JP2010213130A - Digital broadcast communication system and home receiver used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movable home receiver having a configuration in which a transmission wave from a master station of a destination municipality different from an installation source municipality can be automatically received. <P>SOLUTION: A data processing unit 24 extracts a municipality's name from address data of a current location received from a location information display processing unit 23, refers to a data table 25, reads out a municipality code associated with the municipality's name, and sends it to a control unit 13. The control unit 13 holds the municipality code received from the data processing unit 24 and instructs a reception unit 12 to search a frequency. The reception unit 12 performs a frequency search and achieves lock to a frequency transmitted from the master station of the municipality of the current location. When in this state, the control unit 13 confirms that the municipality code included in a broadcast notification signal from the master station that is received by the reception unit 12 is identical to the held municipality code, it informs the inhabitants of the received contents. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a digital broadcast communication system and a door-to-door receiver used therefor, and more particularly to a digital broadcast communication system for transmitting necessary information to residents and a door-to-door receiver used therefor.

  Digital broadcast communication systems for transmitting necessary information to residents are generally installed in local government offices and public related organizations, etc., and transmit call signals indicating the content of notification of required information as transmission waves in a predetermined frequency band. The receiving station, the relay station that receives the transmission wave transmitted from the parent station and transmitting the frequency-converted broadcast wave, and receiving the broadcast wave and emitting the broadcast content from the speaker It consists of multiple slave stations that inform the residents of the content of the report.

  The call signal includes a municipal code for calling a local station for each region. The slave receiver, the door-to-door receiver, compares and verifies whether the municipality code included in the received broadcast wave is the same as the municipality code held by the local station, and the communication contents included in the received call signal in the same case To the residents through a speaker (see, for example, Non-Patent Document 1).

  However, the digital broadcast communication system is operated independently for each municipality, the radio frequency used for each municipality is different, and the frequency that can be received by the individual receiver can only be set to one frequency. The municipality code of the local government held by the receiver is also fixed data that differs for each municipality.

  For this reason, when the door-to-door receiver is movable, the door-to-door receiver that can receive the transmission wave from the master station installed in the government office of the local government of the installation source (for example, A city) When they are in different destination local governments (for example, city B), they cannot receive transmission waves from a master station installed in the destination local government.

  Therefore, when a wide-area disaster occurs in the destination local government, information can be transferred between the staff of the destination local government and the local government of the installation source or in the life-related organization by the digital mobile system, but it is movable For local government officials who are going to support disasters by bringing their own receivers, they cannot use the receivers at their destinations, so there is no way to know the information transmitted to the residents in the disaster-stricken area. Only secondary information can be known.

  Therefore, the broadcast communication system described in Patent Document 1 can receive a paging signal transmitted from a parent station of a municipality where the individual receiver is installed by using the frequency and municipal code of the neighboring municipality. A configuration is disclosed in which a call signal is converted and transmitted. In the broadcast communication system described in Patent Document 1, broadcast is possible from the local government where the individual receiver is installed to the residents of the adjacent local government.

  Further, in Patent Literature 2, a plurality of identification number candidates are stored in a storage unit in a wireless communication system in which an identification number is assigned to each household receiver in order to enable selective calling of the household receiver. A wireless communication system is disclosed in which one identification number candidate is set as its own identification number from among identification number candidates by operation. In this wireless communication system, the identification number assigned to the individual receiver can be easily changed without the person in charge of management going to the place where the individual receiver is installed.

JP 2006-80645 A JP 2006-74470 A

"Municipal digital broadcast system", ARIB STD-86, The Japan Radio Industry Association

  However, the broadcast communication system described in Patent Document 1 is based on the premise that the individual receiver is not installed and moved within the jurisdiction of the local government, and the movable individual receiver is moved from the parent station of the target local government at the destination. The transmission wave cannot be received.

  In addition, the wireless communication system described in Patent Document 2 is effective only in the jurisdiction of the local government of the installation source because the individual receiver can change only the identification number. It is not possible to receive transmission waves from the parent station of the local government.

  Also, if it is possible to receive the transmission wave from the master station of the destination municipality by changing the frequency and municipal code of the door-to-door receiver, the configuration change method is complicated, and if the configuration is changed In this case, if the change work for returning to the original frequency and the municipal code is not performed again after the support activity is completed, the transmission wave from the master station cannot be received by the installing local government, which is extremely complicated.

