JP3430590B2 - Communication device and flow measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for an automatic meter reading system for measuring an integrated value of the amount of gas, water, electricity, etc. used by a gas meter, a water meter, an electric power meter or the like and remotely sucking the integrated value. The present invention relates to a communication device and a flow rate measuring device capable of performing the above.

[0002]

2. Description of the Related Art In recent years, an automatic meter reading system has been introduced in which meter reading values of a gas meter or a water meter are metered using a telephone line. Further, in such an automatic meter reading system, attempts have been made to use wireless for data transmission between a meter and a telephone line. Since a communication device using wireless is expected to operate for 10 years on a battery, an intermittent operation method can be considered. FIG. 2 shows a block diagram of a wireless automatic meter reading system. In FIG. 2, 1 is a gas pipe, 2 is a gas meter, 3 is storage means, 4 is a communication device, 5 and 6 are antennas, 7 is a communication device, and 8 is an interface device for connecting to a telephone line.
NCU (TERMINAL-NETWORK CONT
(OROL UNIT), 9 is a telephone line. The gas flow rate flowing through the gas pipe 1 is detected by the gas meter 2, and the integrated value of the gas flow rate is stored in the storage means 3. The stored integrated value is periodically transmitted to the T-NCU 8 via the communication device 4 and the communication device 7. The transmitted integrated value is transmitted through the telephone line 9 by the operation of the T-NCU 8 to the automatic reading management center (see FIG. 2).
(Not shown). In some cases, the T-NCU 8, the communication device 7,
In some cases, the storage means 3 is activated via the communication device 4 and the integrated value is transmitted to the management center.

FIG. 3 shows the conventional communication devices 4 and 7 shown in FIG.
3 is a block diagram showing the configuration of FIG. In FIG. 3, 10 is a receiving means, 11 is a transmitting means, 12 is a frequency control means, 13
Is a reference frequency generating means, 14 is a frequency error detecting means, 1
Reference numeral 5 is a determination means, 16 is a carrier sense means, 17 is a timer means, and 18 is a power supply control means. The radio wave used is, for example, a low power radio wave in the 400 MHz band, with a channel interval of 12.5 kHz and a frequency shift of 2.4 kHz. The timer means 17 produces an output, for example, every 30 seconds. Power source means 1 by a signal from the timer means 17 every 30 seconds
8 is activated and power is supplied to the circuits except the transmitting means 11. The frequency control means 12 is a so-called face locked loop circuit composed of a voltage controlled oscillator, a frequency divider for dividing the oscillation frequency of the voltage controlled oscillator, and a phase comparator.
The phase of the reference frequency signal from the reference frequency generating means 13 is compared with the phase of the signal from the frequency divider, and the oscillation frequency of the voltage controlled oscillator is controlled by the phase error signal. The oscillation frequency of the voltage controlled oscillator can be selected as an integral multiple of the reference frequency by selecting the frequency division ratio of the frequency divider. A carrier having a frequency corresponding to the frequency selected by the frequency controller 12 is selectively received by the receiver 10. The frequency error detection means 14 detects an error between the frequency oscillated by the frequency control means 12 and the frequency which is an integral multiple of the reference frequency of the reference frequency generation means 13. The judging means 15 judges whether or not the frequency error is within a certain range. That is, when the power supply control means 18 is activated and the circuit starts operating, control data for selecting a frequency is input to the frequency control means 12 from a microcomputer (not shown in FIG. 1). For example, when 400 MHz is selected, the frequency generated by the frequency control means 12 is controlled to be 400 MHz. However, it is not controlled to 400MHz immediately, but gradually approaches 400MHz in an analog manner. Then, for example, when the frequency is in the range of ± 1 kHz with respect to 400 MHz, an output is generated from the judging means 15. Then carrier sense means 1
6 is activated and it is detected whether or not there is a carrier wave of a frequency to be received. When the carrier wave of the frequency to be received exists, the power supply control means 18 is held in the ON state and the receiving means 10 starts receiving the signal. On the other hand, when there is no carrier wave, the power supply control means 18 is turned off to cut off the power supply. Then, after the next 30 seconds, the power supply control means 18 is activated again.
In this way, the receiving operation is performed intermittently, and the average current consumption is reduced by checking whether or not there is a carrier signal from the communication partner.

[0004]

However, in the above-mentioned conventional configuration, when the determination of the frequency error by the determination means 15 is set to, for example, ± 3 kHz, the power supply control means 18 is activated until the carrier sense means 16 is activated. However, if the frequency error is ± 3 kHz, there is a problem that the signal demodulation does not work well, and the determination means 15 is generally used.
The frequency error judgment at is set to a narrow value of ± 1 kHz or less. Therefore, it takes a long time until the carrier sensing means 16 is activated, and power is supplied to the circuit for an unnecessarily long time, which increases the average current consumption and accelerates battery consumption.

