terminal such as a smartphone, a mobile user can know his / her position at an arbitrary location.

  The GPS is composed of a plurality of GPS satellites and a GPS receiver. Each GPS satellite transmits time information by an atomic clock and a GPS signal (ranging signal) including a navigation message. The GPS receiver receives GPS signals from each of a plurality of GPS satellites, and calculates (positions) its own position information from their arrival times.

  For this positioning, the GPS receiver needs to receive GPS signals from at least three GPS satellites. Furthermore, if GPS signals are received from the four GPS satellites, the time error on the receiver side is canceled, and more accurate positioning becomes possible. Actually, there are propagation delay changes due to ionospheric and tropospheric conditions, atomic clock errors, etc., so it is desirable to receive GPS signals from more GPS satellites.

  IMES (Indoor Message System) has been proposed as a system that complements GPS. In IMES, a plurality of transmitters are installed in a facility such as a department store, that is, indoors. In IMES, the transmitter transmits an IMES signal that includes location information rather than a GPS signal that includes a navigation message. Since this IMES signal has the same RF characteristics as the GPS signal, it can be received and demodulated by an existing GPS receiver. Further, since the IMES signal includes the position information itself, positioning is not required at the receiver, and the position information can be obtained by simply receiving the IMES signal from one transmitter. Furthermore, since the IMES signal includes floor information (floor information) as position information, it is possible to specify not only the plane position but also the floor.

  In addition, there exist the following prior art documents as a prior art relevant to this invention.

JP 2001-337157 A JP 2012-109903 A

  In GPS and IMES, a GPS signal or IMES signal transmitted from a transmitter is generated by being put on a carrier wave after being subjected to a diffusion process using a PRN (Pseudo Random Noise) code on a navigation message and position information. The FIG. 13 is a diagram for explaining a GPS signal generation process. In GPS, a navigation message is modulated by BPSK (Binary Phase Shift Keying), and is subjected to spread spectrum direct spread (CDMA) with 1023 chips and an M-sequence pseudorandom number (PRN code) having a period of 1 msec and is carried on a carrier wave. Also in IMES, the same modulation and spreading processes as described above are performed on the IMES signal.

  In the receiver, in order to capture the signal transmitted from the transmitter, a replica signal is generated from the PRN code of the transmitter, and a correlation operation with the received signal is performed. At this time, if the phase of the PRN code is shifted even by 1 bit, there is no correlation with the original sequence. The receiver performs a correlation operation for searching for a phase that can be correlated while shifting the phase of the replica signal by one chip. When the phase of the replica signal matches the phase of the received signal, the received signal can be demodulated.

  Therefore, in principle, demodulation of a received signal requires a capture time TTFF (Tine to First Fix) of a maximum of 1023 chips × code length (= about 1 second). Actually, since the correlation calculation is performed while changing the frequency in order to follow the Doppler fading due to the relative velocity with the GPS satellite, a longer TTFF is required. Here, TTFF can be shortened to the shortest code length (1 msec) by providing a parallel processing circuit for processing correlation operations in parallel. However, doing so disadvantageously increases the circuit scale and current consumption. There is.

  The present invention has been made in view of the above problems, and provides a transmission / reception system capable of reducing a load of demodulation (capture) of a transmitted signal in a transmission / reception system of a plurality of transmitters and receivers. Objective. Specifically, an object of the present invention is to shorten the TTFF of a transmitted signal and reduce power consumption for demodulation of the transmitted signal.

  The transmission / reception system of the present invention is a transmission / reception system including a plurality of transmitters and receivers, wherein the transmitter transmits a position information signal that can be demodulated by a GPS receiver, and the other transmissions. In accordance with the phase of the received signal demodulated by the demodulating unit, the first receiving unit that receives the positional information signal transmitted from the machine as a received signal, the first demodulating unit that demodulates the received signal, A phase control unit that determines a phase of the position information signal transmitted by a transmission unit, and the receiver receives a position information signal transmitted from the transmitter as a received signal; It has a configuration including a second demodulator that demodulates the received signal by performing a correlation operation between the replica signal and the received signal while shifting the phase of the replica signal.

  With this configuration, the plurality of transmitters transmit the position information signal so as to have a predetermined phase. Therefore, the receiver only needs to perform a correlation operation within a predetermined range including the phase, and can perform demodulation processing of the received signal. In addition to reducing the load, the plurality of transmitters can align the phases of the position information signals themselves without requiring an external synchronization server or the like. The position information signal is a signal including position information.

  The second demodulator may perform the correlation calculation by shifting the phase of the replica signal within a predetermined range including the phase of the received signal.

  With this configuration, it is possible to suitably demodulate the position information signal from the transmitter received by the second receiving unit.

  The first demodulator may demodulate the received signal by performing a correlation operation between the replica signal and the received signal while shifting the phase of the replica signal.

  With this configuration, the transmitter can include a receiving unit similar to the receiver.

  One transmitter of the plurality of transmitters may be a master device that determines the phase of the position information signal transmitted by the transmitter, and the received signal from the transmitter that is the master device. The transmitter of the plurality of transmitters that determine the phase of the position information signal transmitted by the transmitter according to the method is configured such that when the transmitter that is the master device fails, the transmitter replaces the transmitter. It may be a master proxy device as a device.

