JP2007258901A - Radio wave module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a wake-up circuit to start a main circuit at proper timing even while properly achieving low power consumption of the wake-up circuit. <P>SOLUTION: When the wake-up circuit 2 detects that a pulse time width of a signal received from the outside is equivalent to a pulse time width of a burst of a pilot signal from a roadside machine, or when the wake-up circuit detects that a pulse cycle of the signal received from the outside is equivalent to a pulse cycle of the burst of the pilot signal from the roadside machine during intermittent operation; the wake-up circuit 2 executes continuous operation by switching from the intermittent operation to the continuous operation in a radio wave module 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention selectively selects one of an intermittent operation for intermittently monitoring a pilot signal from a roadside unit and a continuous operation for continuously monitoring a pilot signal from a roadside unit using the power supplied from the power source as the operating power. The present invention relates to a radio wave module including a wake-up circuit for performing and capable of starting and stopping an operation of a main circuit during continuous operation of the wake-up circuit.

For example, in a radio wave module mounted on a vehicle, a wake-up circuit is always activated, while a main circuit is activated only when necessary to achieve low power consumption. In this case, the wake-up circuit detects that the received electric field strength of the pilot signal from the roadside unit is greater than or equal to the threshold value, and detects that the vehicle is traveling in the communication area, or the vibration sensor detects vibration. If so, the main circuit is activated (see, for example, Patent Document 1).
JP 2004-328263 A

By the way, in order to activate the main circuit, it is necessary to activate the wake-up circuit. However, in the configuration in which the wake-up circuit is always activated, it cannot be said that sufficient low power consumption is achieved. There was room for further improvement in terms of low power consumption. On the other hand, if the wakeup circuit is not activated at an appropriate timing, it becomes difficult for the wakeup circuit to activate the main circuit at an appropriate timing, and it becomes difficult for the main circuit to perform wireless communication normally. There is also a problem.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to achieve a reduction in power consumption of the wakeup circuit appropriately, while the wakeup circuit sets the main circuit at an appropriate timing. An object of the present invention is to provide a radio wave module that can be activated and in which a main circuit can perform radio communication normally.

  According to the first aspect of the present invention, the wake-up circuit continuously monitors the pilot signal from the roadside unit and intermittently monitors the pilot signal from the roadside unit using the power supplied from the power source as the operating power. One of the continuous operations to be monitored is selectively performed, and the pulse time width of the signal received from the outside during the intermittent operation corresponds to the pulse time width of the burst of the pilot signal from the roadside unit (a group of signal trains). Is detected, or when it is detected that the pulse period of the signal received from the outside corresponds to the pulse period of the burst of the pilot signal from the roadside unit, the continuous operation is switched from the intermittent operation to the continuous operation.

  As a result, the wake-up circuit normally performs intermittent operation, and when a pilot signal is received from the roadside machine from that state, the intermittent operation is switched to the continuous operation at that timing, and the continuous operation is performed. Unlike the conventional one that is always activated, the power consumption of the wake-up circuit can be appropriately realized. In addition, since the intermittent operation is switched to the continuous operation at the timing of receiving the pilot signal from the roadside machine and the continuous operation is performed, the wakeup circuit can start the main circuit at an appropriate timing thereafter, and the main circuit Wireless communication can be performed normally.

  In addition, by appropriately realizing low power consumption of the wakeup circuit in this way, if the battery is used as a power source, the battery can be reduced in size, and the entire module can be reduced in size accordingly. Can also be realized.

  According to the second aspect of the present invention, the wake-up circuit performs the continuous operation by switching from the intermittent operation to the continuous operation even when the vibration detecting means detects the vibration during the intermittent operation. By preparing a structure (for example, a step on the road surface) in which the vibration detecting means can detect vibration in advance in a communication area (for example, a toll gate entrance) where the main circuit needs to be activated. For example, the wake-up circuit switches from intermittent operation to continuous operation at the timing when the vibration detection means detects vibration even when it has passed through the communication area that should be originally communicated due to its high moving speed. By performing the continuous operation, the wakeup circuit can start the main circuit at an appropriate timing thereafter.