The present invention is intended to solve the above-mentioned problems, and shortens the time from the start of the power supply to the carrier sensing to prolong the life of the battery, and when the carrier signal is caught, the data can be accurately demodulated. An object of the present invention is to provide a communication device that can be used and a flow rate measuring device that uses the communication device.

[0006]

In order to solve the above-mentioned problems, a communication apparatus of the present invention comprises a timer means for outputting a signal at a certain time interval, and a power source control for starting the supply of power by the signal from the timer means. Means, reference frequency generation means, frequency control means for selecting the frequency of the carrier wave to be received based on the reference frequency from the reference frequency generation means, the frequency controlled by the frequency control means and the reference frequency A frequency error detecting means for detecting an error of the calculated reception frequency, a determining means for determining and outputting a frequency error less than a certain frequency error based on the error signal of the frequency error detecting means, and an output from the determining means. The presence or absence of the carrier signal selected by the frequency control means is detected for a certain time after occurrence, and when the carrier cannot be detected, the power supply control means is controlled. A carrier sense unit configured to cut off the supply of power, upon detection of a carrier wave by the carrier sense unit consists of a control means for controlling the determining means so as to narrow the determination width of the frequency error at the determination unit.

The flow rate measuring device of the present invention comprises a flow meter,
The communication device includes a communication device that transmits the flow rate data collected by the flowmeter, the communication device includes a timer unit that outputs a signal at a certain time interval, and a power supply control unit that starts supply of power according to a signal from the timer unit. A reference frequency generating means, a frequency control means for selecting a frequency of a carrier wave to be received based on the reference frequency from the reference frequency generating means, a frequency controlled by the frequency control means and the reference frequency. Frequency error detection means for detecting an error in the received frequency, determination means for determining and outputting a frequency error less than a certain frequency error based on the error signal of the frequency error detection means, and output from the determination means. For a certain time, the presence or absence of the carrier wave signal selected by the frequency control means is detected, and when the carrier wave cannot be detected, the power supply control means is controlled. A carrier sense unit configured to cut off the supply source, upon detection of a carrier wave by the carrier sense means is a configuration in which a control means for controlling the determining means so as to narrow the determination width of the frequency error at the determination unit.

[0008]

According to the present invention, since the judgment standard of the frequency error can be controlled to be switched in two steps by the above configuration, the frequency error is set wide until the carrier sense and the operation time until the carrier sense is shortened to prevent the consumption of the battery. When a carrier signal is detected as a result of carrier sensing, the frequency error determination criterion can be set narrower so as not to affect the demodulation, so that accurate data demodulation can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A block diagram of an embodiment of a communication device according to the present invention will be described with reference to FIG. In FIG. 1, the same functional blocks as in the conventional example are given the same numbers. 10 is a receiving means, 11 is a transmitting means, 12 is a frequency control means, 13
Is a reference frequency generating means, 14 is a frequency error detecting means, 1
Reference numeral 5 is a determination means, 16 is a carrier sense means, 17 is a timer means, 18 is a power supply control means, and 19 is a control means. The radio wave used is, for example, a low power radio wave in the 400 MHz band, with a channel interval of 12.5 kHz and a frequency shift of 2.4 kHz. The difference between the configuration of FIG. 1 and the conventional example is that the determination reference of the frequency error in the determination means 15 can be switched by a signal from the control means 19. The operation of FIG. 1 will be described below.