  The present invention has been made in view of the above points, and a digital door-to-door receiver that can automatically receive transmission waves from a parent station of a destination local government different from the installation source local government. It is an object to provide an information communication system and a door-to-door receiver used therefor.

In order to achieve the above object, the digital broadcast communication system of the present invention wirelessly transmits a synchronization signal or a broadcast notification signal including a first city code at a predetermined frequency, and a wireless transmission from the parent station. Mobile door-to-door receiver that receives the received signal,
The individual receiver includes a current location information acquisition unit that acquires location information of a current location, a municipal code acquisition unit that acquires a second municipal code corresponding to the acquired location information, and a signal wirelessly transmitted from the master station The reception frequency search means for searching the reception frequency for receiving the received signal and locking the reception frequency to a predetermined frequency at which a reception signal equal to or higher than the set value is obtained, and the synchronization signal at the reception frequency locked by the reception frequency search means Means for determining that synchronization is completed, and comparing whether or not the first municipality code included in the broadcast notification signal received after completion of synchronization matches the second municipality code acquired by the municipality code acquisition means And a notification means for notifying the reception contents of the broadcast notification signal when they match.

  In order to achieve the above object, the door-to-door receiver of the present invention is a mobile receiver that receives a broadcast notification signal including a synchronization signal or a first municipality code that is wirelessly transmitted from a master station at a predetermined frequency. It is a door-to-door receiver, which is wirelessly transmitted from the master station, current position information acquisition means for acquiring position information of the current position, municipal code acquisition means for acquiring a second municipal code corresponding to the acquired position information, and The reception frequency search means for searching the reception frequency for receiving the received signal and locking the reception frequency to a predetermined frequency at which a reception signal equal to or higher than the set value is obtained, and the reception frequency locked by the reception frequency search means A determination unit that receives the synchronization signal and determines that the synchronization is completed, and a second unit in which the first municipality code included in the broadcast notification signal received after the synchronization is completed is acquired by the municipality code acquisition unit. Compared whether coincides with municipal codes, and having and informing means for informing a received content of the broadcast notification signal if they match.

  According to the present invention, even when the door-to-door receiver moves to a local government different from the local government of the installation source, it receives radio waves transmitted from the target master station and transmits it from the master station of the target local government. The contents can be notified to residents near the current position. In addition, according to the present invention, even when the door-to-door receiver returns to the installation source local government from the destination, the transmission wave from the master station is received even in the installation source local government without performing any special change work. be able to.

It is a block diagram of one embodiment of a door-to-door receiver in the digital broadcast communication system of the present invention. It is a flowchart for operation | movement description of FIG. It is a block diagram of other embodiments of a door-to-door receiver of the present invention.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a block diagram of an embodiment of a door-to-door receiver in a digital broadcast communication system according to the present invention. In FIG. 1, a door-to-door receiver 100 according to this embodiment includes a door-to-door receiver 10 and a position information detector 20 and is configured to be movable. The door-to-door reception unit 10 and the position information detection unit 20 are connected to each other by a connection line between the connector 19 and the connector 28, and are configured to be separable. Usually, the two are integrally connected with each other. Moving. This individual receiver 100 constitutes the municipal digital broadcast communication system of this embodiment together with a master station installed in a local government office (not shown).

  The individual reception unit 10 includes a reception antenna 11 that receives radio waves (transmission waves) of the municipal digital broadcast communication system transmitted from the master station, and a reception unit 12 that converts the radio waves received by the reception antenna 11 into reception voice signals. A control unit 13 that comprehensively controls the entire door-to-door reception unit 10, an audio amplification unit 14 that amplifies the received audio signal, a speaker 15 that electro-acoustic converts the received audio signal and emits it as a sound wave to the space, It comprises an operation unit 16, a display unit 17 that performs display, a power supply unit 18, a switch 18a, and a battery unit 18b.

