TWI450544B - Wireless communications system - Google Patents

Description

Wireless communication system

The present invention relates to a wireless communication system for wireless communication using multiple wireless channels.

In recent years, for example, a radio station such as a specific small power radio station is used to perform reception of a control signal for enabling, changing, or terminating a function of a device installed at a remote location, or measurement of a measuring device installed at a remote location. The resulting wireless communication system is gaining popularity. The wireless communication system is adapted to various systems such as a lighting control system, an anti-crime system, a doorphone system, a fire alarm system, an automatic remote inspection system, and the like, for example, the fire alarm system described in Patent Document 1. .

In the fire alarm system described in Patent Document 1, a plurality of fire sensors (wireless devices) are installed in a plurality of locations, and each fire sensor is provided with a wireless communication function. The fire alarm system causes the fire sensor itself to sound an alarm after any fire sensor senses a fire, and continuously transmits a wireless signal including fire perception information to other fire sensors. In addition, other fire sensors that receive wireless signals from the fire sensor that has sensed the fire will sound an alarm based on the fire perception information contained in the wireless signal.

Here, the wireless signal transmitted and received by the fire sensor is composed of a synchronization bit (preamble), a frame synchronization pattern (unique word), a destination address, a source address, and a message. And an error detection code. The former refers to a bit pattern for bit synchronization for alternately arranging 0 and 1 alternately, and the bit length is set to about 8 bytes. Further, the unique word code refers to a bit string of a bit pattern different from the above, and uses a bit pattern that is difficult to be included in a message or the like. The preamble and the unique character code are detected by the fire sensor on the receiving side, thereby determining that the received wireless signal is a wireless signal used in the system, and can receive a destination address or message after the unique word code. Get the necessary information. Further, the error detection code includes, for example, a CRC (Cyclic Redundancy Check), and the like, and the integrity of the received wireless signal can be confirmed, and an abnormality such as bit inversion for some reason can be detected.

In the above wireless communication system, in order to transmit and receive wireless signals between a plurality of radio stations (transmitters and receivers), a plurality of wireless channels are set in a specific frequency band in consideration of use of the wireless signals. In this case, each transmitter selectively selects a wireless channel to transmit a wireless signal, and the receiver scans all wireless channels by, for example, time division for a predetermined period of time. Moreover, the receiver determines the signal strength in each wireless channel according to a Received Signal Strength Indication (RSSI). If the measured signal strength is greater than a predetermined threshold, the foregoing detection is performed and wirelessly performed. The reception of the signal. In this way, the receiver can receive the wireless signal in the wireless channel arbitrarily selected by each transmitter, and can transmit and receive wireless signals between multiple radio stations.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-177340

However, when the transmitter selects a specific wireless channel to transmit a wireless signal, there is a case where the power of the wireless signal leaks in other wireless channels of the wireless channel that is not transmitting the wireless signal. Here, if the distance between the receiver and the transmitter is set to a close distance, the signal strength in other wireless channels sometimes exceeds a prescribed threshold, which may cause the receiver to fix the wireless channel of the receiving object to other The wireless channel starts to receive wireless signals. Therefore, the wireless signal of the wireless channel that the transmitter sends the wireless signal is ignored.

On the other hand, for such a wireless transmission system, a receiver-side radio station can also be shared among a plurality of systems, for example, can be applied to a system in which a receiver receives human body detection from the intercom doorbell system. After detecting the signal and receiving the dimming signal for operating the dimming level of the lighting control system, the dimming level of the lighting device is operated. Furthermore, in the intercom doorbell system and the lighting control system, a plurality of transmitters can be connected separately.

