JP3288161B2 - Wireless system for automatic meter reading - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic meter reading system for collecting data such as gas, water, and electricity usage from a terminal device to a center device using a telephone line. The present invention relates to a wireless system for automatic meter reading that is partially wireless so that devices can be connected via a wireless line.

[0002]

2. Description of the Related Art An automatic meter reading radio system of this type calls a terminal network controller by a no-ringing communication method from a center device via a telephone line, and further calls the terminal device from the terminal network controller via a radio line. And collects data from the terminal device via the reverse route in the center device, or calls a terminal network control device via a wireless line from the terminal device in response to a call request from the terminal device, The center device is called from the terminal network control device via a telephone line, and data from the terminal device is collected in the center device.

In such a wireless system for automatic meter reading,
A wireless device is connected to each of the terminal device and the terminal network control device, so that the terminal device and the terminal network control device communicate with each other via a wireless line using the respective wireless device. More specifically, a master unit of a wireless device (hereinafter, referred to as a master wireless device) that is a network control wireless device is connected to a terminal network control device connected to a telephone line,
The terminal device is connected to a slave unit of a wireless device that is a terminal wireless device (hereinafter, referred to as a child wireless device), and the terminal network control device and the terminal device wirelessly communicate via a parent wireless device and a child wireless device, respectively. Perform communication.

As described above, in the wireless system for automatic meter reading using a wireless line, it is difficult to use a commercial power supply of 100 V AC as an operating power supply for the parent wireless device and the child wireless device due to its installation conditions and the like. Is a necessary condition.

[0005] As described above, the communication method of the automatic meter reading wireless system using the battery-operated parent wireless device and the child wireless device includes a method of using both the parent wireless device and the child wireless device in order to minimize battery consumption. Built-in clock synchronized with
Only when a predetermined wireless communication time has come, the wireless device is activated to perform wireless communication between the two wireless devices, thereby reducing battery consumption.

In such a method, in performing wireless communication, it is premised that the clocks incorporated in the master wireless device and the slave wireless device are completely the same, but the respective clocks are independent. Therefore, when used for a long time, a time lag occurs, and a means for correcting this time lag is required. As a method of correcting such a time lag, for example, a method of performing wireless communication for clock synchronization of a master wireless device and a slave wireless device at a rate of about once a day has been conventionally considered.

[0007] Such clock synchronization communication between the parent wireless device and the child wireless device is indispensable in performing battery-driven wireless communication. If the clock synchronization cannot be performed, the time lag increases. As a result, there is a possibility that wireless communication cannot be performed. Therefore, it is the point of the automatic meter reading wireless system that this time synchronization synchronization communication is reliably performed.

[0008]

As described above, in a wireless system for automatic meter reading, it is important to reliably perform clock synchronization between a master wireless device and a slave wireless device. If alignment can be performed normally,
The clocks of both wireless devices can be synchronized and matched, but if a communication error occurs in such clock synchronization communication, the time lag between the parent wireless device and the child wireless device increases, As a result, there is a problem that wireless communication cannot be performed between the two.

[0009] The present invention has been made in view of the above,
The purpose is to correct even if a communication error occurs in the wireless communication between the two wireless devices and the clock between the two wireless devices drifts, and to properly perform the wireless communication between the two wireless devices. An object of the present invention is to provide a wireless system for automatic meter reading that can be performed.

[0010]

In order to achieve the above object, a wireless system for automatic meter reading according to the present invention connects a center device to a terminal network control device via a telephone line, and connects the center device to the terminal network control device. A wireless communication is performed between the connected network control wireless device and the terminal wireless device connected to the terminal device, data is collected from the terminal device to the center device, and the network control wireless device and the terminal wireless device are collected. The wireless communication for data collection and the synchronization wireless communication for the clock circuit are performed at a predetermined time based on the clock circuits synchronized with each other, respectively, between the network control wireless device and the terminal wireless device. In the wireless communication between the network control wireless device and the terminal wireless device, the transmitting wireless device transmits a transmission carrier a predetermined number of times, and the receiving wireless device transmits the transmission carrier. Is detected by an intermittent carrier sense operation, wherein the number of reception errors that cannot be received at the reception time of the wireless communication between the network control wireless device and the terminal wireless device is counted. Means for counting the number of times a reception error occurs
The number of occurrences of the reception error counted by the number counting means
The next time the carrier sense operation is performed in proportion to the
The gist of the present invention is to have a carrier sense operation increasing means to be executed before and after the transmission time .