  With this configuration, a plurality of transmitters can synchronize with each other in a relay format starting from the master device.

  The phase control unit, when receiving the position information signal from a plurality of transmitters, the position information transmitted by the transmission unit according to the phase of the received signal from a transmitter having a higher priority among them The phase of the signal may be determined.

  With this configuration, when a plurality of transmitters belong to the transmission area of another plurality of transmitters and receive position information signals from the plurality of transmitters, one of the transmitters should be a follow-up destination. Can do.

  The phase control unit, when not receiving the position information signal from the transmitter with the highest priority in the first receiver, according to the received signal from the transmitter with the next highest priority, You may determine the phase of the said positional information signal transmitted in a transmission part.

  With this configuration, the plurality of transmitters can change the synchronization path in a flexible manner even when one of the transmitters fails to transmit the position information signal.

  When the first receiving unit does not receive the position information signal from the transmitter with the highest priority, the phase control unit transmits the transmission according to the received signal from the transmitter with the next highest priority. Until the phase of the position information signal transmitted by the transmission unit is determined, the transmission of the position information signal by the transmission unit may be stopped.

  With this configuration, when a failure occurs in some of the plurality of transmitters, the transmitters after the failed transmitter do not receive the position information signal from the follow-up destination having a high priority. Can be changed.

  The transmitter of the present invention includes a transmitter that transmits a position information signal that can be demodulated by a GPS receiver, a receiver that receives a position information signal transmitted from another transmitter as a received signal, and the received signal. And a phase control unit that determines the phase of the position information signal transmitted by the transmitter according to the phase of the received signal demodulated by the demodulator. Yes.

  With this configuration, the transmitter can align the phase of the position information signal with other transmitters without requiring an external synchronization server or the like.

  The phase control unit, when receiving the position information signal from a plurality of transmitters, the position information transmitted by the transmission unit according to the phase of the received signal from a transmitter having a higher priority among them The phase of the signal may be determined.

  With this configuration, when a transmitter belongs to a transmission area of a plurality of other transmitters and receives position information signals from a plurality of transmitters, one of the transmitters can be a follow-up destination.

  The phase controller, when the receiver does not receive the position information signal from the transmitter with the highest priority, in accordance with the received signal from the transmitter with the next highest priority, The phase of the position information signal to be transmitted may be determined.

  With this configuration, even when any of the other transmitters fails and no longer transmits the position information signal, the synchronization path can be changed as needed.

  The phase controller, when not receiving the position information signal from the transmitter with the highest priority at the receiver, at the transmitter according to the received signal from the transmitter with the next highest priority Until the phase of the position information signal to be transmitted is determined, transmission of the position information signal by the transmitter may be stopped.

  With this configuration, when a failure occurs in some of the plurality of transmitters, the transmitters after the failed transmitter do not receive the position information signal from the follow-up destination having a high priority. Can be changed.

  The transmission method of the present invention includes a transmission step of transmitting a position information signal that can be demodulated by a GPS receiver, a reception step of receiving a position information signal transmitted from another transmitter as a reception signal, and the reception signal. And a phase control step for determining the phase of the position information signal according to the phase of the received signal demodulated by the demodulator, wherein the transmission step is determined by the phase control step. The position information signal is transmitted at the phase that is set.

  With this configuration, it is possible to align the phase of the position information signal with other transmitters by itself without requiring an external synchronization server or the like.

  The transmission program of the present invention includes a transmission unit that transmits a position information signal that can be demodulated by a GPS receiver, a reception unit that receives a position information signal transmitted from another transmitter as a reception signal, and the reception A demodulator that demodulates the signal, and a configuration that functions as a phase controller that determines the phase of the position information signal transmitted by the transmitter according to the phase of the received signal demodulated by the demodulator Yes.

  With this configuration, it is possible to align the phase of the position information signal with other transmitters by itself without requiring an external synchronization server or the like.

  According to the present invention, since the plurality of transmitters transmit the position information signal so as to have a predetermined phase, the receiver may perform the correlation operation within a predetermined range including the phase, and the received signal is demodulated. The processing load can be reduced, and the transmitter can align the phase of the position information signal by itself without requiring an external synchronization server or the like.

The block diagram which shows the structure of IMES in the 1st Embodiment of this invention The figure which shows the example of installation of the some transmitter in the 1st Embodiment of this invention The figure which shows the structure of the type 1 message in the 1st Embodiment of this invention. The figure which shows the structure of the type 3 message in the 1st Embodiment of this invention The figure which shows the relationship of the phase in the some transmitter to which the same PRN code in the 1st Embodiment of this invention was provided. Flowchart of transmitter processing in the first embodiment of the present invention Flowchart of processing of receiver in first embodiment of the present invention The block diagram which shows the structure of IMES in the 2nd Embodiment of this invention. The figure explaining the synchronization of the transmitter in the 2nd Embodiment of this invention The figure which shows a synchronous path | route in case the transmitter belongs to the transmission area of several other transmitters in the 2nd Embodiment of this invention. The figure which shows a synchronous path | route when a failure generate | occur | produces in some transmitters, when the transmitter belongs to the transmission area of several other transmitters in the 2nd Embodiment of this invention. Flow chart of processing of transmitter in second embodiment of the present invention The figure explaining the generation processing of the conventional GPS signal