However, in the prior wireless transmission system, the bit length of the foregoing is set to the minimum necessary bit length (8 bits in the above fire alarm system) for bit synchronization. Therefore, if the transmitter that transmits the wireless signal is increased, when the wireless signal is transmitted in a certain transmitter, the probability that the receiver side scans the other wireless channels becomes higher, and the possibility that the receiver side ignores the foregoing of the wireless signal is improved. . In this case, the transmitter side continuously transmits the same wireless signal again, but when the data length of the transmitted message is long, the necessary time from the previous ignoring until the resending becomes very long, As a result, there arises a problem that the time required for transmission and reception of the wireless signal becomes long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a wireless communication system which can reduce the possibility of a receiver ignoring a wireless signal even when a transmitter and a receiver are disposed at close distances.

Further, the present invention provides a wireless communication system that reduces the possibility that the wireless signal transmitted by the transmitter is ignored, and can transmit and receive wireless signals in a short time.

According to a first aspect of the present invention, a wireless communication system includes: a transmitter that selectively selects a plurality of wireless channels different in frequency from each other to transmit a wireless signal; and a receiver that receives the transmission by the transmitter The wireless signal; the receiver includes: a signal strength detecting unit that measures the signal intensity of each wireless channel of the scanning object sequentially switched in each predetermined scanning period; the memory portion is used for memory a signal strength of each wireless channel measured by the signal strength detecting unit; and a signal receiving unit that preferentially performs a wireless signal on a wireless channel having a greater signal strength stored in the memory unit in the wireless channel of the scanning target receive.

According to the above configuration, the wireless signal is detected in the wireless channel with the strongest signal strength, so that the wireless channel transmitted by the transmitter close to the receiver is given priority over the wireless channel with the power of the wireless signal being leaked. The reception of the signal. Thereby, even in the case where the transmitter and the receiver are set up close to each other, the possibility that the receiver ignores the wireless signal can be reduced.

Further, the wireless signal includes a transmission destination address of a receiver indicating a transmission destination, and the receiver switches the wireless channel until the signal stored in the memory unit from the wireless channel of the scanning target is strong The wireless channel starts to receive the wireless signal of the wireless channel in the destination address of the wireless signal received in sequence, including the destination itself as the transmission destination.

According to a second aspect of the present invention, there is provided a wireless communication system comprising: one or more transmitters for selectively selecting a plurality of wireless channels having different frequencies to transmit a wireless signal; and a receiver receiving the The wireless signal sent by the transmitter; the wireless signal has: a preamble in which a predetermined bit synchronization pattern is repeatedly arranged, and a data including a transmitter identification address and a transmission information, wherein the receiver includes: a synchronization bit a meta detection unit that sequentially switches and scans a wireless channel of the scanning object by time division for each predetermined scanning period, detects the bit synchronization pattern for each wireless channel, and a data receiving unit After detecting the bit synchronization pattern, receiving the above-mentioned data; the foregoing has at least a bit length corresponding to one cycle of the scanning period, and the detection of the bit synchronization pattern is required. The length of the bit after the bit length is added.

Accordingly, since the possibility that the receiver detects the bit synchronization pattern of the wireless signal transmitted by the transmitter is improved, the possibility that the wireless signal transmitted by the transmitter is ignored is reduced, and the wireless can be performed in a short time. Signal transmission and reception.

Further, the receiver may include a channel setting mechanism for setting a plurality of wireless channels to be scanned, and the transmitter may change a length of the foregoing according to a number of channels of the wireless channel set by the channel setting means.

According to this configuration, since the length of the preamble in the transmitter can be increased or decreased according to the number of scans of the radio channel set by the receiver, a better preamble length can be selected, and the preamble of the radio signal transmitted by the transmitter can be reduced. The possibility of ignoring, and thus the wireless signal transmission and reception in a short time.

Furthermore, the receiver may further include a priority setting unit that sets a priority for each wireless channel of the scanning target, and the synchronization bit detecting unit may set the wireless in the scanning cycle according to the priority of each wireless channel. The number of scans of the channel.

Accordingly, for example, in one scan cycle, the wireless signal in the wireless channel with higher priority is detected multiple times, and thus the possibility that the wireless signal from the higher priority transmitter is detected is further improved.