Further, in the radio system for automatic meter reading according to the present invention, the carrier sense operation interval which is increased immediately after the first occurrence of the reception error and the carrier sense operation interval which is increased when the second or subsequent reception error occurs are set to different times. The point is that the carrier sense operation increasing means has a carrier sense operation interval changing means which is set to.

Further, the wireless system for automatic meter reading according to the present invention is characterized in that a wireless communication system between the network control wireless device and the terminal wireless device is provided.
At the time of the wireless communication, the reception error occurrence number counting means has a reception error occurrence number transmission means for transmitting the reception error occurrence number to the transmission side wireless device, and the transmission side wireless device transmits the reception error occurrence number A transmission frequency changing means for changing the transmission frequency of the transmission carrier based on the reception error frequency transmitted by the means.

[0013]

Automatic meter reading radio system the present invention, it counts the received number of errors that could not be received by the receiving time of the radio communication between the network control wireless device and the terminal for a wireless device, a total of
The number of caches that is proportional to the number
The rear sense operation is executed before and after the next reception time.
Let

In the wireless metering system according to the present invention, the carrier sense operation interval that is increased immediately after the first occurrence of a reception error and the carrier sense operation interval that is increased when a second or later reception error occurs are set to different times. Set to.

Further, in the wireless system for automatic meter reading according to the present invention, the number of times of occurrence of a reception error is transmitted to the wireless device on the transmitting side.
The transmitting-side wireless device changes the number of times of transmission of the transmission carrier based on the number of occurrences of the reception error.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a wireless system for automatic meter reading according to a first embodiment of the present invention. The wireless system for automatic meter reading shown in FIG. 1 is installed in, for example, a general home, and collects meter reading data from a meter 29 which is a terminal device for metering usage of gas, water, electricity, etc., in a center device 21. The meter 29 is connected to the child wireless device 28, connected to the parent wireless device 27 via a wireless line from the child wireless device 28, and connected to the terminal network control device (T-NCU) 26 from the parent wireless device 27. It is connected to the exchange 24 through the switch. The center device 21 is connected to the exchange 24 via a network controller for center (C-NCU) 22 or a network controller for automatic incoming call (MA-NCU) 23. Switch 24 has no ringing trunk 2
5 is connected.

In the above configuration, when the center device 21 attempts to collect meter reading data from the meter 29, the center device 21 sends the data via the center network controller 22, the exchange 24, and the no-ringing trunk 25. When no ringing is received by the terminal network controller 26 and the terminal network controller 26 requests the parent wireless device 27 for meter reading data, the parent wireless device 27 sends the meter reading data to the meter 29 via the child wireless device 28. A request is made, and the meter reading data from the meter 29 is transmitted along the reverse route.
Will be collected.

When collecting data or transmitting information to the center device 21 by calling a terminal from the meter 29, when the meter 29 makes a call request to the child radio device 28, the child radio device 28 The wireless device 27 is called, and the terminal network control device 26, the exchange 24,
An incoming call arrives at the center device 21 via the automatic incoming call network control device 23, whereby meter reading data or information from the meter 29 can be transmitted to the center device 21.

FIG. 2 is a block diagram showing a detailed internal configuration of the parent wireless device 27 and the child wireless device 28 shown in FIG. Note that the parent wireless device 27 and the child wireless device 28 are
Have the same circuit configuration as shown in FIG.

As shown in FIG. 2, the master radio apparatus 27 and the slave radio apparatus 28 have an antenna 11 for a radio, and the antenna 11 is connected via a radio section (RF) circuit 12 to a modem (modem). 13 is connected. Modulation / demodulation circuit 13
Is supplied with transmission data from the CPU 14 and supplies received data to the CPU 14. The clock circuit 17 and the interface circuit 20 are connected to the CPU 14. Further, a battery 16 as an operation power supply of the wireless device is provided.
Is directly connected to the CPU 14,
The modem 14 is connected to the modulation / demodulation circuit 13 via a power switch 15 so that the CPU 14 controls the supply of the operating voltage from the battery 16 to the radio section circuit 12 and the modulation / demodulation circuit 13.

The radio section circuit 12 is, for example, 400 MHz.
This circuit performs FM modulation and demodulation in the z radio frequency band.
Further, the radio unit circuit 12 has a built-in carrier sense circuit in its receiving unit for detecting the presence or absence of transmission from the partner radio device.