  Hereinafter, an IMES (transmission / reception system) according to an embodiment of the present invention will be described with reference to the drawings. The embodiment described below shows an example when the present invention is implemented, and the present invention is not limited to the specific configuration described below. In carrying out the present invention, a specific configuration according to the embodiment may be adopted as appropriate.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an IMES according to the first embodiment of this invention. The IMES 100 includes a plurality of transmitters 10 and 10, a receiver 20, and an IMES management server 30. FIG. 1 also shows a GPS satellite 40 and a content server 50. Although two transmitters 10 are illustrated in FIG. 1, more than two transmitters 10 may be included. The plurality of transmitters 10, the receiver 20, the IMES management server 30, and the content server 50 can communicate with each other via a network.

  FIG. 2 is a diagram illustrating an installation example of a plurality of transmitters. The transmission area A of each transmitter 10 is about several meters to 10 meters, and the plurality of transmitters 10 are installed such that the transmission areas A overlap each other. For example, one transmitter 10 is installed in each tenant of a department store. The transmitter 10 may be embedded in a fixture installed on the ceiling, such as a lighting fixture, a sprinkler, and a speaker.

  The receiver 20 is a mobile terminal such as a smartphone having a GPS function, for example. When the IMES 100 is built in a department store as described above, the receiver 20 is a mobile terminal owned by a visitor. The receiver 20 receives a signal from the transmitter 10 in any store when the receiver 20 is in the transmission area A of the transmitter 10 of the store. When the receiver 20 moves in the store and enters the transmission area A (another store) of another transmitter 10, a signal is received from the other transmitter 10.

  Returning to FIG. 1, the transmitter 10 includes a network communication unit 11, a signal generation unit 12, a phase control unit 13, and a transmission unit 14. These configurations may be realized by a computer executing the transmission program of the present embodiment. The network communication unit 11 communicates with other devices such as the IMES management server 30, the content server 50, and other transmitters 10 via the network NW. Communication between the network communication unit 11 and the network NW may be wired communication or wireless communication.

  The signal generator 12 generates an IMES signal to be transmitted to the receiver 20. The IMES signal includes position information of a place where the transmitter 10 is installed and a message such as a transmitter ID for specifying the transmitter 10 and corresponds to a “position information signal”. The IMES signal has the same RF characteristics as the GPS signal.

  There are four types of IMES signal messages: Type 0, Type 1, Type 3, and Type 4. One word of the message is 30 bits, and the number of words in one frame varies depending on the message type. The type 0 message is a message that represents the two-dimensional position information of the transmitter 10 in three words of latitude, longitude, and floor number. A type 1 message is three-dimensional position information consisting of 4 words, and its resolution is twice that of type 0.

  Type 3 and type 4 messages are composed of 1 word and 2 words, respectively, and include a transmitter ID and 1-bit BD (boundary) information. The network communication unit 23 of the receiver 20 acquires the latitude, longitude, altitude, and floor information by accessing the content server 50 via the network NW based on the transmitter ID. Information such as guided evacuation maps and store advertisements can be obtained.

  The BD information means a boundary, and this BD information (1 bit) indicates that the transmitter 10 is at the boundary between indoor and outdoor. When the receiver 20 moves from indoor to outdoor, the search for the PRN code is started with reference to this BD information. On the contrary, when the receiver 20 moves indoors from the outdoors, by receiving this BD information, the receiver 20 knows that it has entered the transmission area of the transmitter 10 and switches the positioning from GPS to IMES.

  FIG. 3 is a diagram showing the structure of a type 1 message. Word 1 includes an 8-bit preamble, a 3-bit message type, 9-bit floor information, and 6-bit parity. In addition, 4 spare bits are reserved for word 1. Word 2 includes a 3-bit counter, 21-bit latitude information (MSBs), and 6-bit parity. Word 3 includes a 3-bit counter, 21-bit longitude information (MSBs), and 6-bit parity. Word 4 includes a 3-bit counter, 12-bit altitude information, 2-bit reserved bits, 3-bit latitude information (LSBs), 4-bit longitude information (LSBs), and 6-bit parity. It is.

  FIG. 4 is a diagram showing the structure of a type 3 message. A type 3 message includes an 8-bit preamble, a 3-bit message type, a 12-bit short ID, 1-bit BD information, and 6-bit parity. This short ID is a unique local ID that can be issued up to 4,095 different IDs in a 12-bit configuration and is shared only within one facility or underground mall. The 33-bit medium ID included in the type 4 message is a global ID that can be used nationwide. By receiving the received local ID or medium ID to the content server 50, the receiver 20 can acquire campaign information and the like of the facility and underground shopping area along with the position information.

  The signal generator 12 spreads the position information with the PRN code in the same manner as the GPS, and then places the carrier on the carrier wave to generate the IMES signal. For this purpose, the signal generator 12 stores various information to be included in the message such as position information and transmitter ID. These pieces of information may be received from the outside by the network communication unit 13 via the network NW. The transmission unit 14 wirelessly transmits the IMES signal. The phase control unit 13 controls the phase of the IMES signal transmitted from the transmission unit 14. This phase control will be described later.

