JP2013098774A - Receiver and radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility of timeout in synchronization processing while shortening a synchronization section of a radio signal.SOLUTION: A reception control part 11 of an embodiment makes a radio reception part 10 stop until second standby time ΔTstop 2 passes, where the second standby time is shorter than first standby time ΔTstop 1 (>ΔTstop 2) that is standby time in the case of receiving no electric wave, when synchronization of a radio signal is not achieved after the electric wave is received. Thereby, the possibility that timeout occurs in synchronization processing of the radio reception part 10 on a synchronization section of a desired wave is reduced as compared with the case such as a conventional example in which standby time when synchronization processing is timed out is equal to the standby time ΔTstop 1 when it is determined in the electric wave check that no electric wave exists. As a result, the possibility of the timeout in the synchronization processing can be reduced while shortening the synchronization section of the radio signal.

Description

  The present invention relates to a receiver for receiving a radio signal transmitted from a transmitter, and a radio communication system including the transmitter and the receiver.

  A conventional example of a wireless communication system including a transmitter and a receiver is disclosed in Patent Document 1. This conventional example detects a surrounding brightness or the presence of a human body, and transmits a detection result by a radio signal using radio waves as a medium, and according to the detection result obtained by receiving a radio signal. And a receiver for controlling (flashing) a load (for example, a lighting load). The receiver includes a switching element connected in series with the lighting load with respect to the commercial power source, and blinks the lighting load by opening and closing the switching element according to the detection result.

  For example, a transmitter and a receiver are installed on the wall of a room, and when there are people in the room, the transmitter detects the presence of the person and transmits it with a radio signal for lighting the lighting load, and receives the radio signal In the receiver, the switch element is turned on and the illumination load is turned on. Then, when there is no person in the room, the transmitter transmits a radio signal for turning off the lighting load, and the switch element is turned off in the receiver that has received the radio signal, and the lighting load is turned off.

  Here, the transmitter uses a battery as a power source in order to increase the degree of freedom of installation, and it is desirable to shorten the frame length of the radio signal (transmission signal) in order to extend the life of the battery. A radio communication frame is generally composed of a preamble for symbol synchronization, a unique word for frame synchronization, control information (such as address information of the communication partner), data, and a check code for error detection. . When the frame length is shortened, the preamble and unique word (hereinafter referred to as a synchronization unit) are usually shortened.

  On the other hand, since the receiver is connected to an external power source (commercial AC power source) via an illumination load, it can be constantly supplied with power from the external power source. However, it is conceivable to intermittently receive the receiver in order to reduce power consumption and save energy. In other words, the receiver circuit is activated every certain time to check whether or not to receive radio waves (radio wave check), if the radio waves are not received, the receiver circuit is stopped, and if radio waves are received, symbol synchronization continues, Further, the process for obtaining frame synchronization is continued. Here, the interval at the end of the radio wave check is defined as the intermittent reception cycle ΔT1, and the interval from the end of the previous radio wave check to the start of the next radio wave check is defined as the waiting time ΔTstop1. In order to ensure symbol synchronization and frame synchronization at the next reception opportunity even when a radio signal arrives immediately after the radio wave check is completed, the length of the frame synchronization unit is symbol synchronization and frame synchronization. Therefore, it is necessary to be longer than the sum of the processing time required and the standby time ΔTstop1 (see FIG. 3A).

JP 2011-198654 A

  By the way, various radio waves come and go in the air, and radio waves (interference waves) other than the radio signal radio waves (desired waves) transmitted from the transmitter are caught in the radio wave check, and reception processing at the receiver continues erroneously (See FIG. 3B). However, since the symbol synchronization cannot be achieved even if the interference wave is received, the receiver times out the synchronization process and stops the reception circuit until the standby time ΔTstop1 elapses from the timeout, and the elapse of the standby time ΔTstop1. Check the signal again later. When the desired wave is received at this time, the synchronization process is performed. However, depending on the timing at which the desired wave arrives, there is a possibility that the synchronization process may time out due to the lack of the length of the synchronization unit.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the synchronization processing timeout while shortening the synchronization portion of the radio signal.