Furthermore, the receiver may further include a priority setting unit that sets a priority for each wireless channel of the scanning target, and the synchronization bit detecting unit may set the scanning period according to the priority of each wireless channel. Scan time of the wireless channel.

Accordingly, for example, in a single scanning cycle, the period during which the wireless signal in the wireless channel having the higher priority is detected becomes longer, and thus the possibility that the wireless signal from the higher priority transmitter is detected is further improved.

In the wireless signal, the frame synchronization pattern including the bit pattern different from the bit synchronization pattern is arranged after the bit synchronization pattern, and the receiver includes: a signal strength detecting unit, and the signal strength of the wireless channel And detecting the frame synchronization pattern; and detecting that the frame synchronization pattern is not detected until a predetermined time elapses after the signal strength detecting unit detects a signal intensity equal to or greater than a predetermined intensity; In this case, the scanning of the wireless channel can also be started again.

According to this, when the frame sync pattern is not detected, the wireless signal is detected again, so that it is possible to avoid the situation in which other normal wireless signals cannot be received due to the incorrect wireless signal.

Further, the receiver includes a signal strength detecting unit that detects a signal strength of the wireless channel, and when the data receiving unit receives the data, when the signal strength detected by the signal strength detecting unit is lower than a predetermined intensity, The reception of the wireless signal can be interrupted, and the scanning of the wireless channel is started again.

Accordingly, in the reception of the wireless signal, if the signal strength is weak, the reception is interrupted, and the wireless signal is detected again, so that the situation that the normal wireless signal cannot be received due to the incorrect wireless signal can be avoided.

The above described features and advantages of the present invention will be more apparent from the following description.

The objects and features of the present invention will become more apparent from the description of the preferred embodiments illustrated herein.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings which form a part of this specification. In the drawings, the same or similar components are designated by the same reference numerals, and the description is omitted.

<Embodiment 1>

Hereinafter, Embodiment 1 of the present invention will be described with reference to Figs. 1 and 2 (a), (b) and (c).

As shown in FIG. 1, the wireless communication system according to the first embodiment includes a single receiver 10 and a plurality of transmitters 20. In the present embodiment, the transmitter 20 formed by connecting a total of seven transmitters 20a to 20d and 20x to 22z is described. However, the present invention is not limited thereto.

The transmitters 20a...20d together with the receiver 10 constitute an intercom doorbell system. Each of the transmitters 20a...20d is an intercom doorbell that transmits an outgoing signal according to the operation of the visitor, and is, for example, a human body detection sensor that includes a camera or the like and transmits a human body detection signal, or is mounted on a door of a porch or the like. Send the lock of the opening and closing signal of the key, etc. Further, the transmitters 20x to 20z together with the receiver 10 constitute a lighting control system. Each of the transmitters 20x to 20z is a remote control device that transmits a dimming signal according to a user's operation, a lighting device for outputting a lighting signal indicating a lighting state of the light source, or an output for indicating installation on a ceiling surface or the like. The illuminance sensor of the illumination area of the illumination area is detected by an illuminance sensor or the like.

Each of the transmitters 20 includes, for example, a transmitting unit 21 including a specific small power radio station, and transmits a wireless signal including information corresponding to the type of each transmitter 20 or the type of the system to which it belongs. The transmitting unit 21 selects a specific wireless channel from among a plurality of wireless channels set in a specific frequency band to transmit the wireless signal to the receiver 10. Furthermore, in the present embodiment, Ch1, Ch2, ..., Ch7 are respectively selected as the wireless channels used by the respective transmitters 20a, 20d, 20x, ..., 20z.

The receiver 10 also serves as a control master in two systems of the intercom doorbell system and the lighting control system, and includes, for example, a control unit 11 including a microcomputer or the like, a receiving unit 12 including, for example, a specific small power radio station, and a non-volatile one. The memory unit 13 of the semiconductor memory.