  The control unit 13 analyzes the received radio wave of the municipal digital broadcast communication system, and controls each unit in the door-to-door reception unit 10 based on the analysis result. The operation unit 16 includes a power switch, a speaker volume, and the like. The display unit 17 is composed of, for example, a light emitting diode (LED), and displays an operation state of a power source or the like. The power supply unit 18 supplies AC 100 V commercial AC power from a power outlet, for example. The battery part 18b is comprised with the dry cell so that power supply can be performed also at the time of a power failure. The switch 18a switches the power supply voltage supplied to the control unit 13 to a DC power supply from the battery unit 18b instead of the AC power supply from the power supply unit 18 in the event of a power failure.

  The position information detection unit 20 includes an information processing unit 21 whose connector 28 is connected to the connector 19 of the control unit 13 through a connection line, and a position information display unit 26. The information processing unit 21 includes a position information collection processing unit 22, a position information display processing unit 23, a data processing unit 24, and a data table 25, and is connected to the receiving antenna 27.

  The receiving antenna 27 receives, for example, a GPS signal from an artificial satellite that constitutes a known global positioning system (GPS). The location information collection processing unit 22 calculates the latitude and longitude information of the current location of the individual receiver 100 based on the GPS signal received by the receiving antenna 27, and the location information display processing unit 23 as the location information. To supply.

  The position information display processing unit 23 plots the current position on the map data based on the position information (latitude and longitude information) supplied from the position information collection processing unit 22, and displays the result plotted on the map data as the position information. The data is output to the display unit 26. Further, the position information display processing unit 23 extracts address data from the result plotted on the map data, and delivers it to the data processing unit 24.

  The data processing unit 24 extracts the municipality name from the address data delivered from the location information display processing unit 23, refers to the data table 25, acquires the municipality code corresponding to the municipality name, and receives it by the control unit 13. hand over. The data table 25 is a database that stores municipal codes that are associated with municipal names in advance as a table.

  The control unit 13 overwrites the municipality code set by the data processing unit 24 with the set municipality code, holds it as reception data for the municipal digital broadcast communication system, and sends a frequency search instruction to the reception unit 12. Command.

  When receiving the frequency search instruction from the control unit 13, the receiving unit 12 starts the frequency search. When the set condition is satisfied, the receiving unit 12 stops the frequency search and locks the frequency. When the receiving unit 12 receives the synchronization signal of the municipal digital broadcast communication system from the center facility (master station) at the locked frequency and establishes the synchronization, the control unit 13 determines that the synchronization is established. Notify unit 21.

  The information processing unit 21 displays in the position information display unit 26 that synchronization has been established and data of the municipal digital broadcast communication system can be received. In this state, the door-to-door reception unit 10 receives the radio wave for broadcast broadcasting (broadcast notification signal) transmitted from the center facility (master station) by the receiving antenna 11 and is included in the received broadcast notification signal. When the municipality code matches the municipality code held, the data indicating the notification content of the broadcast notification signal received by the control unit 13 is converted into an analog audio signal and amplified by the audio amplification unit 14 Then, the speaker 15 notifies the residents as sound.

  The position information display unit 26 is configured by a display, for example. Furthermore, since the position information display unit 26 also serves as a user interface of the information processing unit 21, a display with a touch panel is desirable.

  Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG.

  The information processing unit 21 monitors whether or not the GPS signal indicating the current position information has been received by the receiving antenna 27 (step S1), and if received, the position information collection processing unit 22 performs the individual receiver 100 based on the GPS signal. The latitude / longitude information of the current position is acquired (step S2). The position information display processing unit 23 plots the current position on the map data based on the latitude / longitude information of the current position acquired by the position information collection processing unit 22 (step S3). The position information display unit 26 displays the current position on the map data plotted by the position information display processing unit 23 and displays that it is operating (step S4). Further, the position information display processing unit 23 extracts the city name (address data) of the current position on the plotted map data from the map data, and delivers it to the data processing unit 24 (step S5).

  The data processing unit 24 refers to the data table 25 with the city name (address data) of the current position delivered from the position information display processing unit 23, and the city name (address data of the current position) stored in the data table 25. ) Is acquired from the data table (step S6). Subsequently, the data processing unit 24 creates reception data for the municipal digital broadcast communication system in which the acquired municipality code is set (step S7), and delivers the created reception data for the municipal digital broadcast communication system to the control unit 13. (Step S8).

  After holding the reception data for the municipal digital broadcast communication system, the control unit 13 instructs the receiving unit 12 to perform a frequency search instruction (step S9). Based on the frequency search instruction, the reception unit 12 sets the first reception frequency among a plurality of reception frequencies set in advance, and whether the reception signal is equal to or more than the input value set at the set reception frequency. It is determined whether or not (step S10).