The timer means 17 generates an output, for example, every 30 seconds, as in the conventional example. The power supply control means 18 is activated by a signal from the timer means 17 every 30 seconds, and power is supplied to the circuits except the transmission means 11. The frequency control means 12 is a so-called face locked loop circuit composed of a voltage controlled oscillator, a frequency divider for dividing the oscillation frequency of the voltage controlled oscillator, and a phase comparator. The phase of the reference frequency signal from the reference frequency generating means 13 is compared with the phase of the signal from the frequency divider, and the oscillation frequency of the voltage controlled oscillator is controlled by the phase error signal. The oscillation frequency of the voltage controlled oscillator can be selected as an integral multiple of the reference frequency by selecting the frequency division ratio of the frequency divider. A carrier having a frequency corresponding to the frequency selected by the frequency control means 12 is received by the receiving means 10.
It is selectively received by. In the frequency error detection means 14, the frequency oscillated by the frequency control means 12 and the reference frequency generation means 1
An error of a frequency that is an integral multiple of the reference frequency of 3 is detected. The judging means 15 judges whether or not the frequency error is within a certain range. That is, when the power supply control means 18 is activated and the circuit starts operating, control data for selecting a frequency is input to the frequency control means 12 from a microcomputer (not shown in FIG. 1). For example, if 400 MHz is selected, the frequency generated by the frequency control means 12 is 400
It is controlled to become MHz. However, it is not controlled immediately to 400MHz, but gradually becomes 400MHz in an analog manner.
Approaching. Then, for example, when the frequency is in the range of ± 3 kHz with respect to 400 MHz, an output is generated from the judging means 15. Then, the carrier sense means 16 is activated and it is detected whether or not there is a carrier of a frequency to be received. Normally, the receiving bandwidth of the receiving means 10 is approximately ± 5 kHz, and if the frequency error is within ± 3 kHz, there will be no hindrance in the operation of carrier sensing. When there is no carrier wave, the power supply control means 18 is turned off to cut off the power supply. Then, after the next 30 seconds, the power supply control means 18 is activated again. On the other hand, if there is a carrier wave of the frequency to be received, the power supply control means 1
8 is maintained in the ON state, and the control means 19 is operated to switch the determination standard of the frequency error of the determination means 15 so as to narrow within ± 1 kHz. When the frequency error falls within the set frequency error range again, the receiving means 10 starts demodulating the data.

The flow rate measuring device of the present invention can be constructed by applying the communication device of FIG. 1 to the communication device of FIG.

[0012]

As described above, according to the communication device of the present invention, by broadening the frequency error determination criterion at first, the time until carrier sensing at the time of intermittent operation can be shortened. Is effective. When a carrier signal is received by the carrier sense function, the frequency error judgment criterion is reset to a narrow range, and after confirming that the frequency error is within the newly set narrow range, demodulation of data is started and accurate data There is an effect that demodulation can be performed.

Further, by applying the communication device of FIG. 1 to the flow rate measuring device of the present invention, an automatic meter reading system capable of operating with a lithium battery for 10 years without deteriorating the reliability of important data in the automatic meter reading system. There is an effect that can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a communication device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an automatic meter-reading system using the flow rate measuring device of the present invention.

FIG. 3 is a block diagram of a conventional communication device.

[Explanation of symbols]

2 gas meters 4 Communication device 7 Communication device 8 T-NCU 12 Frequency control means 13 Reference frequency generating means 14 Frequency error detection means 15 Judgment means 16 Carrier sense means 17 Timer means 18 power supply means 19 Control means

Front page continuation (72) Inventor Masahiro Yamamoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-5-207174 (JP, A) JP-A-60-182234 (JP) , A) JP-A-5-145414 (JP, A) JP-A-3-201198 (JP, A) JP-A-5-284098 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) H04M 11/00-11/10

Claims (2)

(57) [Claims] 1. A timer means for outputting a signal at a certain time interval, a power source control means for starting power supply by a signal from the timer means, a reference frequency generating means, and a reference frequency from the reference frequency generating means. Frequency control means for selecting the frequency of the carrier wave to be received based on, frequency error detection means for detecting the error between the frequency controlled by the frequency control means and the reference frequency, and the frequency Based on the error signal of the error detecting means, a judging means for judging and outputting that the frequency error is equal to or less than a certain frequency error, and a presence or absence of a carrier signal selected by the frequency controlling means for a certain time after an output is generated from the judging means. Carrier sense means for controlling the power supply control means to shut off the power supply when the carrier wave cannot be detected. In the determination means it said is constituted by a control means for controlling the determining means communication device so as to narrow the determination width of the frequency error at the time of detecting the carrier. 2. A flow meter and a communication device for transmitting flow rate data collected by the flow meter, wherein the communication device outputs a signal at a certain time interval, and a power supply by a signal from the timer means. Is controlled by the frequency control means, the frequency control means for starting the supply of the power source, the reference frequency generation means, the frequency control means for selecting the frequency of the carrier wave to be received based on the reference frequency from the reference frequency generation means. Frequency error detecting means for detecting an error between the received frequency calculated from the frequency and the reference frequency, and a determining means for determining and outputting a frequency error equal to or less than a certain frequency error based on the error signal of the frequency error detecting means. , When the presence or absence of the carrier signal selected by the frequency control means is detected for a certain time after the output from the determination means and the carrier wave cannot be detected, Carrier sense means for controlling the power source control means to cut off the supply of power, and control for controlling the judging means so as to narrow the judgment width of the frequency error in the judging means when the carrier sense means detects the carrier wave. And a flow rate measuring device.