The receiving unit 12 operates under the control of the control unit 11, and after specifying the wireless channel to be scanned, the signal strength detecting unit 12a measures the signal strength of the wireless channel designated by the control unit 11 based on, for example, RSSI, and The measurement result is output to the control unit 11. Further, after receiving the wireless channel to be received by the control unit 11, the receiving unit 12 receives the wireless signal flowing in the designated wireless channel, and outputs various control information included in the received wireless signal. To the control unit 11.

The memory unit 13 stores information recorded by the control unit 11, and here, the signal strength measured by the signal intensity detecting unit 12a of the receiving unit 12 for each wireless channel to be scanned is stored.

The control unit 11 activates the receiving unit 12 for each scanning cycle by means of a built-in timer (not shown) to measure the signal strength of the wireless channel to be scanned and control the reception according to the signal strength of each wireless channel. The unit 12 is adapted to receive wireless signals transmitted by any of the transmitters 20. In the present embodiment, the signal strength is measured for each wireless channel in units of, for example, 2 ms, and the time period of one cycle period required for measuring the signal strength of all the wireless channels (Ch1 to Ch7) is set. It is 14 ms (refer to (b) of Fig. 2).

The wireless signal sent by the transmitter 20 to the receiver 10 is in the format shown in (a) of FIG. 2, from the foregoing PA, the unique word UW, the destination address DA, the source address SA, the message MG, And an error detection code CR is formed. The foregoing PA is a bit string including, for example, a bit synchronization pattern in which 0 and 1 are alternately repeated, for example, the leading bit is set to 0, the last bit is set to 1, and the receiver is received during the receiving of the bit string. Frequency introduction is possible. The unique word UW includes a bit different from the previous PA. In the present embodiment, it is set to a length of, for example, 32 bits. The destination address DA is a bit string for identifying the receiver 10 that is the destination of the wireless signal, and the transmission source address SA is a bit column for uniquely identifying the transmitter 20 that transmits the wireless signal. Further, the message MG is a bit string including the transmission information transmitted by the transmitter 20, and the bit length can be made variable according to the content of the transmission information to be transmitted. The error detection code CR is, for example, a bit string including a CRC, and is set to detect at least an abnormality such as bit inversion in the bit column constituting the message MG when the signal is transmitted and received.

Here, the operation when the receiver 10 receives the wireless signal will be described. First, the control unit 11 of the receiver 10 activates the receiving unit 12 every scanning period, and uses the receiving unit 12 to measure the signal strength in all the wireless channels to be scanned. The measurement results obtained by the measurement are sequentially stored in the memory unit 13 by the control unit 11. The signal strength in each wireless channel becomes, for example, the result shown in FIG. 2(c). In the following description, the signal strength of Ch4 is set to the maximum and in the order of Ch2, Ch1, Ch5, Ch3, Ch6, and Ch7. The signal intensity is gradually reduced to explain. Furthermore, the signal strengths of Ch1 to 5 are greater than the threshold value th of the signal strength determined to be valid in the receiving unit 12, and the signal strengths of Ch6 and 7 are less than the threshold value th.

Next, the control unit 11 sets the wireless channel of the wireless channel (here, Ch4) having the highest signal strength as the wireless channel to be received, and specifies the wireless channel to the receiving unit 12, so that the receiving unit 12 starts receiving the wireless signal. The receiving unit 12 is fixed to the wireless channel to be received, and detects the bit pattern corresponding to the foregoing PA, the unique word UW, the destination address DA, the transmission source address SA, the message MG, and the error detection code CR. Further, when the receiving unit 12 correctly detects the bit pattern, and there is no abnormality of the signal information based on the error detecting code, and if the destination address DA includes the destination itself as the transmission target, it is determined that the valid wireless signal is received. The unit 12 outputs the information stored in the message MG to the control unit 11. Thereby, the wireless signal flowing in the wireless channel with the strongest signal strength can be correctly received by the receiver 10.

