JP6512958B2 - Communication system, communication apparatus, and communication method - Google Patents

Description

  The present invention relates to a communication system, communication apparatus, and communication method for performing communication via a communication line shared by data communication by a half duplex communication method and voice communication by a full duplex communication method.

  At present, there is known a communication system in which communication is performed via a communication line shared by data communication by a half duplex communication method and voice communication by a full duplex communication method. In such a communication system, for example, data communication using ASK (Amplitude Shift Keying) modulation is adopted, and voice communication using FM (Frequency Modulation) is adopted. In order to prevent interference, a sufficient difference is provided between the three frequencies of the carrier frequency used in ASK modulation and the two carrier frequencies used in FM.

  For example, Patent Document 1 discloses a hot water supply apparatus in which the frequency of a carrier wave used to modulate an operation signal is 200 kHz and the frequency of a carrier wave used to modulate an audio signal is 150 kHz and 250 kHz. Here, the range of usable frequencies may be limited in consideration of the influence of electromagnetic waves on other wireless communication systems. For example, it is strongly required to keep the signal level in the frequency band of 150 kHz or more below the allowable value in consideration of the influence on radio communication systems such as long wave radio, AM (Amplitude Modulation) radio, ship / airline communication etc. There is a case.

JP 2000-283559 A

  However, the hot water supply device disclosed in Patent Document 1 is not designed to meet such a demand. Here, in order to respond to such a demand, for example, a method of bringing the three frequencies described above close to each other within a range not exceeding 150 kHz may be considered. However, in the case of this method, it is actually necessary to consider not only the upper limit of 150 kHz but also the lower limit of about 30 kHz. This lower limit value is a lower limit value to be considered in order to avoid interference between the baseband signal of the data signal or the voice signal and the carrier wave, and is about 10 times the upper limit value (for example, about 3 kHz) of the frequency of the baseband signal. It is a value.

  Here, in the case where the above-described three frequencies are set within a narrow range of 30 kHz to 150 kHz, it is necessary to separate the signal with a reception filter having a high Q value or order. However, adopting a reception filter with a high Q value or order results in an increase in delay time and a decrease in communication speed. Therefore, in a communication system in which communication is performed via a communication line shared by data communication by a half duplex communication method and voice communication by a full duplex communication method, the carrier wave frequency is suppressed to a predetermined upper limit frequency or less. There is a need for a technique to increase the communication speed.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a communication system in which communication is performed via a communication line shared by data communication by half duplex communication method and voice communication by full duplex communication method. An object is to provide a communication system, a communication device, and a communication method, which increase a communication speed while suppressing the frequency to a predetermined upper limit frequency or less.

In order to achieve the above object, the communication system according to the present invention is
A communication system comprising a first communication device and a second communication device that mutually communicate via a communication line shared by data communication by a half duplex communication scheme and voice communication by a full duplex communication system,
The first communication device is
A data signal transmission circuit for transmitting a modulated data signal generated by modulating a carrier wave of a first frequency not higher than a predetermined upper limit frequency with a digital data signal to the second communication apparatus;
A data signal receiving circuit for receiving the modulated data signal transmitted by the second communication device;
An audio signal transmission circuit for transmitting an unmodulated analog audio signal to the second communication device;
A modulated voice signal transmitted by the second communication device and generated by modulating a carrier wave of a second frequency lower than the first frequency and higher than the frequency of the unmodulated analog voice signal with an analog voice signal An audio signal receiving circuit for receiving;
The second communication device is
A data signal transmission circuit that transmits a modulated data signal received by a data signal reception circuit included in the first communication device to the first communication device;
A data signal receiving circuit that receives the modulated data signal transmitted by the data signal transmitting circuit included in the first communication device;
An audio signal transmission circuit for transmitting the modulated audio signal to the first communication device;
And an audio signal receiving circuit for receiving the unmodulated analog audio signal.

  In the present invention, data communication between the first communication device and the second communication device is modulated data generated by modulating a carrier wave of the first frequency, which is equal to or less than a predetermined upper limit frequency, with a digital data signal. A voice communication from the first communication device to the second communication device is realized by a non-modulated analog voice signal, and a voice communication from the second communication device to the first communication device is more than the first frequency. This is realized by a modulated voice signal generated by modulating, with an analog voice signal, a carrier wave of a second frequency lower than the frequency of the low unmodulated analog voice signal. Therefore, according to the present invention, the communication speed can be increased while suppressing the frequency of the carrier wave to a predetermined upper limit frequency or less.

It is a block diagram of the communication system 1000 which concerns on Embodiment 1 of this invention. It is a figure which shows magnitude correlation with a 1st frequency, a 2nd frequency, and a 3rd frequency. It is a figure which shows a conversion table. It is a flowchart which shows the 1st telephone call processing which remote control device 200 concerning Embodiment 1 of the present invention performs. It is a flowchart which shows the 2nd telephone call processing which remote control device 300 concerning Embodiment 1 of the present invention performs. It is a block diagram of the communication system 1100 which concerns on Embodiment 2 of this invention. It is a block diagram of the communication system 1200 which concerns on Embodiment 3 of this invention.