  The receiver 20 includes a reception unit 21, a demodulation unit 22, a network communication unit 23, and an output unit 24. These configurations may be realized by a computer executing the reception program of the present embodiment. The receiver 21 receives the IMES signal transmitted from the transmitter 14 of the transmitter 10. The demodulator 22 generates a replica signal from the PRN code of the transmitter 10 in order to capture the IMES signal transmitted from the transmitter 10, and the received position information signal (hereinafter also referred to as “received signal”). The correlation calculation is performed. The demodulator 22 performs a correlation operation to search for a phase that can be correlated while shifting the phase of the replica signal by one chip.

  In IMES 100, 10 types of PRN codes are prepared. When the IMES signal is received by the receiving unit 21, the transmitter 10 that transmitted the IMES signal is unknown in the receiver 20, and therefore the demodulating unit 22 sequentially generates replica signals for 10 types of PRN codes. As described above, the correlation calculation is performed while shifting the phase of each replica signal by one chip. The receiving unit 21 can also receive GPS signals transmitted from the GPS satellites 40, and the demodulating unit 22 can also demodulate GPS signals received from the GPS satellites 40.

  The network communication unit 23 performs wireless communication with the network NW. As described above, the IMES signal demodulated by the demodulator 22 also includes a transmitter ID that identifies the transmitter 10, and the network communication unit 23 transmits the transmitter ID to the content server 50. The content corresponding to the transmitter ID is acquired from the content server 50. This content is, for example, campaign information of the transmission area (store).

  The output unit 24 outputs the position information included in the position information signal demodulated by the demodulation unit 22 and the content received from the content server 50 by the network communication unit 23. The output unit 24 is, for example, a display that outputs image content.

  Hereinafter, the configuration and operation for reducing the load of the demodulation process of the IMES signal in the receiver 20 in the IMES 100 will be described in detail. As described above, the GPS receiver performs the correlation calculation while shifting the phase of the replica signal with respect to the received signal. The GPS receiver performs positioning by calculating a pseudo distance using this phase difference. Therefore, in the case of GPS, the GPS signal from each GPS satellite must have a phase difference corresponding to the distance. A maximum of about 1 second (1023 chips × code length) TTFF is required until the correlation between the received signal and the replica signal can be obtained.

  On the other hand, in IMES, the position information itself is included in the IMES signal, so that the IMES signal does not need to have a phase difference corresponding to the position as long as the IMES signal can be demodulated. However, when a plurality of transmitters 10 are operated independently, the phase of the IMES signal transmitted by each transmitter 10 is unknown. Therefore, if the receiver 20 does not search for the phase difference, the IMES signal is It cannot be demodulated.

  Therefore, in the present embodiment, the phases of the IMES signals of the plurality of transmitters 10 are synchronized with each other. For this synchronization, the IMES management server 30 on the network NW is provided as described above, and each transmitter 10 communicates with the IMES management server 30 via the network NW. The plurality of transmitters 10 synchronize with each other via the IMES management server 30 (network synchronization), and align the phases of the IMES signals.

  Specifically, the IMES management server 30 transmits synchronization information to the network NW, and the phase control unit 13 of each transmitter 10 receives the synchronization information from the IMES management server 30 via the network communication unit 11. Thus, the phase of the IMES signal transmitted from the transmitter 14 is synchronized with the other transmitters 10. The plurality of transmitters 10 may be synchronized with each other by directly communicating between the transmitters 10 using any one of them as a master device.

  When the receiver 20 first receives an IMES signal from one of the transmitters 10 of the IMES 100, the receiver 20 performs a correlation operation with the received signal while shifting the phase of the replica signal in the same manner as the GPS, and demodulates the IMES signal. (Capture). After that, when moving and entering the transmission area of another transmitter 10, the IMES signal from the other transmitter 10 is received. In this case, the phase of the IMES signal of the first transmitter 10 is received. Since the phases of the IMES signals of the other transmitters 10 are aligned, the receiver 20 performs the correlation operation by shifting the phase of the replica signal within a predetermined range including the phase of the IMES signal captured first.

  For this reason, when the demodulator 22 first supplements the IMES signal, the demodulator 22 stores the phase thereof, and when receiving the IMES signal from another transmitter 10 after that, the demodulator 22 stores the phase. Correlation is performed by shifting the phase of the replica signal within a predetermined range (number of chips) before and after the phase.

  In this way, by limiting the range in which the phase of the replica signal is shifted (hereinafter also referred to as “search range”), it is possible to speed up the capture of the IMES signal, reduce the number of correlation operations, and thus for demodulation. Processing load can be reduced and demodulation can be speeded up.

  If the phases of the IMES signals in the plurality of transmitters 10 are completely synchronized, the receiver 20 may perform a correlation operation with the replica signal using only the phase, but in practice, there is a limit to the accuracy of synchronization. Yes, fluctuations occur. Therefore, as described above, the demodulator 22 performs the correlation calculation by shifting the phase within a predetermined search range centered on the stored phase.