  According to the invention described in claim 3, the wake-up circuit detects that the pulse time width of the signal received from the outside during the continuous operation corresponds to the pulse time width of the burst of the pilot signal from the roadside unit, and When it is detected that the pulse period of the signal received from the outside corresponds to the pulse period of the pilot signal burst from the roadside device, the operation of the main circuit is started. As a result, the main circuit can be activated at an appropriate timing that is likely to enter the communication area.

  According to the invention described in claim 4, the wake-up circuit has only one of the circuit for determining the pulse time width of the signal received from the outside and the circuit for determining the pulse period of the signal received from the outside during the intermittent operation. To work. Accordingly, by operating only one of the circuit for determining the pulse time width and the circuit for determining the pulse period, it is possible to further reduce the power consumption of the wakeup circuit.

  According to the invention described in claim 5, the wake-up circuit determines whether or not the pulse time width of the signal received from the outside corresponds to the pulse time width of the burst of the pilot signal from the roadside unit. The determination level for determining whether the level and the pulse period of the signal received from the outside correspond to the pulse period of the burst of the pilot signal from the roadside device is set low for the weak electric field and high for the strong electric field.

  Thereby, the determination level for determining whether the pulse time width or pulse period of the signal received from the outside corresponds to the pulse time width or pulse period of the burst of the pilot signal from the roadside unit is set according to the electric field level. By changing, the detection accuracy can be improved, and the accuracy of the timing at which the wakeup circuit switches from the intermittent operation to the continuous operation and the timing at which the wakeup circuit starts the main circuit can be increased.

Hereinafter, an embodiment in which the present invention is applied to a radio wave module that can be attached to a vehicle will be described with reference to the drawings. FIG. 1 shows a functional block diagram of the radio wave module. The radio module 1 includes a wakeup circuit 2 and a main circuit 3.
The wakeup circuit 2 includes a wakeup detection circuit 4, a wakeup determination circuit 5, a low frequency oscillation unit 6, a vibration sensor 7 (vibration detection means in the present invention), and a power supply control unit 8. When the signal received by the antenna 9 from the outside is input via the changeover switch 10, the wake-up detection circuit 4 generates an detection signal by detecting an envelope of the input signal, and based on the generated detection signal. An output signal is generated and output to the wakeup determination circuit 5. The vibration sensor 7 measures the vibration of the vehicle and outputs the vibration level to the wake-up determination circuit 5.

  The wake-up determination circuit 5 operates using the low-frequency clock supplied from the low-frequency oscillation unit 6 as an operation clock. When an output signal is input from the wake-up detection circuit 4, the input output signal is determined and the determination result Based on the above, a switch switching signal is output to the selector switch 10 and a power-on signal or a power-off signal is output to the power switch 11. In addition, when the vibration level is input from the vibration sensor 7, the wakeup determination circuit 5 determines the input vibration level, and also outputs a switch switching signal to the changeover switch 10 based on the determination result and a power-on signal or A power off signal is output to the power switch 11. The power supply control unit 8 outputs the power supplied from the battery 12 as operating power to the function blocks 4 to 6 and the vibration sensor 7.

  The main circuit 3 includes a wireless communication unit 13, a communication processing unit 14, a storage unit 15, a high frequency oscillation unit 16, and a power supply control unit 17. The wireless communication unit 13 operates using the high frequency clock supplied from the high frequency oscillation unit 16 as an operation clock, and controls wireless communication. The communication processing unit 14 operates using the high frequency clock supplied from the high frequency oscillation unit 16 as an operation clock, and controls communication processing by writing data into the storage unit 15 and reading data from the storage unit 15. The power control unit 17 outputs the power supplied from the battery 12 via the power switch 11 to the function blocks 13 to 16 as operating power.