  The receiver of the present invention includes a receiving unit that receives a radio signal using radio waves as a medium, and a reception control unit that controls the receiving unit, and the radio signal has a synchronization unit at the head for synchronization. The reception control means intermittently activates the reception means and checks whether or not the radio wave is received. If the radio wave is not received, the reception control means stops the reception means until a predetermined first waiting time elapses. If the radio wave is received, the receiving means continues to receive the radio wave, and if the radio signal cannot be synchronized after the radio wave is received, the first waiting time is shorter than the first waiting time. The receiving means is stopped until two standby times have elapsed.

  In this receiver, it is preferable that the reception control unit makes a period for intermittently starting the reception unit constant regardless of the result of the presence or absence of the radio wave reception.

  In this receiver, the reception means has a variable signal processing speed for the radio signal, and at least the processing speed in the first waiting time is slower than the processing speed in other than the first waiting time. It is preferable to do.

  In this receiver, it is preferable that the receiving means make the processing speed in the second waiting time the same as the processing speed in the time other than the first and second waiting times.

  A wireless communication system according to the present invention includes any one of the receivers and a transmitter that transmits the wireless signal.

  The receiver and the wireless communication system of the present invention have an effect that the synchronization processing timeout can be reduced while shortening the synchronization unit of the wireless signal.

4 is a time chart for explaining operations of the receiver and the radio communication system according to the present invention. It is a block diagram of a receiver and a transmitter same as the above. It is a time chart for operation | movement explanation of a prior art example.

  Hereinafter, embodiments of a receiver and a wireless communication system according to the present invention will be described in detail with reference to the drawings. However, in this embodiment, the technical idea of the present invention is applied to a load control system in which a receiver controls (blinks) a load (lighting load) in accordance with a control command included in a radio signal transmitted from the transmitter. However, the technical idea of the present invention is applicable to receivers and wireless communication systems in general.

  The wireless communication system (load control system) of the present embodiment includes a transmitter 2 and a receiver 1 as shown in FIG. The receiver 1 includes a wireless reception unit 10, a reception control unit 11, a switch element 12, a current transformer 13, two rectifiers 14 and 15, a voltage conversion unit 16, a pair of connection terminals 17 and 18, and the like. For example, the wireless receiving unit 10 includes a wireless communication circuit that performs wireless communication conforming to a standard of a specific low-power wireless station specified by the Radio Law, and receives a wireless signal using a radio wave as a medium. However, since such a wireless receiving unit 10 can be realized using a conventionally known wireless communication technique, detailed description thereof will be omitted.

  An external power source (commercial AC power source) 3 and a lighting load 4 are connected to the pair of connection terminals 17 and 18 via electric wires, respectively. The switch element 12 is composed of, for example, a latching mechanical relay, and is inserted into a power supply path from the external power source 3 to the lighting load 4 via a pair of connection terminals 17 and 18 to open and close (on / off) the power supply path. To do. The current transformer 13 has a primary winding inserted into the feed path and a rectifier 14 connected to the secondary winding. The rectifier 14 rectifies an alternating voltage (alternating current) induced in the secondary winding of the current transformer 13 when the switch element 12 is on, and outputs the rectified voltage to the voltage converter 16. The rectifier 15 rectifies the AC voltage applied to both ends of the switch element 12 when the switch element 12 is off, and outputs the rectified voltage to the voltage conversion unit 16. However, the current rectified by the rectifier 15 is limited to such a small value that the luminous flux emitted from the illumination load 4 can be ignored.

  The voltage conversion unit 16 includes a storage capacitor (electrolytic capacitor) (not shown) and a power supply circuit. The DC voltage rectified by the rectifier 14 and smoothed by the capacitor is used as an operating power source for the radio reception unit 10 and the reception control unit 11. It is converted to voltage. Further, the voltage conversion unit 16 converts the DC voltage rectified by the rectifier 15 and smoothed by the capacitor when the switch element 12 is off to the operating power supply voltage of the radio reception unit 10 and the reception control unit 11. .