  Subsequently, when the reception signal is less than the set input value (N in Step S10), the reception unit 12 monitors whether the reception signal is equal to or more than the set input value for a predetermined time (N in Step S11). Step S10). When the received signal is less than the set input value for a predetermined time (Y in step S11), the receiving unit 12 sets the second received frequency (step S12), and the received signal is again set at the set received frequency. It is determined whether or not there is a set input value or more (step S10).

  Thereafter, the receiving unit 12 repeats the same operation as described above while switching the reception frequency until a reception signal equal to or greater than the input value set at the set reception frequency is input (executes a frequency search). When a reception signal equal to or greater than the input value set at the set reception frequency is input (Y in step S10), the reception unit 12 locks the current reception frequency (step S13).

  Subsequently, the control unit 13 monitors for a predetermined time whether or not the synchronization signal in the digital broadcast communication system signal from the reception antenna 11 has been received at the reception frequency locked by the reception unit 12 (N in step S14). N of step S15). When the synchronization signal cannot be received within a predetermined time (Y in step S15), the control unit 13 moves the reception frequency of the reception unit 12 to the next frequency (step S16) and again monitors the reception of the synchronization signal. (Step S14).

  When the synchronization signal can be received within the predetermined time (Y in step S14), the control unit 13 determines that synchronization is established, notifies the information processing unit 21 that synchronization is established, and indicates that synchronization is completed as position information. It is displayed on the display unit 26 (step S17). Thereby, the user of the door-to-door receiver 100 can be made to confirm the presence or absence of an operating condition.

  Upon completion of synchronization, the door-to-door reception unit 10 is in a state where it can receive radio waves (broadcast notification signals) of the municipal digital broadcast communication system transmitted from the center facility (parent station) of the local government at the current position. In this state, the door-to-door reception unit 10 controls the reception data obtained by receiving the radio wave (broadcast notification signal) of the municipal digital broadcast communication system transmitted from the center facility (master station) by the reception unit 12. The municipality code included in the received broadcast notification signal is compared with the municipality code in the reception data for the municipal digital broadcast communication system created in step S7 and held in step S8. When they match, the data of the notification content of the received broadcast notification signal is converted into an analog audio signal, the analog audio signal is amplified by the audio amplifying unit 14, and then notified to the residents as audio from the speaker 15.

  As described above, according to the present embodiment, even when the individual receiver 100 moves to a local government different from the local government of the installation source, the current position information of the individual receiver 100 is collected and the municipalities corresponding to the current position information are collected. Since the code is automatically acquired and the frequency is automatically changed to a frequency that can be received at the current position by the frequency search, the radio wave transmitted from the center facility (master station) of the destination local government is received by the receiving unit 12. The transmission content from the center facility (parent station) of the destination municipality can be notified to the residents near the current position.

  In addition, when a local government employee or the like returns to the local government of the installation source together with the door-to-door receiver 100 after the support activities at the destination, the door-to-door receiver 100 changes the above-mentioned municipal code and frequency. Since it is automatically performed according to the algorithm of the flowchart shown in FIG. 2, even if the special change work is not performed, the transmission wave from the master station can be received even in the installation local government.

  Further, in this embodiment, since the position information of the current position is acquired using GPS signals, the individual receiver 100 is used throughout Japan if the local government is installing a municipal digital broadcast communication system. can do.

  In addition, according to the present embodiment, the position information detection unit 20 that detects position information and the door-to-door reception unit 10 that receives radio waves of the municipal digital broadcast communication system are separable. By adopting a configuration in which a plurality of frequencies can be set, the position information detection unit 20 can be connected as an additional device.

  Further, according to the present embodiment, when the position information is detected, the radio wave of the municipal digital broadcast communication system is received after the frequency search is completed, and the synchronization is established, the synchronization information is displayed on the position information display unit 26. Therefore, the user of the door-to-door receiver 100 can be made to confirm the presence / absence of the operation status.

  Next, another embodiment of the present invention will be described.