On the other hand, when the receiving unit 12 does not normally detect the bit pattern from the wireless channel to be received, or the destination address DA does not include the destination itself, the control unit 11 causes the receiving unit 12 to The reception of the wireless signal in the wireless channel is interrupted. Thereafter, the control unit 11 performs the wireless channel (here, Ch2) having the second largest signal strength as the wireless channel of the receiving target from the signal strength of each wireless channel stored in the storage unit 13 to the receiving unit 12. The designation causes the receiving unit 12 to start receiving the wireless signal.

The control unit 11 waits until the receiving unit 12 receives the valid wireless signal and obtains the message MG included in the received signal, and the wireless channel sequence from the third (Ch1) and the fourth (Ch5) of the signal strength is sequentially The above receiving action is repeatedly performed. However, when the signal strength of the wireless channel to be received is less than the signal strength of the threshold th, the signal reception in the subsequent wireless channel is not performed, but the signal strength is started again at each prescribed scanning period. Determination. That is, in the case of the signal strength shown in (c) of FIG. 2, the reception of the wireless signal is attempted until the valid wireless signal is received in the order of Ch4, Ch2, Ch1, Ch5, and Ch3. Moreover, even if an attempt is made to receive the wireless signal in Ch3, as long as the valid wireless signal cannot be received, the signal strength is measured again at each scanning cycle.

In this way, since the signal reception in the wireless channel with the strong signal strength is prioritized, the signal reception in the wireless channel whose signal strength exceeds the threshold value th due to the leakage of power is started, thereby reducing the transmission of the transmitter. The wireless signal in the wireless channel is ignored.

Moreover, since the wireless channel having a strong signal strength starts to receive the wireless signal in sequence, the receiving process can be performed even if the destination address of the wireless signal having a large signal strength does not include the destination itself. Receive wireless signals flowing in other channels. Therefore, even if different wireless communication systems are arranged close to each other, the wireless signals transmitted and received by the respective wireless addresses can be used to reduce the fact that the wireless signals including the destinations in the destination address are ignored, thereby improving communication efficiency.

Furthermore, when the detection of each element pattern cannot be performed normally, or when the destination address DA does not include the destination itself, the receiving unit 12 can perform the measurement of the signal strength again and the signal strength is second strong. The wireless channel is used as the receiving object. In this way, the wireless signal can always be received according to the latest signal strength, which can reduce the possibility that the newly transmitted wireless signal is ignored.

<Embodiment 2>

Hereinafter, a second embodiment of the present invention will be described with reference to Figs. 3 to 5 .

As shown in FIG. 3, in the wireless communication system according to the second embodiment, the receiver 10 further includes an operation input unit 14 including a liquid crystal panel, a switch, and the like. Hereinafter, a description will be given focusing on a portion different from the first embodiment.

The receiving unit 12 operates under the control of the control unit 11, and after specifying the wireless channel to be scanned, the signal strength detecting unit 12a measures the signal strength in the wireless channel, for example, based on the RSSI. When the measured signal strength is higher than a predetermined threshold, the wireless signal flowing in the wireless channel is received and output to the control unit 11, but when the signal strength is lower than the predetermined threshold, the wireless signal is not performed. The reception is waited until the wireless channel is designated again by the control unit 11.

The information recorded by the control unit 11 is stored in the storage unit 13. In the second embodiment, information such as the priority of each transmitter 20, the address for identification, and the number of the wireless channel are stored. In the present embodiment, the operation input unit 14 includes a channel setting unit 14a and a priority setting unit 14b, and stores setting information such as that shown in FIG. 5 based on an operation input of the operation input unit 14. For example, for the transmitter 20a, the identification address is set to 001, the wireless channel is set to ch1, and the priority is set to "2", and the transmitters 20b...20d, 20x...20z are also set the same. Further, regarding the priority, for example, as the number becomes smaller, the priority becomes higher, and "1" is set to have the highest priority.