  When the switch 10 receives a switch switching signal from the wakeup determination circuit 5, the selector switch 10 outputs a signal received by the antenna 9 from the outside to the wakeup detection circuit 4 based on the input switch switching signal. The state is switched between the second connection state in which the signal received from the antenna 9 is output to the wireless communication unit 13 and the signal input from the wireless communication unit 13 is transmitted from the antenna 9. When the power switch 11 receives a power-on signal from the wake-up determination circuit 5, the power switch 11 starts a power supply operation to the power control unit 17 of the main circuit 3. On the other hand, when a power-off signal is input from the wake-up determination circuit 5, The power supply operation to the power control unit 17 of the main circuit 3 is stopped.

  Here, operations of the wakeup detection circuit 4 and the wakeup determination circuit 5 will be described with reference to FIGS. 4 and 5. The wakeup detection circuit 4 determines a signal received from the outside by the antenna 9 according to a determination level. As a determination method in this case, a pulse of a signal received by the antenna 9 from the outside is peak-held, and an average value thereof is determined to determine a determination level. In other words, the wake-up detection circuit 4 sets the determination level low for a weak electric field (for example, “several tens of mV”), and sets the determination level high for a strong electric field (for example, “several hundred mV”). To do). In the weak electric field, since the determination level is set low, noise may be detected. Therefore, the determination level may be offset.

  In this case, the wake-up detection circuit 4 generates a detection signal by envelope detection of the signal received from the antenna 9 from the outside, and converts the generated detection signal from an analog value to a digital value based on the determination level. An output signal is generated, and the generated output signal is output to the wakeup determination circuit 5.

  When the output signal is input from the wakeup detection circuit 4, the wakeup determination circuit 5 measures the pulse period and the pulse time width of the input output signal, and the pulse period of the input output signal is the pilot signal from the roadside unit. It is determined whether or not it corresponds to the pulse period of a burst (a group of signal trains), and whether or not the pulse time width of the input output signal corresponds to the pulse time width of the pilot signal burst from the roadside unit Determine.

The radio wave module 1 configured as described above has a structure in which a portion corresponding to the antenna 9 is formed of a resin capable of transmitting radio waves and cannot be mechanically opened.
Next, the operation of the above configuration will be described with reference to FIGS. Here, FIG. 2 shows a process performed by the wake-up circuit 2 as a flowchart.

  When the battery 12 is normally attached to the radio wave module 1, the wake-up circuit 2 starts the intermittent operation because the power of the battery 12 is supplied as the operating power immediately after that (step S1). The timing at which the battery 12 is normally attached to the radio module 1 is, for example, the timing at which the radio module 1 is attached to the vehicle. The wake-up circuit 2 performs an operation of repeating a start time of “500 ms” and a stop time of “500 ms” as an intermittent operation, for example. As described above, the wake-up circuit 2 performs the intermittent operation immediately after the battery 12 is normally attached to the radio wave module 1, thereby realizing a reduction in power consumption of “50%” from the case of performing the continuous operation. .

  Next, the wake-up circuit 2 detects the pulse period of the pilot signal burst by determining whether or not the pulse period of the signal received by the antenna 9 from the outside corresponds to the pulse period of the pilot signal burst. (Step S2), and by determining whether the pulse time width of the signal received from the outside by the antenna 9 corresponds to the pulse time width of the pilot signal burst, It is determined whether the pulse time width is detected (step S3), and the vibration level of the vehicle is determined by determining the vibration level input from the vibration sensor 7 (step S4).

  Here, when the vehicle reaches the end of the communication area, the radio wave module 1 receives the pilot signal with a weak electric field. At this time, the wake-up circuit 2 has the pulse time width of the pilot signal burst and the pilot signal. Either one of the burst pulse periods is detected first. When the wake-up circuit 2 detects either the pulse time width of the pilot signal burst or the pulse period of the pilot signal burst (“YES” in step S2) (FIG. 3 shows the case where the pulse period is detected. When the intermittent operation is finished, the continuous operation is started. That is, the intermittent operation is switched to the continuous operation and the continuous operation is performed (step S5) (see “t1” in FIG. 3), and the time measurement for the specified time is started. (Step S6). Then, the wakeup circuit 2 determines whether or not both the pulse period and the pulse time width of the pilot signal burst are detected (step S7).