  FIG. 3 shows a block diagram of another embodiment of a door-to-door receiver according to the present invention. The door-to-door receiver 110 according to the present embodiment is a mobile radio terminal device that includes the radio 30 and the position information detection unit 40 and is configured to be movable. The radio device 30 and the position information detection unit 40 are connected to each other by a connection line between the connector 37 and the connector 49 and are separable. Usually, the two move together in a connected state. To do.

  The radio device 30 includes an antenna 31, a transmission / reception unit 32, a control unit 33, an operation unit 34, a display unit 35, and a power supply unit 36, and performs transmission / reception with a partner terminal (not shown). The control unit 33 analyzes the received radio wave and controls each unit in the wireless device 30 based on the analysis result. The operation unit 34 includes a power switch, various information input keys, and the like. The display unit 35 is configured by a light emitting diode (LED), for example, and displays an operating state of a power source or the like. The power supply unit 36 supplies a power supply voltage to each unit in the wireless device 30.

  The position information detection unit 40 includes an information processing unit 41 whose connector 49 is connected to the connector 37 of the control unit 33 through a connection line, and a position information display unit 47. The information processing unit 41 includes a position information collection processing unit 42, a position information display processing unit 43, a data processing unit 44, a data table 45, and a signal generation processing unit 46, and is connected to the receiving antenna 48. The position information collection processing unit 42 and the position information display processing unit 43 perform the same operations as the position information collection processing unit 22 and the position information display processing unit 23 in FIG.

  The data processing unit 44 extracts address data from the position information delivered from the position information display processing unit 43, associates the data classified for each address with the address data, and writes the data in the data table 45. The data classified by address includes, for example, a call number (ID) of a radio terminal such as a door-to-door receiver of communication equipment having different information for each municipality.

  The signal generation processing unit 46 reads the call number (ID) of the radio terminal with reference to the data table 45, or creates information on a facility such as a library or a fire station in the municipality at the current position, and a position information display unit 47 To display. Further, the signal generation processing unit 46 outputs a unique call number (ID) assigned to the radio terminal to the radio 30 as necessary. The wireless device 30 calls the wireless device terminal at the current position using the calling number (ID) of the wireless device terminal.

  As described above, in this embodiment, various data related to the address data can be generated from the position information by the signal generation processing unit 46 and output to the radio device 30 or the external device, so that information can be obtained using the current position information. The effect of enabling rewriting and control is obtained.

  The present invention is not limited to the above embodiment. For example, the location information can be acquired from the location information of the radio base station by providing a radio unit that can communicate with the radio base station. .

DESCRIPTION OF SYMBOLS 10 House-receiving part 11,27,31,48 Antenna 12 Reception part 13 Control part 14 Audio | voice amplification part 15 Speaker 16, 34 Operation part 17, 35 Display part 18, 36 Power supply part 18b Battery part 20, 40 Position information detection part 21 , 41 Information processing unit 22, 42 Position information collection processing unit 23, 43 Position information display processing unit 24, 44 Data processing unit 25, 45 Data table 26, 47 Position information display unit 30 Radio 32 Transmission / reception unit 46 Signal generation processing unit 100, 110 individual receiver

Claims (7)