The operation input unit 14 outputs an operation input signal to the control unit 11 in accordance with an input operation of the user. The user can operate the switch or the like of the operation input unit 14 based on the characters, graphics, and the like displayed on the liquid crystal panel or the like of the operation input unit 14, and the address for identification in each of the transmitters 20, The setting of the priority, the number of the wireless channel, and the total number of the transmitters 20 are changed, such as addition, change, and deletion. Further, the setting information by the user in the operation input unit 14 is stored in the storage unit 13 via the control unit 11, and the control unit 11 operates based on the information recorded in the storage unit 13.

Here, the wireless signal transmitted by the transmitter 20 to the receiver 10 is in the format shown in FIG. 4(a), and is composed of the foregoing PA, the unique word UW, the data DA, and the error detection code CR. The foregoing PA is a bit column including, for example, a bit synchronization pattern in which 0 and 1 are alternately repeated, the leading bit is set to 0, and the last bit is set to 1, only when the bit is listed as consecutive 64 bits. In the case of more than one yuan, the bit column can be regarded as the former PA. The unique character UW (frame sync pattern) includes a bit different from the previous PA, and in the present embodiment, it is set to a length of 32 bits. The data DA is a bit string including the transmitted identification address of the transmitter 20 and the transmission information transmitted by the transmitter 20, and the bit length can be made variable according to the content of the transmission information to be transmitted. The error detection code CR is, for example, a bit string including a CRC, and is set to detect at least an abnormality such as bit inversion in a bit column constituting the material DA when the signal is transmitted and received.

The control unit 11 activates the receiving unit 12 every predetermined time interval (scanning period) by a built-in timer (not shown), sequentially scans the preset wireless channels, and receives the transmission from any of the transmitters 20. Wireless signal. In the present embodiment, as shown in FIG. 4(b), each wireless channel is scanned in units of 2 ms based on the setting information stored in the storage unit 13. At this time, since the priority of the wireless channels ch5 to ch7 set in the transmitters 20x to 20z is set to "1", it is set to perform scanning twice per period, and the transmitters 20a to 20d are placed. Since the priority is set to "2", the scan is performed once per cycle, and the time period of one cycle required for scanning all the wireless channels is 20 ms.

As a specific scanning method for each wireless channel, the control unit 11 controls the receiving unit 12 to cause the signal strength detecting unit 12a to detect the signal strength in the predetermined wireless channel, and if the detected signal strength is sufficient, the wireless signal is self-selected. The receiving unit 12 is input to the control unit 11. Next, the control unit 11 performs the above-described detection of the bit synchronization pattern on the wireless signal input from the receiving unit 12 by the synchronization bit detecting unit 11a. In each of the wireless channels, when the bit synchronization pattern is not detected during the period of 2 ms, the wireless channel of the scanning target is switched to the next wireless channel, and the detection of the bit synchronization pattern is performed again. Further, when the bit synchronization pattern is detected during the period of 2 ms, the wireless channel to be scanned is fixed to the wireless channel, and after the predetermined time elapses, the unique character UW is detected by the frame detecting unit 11b. . In the present embodiment, the predetermined time for detecting is set to 40 ms from the start of the detection of the bit sync pattern, which is the time after the following time is added, that is, for all the wireless channels. The time required for scanning is 20 ms, the 13.3 ms corresponding to the 64-bit required to determine the bit column, and the 6.7 ms corresponding to the 32-bit length of the unique word UW. .

Second, when the unique word UW is not detected, the receiver 10 suspends reception of the wireless signal in the wireless channel and starts scanning of each wireless channel again. On the other hand, when the unique word UW is detected, the data receiving unit 12b continues to receive the data DA, and the error correction code CR confirms whether or not the signal information is abnormal. If there is no abnormality, the data is stored in the wireless signal. News. Furthermore, the receiving unit 12 periodically detects the signal strength when receiving the data DA. When the signal strength is lower than the predetermined threshold, the signal indicating that the signal strength is reduced is output to the control unit 11, according to the control unit. The action control of 11 ends the reception of the wireless signal of the wireless channel, and starts scanning of the wireless signal in the next wireless channel.