(Embodiment 1)
First, a communication system 1000 according to Embodiment 1 of the present invention will be described with reference to FIG. In the present embodiment, in the communication system 1000, the water heater 100, the remote control device 200, and the remote control device 300 mutually connected via the communication line 401 and the communication line 402 mutually communicate data and voice. It shall be a hot water supply system to carry out.

  Data communication is half duplex communication, and digital communication using ASK (Amplitude Shift Keying) modulation. Data communication is performed between the water heater 100 and the remote control device 200, between the water heater 100 and the remote control device 300, and between the remote control device 200 and the remote control device 300.

  On the other hand, voice communication is full-duplex communication, is analog communication without modulation or analog communication using FM (Frequency Modulation). Voice communication is performed between remote control device 200 and remote control device 300. Here, voice communication from remote control device 200 to remote control device 300 is non-modulated analog communication, and voice communication from remote control device 300 to remote control device 200 is analog communication using FM.

  Hereinafter, the frequency of the carrier wave used for ASK modulation is referred to as a first frequency, the frequency of the carrier wave used for FM is referred to as a second frequency, and the upper limit value of the frequency of the unmodulated analog audio signal is referred to as a third frequency. In the present embodiment, it is assumed that the upper limit value of the frequency usable for communication is 150 kHz, and the upper limit value of the frequency of the non-modulated analog audio signal (upper limit value of the audio frequency) is 3 kHz. Therefore, as described later, the first frequency is 120 kHz, which is lower than 150 kHz, and the second frequency is 30 kHz, which is 10 times 3 kHz.

  The communication system 1000 includes a water heater 100, a remote control device 200, and a remote control device 300. The water heater 100 is an appliance that converts water into hot water and supplies the water and is operated by both the remote control device 200 and the remote control device 300. Remote control device 200 is a device for operating water heater 100. Remote control device 300 is a device for operating water heater 100. Water heater 100, remote control device 200, and remote control device 300 are mutually connected via communication line 401 and communication line 402. The communication line 401 and the communication line 402 have a function as a power supply line supplying power and a function as a communication line for data communication and voice communication. For example, the communication line 401 is a power supply line to which a power supply potential is applied, and the communication line 402 is a ground line to which a ground potential is applied.

  Water heater 100 supplies power to remote control device 200 and remote control device 300 via communication line 401 and communication line 402. The water heater 100 and the remote control device 200 can mutually communicate data via the communication line 401 and the communication line 402. Further, the water heater 100 and the remote control device 300 can mutually communicate data via the communication line 401 and the communication line 402. Remote control device 200 and remote control device 300 can mutually perform data communication and voice communication via communication line 401 and communication line 402.

  Here, the configuration of the water heater 100 will be described. Water heater 100 has a configuration for data communication. Water heater 100 includes filter circuit 101, ASK reception circuit 102, ASK demodulation circuit 103, control unit 104, ASK modulation circuit 105, ASK transmission circuit 106, DC power supply 107, and power supply circuit 108. .

  The filter circuit 101 extracts an ASK signal by removing an unmodulated analog audio signal and an FM signal from the signals supplied from the communication line 401 and the communication line 402, and extracts the extracted ASK signal from the ASK receiving circuit 102. And the ASK transmission circuit 106. The filter circuit 101 also extracts an ASK signal by removing an unmodulated analog audio signal and an FM signal from the signals supplied from the ASK receiving circuit 102 and the ASK transmitting circuit 106, and extracting the extracted ASK signal. Are supplied to the communication line 401 and the communication line 402.

  Here, the ASK signal is a modulated data signal generated by ASK modulating the carrier wave of the first frequency with a digital data signal. The unmodulated analog audio signal is an unmodulated analog audio signal whose upper limit value of frequency is the third frequency. The FM signal is a modulated voice signal generated by frequency modulating the carrier wave of the second frequency with a digital data signal. Note that extracting the ASK signal means extracting the signal component of the first frequency, and removing the signal component of the second frequency and the signal component of the third frequency.

  The filter circuit 101 is, for example, a band pass filter having a first frequency as a center frequency. In addition, the Q value and the order of the filter circuit 101 have a value enough to sufficiently attenuate the signal component of the second frequency and the signal component of the third frequency so as not to affect the reception of the ASK signal by the ASK receiving circuit 102. Set to The filter circuit 101 includes, for example, an LC filter circuit.

  The ASK receiving circuit 102 receives the ASK signal transmitted from the remote control device 200 or the remote control device 300 via the filter circuit 101. The ASK receiving circuit 102 amplifies the ASK signal so that the ASK demodulation circuit 103 can demodulate the ASK signal. The ASK receiving circuit 102 includes, for example, a transistor circuit.