  This search range may be fixed or variable. When variable, the IMES management server 30 generates synchronization accuracy information indicating the accuracy of synchronization among the plurality of transmitters 10 and transmits the synchronization accuracy information to the receiver 20 via the network NW. In the receiver 20, the NW communication unit 23 receives the synchronization accuracy information, and the demodulation unit 22 determines a phase error range based on the synchronization accuracy information, and uses the phase error range as a search range, and replicates within the search range. Correlation is performed by shifting the phase of the signal. The IMES management server 30 corresponds to an “error information transmission unit”. The synchronization accuracy information may be distributed to the receiver 20 using WiFi (registered trademark) or the like from an access point for that purpose, not the IMES management server 30. In this case, this access point corresponds to an “error information transmitting unit”.

  In this way, by determining the search range based on the synchronization accuracy or error range, the search range can be minimized, the demodulation process can be speeded up, and the load of the demodulation process can be reduced and consumed. Current can be reduced.

  On the other hand, when the accuracy of synchronization among the plurality of transmitters 10 is not clear, the demodulator 22 of the receiver 20 may, for example, be a predetermined chip within 10 chips (10 μs) before and after the phase of the IMES signal that has already been supplemented. The number may be the search range. Even if the search range is set to 10 chips (20 chips) before and after the phase of the known IMES signal, the search can be completed in about one-fifth of the time when all the 1023 chips are set as the search range.

  Further, the IMES 100 of the present embodiment has the following configuration in order to provide a more detailed location information service. As described above, in the IMES 100, each transmitter 10 transmits an IMES signal including position information. Therefore, the receiver 20 can acquire position information only by receiving an IMES signal from one transmitter. . However, this means that the position information is all the same in the transmission area of one transmitter 10.

  Therefore, in order to provide more detailed position information, it is advantageous to reduce the distance between the transmitters 10 and arrange more transmitters 10 in the same range. However, since the types of PRN codes given to the IMES 100 are limited (for example, 10), when the transmitters 10 are densely arranged, interference may occur between the same PRN codes.

  Therefore, in the IMES 100 of the present embodiment, the signals cannot be demodulated if the phase of the IMES signal is shifted even by one chip, and conversely, if the phase of the IMES signal is shifted even by one chip, the signals are not synchronized. The same PRN code is given by using the phase control unit 13 that controls the phase of transmission of the IMES signal provided in each of the plurality of transmitters 10 by using the property of being distinguishable. For the plurality of transmitters 10, the phase difference of the IMES signal is intentionally shifted by a certain number of chips.

  FIG. 5 is a diagram illustrating a phase relationship in a plurality of transmitters to which the same PRN code is assigned. In the example of FIG. 5, in the transmitters A, B, and C having the same PRN code, the phase of the IMES signal is shifted by 3 chips between the transmitter A and the transmitter B, and the transmitter B and the transmitter C Is further shifted by 3 chips.

  This phase difference information is transmitted together with the transmitter ID from the IMES management server 30 to the receiver 20 via the network NW. The receiver 20 is connected to the transmitter ID by the network communication unit 23. The demodulator 22 receives the information and stores it. When receiving the IMES signal from the transmitter 10 with the receiving unit 21, the demodulating unit 22 demodulates the signal to obtain the transmitter ID. Then, the phase of a transmitter different from the currently captured transmitter is periodically searched. This phase difference information may also be distributed to the receiver 20 using WiFi (registered trademark) or the like from an access point for that purpose instead of the IMES management server 30.

  According to this, even when the types of PRN codes are limited, the transmitters 10 can be densely arranged without considering the possibility of interference, and a large number of transmitters can be installed in a certain range.

  FIG. 6 is a flowchart of processing in the transmitter 10. The transmitter 10 receives the synchronization information from the IMES management server 30 at the network communication unit 11 (step S61). The signal generator 12 generates an IMES signal including position information (step S62). In addition, the phase control unit 13 instructs the transmission unit 14 to transmit the IMES signal in a phase synchronized with the other transmitters 10 based on the synchronization information received by the network communication unit 11 (Step S1). S63). The transmitter 14 wirelessly transmits the IMES signal at the phase instructed by the phase controller 13 (step S64).

  The generation of the IMES signal by the signal generation unit 12 may be performed independently of the reception of the synchronization information in the network communication unit 11 and the instruction of the phase by the phase control unit 13, and the timing thereof is the reception of the synchronization information and the phase. You can go back and forth with the instructions.

  FIG. 7 is a flowchart of processing in the receiver 20. When the receiving unit 21 receives the IMES signal (step S71), the demodulating unit 22 determines whether or not the phase is already stored in the IMES 100 (step S72). When there is no stored phase (NO in step S72), that is, when the IMES signal is received for the first time at the IMES 100, the phase of the replica signal is sequentially shifted from the predetermined start point, and the correlation with the received signal is performed. Calculation is performed (step S73).

  If there is a stored phase (YES in step S72), the search range is further determined based on the stored synchronization accuracy information, and the correlation in the search range centered on the stored phase An operation is performed (step S74). When the IMES signal is demodulated as a result of the correlation calculation, the network communication unit 23 transmits the transmitter ID included therein to the content server 50 (step S75). Then, the network communication unit 23 acquires content corresponding to the transmitter ID from the content server 50 (step S76), and the output unit 24 outputs the content (step S77).