The modulation / demodulation circuit 13 modulates a digital signal from the CPU 14 into an analog signal in an audio band (300 Hz to 3.4 kHz band) such as, for example, a binary FSK signal or an MSK signal, or performs the reverse demodulation. .

The clock circuit 17 is a circuit for performing time management and time measurement of the wireless device. For example, the clock circuit 17 has a time until the next wireless communication between the master wireless device 27 and the slave wireless device 28 is started. At this time, a start signal is output from the clock circuit 17 to the CPU 14, and after the start, the time is counted by the control of the CPU 14.

The interface circuit 20 includes the parent wireless device 2
7 is an interface circuit for connecting to the terminal network control device 26, and the slave radio device 28 is an interface circuit for connecting to the meter 29. For example, level conversion of the data signal from the processor 29 is performed.

Further, the CPU 14 has a function of constantly stopping its operation and starting its operation in response to a start signal from the clock circuit 17, and also receives a signal from the meter 29 or the terminal network controller 26 through the interface circuit 20. When a message is received, it also has a function of starting operation and temporarily storing the message, and a function of counting the number of times a reception error has occurred during wireless communication and storing the information.

FIGS. 3 and 4 are diagrams showing a wireless communication procedure between the parent wireless device 27 and the child wireless device 28.

As shown in FIG. 3, the master wireless device 27 transmits data to the slave wireless device 28 at a predetermined communication cycle T, and performs a two-way communication in which the slave wireless device 28 returns a response thereto. In addition to the above-described two-way communication, the parent wireless device 27 performs clock synchronization from the parent wireless device 27 to the child wireless device 28, for example, about once a day, as shown in FIG. Communication for preventing the clock error from increasing.

In any of the communications shown in FIGS. 3 and 4, in order to ensure that the wireless communication from the transmitting side is detected on the receiving side, the transmission time on the transmitting side and the carrier on the receiving side as shown in FIG. What is necessary is just to set the sense timing.

That is, in the wireless system for automatic meter reading,
When using the specified low power radio you do not need a radio station license (hereinafter transmission output 10 mW) as a wireless type, transmission time T ₁ and the transmission suspension time length T ₂ to the time limit of the wireless device is provided by the legal regulations. For example, in the case of small power security standards (RCR STDD-30), the transmission time T ₁ is less than 3 seconds, the transmission suspension time T ₂ is defined as more than 2 seconds.

Therefore, the transmission suspension time T ₂ is equal to the transmission time T ₁
Is larger than (T ₂ <T ₁ ),
As shown in FIG. 5, when the transmitting side continuously repeats “transmission → pause → transmission →...”, The carrier sense period T ₃ on the receiving side is changed to the transmission pause time T ₂ <carrier sense period T ₃ < A transmission carrier can be detected by setting the transmission time as T ₁ and performing the carrier sense twice on the receiving side.

FIG. 6 is an explanatory diagram showing the worst combination of clock errors when it is assumed that the clock in the wireless device generates an error of "± ΔT" during the wireless communication period T as described above.

As shown in FIG. 6, when the clock in the radio apparatus has an error of ± ΔT within the radio communication cycle T, the worst combination of the clock error causes the transmission side to change the clock before and after the transmission time. If transmission is performed during ± 2ΔT ”, the reception side can receive.

However, this is the case where the receiving side can surely receive the data by wireless communication every time. If a receiving error occurs, the clock error at the next communication is changed from “± ΔT” to “± ΔT”. ± 2ΔT ”. Then, each time a reception error occurs continuously, the clock error becomes “± 2ΔT” and “± 2ΔT”.
3ΔT ”,..., And if the transmission time on the transmitting side is fixed at“ ± 2ΔT (4ΔT) ”, wireless communication may not be performed.

According to the present invention, as described above, even when a reception error occurs and a clock error increases due to the reception error, this can be properly corrected and the wireless communication between the two wireless devices can be performed properly. This is specifically described below.

The operation of the first embodiment of the present invention will be described with reference to the operation explanatory diagram shown in FIG.

First, as shown in FIG. 6, a clock in the radio apparatus generates an error of “± ΔT” during the communication cycle T, and the transmitting side performs transmission for “± 2ΔT” before and after the transmission time. Think about the case.

Under these preconditions, FIG.
FIG. 4 is an operation explanatory diagram when a communication error (NG) occurs once.