  The ASK demodulation circuit 103 demodulates the ASK signal supplied from the ASK reception circuit 102 to generate a digital data signal. The digital data signal is, for example, at a first level (e.g. 5 V) while the ASK signal has a carrier and at a second level (e.g. 0 V) different from the first level while the ASK signal has no carrier. Is a signal that The digital data signal is, for example, a voltage signal. The ASK demodulation circuit 103 includes, for example, a diode detection circuit and a microcontroller.

  Control unit 104 controls the overall operation of water heater 100. The control unit 104 has a function of performing data communication with the remote control device 200 and the remote control device 300. Specifically, the control unit 104 acquires reception data indicated by the digital data signal supplied from the ASK demodulation circuit 103. Further, the control unit 104 generates a digital data signal indicating transmission data, and supplies the digital data signal to the ASK modulation circuit 105. The transmission data and the reception data are data represented by a combination of the first value and the second value. For example, the first value is "1" and the second value is "0".

  For example, when the received digital data signal maintains a first level (for example, 5 V) during one bit period, the control unit 104 obtains a first value (for example, “1”), When the received digital data signal maintains a second level (e.g., 0 V) for one bit period, a second value (e.g., "0") is obtained. In addition, for example, when the transmission data has a first value (for example, “1”) as the digital data signal to be transmitted, the control unit 104 performs the first level (for example, 5 V) for one bit period. And when the transmission data is a second value (eg, “0”), generate a digital data signal that maintains the second level (eg, 0 V) for one bit period. The control unit 104 includes, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a flash memory, and a real time clock (RTC). The CPU executes a program stored in the ROM while using, for example, the RAM as a temporary storage area.

  The ASK modulation circuit 105 generates an ASK signal by modulating the carrier wave of the first frequency with the digital data signal supplied from the control unit 104. For example, the ASK modulation circuit 105 has a carrier wave while the digital data signal is at a first level (for example, 5 V) and has a carrier wave while the digital data signal is at a second level (for example, 0 V). Generates no ASK signal. The ASK modulation circuit 105 includes, for example, a multiplier or a microcontroller that multiplies a digital data signal by a carrier wave.

  The ASK transmission circuit 106 amplifies the ASK signal supplied from the ASK modulation circuit 105 to the extent that transmission is possible. The ASK transmission circuit 106 includes, for example, a transistor circuit.

  DC power supply 107 supplies DC power for operating water heater 100. The DC power supply 107 also supplies DC power to the remote control device 200 and the remote control device 300 via the power supply circuit 108. The DC power supply 107 includes a bypass capacitor with a large capacity between the power supply terminal and the ground terminal. Due to the influence of the bypass capacitor, the DC power supply 107 has low impedance to the ASK signal, the FM signal, and the unmodulated analog audio signal. Therefore, when the DC power supply 107 is directly connected to the communication line 401 and the communication line 402 without the feed circuit 108, data communication and voice communication using the communication line 401 and the communication line 402 can not be performed. . Therefore, the DC power supply 107 is connected to the communication line 401 and the communication line 402 via the feeding circuit 108.

  The power supply circuit 108 supplies DC power supplied from the DC power supply 107 to the remote control device 200 and the remote control device 300 via the communication line 401 and the communication line 402. The feed circuit 108 is a circuit that raises the impedance to the ASK signal, the FM signal, and the unmodulated analog audio signal. The feed circuit 108 includes, for example, a choke coil.

  Next, the configuration of remote control device 200 will be described. Remote control device 200 has a configuration for data communication and a configuration for voice communication. The configuration for data communication included in remote control device 200 is basically the same as the configuration for data communication included in water heater 100. The configuration for voice communication includes a configuration for transmitting an audio signal to remote control device 300 and a configuration for receiving an audio signal from remote control device 300. Remote control device 200 includes filter circuit 201, ASK reception circuit 202, ASK demodulation circuit 203, control unit 204, ASK modulation circuit 205, ASK transmission circuit 206, power supply circuit 207, power reception circuit 208, and a button. 209, a filter circuit 211, an FM reception circuit 212, an FM demodulation circuit 213, an interphone circuit 214, a level detection circuit 215, an audio signal transmission circuit 216, a filter circuit 217, a microphone 218, a speaker 219 and Equipped with

  The filter circuit 201 extracts an ASK signal by removing an unmodulated analog audio signal and an FM signal from the signals supplied from the communication line 401 and the communication line 402, and extracts the extracted ASK signal with the ASK receiving circuit 202. The signal is supplied to the ASK transmission circuit 206. The filter circuit 201 is, for example, a band pass filter having a first frequency as a center frequency. In addition, the Q value and the order of the filter circuit 201 have a value enough to sufficiently attenuate the signal component of the second frequency and the signal component of the third frequency so as not to affect the reception of the ASK signal by the ASK reception circuit 202. Set to The filter circuit 201 includes, for example, an LC filter circuit.