  Here, when the vehicle approaches the center of the communication area, the radio wave module 1 receives the pilot signal with a strong electric field. At this time, the wake-up circuit 2 receives the pilot signal as shown in FIG. Both the pulse period of the burst and the pulse time width are detected. When the wake-up circuit 2 detects both the pulse period and the pulse time width of the burst of the pilot signal (“YES” in step S7), the wake-up circuit 2 outputs a switch change signal to the changeover switch 10, and the antenna 9 and the main circuit 3 Are connected via the change-over switch 10 and a power-on signal is output to the power switch 11 to start the operation of the main circuit 3 by starting the supply of operating power from the battery 12 to the main circuit 3 ( Step S8) (see “t2” in FIG. 3).

  Next, the wake-up circuit 2 determines whether or not the main circuit 3 and the roadside machine have normally ended wireless communication (step S9), and determines whether or not a specified time has elapsed (step S10). Then, the wake-up circuit 2 detects that the main circuit 3 and the roadside machine have completed the wireless communication normally (“YES” in step S9), or that the specified time has passed in the no-communication state. Is detected ("YES" in step S10), a switch change signal is output to the change switch 10, the antenna 9 and the wake-up circuit 2 are connected via the change switch 10, and a power OFF signal is sent to the power switch 11. The operation of the main circuit 3 is terminated by terminating the supply of the operating power from the battery 12 to the main circuit 3 (step S12).

  Then, the wake-up circuit 2 starts the intermittent operation simultaneously with the end of the continuous operation, that is, performs the intermittent operation by switching from the continuous operation to the intermittent operation (step S13), returns to the above-described step S2, and returns to the above-described series of operations. Repeat the process. In addition, when the wake-up circuit 2 determines that the vibration level input from the vibration sensor 7 is equal to or higher than the determination level and detects vehicle vibration ("YES" in step S4), the wake-up circuit 2 also performs intermittent operation in this case. At the same time, the continuous operation is started, that is, the intermittent operation is switched to the continuous operation to perform the continuous operation, and thereafter, the above-described series of processing is executed.

  As described above, according to the present embodiment, in the radio wave module 1, the pulse time width of the signal received from the outside during the intermittent operation of the wake-up circuit 2 becomes the pulse time width of the burst of the pilot signal from the roadside device. When it is detected that it corresponds, or when it is detected that the pulse period of the signal received from the outside corresponds to the pulse period of the burst of the pilot signal from the roadside device, the wake-up circuit 2 switches from intermittent operation to continuous operation. Since it is configured to perform continuous operation, it is possible to appropriately realize low power consumption of the wakeup circuit 2, unlike the conventional one in which the wakeup circuit 2 is always activated.

  In addition, since the intermittent operation is switched to the continuous operation at the timing of receiving the pilot signal from the roadside machine and the continuous operation is performed, the wake-up circuit 3 can subsequently start the main circuit 3 at an appropriate timing. The circuit 3 can perform wireless communication normally. In addition, by appropriately realizing the low power consumption of the wakeup circuit 2 as described above, if the battery 12 is used as the power source as in the present embodiment, the battery can be downsized. Accordingly, the entire module 1 can be reduced in size.

  Further, even when the vibration sensor 7 detects the vibration of the vehicle while the wake-up circuit 2 is intermittently operated, it is necessary to start the main circuit 3 because the operation is switched from the intermittent operation to the continuous operation. By preparing a structure (for example, a step on the road surface) in which the vibration sensor 7 can detect vibration in advance in a certain communication area (for example, an entrance of a toll gate), for example, the moving speed is high. Therefore, even if it passes through the communication area that should originally communicate, the wake-up circuit 2 switches from intermittent operation to continuous operation at the timing when the vibration sensor 7 detects vibration, so that the continuous operation is performed. Thereafter, the wakeup circuit 2 can start the main circuit 3 at an appropriate timing.