A master station that wirelessly transmits a broadcast notification signal including a synchronization signal or a first city code at a predetermined frequency;
It consists of a movable door-to-door receiver that receives signals wirelessly transmitted from the master station,
The door-to-door receiver
Current position information acquisition means for acquiring position information of the current position;
A municipality code obtaining means for obtaining a second municipality code corresponding to the obtained location information;
A reception frequency search means for searching for a reception frequency for receiving a signal wirelessly transmitted from the master station and locking the reception frequency to the predetermined frequency at which a reception signal equal to or higher than a set value is obtained;
A determination unit that receives the synchronization signal at the reception frequency locked by the reception frequency search unit, and determines that the synchronization is completed;
The first municipality code included in the broadcast notification signal received after the synchronization is completed is compared with the second municipality code acquired by the municipality code acquisition means. A digital broadcast communication system comprising: notifying means for notifying the reception contents of the report notification signal. A master station that wirelessly transmits a broadcast notification signal including a synchronization signal or a first city code at a predetermined frequency;
It consists of a movable door-to-door receiver that receives signals wirelessly transmitted from the master station,
The door-to-door receiver
Current position information acquisition means for acquiring position information of the current position;
A database in which address data and city codes are linked and stored in advance;
Extracting address data of the current position based on the acquired position information, and acquiring a second municipal code corresponding to the position information acquired from the database based on the address data;
A reception frequency search means for searching for a reception frequency for receiving a signal wirelessly transmitted from the master station and locking the reception frequency to the predetermined frequency at which a reception signal equal to or higher than a set value is obtained;
A determination unit that receives the synchronization signal at the reception frequency locked by the reception frequency search unit and determines that the synchronization is completed;
The first municipality code included in the broadcast notification signal received after the synchronization is completed is compared with the second municipality code acquired by the municipality code acquisition means. A digital broadcast communication system comprising: notifying means for notifying the reception contents of the report notification signal.   The determination means monitors whether or not the synchronization signal can be received at the reception frequency locked by the reception frequency search means, and when the synchronization signal cannot be received, the reception frequency is next to the locked reception frequency. 3. The operation of moving to a predetermined reception frequency as the frequency of the signal and monitoring whether or not the synchronization signal can be received again is repeated until the synchronization signal is received. Digital broadcast communication system. A movable door-to-door receiver that receives a broadcast notification signal including a synchronization signal or a first municipality code wirelessly transmitted from a master station at a predetermined frequency,
Current position information acquisition means for acquiring position information of the current position;
A municipality code obtaining means for obtaining a second municipality code corresponding to the obtained location information;
A reception frequency search means for searching for a reception frequency for receiving a signal wirelessly transmitted from the master station and locking the reception frequency to the predetermined frequency at which a reception signal equal to or higher than a set value is obtained;
A determination unit that receives the synchronization signal at the reception frequency locked by the reception frequency search unit and determines that the synchronization is completed;
It is compared whether or not the first municipality code included in the broadcast notification signal received after completion of synchronization matches the second municipality code acquired by the municipality code acquisition means. A door-to-door receiver comprising: an informing means for informing the reception contents of the notification signal. A movable door-to-door receiver that receives a broadcast notification signal including a synchronization signal or a first municipality code wirelessly transmitted from a master station at a predetermined frequency,
Current position information acquisition means for acquiring position information of the current position;
A database in which address data and city codes are linked and stored in advance;
Extracting address data of the current position based on the acquired position information, and acquiring a second municipal code corresponding to the position information acquired from the database based on the address data;
A reception frequency search means for searching for a reception frequency for receiving a signal wirelessly transmitted from the master station and locking the reception frequency to the predetermined frequency at which a reception signal equal to or higher than a set value is obtained;
Determination means for receiving the synchronization signal at the reception frequency locked by the reception frequency search means, and determining completion of synchronization;
It is compared whether or not the first municipality code included in the broadcast notification signal received after completion of synchronization matches the second municipality code acquired by the municipality code acquisition means. A door-to-door receiver comprising: an informing means for informing the reception contents of the notification signal. A door-to-door reception unit that receives a broadcast signal including a synchronization signal or a first municipality code wirelessly transmitted from the master station at a predetermined frequency is connected to a position information detection unit that detects position information of the current position. A movable door-to-door receiver,
The door-to-door receiver is
Receiving means for receiving a signal wirelessly transmitted from the master station;
A reception frequency search means for searching for a reception frequency for receiving a signal wirelessly transmitted from the master station and locking the reception frequency to the predetermined frequency at which a reception signal equal to or higher than a set value is obtained;
Determination means for receiving the synchronization signal at the reception frequency locked by the reception frequency search means, and determining completion of synchronization;
The first municipality code included in the broadcast notification signal received after the synchronization is completed is compared with the second municipality code acquired by the location information detection unit, and the broadcast notification is received when they match. An informing means for informing the reception content of the signal, the position information detecting unit,
Current position information acquisition means for acquiring position information of the current position;
A door-to-door receiver, comprising: a municipality code acquisition unit that acquires the second municipality code corresponding to the acquired location information and outputs the second municipality code to the determination unit.   The determination means monitors whether or not the synchronization signal can be received at the reception frequency locked by the reception frequency search means, and when the synchronization signal cannot be received, the reception frequency is next to the locked reception frequency. 7. The operation of moving to a predetermined reception frequency as the frequency of the signal and monitoring whether or not the synchronization signal can be received again is repeated until the synchronization signal is received. The door-to-door receiver as described in any one.

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