  The ASK receiving circuit 202 receives the ASK signal transmitted from the water heater 100 or the remote control device 300 via the filter circuit 201. The ASK reception circuit 202 amplifies the ASK signal so that the ASK demodulation circuit 203 can demodulate the ASK signal. The ASK receiving circuit 202 includes, for example, a transistor circuit.

  The ASK demodulation circuit 203 demodulates the ASK signal supplied from the ASK reception circuit 202 to generate a digital data signal. The ASK demodulation circuit 203 demodulates the ASK signal on the assumption that the frequency of the carrier wave of the ASK signal is the first frequency. The ASK demodulation circuit 203 includes, for example, a diode detection circuit and a microcontroller.

  Control unit 204 controls the overall operation of remote control device 200. Control unit 204 has a function of performing data communication with water heater 100 and remote control device 300. The control unit 204 also has a function of performing voice communication with the remote control device 300. Specifically, the control unit 204 controls the interphone circuit 214 to output the analog audio signal supplied from the FM demodulation circuit 213 to the speaker 219. Further, the control unit 204 controls the interphone circuit 214 to supply the audio signal transmission circuit 216 with the analog audio signal supplied from the microphone 218. The analog audio signal is, for example, an analog voltage signal.

  The control unit 204 also executes various processes based on the operation signal supplied from the button 209. The process performed by the control unit 204 is, for example, a process of turning on / off the power of the interphone circuit 214 or a process of performing data communication with the water heater 100 or the remote control device 300.

  Further, the control unit 204 adjusts the gain of the audio signal transmission circuit 216 based on the analog voltage signal supplied from the level detection circuit 215. For example, the control unit 204 specifies the gain corresponding to the signal level indicated by the analog voltage signal among the gains indicated by the conversion table stored in the storage unit 2041 included in the control unit 204, and specifies the specified gain as an audio signal. The transmission circuit 216 is set. The control unit 204 specifies a digital value obtained by A / D (Analog / Digital) conversion of an analog voltage signal as a signal level indicated by the analog voltage signal. The control unit 204 includes, for example, a microcontroller.

  The ASK modulation circuit 205 generates an ASK signal by modulating the carrier wave of the first frequency with the digital data signal supplied from the control unit 204. The ASK modulation circuit 205 includes, for example, a multiplier or a microcontroller that multiplies a digital data signal by a carrier wave.

  The ASK transmission circuit 206 amplifies the ASK signal supplied from the ASK modulation circuit 205 to the extent that transmission is possible. The ASK transmission circuit 206 includes, for example, a transistor circuit.

  The power supply circuit 207 supplies DC power for operating the remote control device 200. Power supply circuit 207 receives DC power from water heater 100 via power reception circuit 208. The power supply circuit 207 includes a bypass capacitor with a large capacitance between the power supply terminal and the ground terminal. Due to the influence of the bypass capacitor, the power supply circuit 207 has low impedance to the ASK signal, the non-modulated analog audio signal, the FM signal, and the non-modulated analog audio signal. Therefore, when the power supply circuit 207 is directly connected to the communication line 401 and the communication line 402 without passing through the power receiving circuit 208, data communication and voice communication using the communication line 401 and the communication line 402 can not be performed. . Therefore, the power supply circuit 207 is connected to the communication line 401 and the communication line 402 through the power receiving circuit 208.

  The power receiving circuit 208 supplies the DC power supplied from the water heater 100 to the power supply circuit 207 via the communication line 401 and the communication line 402. The power receiving circuit 208 is a circuit that raises the impedance to an ASK signal, an unmodulated analog audio signal, an FM signal, and an unmodulated analog audio signal. The power reception circuit 208 includes, for example, a choke coil.

  A button 209 receives various operations from the user. The button 209 supplies the control unit 204 with an operation signal corresponding to the received operation. The operation received by the button 209 is, for example, an operation of instructing the on / off of the power supply of the interphone circuit 214 or an operation of instructing the operation of the water heater 100.

  The filter circuit 211 extracts the FM signal by removing the ASK signal and the unmodulated analog audio signal from the signals supplied from the communication line 401 and the communication line 402, and outputs the extracted FM signal to the FM reception circuit 212. Supply. Further, the filter circuit 211 extracts the FM signal by removing the ASK signal and the non-modulated analog audio signal from the signal supplied from the FM receiving circuit 212, and extracts the extracted FM signal from the communication line 401 and the communication line 402. And supply. The filter circuit 211 is, for example, a band pass filter whose center frequency is the second frequency. Further, the Q value of the filter circuit 211 is set to a value sufficient to attenuate the components of the first frequency and the third frequency so as not to affect the reception of the FM signal by the FM reception circuit 212. The filter circuit 211 includes, for example, an LC filter circuit.