  As described above, according to the IMES 100 of the present embodiment, the transmitter 10 transmits the IMES signal with the phases synchronized with each other. Therefore, the receiver 20 includes a predetermined phase including the phase already recognized. The IMES signal can be demodulated (captured) by searching within the range.

  In the processing flow of the receiver 20, the receiver 20 demodulates the IMES signal and then acquires the content corresponding to the transmitter ID included therein, but simply outputs the position information included in the IMES signal. It may be output from the unit 24 or may be simply processed using the position information.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment, the phase of the IMES signal is synchronized in the plurality of transmitters constituting the IMES as described above, but this embodiment relates to the improvement of the synchronization.

  FIG. 8 is a block diagram showing the configuration of the IMES according to the present embodiment. The transmitter 10 ′ of the present embodiment further includes a receiver 15 and a demodulator 16 in addition to the configuration of the transmitter 10 of the first embodiment shown in FIG. The receiving unit 15 and the demodulating unit 16 have the same configuration as the receiving unit 21 and the demodulating unit 22 of the receiver 20. That is, in the present embodiment, each transmitter 10 ′ receives and demodulates IMES signals transmitted from other transmitters 10 ′, similarly to the receiver 20. Since the configuration of the receiver 20 is the same as that of the first embodiment, details are omitted in FIG. Note that the configuration of the transmitter 10 ′ may be realized by a computer executing the transmission program of the present embodiment.

  In the IMES 100 ′ according to the present embodiment, in order to synchronize a plurality of transmitters 10 ′, a transmitter 10 ′ is a master device, other transmitters are slave devices, and nearby transmitters 10 ′ are Establishes a synchronization system in the entire transmitter 10 'of the IMES 100.

  FIG. 9 is a diagram illustrating transmitter synchronization. In the example of FIG. 9, the transmitter 101 serves as a master device and slave synchronization is performed. The transmission area of the transmitter 101 and the transmission area of the transmitter 102 overlap, and the transmission area of the transmitter 102 and the transmission area of the transmitter 103 overlap. Therefore, the transmitter 102 can receive the IMES signal transmitted from the transmitter 101, and the transmitter 103 can receive the IMES signal transmitted from the transmitter 102.

  The transmitter 101 which is a master device has a highly accurate clock. The transmitter 12 of the transmitter 101 transmits an IMES signal. The receiver 15 of the transmitter 102 receives the IMES signal transmitted from the transmitter 101, and the demodulator 16 demodulates the IMES signal. The transmitter 102 recognizes its phase and frequency by demodulating the IMES signal from the transmitter 101. Then, the phase control unit 13 of the transmitter 102 controls the transmission unit 14 to transmit the IMES signal with the phase and frequency recognized by the demodulation unit 16.

  Then, the receiving unit 15 of the transmitter 103 receives the IMES signal transmitted from the transmitter 102, and the demodulating unit 16 demodulates the IMES signal. Then, as in the case of the transmitter 102, the phase and frequency of the IMES signal transmitted from the transmitter 102 are recognized, and the phase control unit 13 transmits the IMES signal with the recognized phase and frequency. The unit 14 is controlled.

  By transmitting the phase and frequency one after another in this way, synchronization in the entire IMES 100 ′ system is realized. Thus, according to IMES 100 ′ of the present embodiment, a plurality of transmitters 10 ′ can synchronize with each other without having an external device such as a synchronization server. As described above, the plurality of transmitters 10 ′ do not need to communicate with other external devices via the communication network as in the case of network synchronization, and therefore may not include the network communication unit 11. That is, according to the present embodiment, it is possible to synchronize each other even if the transmitter 10 'does not have a network communication function.

  Next, a synchronization method when the transmitter belongs to the transmission area of a plurality of other transmitters will be described. FIG. 10 is a diagram illustrating a synchronization path when the transmitter belongs to a transmission area of a plurality of other transmitters. FIG. 10 shows transmitters 101 to 106 and their transmission areas A1 to A6. As shown in FIG. 10, each transmission area A1-A6 has a part which overlaps with the transmission area of several other transmitters, and each transmitter 101-106 is a transmission area of several other transmitters. In.

  In such a case, the transmitter can receive IMES signals from multiple other transmitters. In that case, it is unclear which phase and frequency of the IMES signal received from any other transmitter (following destination or synchronization destination) is synchronized with its own phase and frequency. Therefore, each transmitter other than the master stores a priority list of other transmitters to be followed.

  In the case of FIG. 10, the transmitter 101 is the master device. For example, the transmitter 105 is in the transmission areas A2, A4, and A6 of the transmitters 102, 104, and 106, and can receive the IMES signal from any of the transmitters 102, 104, and 106. Is stored in the order of the transmitter 102, the transmitter 104, and the transmitter 106. In this case, the transmitter 105 does not use the IMES signal received from the transmitter 104 or the transmitter 106 with a low priority (there is another transmitter with a high priority) for synchronization, The phase and frequency of its own IMES signal are determined according to the phase and frequency of the IMES signal received from the transmitter 102 having the highest priority. Similarly, other transmitters store the priorities of other transmitters to be followed.