In this manner, the receiver 10 performs reception of the wireless signal including the foregoing PA through each wireless channel every predetermined scanning period (20 ms).

Here, the bit length of the foregoing PA is set to be 96 bits which are equal to the 96-bit element corresponding to the scanning period (20 ms) in the receiver 10 and the 64-bit element required for the detection of the foregoing PA. By setting in this way, the possibility that the receiver 10 detects the bit synchronization pattern becomes high during the period of 96 bits from the leading bit of the foregoing PA, and thereafter, at least the detection station of the foregoing PA is succeeded. The required 64-bit bit synchronization pattern, so the receiver 10 can detect the previous PA and receive the wireless signal. Thereby, since the probability that the wireless signal transmitted by the transmitter 20 is received by the receiver 10 is increased, the necessity for the transmitter 20 to transmit the same wireless signal again becomes lower, so that the time required for transmitting and receiving the signal can be reduced.

Furthermore, as shown in FIG. 4(c), the receiver 10 can also scan the wireless channels ch5 to ch7 having higher priorities longer than the scanning channels of the lower priority wireless channels ch1 to ch4. For example, the scan time for ch1 to ch4 is 2 ms, and the scan time for ch5 to ch7 is 4 ms.

Further, in the present embodiment, the bit length of the preamble PA of each transmitter 20 is a fixed length of 160 bits, but a setting mechanism may be provided in each of the transmitters 20, and according to the receiver 10. The number of the set wireless channels and the length of one cycle of scanning each wireless channel are changed, and the change mechanism may be changed after the user changes the setting of the receiver 10 via the operation input unit 14. The indicator signal for indicating the length of the message by the receiver 10 is transmitted, and the length of the preamble of the wireless signal transmitted by the transmitter 20 is changed according to the instruction signal received by the transmitter 20.

Further, in the present embodiment, an example in which the present wireless communication system is adapted to the intercom doorbell system and the illumination control system has been described, but it does not limit the adaptable system, and it can be adapted to various systems such as a remote examination system. . For example, the present invention is applied to a remote inspection system that automatically measures a measurement device such as a power meter, a gas meter, a water meter, or the like installed at a remote place, and transmits and receives the measurement result as remote inspection information. Moreover, the present invention is also applicable to a fire alarm system.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments, and various changes and modifications may be made without departing from the scope of the appended claims. category.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10. . . receiver

11. . . Control department

11a. . . Sync bit detection unit

11b. . . Frame detection unit

12. . . Receiving department

12a. . . Signal strength detection unit

12b. . . Data receiving department

13. . . Memory department

14. . . Operation input

14a. . . Channel setting mechanism

14b. . . Priority setting unit

20a. . . Transmitter

20b. . . Transmitter

20c. . . Transmitter

20d. . . Transmitter

20x. . . Transmitter

20y. . . Transmitter

20z. . . Transmitter

twenty one. . . Sending department

Fig. 1 is a schematic block diagram showing a wireless communication system according to a first embodiment of the present invention.

(a) of FIG. 2 is a schematic diagram showing a format of a radio signal of the radio communication system according to the first embodiment, and (b) of FIG. 2 is a schematic diagram for explaining a time division method for scanning the radio signal of the first embodiment. FIG. 2(c) is a graph showing an example of measurement results of signal strength of the wireless signal according to the first embodiment.

Fig. 3 is a schematic block diagram showing a configuration of a wireless communication system according to a second embodiment;

Fig. 4 (a) is a schematic diagram showing the format of a radio signal of the radio communication system according to the second embodiment, and (b) and (c) of Fig. 4 are schematic diagrams showing the timing of scanning the radio signal of the second embodiment. .