  The FM reception circuit 212 receives the FM signal transmitted from the remote control device 300 via the filter circuit 211. The FM reception circuit 212 amplifies the FM signal so that the FM demodulation circuit 213 can demodulate the FM signal. The FM reception circuit 212 includes, for example, a transistor circuit.

  The FM demodulation circuit 213 demodulates the FM signal supplied from the FM reception circuit 212 to generate an analog audio signal. The FM demodulation circuit 213 demodulates the FM signal on the assumption that the frequency of the carrier wave of the FM signal is the second frequency. The FM demodulation circuit 213 includes, for example, a PLL (Phase Locked Loop) circuit.

  The interphone circuit 214 performs voice communication with the remote control device 300 under the control of the control unit 204. Specifically, the interphone circuit 214 supplies the analog audio signal supplied from the FM demodulation circuit 213 to the speaker 219, and supplies the analog audio signal supplied from the microphone 218 to the audio signal transmission circuit 216. The interphone circuit 214 supplies the analog audio signal supplied from the FM demodulation circuit 213 to the speaker 219 when the power is turned on, and supplies the analog audio signal supplied from the microphone 218 to the audio signal transmission circuit 216. Start processing The power supply of the interphone circuit 214 is turned on / off by the control unit 204.

  The level detection circuit 215 detects the signal level of the carrier wave or FM signal of the second frequency received by the FM reception circuit 212, and supplies an analog voltage signal indicating the detected signal level to the control unit 204. The signal level of the carrier or FM signal of the second frequency is a signal level according to the amplitude of the carrier or FM signal of the second frequency, and the voltage obtained when the carrier or FM signal of the second frequency is rectified It shall be a level. Here, the carrier wave or the FM signal of the second frequency attenuates in the period from being transmitted by the FM transmission circuit 316 to being received by the FM reception circuit 212. Accordingly, the signal level of the carrier or FM signal of the second frequency received by the FM reception circuit 212 is smaller than the ideal value of the signal level of the carrier or FM signal of the second frequency transmitted by the FM transmission circuit 316. In this embodiment, this ideal value is 5V.

  In the present embodiment, the drop of the audio signal by the communication line 401 and the communication line 402 is dominant, and the load connected to the communication line 401 and the communication line 402 (for example, the filter circuit 211, the filter circuit 317, It is assumed that the voice signal is attenuated more by the communication line 401 and the communication line 402 than the FM transmission circuit 316). Here, the degree of attenuation of the carrier or FM signal at the second frequency and the degree of attenuation of the unmodulated analog audio signal are basically correlated. In other words, when the carrier wave or the FM signal of the second frequency is greatly attenuated while passing through the communication line 401 and the communication line 402, the unmodulated analog voice signal also passes through the communication line 401 and the communication line 402. It attenuates greatly. Therefore, in this embodiment, the degree of attenuation of the non-modulated analog audio signal is estimated from the degree of attenuation of the carrier of the second frequency or the FM signal, and the non-modulated analog audio signal is amplified according to the estimated degree. . The level detection circuit 215 includes, for example, a diode detection circuit.

  The audio signal transmission circuit 216 is a circuit that amplifies the signal level of the analog audio signal to a required signal level. The amplification factor of the audio signal transmission circuit 216 is variable by an external control signal. The audio signal transmission circuit 216 amplifies the analog audio signal supplied from the interphone circuit 214 according to the gain set by the control unit 204, and supplies the amplified analog audio signal to the filter circuit 217. The audio signal transmission circuit 216 includes, for example, an amplifier circuit provided with an AGC (Automatic Gain Control).

  The filter circuit 217 extracts the unmodulated analog audio signal by removing the ASK signal and the FM signal from the signals supplied from the communication line 401 and the communication line 402, and extracts the extracted unmodulated analog audio signal. The signal transmission circuit 216 is supplied. The filter circuit 211 also extracts an unmodulated analog audio signal by removing the ASK signal and the FM signal from the signal supplied from the audio signal transmission circuit 216, and extracts the extracted unmodulated analog audio signal as a communication line. It supplies to 401 and the communication wire 402. The filter circuit 217 is, for example, a low pass filter that greatly attenuates components of frequencies above the third frequency. Alternatively, the filter circuit 217 may be, for example, a band pass filter whose center frequency is a frequency equal to or lower than the third frequency. In addition, the Q value and the order of the filter circuit 217 are values to the extent that the components of the first frequency and the second frequency are sufficiently attenuated so as not to affect the transmission of the unmodulated analog audio signal by the audio signal transmission circuit 216. Set to The filter circuit 217 includes, for example, an LC filter circuit.

  The microphone 218 converts voice into an analog voice signal and supplies the analog voice signal to the interphone circuit 214.