  In this way, even when the transmitter receives IMES signals from a plurality of other transmitters, it becomes clear which of them determines the phase and frequency of its own IMES signal. In addition, as described above, by defining the priority order for other transmitters to follow, even if some transmitters fail as described below, it is possible to respond flexibly. can do.

  FIG. 11 is a diagram illustrating a synchronization path when a failure occurs in some of the transmitters when the transmitter belongs to the transmission area of a plurality of other transmitters. In the example of FIG. 11, a failure has occurred in the transmitter 102. In this case, since the transmitter 102 cannot transmit the IMES signal, and therefore the transmitter 105 cannot receive the IMES signal from the transmitter 102, the transmitter 105 follows the transmitter 104 with the second highest priority. The phase and frequency are determined according to the IMES signal received from the transmitter 104.

  In order to detect a failure of the transmitter 102, the following failure information is transmitted. First, regardless of whether or not each transmitter is a follow-up destination, it checks whether or not it has received a signal from an adjacent transmitter. When there is one receiver 15 in the transmitter, the reception check is performed sequentially, and when there are a plurality of receivers 15, the reception check is performed collectively. If there is a transmitter that does not output a signal, its ID is output as an IMES signal. The adjacent transmitters that have received the IMES signal further output the received ID as IMES signals. If such an operation is repeated, the ID of the failed transmitter is output from all transmitters. Therefore, by using the monitor receiver, the ID of the failed transmitter can be received in the transmission area of any transmitter. Each transmitter can perform such an operation by storing the ID and PRN code of an adjacent transmitter in advance. Of course, the IDs and PRN codes of all transmitters other than adjacent transmitters may be stored. Further, for example, a spare bit of the type 1 message shown in FIG.

  Also, in the transmitter 103, as shown in FIG. 10, the transmitter 102 having the highest priority is normally followed as the follow-up destination. However, if the transmitter 102 is out of order, the transmitter 102 Since the IMES signal cannot be received, as shown in FIG. 11, the transmitter 106 having the second priority is set as the follow-up destination.

  On the other hand, as shown in FIG. 10, the transmitter 106 normally uses the transmitter 103 with the highest priority as the follow-up destination. However, if the transmitter 102 fails, the transmitter 106 transmits in reverse as described above. Since the transmitter 103 follows the transmitter 106, the transmitter 106 sets the transmitter 105 having the second priority as the follow-up destination.

  As in the case of the transmitter 106 in the example of FIG. 11, in the case where a transmitter failure occurs in the far position of the synchronous transmission sequence, each transmitter transmits an IMES signal from the tracking destination in order to reliably change the transmission path. , The transmission of the IMES signal is stopped by itself. In the example of FIG. 11, when the transmitter 103 stops receiving the IMES signal from the normal follow-up destination (follow-up destination with the highest priority), the transmitter 103 temporarily stops sending the IMES signal itself.

  As a result, the transmitter 106 cannot receive the IMES signal from the transmitter 103 that is the normal follow-up destination, so the transmitter 105 having the second priority is changed to the follow-up destination. Then, since the transmitter 106 determines the phase and frequency according to the IMES signal received from the transmitter 105 and transmits the IMES signal, the transmitter 103 sets the transmitter 106 having the second priority as the follow-up destination. change.

  In the example of FIG. 11, if a failure occurs in the transmitter 101 that is the master device, IMES transmission is stopped in the transmitters 102 and 104 that follow the transmitter 101. Will be propagated one after another, and IMES transmission will be stopped in all transmitters. Therefore, in the present embodiment, one transmitter among a plurality of transmitters having the master device as the follow-up destination is designated as the master proxy device.

  In the example of FIG. 11, for example, the transmitter 104 is designated as the master proxy device. Then, when a failure occurs in the transmitter 101 and the transmitters 102 and 104 cannot receive the IMES signal from the transmitter 101 that is the follow-up destination, the transmitter 102 stops its own IMES transmission as usual, Wait for the IMES signal from the transmitter 105 which is the next follow-up destination. On the other hand, the transmitter 104 designated as the master proxy device transmits the IMES signal using its own clock. Thereby, even when the master device fails, the synchronization of a plurality of transmitters can be maintained. Note that the phase control unit 13 performs the identification of the follow-up destination and the stop of the IMES signal transmission.

  FIG. 12 is a flowchart of a process for synchronizing with another transmitter in the transmitter according to the present embodiment. This processing flow is executed in each transmitter 10 '. The transmitter 10 ′ first determines whether or not an IMES signal has been received from a transmitter with the highest priority as a follow-up destination (step S121). If the IMES signal is received from the transmitter with the highest priority as the follow-up destination (YES in step S121), the IMES signal is transmitted according to the phase and frequency of the received signal (step S122).

  On the other hand, when the IMES signal is not received from the transmitter having the highest priority as the follow-up destination (NO in step S1221), first, transmission of its own IMES signal is stopped (step S123). Then, it waits for the IMES signal from the transmitter with the next highest priority (step S124), and when it is received (YES in step S124), it sends its own IMES signal according to the phase and frequency of the received signal. Transmit (step S122).