Fig. 5 is a table showing setting contents set in a receiver of the wireless communication system according to the second embodiment.

10. . . receiver

11. . . Control department

12. . . Receiving department

12a. . . Signal strength detection unit

13. . . Memory department

20a. . . Transmitter

20b. . . Transmitter

20c. . . Transmitter

20d. . . Transmitter

20x. . . Transmitter

20y. . . Transmitter

20z. . . Transmitter

twenty one. . . Sending department

Claims (9)

A wireless communication system comprising: a transmitter that selectively selects a plurality of wireless channels having different frequencies to transmit a wireless signal; and a receiver that receives the wireless signal transmitted by the transmitter; the receiver includes: a signal An intensity detecting unit that measures a signal intensity of each wireless channel of the scanning target that is sequentially switched for each predetermined scanning period; and a memory unit that memorizes each of the signals measured by the signal intensity detecting unit The signal strength of the wireless channel; and the signal receiving unit that preferentially receives the wireless signal by the wireless channel having the greater signal strength stored in the memory unit in the wireless channel of the scanning target. The wireless communication system of claim 1, wherein the wireless signal includes a destination address of a receiver indicating a destination, and the receiver switches the wireless channel until the wireless channel from the scanning target The wireless destination of the wireless signal that is received by the wireless channel having the strong signal strength stored in the memory unit includes the destination itself as the transmission destination, and receives the wireless signal of the wireless channel. A wireless communication system comprising: one or more transmitters that selectively select a plurality of wireless channels having different frequencies to transmit a wireless signal; and a receiver that receives the wireless signal transmitted by the transmitter; the wireless The signal has: a preamble in which a predetermined bit synchronization pattern is repeatedly arranged, and a data including a transmitter identification address and a transmission information, and the receiver includes: a synchronization bit detection unit, each of which is specified Scanning period, sequentially switching and scanning the wireless channel of the scanning object by time division, detecting the bit synchronization pattern for each wireless channel; and receiving the bit synchronization pattern after receiving the bit synchronization pattern According to the above-mentioned data, the foregoing has at least a bit length corresponding to one cycle of the scanning period and a bit length added to the bit length required for detection of the bit synchronization pattern. . The wireless communication system of claim 3, wherein the receiver comprises a channel setting mechanism for setting a plurality of wireless channels of the scanning target, and the transmitter is configured according to a number of channels of the wireless channel set by the channel setting mechanism. And the length of the previous text changes. The wireless communication system according to claim 3, wherein the receiver includes a priority setting unit that sets a priority for each wireless channel of the scanning target, and the synchronization bit detecting unit is configured according to each The number of scans of the wireless channel in the above scanning period is set by the above priority of the wireless channel. The wireless communication system according to claim 3, wherein the receiver includes a priority setting unit that sets a priority for each wireless channel of the scanning target, and the synchronization bit detecting unit is configured according to each The scanning time of the wireless channel in the above scanning period is set by the above priority of the wireless channel. The wireless communication system of claim 3, wherein the wireless signal further has a frame synchronization pattern, and the bit pattern is different from the bit synchronization pattern, and after the bit synchronization pattern And the receiver includes: a signal intensity detecting unit that detects a signal strength of the wireless channel; and a frame detecting unit that detects the frame synchronization pattern, wherein the signal strength detecting unit detects a signal intensity equal to or greater than a predetermined intensity When the frame synchronization pattern is not detected until a predetermined period of time elapses, scanning of the wireless channel is resumed. The wireless communication system of claim 3, wherein the receiver includes a signal strength detecting unit that detects a signal strength of the wireless channel, and the signal strength is received when the data receiving unit receives the data. When the signal strength detected by the detecting unit is lower than the predetermined intensity, the reception of the wireless signal is interrupted, and the scanning of the wireless channel is started again. The wireless communication system of claim 1 or 3, wherein the wireless communication system is a remote inspection system, and the wireless signal is a signal including remote inspection information.