  The speaker 219 outputs the sound indicated by the analog sound signal supplied from the interphone circuit 214.

  Next, the configuration of remote control device 300 will be described. Remote control device 300 includes filter circuit 301, ASK reception circuit 302, ASK demodulation circuit 303, control unit 304, ASK modulation circuit 305, ASK transmission circuit 306, power supply circuit 307, power reception circuit 308, and a button. A filter circuit 311, an audio signal reception circuit 312, an interphone circuit 314, an FM modulation circuit 315, an FM transmission circuit 316, a filter circuit 317, a microphone 318, and a speaker 319 are provided.

  The filter circuit 301 extracts an ASK signal by removing an unmodulated analog audio signal and an FM signal from the signals supplied from the communication line 401 and the communication line 402, and extracts the extracted ASK signal with the ASK receiving circuit 302. It supplies to the ASK transmission circuit 306. The filter circuit 301 is, for example, a band pass filter whose center frequency is the first frequency. In addition, the Q value and the order of the filter circuit 301 have a value enough to sufficiently attenuate the signal component of the second frequency and the signal component of the third frequency so as not to affect the reception of the ASK signal by the ASK reception circuit 302. Set to The filter circuit 301 includes, for example, an LC filter circuit.

  The ASK receiving circuit 302 receives the ASK signal transmitted from the water heater 100 or the remote control device 200 via the filter circuit 301. The ASK receiving circuit 302 amplifies the ASK signal so that the ASK demodulation circuit 303 can demodulate the ASK signal. The ASK receiving circuit 302 includes, for example, a transistor circuit.

  The ASK demodulation circuit 303 demodulates the ASK signal supplied from the ASK reception circuit 302 to generate a digital data signal. The ASK demodulation circuit 303 demodulates the ASK signal on the assumption that the carrier frequency of the ASK signal is the first frequency. The ASK demodulation circuit 303 includes, for example, a diode detection circuit and a microcontroller.

  Control unit 304 controls the overall operation of remote control device 300. Control unit 304 has a function of performing data communication with water heater 100 or remote control device 200. Further, the control unit 304 has a function of performing voice communication with the remote control device 200. Specifically, the control unit 304 controls the interphone circuit 314 to output the analog audio signal supplied from the audio signal receiving circuit 312 to the speaker 319. Further, the control unit 304 controls the interphone circuit 314 to supply the analog audio signal supplied from the microphone 318 to the FM modulation circuit 315.

  The control unit 304 executes various processes based on the button signal supplied from the button 309. The process executed by the control unit 304 is, for example, a process of turning on / off the power of the interphone circuit 314 or a process of performing data communication with the water heater 100 or the remote control device 200. The control unit 304 includes, for example, a microcontroller.

  The ASK modulation circuit 305 generates an ASK signal by modulating the carrier wave of the first frequency with the digital data signal supplied from the control unit 304. The ASK modulation circuit 305 includes, for example, a multiplier or a microcontroller that multiplies a digital data signal by a carrier wave.

  The ASK transmission circuit 306 amplifies the transmission ASK signal supplied from the ASK modulation circuit 305 to the extent that transmission is possible. The ASK transmission circuit 306 includes, for example, a transistor circuit.

  The power supply circuit 307 supplies DC power for operating the remote control device 300. Power supply circuit 307 receives DC power from water heater 100 via power reception circuit 308. The power supply circuit 307 is connected to the communication line 401 and the communication line 402 through the power receiving circuit 308.

  The power receiving circuit 308 supplies the DC power supplied from the water heater 100 to the power supply circuit 307 through the communication line 401 and the communication line 402. The power receiving circuit 308 is a circuit that raises the impedance to the ASK signal, the unmodulated analog audio signal, and the FM signal. The power reception circuit 308 includes, for example, a choke coil.

  A button 309 receives various operations from the user. The button 309 supplies the control unit 304 with an operation signal according to the received operation. The operation received by the button 309 is, for example, an operation of instructing the power on / off of the interphone circuit 314 or an operation of instructing the operation of the water heater 100.

  The filter circuit 311 extracts the non-modulated analog audio signal by removing the ASK signal and the FM signal from the signals supplied from the communication line 401 and the communication line 402, and extracts the extracted non-modulated analog audio signal. The signal reception circuit 312 is supplied. Further, the filter circuit 311 extracts the non-modulated analog audio signal by removing the ASK signal and the FM signal from the signal supplied from the audio signal receiving circuit 312, and extracts the non-modulated analog audio signal as a communication line. It supplies to 401 and the communication wire 402. The filter circuit 311 is, for example, a low pass filter that greatly attenuates components of frequencies above the third frequency. Alternatively, the filter circuit 311 may be, for example, a band pass filter whose center frequency is a frequency equal to or lower than the third frequency. In addition, the Q value and the order of the filter circuit 311 are values sufficient to sufficiently attenuate the components of the first frequency and the second frequency so as not to affect the reception of the unmodulated analog audio signal by the audio signal receiving circuit 312. Is desirable. The filter circuit 311 includes, for example, an LC filter circuit.