  As described above, according to the second embodiment, each transmitter is connected to a network without preparing an external device such as the IMES management server 30 of the first embodiment that functions as a synchronization server. Even if it does not have a communication function, it is possible to synchronize the entire system in a relay format by using the IMES signal. Further, in the case of performing such relay-type synchronization, even when some transmitters break down, synchronization can be achieved by changing the transmission path as needed.

  In the present invention, since a plurality of transmitters transmit position information signals so as to have a predetermined phase, the receiver may perform a correlation operation within a predetermined range including the phase, and the demodulation processing of the received signal may be performed. The load can be reduced, and the transmitter has the effect of aligning the phase of the position information signal by itself without the need for an external synchronization server or the like, and transmits the position information signal from the transmitter to the receiver. It is useful as a transmission / reception system.

100 IMES
DESCRIPTION OF SYMBOLS 10, 10 ', 101-106 Transmitter 11 Network communication part 12 Signal generation part 13 Phase control part 14 Transmission part 15 Reception part 16 Demodulation part 20 Receiver 21 Reception part 22 Demodulation part 23 Network transmission part 24 Output part 30 IMES management Server 40 GPS satellite 50 Content server

Claims (13)

A transmission / reception system including a plurality of transmitters and receivers,
The transmitter is
A transmitter that transmits a position information signal that can be demodulated by a GPS receiver;
A first receiving unit that receives a position information signal transmitted from another transmitter as a received signal;
A first demodulator for demodulating the received signal;
In accordance with the phase of the received signal demodulated by the demodulator, a phase controller that determines the phase of the position information signal transmitted by the transmitter;
With
The receiver
A second receiving unit that receives a position information signal transmitted from the transmitter as a received signal;
A second demodulator that demodulates the received signal by performing a correlation operation between the replica signal and the received signal while shifting the phase of the replica signal;
A transmission / reception system comprising:   2. The transmission / reception system according to claim 1, wherein the second demodulator performs the correlation calculation by shifting a phase of the replica signal within a predetermined range including a phase of the reception signal.   The first demodulator demodulates the received signal by performing a correlation operation between the replica signal and the received signal while shifting the phase of the replica signal. Transmission / reception system. One transmitter of the plurality of transmitters is a master device that determines the phase of the position information signal to be transmitted by the transmitter,
One transmitter among a plurality of transmitters that determine the phase of the position information signal to be transmitted by the transmitter according to the received signal from the transmitter that is the master device is the transmitter that is the master device. The transmission / reception system according to any one of claims 1 to 3, wherein the transmission / reception system is a master proxy device that becomes a master device in place of the transmitter when a failure occurs.   The phase control unit, when receiving the position information signal from a plurality of transmitters, the position information transmitted by the transmission unit according to the phase of the received signal from a transmitter having a higher priority among them The transmission / reception system according to claim 1, wherein the phase of the signal is determined.   The phase control unit, when not receiving the position information signal from the transmitter with the highest priority in the first receiver, according to the received signal from the transmitter with the next highest priority, The transmission / reception system according to claim 5, wherein a phase of the position information signal transmitted by a transmission unit is determined.   When the first receiving unit does not receive the position information signal from the transmitter with the highest priority, the phase control unit transmits the transmission according to the received signal from the transmitter with the next highest priority. The transmission / reception system according to claim 6, wherein transmission of the position information signal by the transmission unit is stopped until a phase of the position information signal transmitted by the unit is determined. A transmitter that transmits a position information signal that can be demodulated by a GPS receiver;
A receiving unit that receives a position information signal transmitted from another transmitter as a received signal;
A demodulator that demodulates the received signal;
In accordance with the phase of the received signal demodulated by the demodulator, a phase controller that determines the phase of the position information signal transmitted by the transmitter;
A transmitter characterized by comprising:   The phase control unit, when receiving the position information signal from a plurality of transmitters, the position information transmitted by the transmission unit according to the phase of the received signal from a transmitter having a higher priority among them The transmitter of claim 8, wherein the phase of the signal is determined.   The phase controller, when the receiver does not receive the position information signal from the transmitter with the highest priority, in accordance with the received signal from the transmitter with the next highest priority, The transmitter according to claim 9, wherein a phase of the position information signal to be transmitted is determined.   The phase controller, when not receiving the position information signal from the transmitter with the highest priority at the receiver, at the transmitter according to the received signal from the transmitter with the next highest priority The transmitter according to claim 10, wherein transmission of the position information signal by the transmission unit is stopped until a phase of the position information signal to be transmitted is determined. A transmission step of transmitting a position information signal that can be demodulated by a GPS receiver;
A reception step of receiving a position information signal transmitted from another transmitter as a received signal;
A demodulation step of demodulating the received signal;
A phase control step for determining the phase of the position information signal according to the phase of the received signal demodulated by the demodulator;
Including
The transmission method includes transmitting the position information signal at a phase determined in the phase control step. Computer
A transmitter that transmits a position information signal that can be demodulated by a GPS receiver;
A receiving unit that receives a position information signal transmitted from another transmitter as a received signal;
A demodulator that demodulates the received signal; and a phase controller that determines a phase of the position information signal to be transmitted by the transmitter according to a phase of the received signal demodulated by the demodulator;
A transmission program characterized by functioning as:

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