As shown in FIG. 7A, when the communication error is 1
If this occurs twice, the clock error in the wireless device expands to a maximum of “± 2ΔT” at the next communication.

In this state, transmission of "± 2ΔT (4ΔT)" is performed from the transmission side as in the conventional case, and FIG.
When the carrier sense operation shown in FIG. 5 is performed once on the receiving side as indicated by the bold arrow, normal reception cannot be performed at the worst combination of clock errors between the parent wireless device and the child wireless device. .

Therefore, when a carrier sense operation is added before and after “± 2ΔT” before and after the reception time as shown by the broken arrow in FIG. 7A, the worst clock error of the parent wireless device and the child wireless device can be obtained. Even when combined, it becomes possible to receive.

FIG. 7B is a diagram for explaining the operation when a communication error (NG) occurs twice consecutively.

As described above, when a communication error occurs twice in succession, as in the case where one communication error occurs, FIG.
In the worst combination of the clock error between the parent wireless device and the child wireless device, it is not possible to normally receive data by performing the carrier sense operation only three times as indicated by the bold arrow in (b). Before and after the operation, reception can be performed by adding a carrier sense operation at a timing of “± 2ΔT” as shown by a broken arrow in FIG. 7B.

As described above, every time a continuous communication error increases, reception can be performed in any case by adding a carrier sense operation at ± 2ΔT before and after.

FIG. 8 is an operation explanatory view showing the operation of the second embodiment of the present invention. FIG. 8A shows a communication error (NG).
FIG. 8B shows a case where a communication error has occurred twice, and FIG. 8B shows a case where a communication error has occurred twice.

In the case of the first embodiment shown in FIG. 7, the addition of the carrier sense operation in the first and second communication errors is performed at the same time interval of ± 2ΔT. In the second embodiment, as shown in the figure, in the case of the first communication error, the time interval is set to ± 3ΔT,
The time interval is set to a different value, such as setting the time interval after the second time to ± 2ΔT. Even if the time interval is set to such a different value, the same effect can be obtained. it can.

FIG. 9 is an operation explanatory diagram showing the operation of the third embodiment of the present invention.

While the first and second embodiments correct the synchronization deviation on the receiving side, the third embodiment is designed to further improve the reliability of wireless communication. In order to take countermeasures, the number of transmissions on the transmission side is increased according to a communication error occurrence situation.

That is, as shown in FIG. 9A, one-way communication for clock synchronization is performed from the parent wireless device,
In this communication, by performing the process of changing the number of carrier sense operations according to the communication error by the method shown in the first and second embodiments described above, the clock error between the parent wireless device and the child wireless device is prevented from increasing. At the same time, the number of continuous occurrences of communication errors in the one-way clock synchronization communication is counted by the slave wireless device, and the counted number of continuous communication error occurrences is transmitted to the master wireless device when communicating with the master wireless device.

In the parent wireless device, as shown in FIG. 9 (b), a time synchronous communication / transmission number table storing the number of transmissions with respect to the number of consecutive occurrences of communication errors (NG) is stored in advance as setting data. deep. When the master wireless device receives the communication error continuous occurrence count information received from the child wireless device, the parent wireless device reads the transmission count information corresponding to the communication error continuous occurrence count from the table, and determines the read transmission count for the next and subsequent times. It is determined as the number of transmissions during the clock synchronization communication. That is, the number of transmissions is made variable according to the communication error occurrence situation.

As described above, according to the communication error occurrence situation,
By appropriately increasing the number of transmissions, the reliability of wireless communication can be further improved.

[0052]

As described above, according to the present invention,
The number of reception errors that could not be received at the reception time of the wireless device between the network control wireless device and the terminal wireless device was counted, and the number was proportional to the counted number of reception errors.
Carrier sense operation before and after the next reception time
Since executing, receive error, i.e., a communication error occurs, the carrier sense operation performed accurately, receives the transmission carrier, to correct the time lag in both the wireless device to accurately, between the wireless device Wireless communication can be performed accurately. In this case, the same effect can be obtained even if the carrier sense operation interval that is increased immediately after the first occurrence of the reception error and the carrier sense operation interval that is increased when the second or subsequent reception error occurs are set to different times. be able to.