  The reception control unit 11 includes a microcontroller and opens / closes (turns on / off) the switch element 12 in accordance with a control command included in a radio signal received by the radio reception unit 10 as described later.

  On the other hand, the transmitter 2 includes a transmission control unit 20, a detection unit 21, a wireless transmission unit 22, an operation unit 23, and the like, and each unit 20 to 23 operates with a battery (not shown) as a power source. Similarly to the wireless receiver 10 of the receiver 1, the wireless transmitter 22 has a wireless communication circuit that performs wireless communication in accordance with the standard of a specific low-power wireless station specified by the Radio Law, and is wireless using radio waves as a medium. Send a signal. However, since such a wireless transmission unit 22 can be realized using a conventionally known wireless communication technique, detailed description thereof will be omitted.

  The detection unit 21 includes, for example, a human body detection sensor that detects the presence of a person by detecting heat rays emitted from the human body, a brightness sensor that detects ambient brightness (ambient illuminance), and the like. That is, the detection unit 21 uses a person's presence or ambient illuminance below a predetermined value as a trigger, and outputs a trigger signal to the transmission control unit 20 when the trigger is detected. The operation unit 23 includes, for example, a push button switch (not shown), and accepts an operation input when the push button switch is pressed, and outputs an operation signal to the transmission control unit 20.

  The transmission control unit 20 is composed of a microcontroller or the like, and generates a control command (control command for lighting the illumination load 4) based on the trigger signal output from the detection unit 21 and the operation signal output from the operation unit 23. It passes to the wireless transmission unit 22. Further, the transmission control unit 20 adds information on the lighting holding time to the control command based on the trigger signal. The radio transmission unit 22 generates a transmission signal by modulating a frame in which the control command passed from the transmission control unit 20 is stored in the data field, and transmits the transmission signal (radio signal) from an antenna (not shown). . The frame of the radio signal transmitted from the transmitter 2 has a synchronization part (preample and unique word) at the head as described in the conventional example, and a data field in which a control command is stored after the synchronization part. Have.

  In the receiver 1, when the wireless signal is received by the wireless receiver 10, the reception controller 11 turns on the switch element 12 in response to the control command, and further switches during the lighting holding time added to the control command. Do not turn off element 12. When receiving the control command to which the lighting holding time is added during the lighting holding time, the reception control unit 11 restarts the lighting holding time, and when the lighting holding time is finished, the switch element 12 To turn off the illumination load 4.

  Here, the operation of the transmission control unit 20 will be described in detail. The transmission control unit 20 waits for input of the operation signal output from the operation unit 23, and turns on the lighting load 4 when the trigger signal output from the detection unit 21 is input while waiting for input of the operation signal. Control command (load control command) is generated. Then, the transmission control unit 20 causes the radio transmission unit 22 to transmit a radio signal including the generated load control control command.

  On the other hand, when the operation signal output from the operation unit 23 is input, the transmission control unit 20 generates a control command for confirming reception of the radio signal, and wirelessly transmits the radio signal including the generated control command for confirmation of reception. The data is transmitted from the unit 22.

  By the way, also in the receiver 1 of the present embodiment, the reception control unit 11 causes the wireless reception unit 10 to perform intermittent reception in order to reduce the power consumption of the receiver 1 as in the conventional example. Furthermore, in the present embodiment, if the power consumption when the switch element 12 is turned off increases, there is a risk that the switch element 12 cannot be turned on due to insufficient storage power (charged charge) of the capacitor of the voltage conversion unit 16, It is important to reduce the power consumption of the wireless reception unit 10 by intermittent reception.

  Therefore, the reception control unit 11 activates the radio reception unit 10 for every intermittent reception period ΔT1 to check the radio wave, stops the radio reception unit 10 if no radio wave is received, and continues to receive the radio wave when the radio wave is received. 10 continues the synchronization processing for symbol synchronization and frame synchronization. When activated, the radio receiving unit 10 performs a setting process such as a reception frequency, and then checks the radio wave by comparing the intensity of the radio wave received by an antenna (not shown) with a predetermined threshold. It is determined that there is a radio wave when the threshold is exceeded, and no radio wave when the threshold is not exceeded. As shown in FIG. 3A, the interval at the end of the radio wave check is defined as an intermittent reception cycle ΔT1, and the interval from the end of the previous radio wave check to the start of the next radio wave check is defined as a waiting time ΔTstop1.