  Further, it is detected that the pulse time width of the signal received from the outside during continuous operation of the wake-up circuit corresponds to the pulse time width of the burst of the pilot signal from the roadside device, and the pulse period of the signal received from the outside is the roadside Since it is configured to start the operation of the main circuit 3 when it is detected that it corresponds to the pulse period of the pilot signal burst from the aircraft, at an appropriate timing that is likely to enter the communication area from now on. The main circuit 3 can be activated.

Furthermore, the wake-up circuit 2 operates using the low frequency clock as an operation clock,
Since the main circuit 3 is configured to operate using the high-frequency clock as an operation clock, the wake-up circuit 2 can realize lower power consumption, and the main circuit 3 can realize high-speed processing. Both low power consumption and high-speed processing can be achieved.

The present invention is not limited to the above-described embodiment, and can be modified or expanded as follows.
In the wake-up circuit, only one of the circuit that judges the pulse time width of the signal received from the outside and the circuit that judges the pulse period of the signal received from the outside is operated during the intermittent operation. The configuration may be such that both circuits are operated after switching to, and if so configured, the power consumption of the wake-up circuit can be further reduced.
When determining the pulse period, the configuration is not limited to the determination at the rising timing of the signal, but may be determined at the falling timing of the signal, or may be determined at both.

  When the vibration sensor has a certain length of structure that can detect vibration, and the vibration level input from the vibration sensor is equal to or higher than the judgment level for a specified time, the wake-up circuit will start from intermittent operation. It may be configured to perform continuous operation by switching to continuous operation, and in that case, for example, temporary wake-up circuit caused by temporary vibration caused by engine start or temporary vibration caused by gravel or falling objects However, it is possible to prevent the continuous operation from being switched from the intermittent operation to the continuous operation unnecessarily.

Functional block diagram showing an embodiment of the present invention flowchart The figure which shows the operation | movement aspect of a wakeup circuit and a main circuit The figure which shows the detection signal and output signal of the wakeup detection circuit in a weak electric field The figure which shows the detection signal and output signal of the wakeup detection circuit in a strong electric field

Explanation of symbols

  In the drawing, 1 is a radio wave module, 2 is a wake-up circuit, 3 is a main circuit, and 7 is vibration detection means.

Claims (5)

Wake-up circuit that selectively performs either intermittent operation for intermittently monitoring the pilot signal from the roadside unit or continuous operation for continuously monitoring the pilot signal from the roadside unit using the power supplied from the power supply as the operating power A radio wave module configured to be able to start and stop the operation of the main circuit during continuous operation of the wake-up circuit,
The wake-up circuit detects that the pulse time width of the signal received from the outside during the intermittent operation corresponds to the pulse time width of the burst of the pilot signal from the roadside device, or the pulse period of the signal received from the outside is A radio wave module that performs continuous operation by switching from intermittent operation to continuous operation when it is detected that the pulse period corresponds to a pulse period of a pilot signal from a roadside device. In the radio wave module according to claim 1,
Equipped with vibration detection means for detecting vibration,
The radio wave module according to claim 1, wherein the wake-up circuit performs continuous operation by switching from intermittent operation to continuous operation even when the vibration detection means detects vibration during intermittent operation. In the radio wave module according to claim 1 or 2,
The wake-up circuit detects that the pulse time width of the signal received from the outside during continuous operation corresponds to the pulse time width of the burst of the pilot signal from the roadside device, and the pulse period of the signal received from the outside is the roadside A radio wave module characterized in that the operation of the main circuit is started when it is detected that it corresponds to a pulse period of a pilot signal burst from the aircraft. In the radio wave module according to any one of claims 1 to 3,
The wake-up circuit operates only one of a circuit for determining a pulse time width of a signal received from outside and a circuit for determining a pulse period of a signal received from outside during intermittent operation. . In the radio wave module according to any one of claims 1 to 4,
The wake-up circuit includes a determination level for determining whether a pulse time width of a signal received from the outside corresponds to a pulse time width of a burst of a pilot signal from a roadside device, and a pulse period of the signal received from the outside A radio wave module characterized in that a determination level for determining whether or not corresponds to a pulse period of a burst of pilot signals from a roadside device is set low for a weak electric field and high for a strong electric field.

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