  The audio signal reception circuit 312 receives the unmodulated analog audio signal transmitted from the remote control device 200 via the filter circuit 311. The audio signal reception circuit 312 amplifies the unmodulated analog audio signal so that the speaker 319 reproduces an audio of a proper size. The audio signal reception circuit 312 includes, for example, a transistor circuit.

  The interphone circuit 314 performs voice communication with the remote control device 200 under the control of the control unit 304. Specifically, the interphone circuit 314 supplies the analog audio signal supplied from the audio signal reception circuit 312 to the speaker 319, and supplies the analog audio signal supplied from the microphone 318 to the FM modulation circuit 315. The interphone circuit 314 supplies the analog audio signal supplied from the audio signal reception circuit 312 to the speaker 319 when the power is turned on, and supplies the analog audio signal supplied from the microphone 318 to the FM modulation circuit 315. Start processing The power supply of the interphone circuit 314 is turned on / off by the control unit 304.

  The FM modulation circuit 315 generates an FM signal by changing the frequency of the carrier wave of the second frequency in accordance with the voltage level of the analog audio signal supplied from the interphone circuit 314. The FM modulation circuit 315 includes, for example, an RC oscillation circuit and an LC oscillation circuit whose oscillation frequency can be controlled by an input voltage.

  The FM transmission circuit 316 amplifies the FM signal supplied from the FM modulation circuit 315 to the extent that transmission is possible. The FM transmission circuit 316 includes, for example, a transistor circuit.

  The microphone 318 converts the voice into an analog voice signal and supplies the analog voice signal to the interphone circuit 314.

  The speaker 319 outputs the sound indicated by the analog sound signal supplied from the interphone circuit 314.

  Next, with reference to FIG. 2, the magnitude relationship among the first frequency, the second frequency, and the third frequency will be described. The first frequency is the frequency of the carrier wave of the ASK signal transmitted and received among the water heater 100, the remote control device 200 and the remote control device 300. The second frequency is the frequency of the carrier wave of the FM signal that remote control device 200 receives from remote control device 300. The third frequency is the upper limit value of the frequency of the non-modulated analog audio signal that remote control device 300 receives from remote control device 200.

  In this embodiment, it is assumed that the use of the frequency from 150 kHz to 30 MHz is restricted by the standard. In this case, since it is not realistic to use a frequency of 30 MHz or more, a frequency of 150 kHz or less will be used. As described above, in the present embodiment, the upper limit (hereinafter referred to as “upper limit frequency”) of the frequency that can be used as the frequency of the carrier wave is 150 kHz. In this case, the first frequency, the second frequency and the third frequency are selected in the range of 0 Hz to 150 kHz. However, it is required that the first frequency, the second frequency, and the third frequency be sufficiently different from each other so that desired frequency components can be appropriately extracted and separated.

  In this embodiment, it is assumed that the digital data signal which is a baseband signal of the ASK signal has a frequency of about 3 kHz. Therefore, in order to be able to separate the ASK signal and the digital data signal, the first frequency is preferably 30 kHz or more, which is 10 times 3 kHz. The third frequency is the upper limit value of the frequency of the non-modulated analog audio signal, and is a value of about 3 kHz. Therefore, in order to be able to separate the FM signal and the non-modulated analog audio signal, the second frequency is preferably 30 kHz or more, which is 10 times 3 kHz.

  Here, in the ASK modulation, the higher the frequency of the carrier wave, the shorter the delay time from the fall of the digital data signal to be transmitted to the fall of the digital data signal to be received. As the delay time is shorter, communication errors are reduced, and as a result, the communication speed is improved. Therefore, in order to improve the communication speed, it is desirable that the frequency for ASK modulation be as high as possible. Therefore, it is preferable to make the first frequency, which is a frequency for ASK modulation, higher than the second frequency. In the present embodiment, the first frequency is set to 120 kHz.

  Next, the second frequency is set in the range of 30 kHz to 120 kHz. Here, in order to suppress interference between the ASK signal and the FM signal, it is preferable that the first frequency and the second frequency be sufficiently different. Therefore, in the present embodiment, the second frequency is set to 30 kHz. In this case, the first frequency and the second frequency become a difference of 2 octaves, and the interference is sufficiently suppressed. In FIG. 2, f1 represents a first frequency, f2 represents a second frequency, and f3 represents a third frequency. Further, in FIG. 2, BPF1 represents a gain characteristic of a band pass filter for extracting f1, BPF2 represents a gain characteristic of a band pass filter for extracting f2, and an LPF is a low pass filter for extracting f3. Represents the gain characteristic of