  As described in the prior art, the synchronization process times out because symbol synchronization cannot be obtained even if an interference wave is received, and the radio reception unit 10 stops until the waiting time ΔTstop1 elapses from the timeout. At this time, if the waiting time until the wireless receiving unit 10 is activated again is the same as the waiting time ΔTstop1 when the radio wave check determines that there is no radio wave, the length of the synchronization unit depends on the timing at which the desired wave arrives. There is a risk that the synchronization process will time out due to lack of.

  Therefore, in the present embodiment, when the radio signal cannot be synchronized after the radio wave is received, the reception control unit 11 performs the second standby time ΔTstop2 () shorter than the first standby time ΔTstop1 when the radio wave is not received. The wireless receiver 10 is stopped until <ΔTstop1) has elapsed (see FIG. 1). Therefore, compared to the case where the standby time when the synchronization processing times out as in the conventional example is the same as the standby time ΔTstop1 when the radio wave check determines that there is no radio wave, it is wireless to the synchronization part of the desired wave The possibility that the synchronization processing of the receiving unit 10 will time out is reduced. As a result, the synchronization processing timeout can be reduced while shortening the synchronization unit of the radio signal. Note that the period (intermittent reception period ΔT1) at which the reception control unit 11 intermittently activates the radio reception unit 10 may be constant regardless of the result of presence / absence of radio wave reception. However, when the time required for the synchronization processing is equal to the first standby time ΔTstop1, the intermittent reception cycle ΔT1 can be made constant by setting the second standby time ΔTstop2 to zero.

  By the way, the wireless communication circuit of the wireless reception unit 10 and the microcontroller of the reception control unit 11 may be configured as one integrated circuit, and the reception control unit 11 may be used as both reception control means and reception means. In this case, if the processing speed (operating frequency) of the integrated circuit (receiving means) is variable, at least the processing speed (operating frequency) in the first waiting time ΔTstop1 is set to the processing speed (operating frequency other than the first waiting time ΔTstop1). ) Is preferably slower (lower). In this way, the power consumption of the receiver 1 can be reduced without reducing the processing speed of signal processing for radio signals such as synchronization processing. However, in the second waiting time ΔTstop2 when the synchronization processing times out, it is preferable that the processing speed is the same as the processing speed other than the first and second waiting times ΔTstop1 and ΔTstop2. Accordingly, the reception control unit 11 can accurately manage the second standby time ΔTstop2, and as a result, the synchronization process after the second standby time ΔTstop2 has elapsed can be smoothly executed.

1 Receiver 2 Transmitter
10 Wireless receiver (reception means)
11 Reception control unit (reception control means)
ΔTstop1 1st waiting time ΔTstop2 2nd waiting time

Claims (5)

  A reception unit that receives a radio signal using radio waves as a medium; and a reception control unit that controls the reception unit; and the radio signal has a synchronization unit at the head for synchronization, and the reception control unit includes: The receiving means is intermittently activated and the presence or absence of reception of the radio wave is checked. If the radio wave is not received, the reception means is stopped until a predetermined first waiting time elapses, and the radio wave is not received. If the radio signal is continuously received by the receiving means and the radio signal is not synchronized after the radio wave is received, a second standby time shorter than the first standby time elapses. A receiver characterized in that the receiving means is stopped.   The receiver according to claim 1, wherein the reception control unit makes a period for intermittently starting the reception unit constant regardless of a result of presence / absence of the radio wave reception.   The receiving means is characterized in that a processing speed of signal processing for the radio signal is variable, and at least the processing speed in the first waiting time is slower than the processing speed in a time other than the first waiting time. The receiver according to claim 1 or 2.   4. The receiver according to claim 3, wherein the receiving unit makes the processing speed in the second waiting time equal to the processing speed in the time other than the first and second waiting times.   A wireless communication system comprising the receiver according to claim 1 and a transmitter for transmitting the wireless signal.

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