[0053] Further, according to the present invention, in addition to the above, the network
At the time of wireless communication between the control wireless device and the terminal wireless device
, The reception error occurrence count is transmitted to the transmission-side wireless device,
Since the wireless device on the transmitting side changes the number of transmissions of the transmission carrier based on the number of occurrences of the reception error, the reliability on the transmitting side can be increased, and wireless communication between the two wireless devices can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a wireless system for automatic meter reading according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed internal configuration of a parent wireless device and a child wireless device used in the automatic meter reading wireless system shown in FIG. 1;

FIG. 3 is a diagram showing a wireless communication procedure between a parent wireless device and a child wireless device.

FIG. 4 is a diagram showing a wireless communication procedure between a parent wireless device and a child wireless device.

FIG. 5 is a diagram illustrating a transmission time of a transmitting-side wireless device and a carrier sense timing of a receiving-side wireless device.

FIG. 6 shows that the clock in the wireless device is set to “±” during the wireless communication cycle T.
FIG. 11 is an explanatory diagram showing the worst combination of clock errors when it is assumed that an error of “ΔT” occurs.

FIG. 7 is an operation explanatory diagram showing an operation of the first exemplary embodiment of the present invention.

FIG. 8 is an operation explanatory view showing the operation of the second embodiment of the present invention.

FIG. 9 is an operation explanatory view showing the operation of the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Antenna 12 Radio | wireless circuit 13 Modulation / demodulation circuit 14 CPU 17 Clock circuit 21 Center device 26 Terminal network control device 27 Master radio device 28 Child radio device 29 Meter

──────────────────────────────────────────────────続 き Continuing on the front page (72) Nagano Uno 2-3 Nakase, Mihama-ku, Chiba City, Chiba Prefecture Inside the Information Technology Laboratory, Tokyo Gas Co., Ltd. (72) Hajime Furusawa 2, Nakase, Mihama-ku, Chiba City, Chiba Prefecture -3 Inside the Information Technology Laboratory, Tokyo Gas Co., Ltd. (72) Inventor Jun Fujiwara 2-3, Nakase, Mihama-ku, Chiba City, Chiba Prefecture Inside the Information Technology Laboratory, Tokyo Gas Co., Ltd. (72) Toshihiko Kawai Kawasaki, Kanagawa Prefecture 70 Yanagicho, Sachi-ku Co., Ltd. Toshiba Yanagimachi Plant (72) Inventor Tetsuya Hara 70, Yanagimachi, Sachi-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Yanagimachi Plant (58) Fields investigated (Int.Cl. ⁷ , DB name ) H04Q 9/00

Claims (3)

(57) [Claims] 1. A center device is connected to a terminal network control device via a telephone line, and a network control wireless device connected to the terminal network control device and a terminal wireless device connected to the terminal device are connected. Wireless communication is performed between the terminal devices, data is collected from the terminal device to the center device, and the data is stored at a predetermined time based on the time of a clock circuit that is built in the network control wireless device and the terminal wireless device and is synchronized with each other. Wireless communication for collection and synchronization wireless communication for synchronizing the clock circuit are performed between the network control wireless device and the terminal wireless device, and the wireless communication between the network control wireless device and the terminal wireless device is performed. An automatic meter reading wireless system in which a transmitting carrier is transmitted a predetermined number of times from a transmitting wireless device, and a receiving wireless device detects the transmitting carrier by intermittent carrier sensing operation. A reception error occurrence number counting means for counting the reception number of errors that could not be received by the receiving time of the radio communication between the network control wireless device and a terminal for a wireless device, the receive error
-The reception error count counted by the occurrence count means
The next time carrier sense operation is received in proportion to the number of births
And a carrier sense operation increasing means executed before and after the reception time of the hour . 2. The carrier sense operation increasing means sets a carrier sense operation interval to be increased immediately after the first occurrence of a reception error and a carrier sense operation interval to be increased when a second or subsequent reception error occurs to different times. The wireless system for automatic meter reading according to claim 1, further comprising a carrier sense operation interval changing unit that performs the operation. Wherein the reception error occurrence number counting means, before
The wireless communication between the network control wireless device and the terminal wireless device;
During communication, the apparatus further includes a reception error occurrence number transmission unit that transmits the reception error occurrence number to the transmission side wireless device, and the transmission side wireless device transmits the reception error occurrence number transmitted by the reception error occurrence number transmission unit. The wireless system for automatic meter reading according to claim 1 or 2, further comprising transmission number changing means for changing the number of transmissions of the transmission carrier based on the number of times.