  BPF1 is a band pass filter whose center frequency is f1. Therefore, the BPF 1 does not attenuate the signal level of the frequency near f 1 so much, and has a gain characteristic that largely attenuates the signal level at the frequency having a large difference from f 1. That is, the BPF 1 does not attenuate the ASK signal so much, and greatly attenuates the FM signal and the unmodulated analog audio signal. BPF2 is a band pass filter whose center frequency is f2. Therefore, the BPF 2 does not attenuate the signal level of the frequency near f 2 so much, and has a gain characteristic that largely attenuates the signal level at the frequency where the difference with f 2 is large. That is, the BPF 2 does not attenuate the FM signal very much, and greatly attenuates the ASK signal and the unmodulated analog audio signal. The LPF is a low pass filter that greatly attenuates the signal level of frequencies higher than f3. Therefore, the LPF does not attenuate the signal level of the frequency smaller than f3 so much, and has a gain characteristic that largely attenuates the signal level of the frequency larger than f3 and the difference from f3. That is, the LPF does not significantly attenuate the non-modulated analog audio signal, but greatly attenuates the ASK signal and the FM signal.

  BPF1 is a gain characteristic of the filter circuit 101, the filter circuit 201, and the filter circuit 301. BPF 2 is a gain characteristic of the filter circuit 211 and the filter circuit 311. The LPF is a gain characteristic of the filter circuit 217 and the filter circuit 317. Here, as the difference between the first frequency and the second frequency is larger, the Q value and the order of the BPF 1 can be lowered. The lower the Q value or order of the BPF 1, the higher the speed of data communication using the ASK signal. Further, as the difference between the first frequency and the second frequency is larger and the difference between the second frequency and the third frequency is larger, the Q value and the order of the BPF 2 can be lowered. The lower the Q factor and order of the BPF 2, the faster the voice communication using the FM signal. Also, as the difference between the second frequency and the third frequency is larger, the Q value and the order of the LPF can be lowered. The lower the Q value and the order of the LPF, the higher the speed of voice communication using a non-modulated analog voice signal.

  Next, the conversion table will be described with reference to FIG. The conversion table is stored in the storage unit 2041 included in the control unit 204. The conversion table is a conversion table for converting the signal level indicated by the analog voltage signal supplied from the level detection circuit 215 to the control unit 204 into the gain to be set in the audio signal transmission circuit 216. The conversion table converts smaller signal levels into smaller gains. FIG. 3 shows an example in which signal levels of 0 V to 5 V are divided into 1 V intervals and gains are set in five steps.

  Specifically, in FIG. 3, a gain of 1.0 is set when the signal level is in the range of 5 V to 4 V, and when the signal level is in the range of 4 V to 3 V. A gain of 2 is set and a gain of 1.6 is set when the signal level is in the range of 3 V to 2 V, and 2.5 times when the signal level is in the range of 2 V to 1 V An example is shown in which the gain of is set and the gain of 5.0 is set when the signal level is in the range of 1V to 0V.

  Next, the first call processing executed by remote control device 200 will be described with reference to the flowchart shown in FIG. The first call process is started in response to power on of remote control device 200.

  First, the control unit 204 determines whether there is a call start operation (step S101). Specifically, the control unit 204 determines whether or not an operation signal instructing to start a call is supplied from the button 209. The operation signal is a signal supplied from the button 209 to the control unit 204 in response to the button 209 being pressed.

  When determining that there is no call start operation (step S101: NO), the control unit 204 determines whether a call start request has been received (step S102). The call start request is a request to start a call, and is a request to be notified from the remote control device on which the call start operation has been performed to another remote control device. Here, control unit 204 determines whether a call start request has been received from remote control device 300 or not. The call start request is notified by data communication.

  For example, remote control device 300 transmits to remote control device 200 via communication line 401 and communication line 402 an ASK signal generated by ASK modulating a carrier wave of the first frequency with a digital data signal indicating a call start request. . In this case, the ASK reception circuit 202 supplies the ASK signal received via the filter circuit 201 to the ASK demodulation circuit 203. The ASK demodulation circuit 203 demodulates the supplied ASK signal to acquire a digital data signal, and supplies the acquired digital data signal to the control unit 204. The control unit 204 can detect that a call start request has been made from the remote control device 300 by being supplied with a digital data signal indicating the call start request.

  If the control unit 204 determines that the call start request has not been received (step S102: NO), the process returns to step S101. Here, when determining that there is a call start operation (step S101: YES), the control unit 204 transmits a call start request (step S103).

  For example, the control unit 204 supplies the ASK modulation circuit 205 with a digital data signal indicating a call start request. On the other hand, the ASK modulation circuit 205 generates an ASK signal by ASK modulating the carrier wave of the first frequency with the supplied digital data signal, and supplies the generated ASK signal to the ASK transmission circuit 206. Then, the ASK transmission circuit 206 transmits the supplied ASK signal to the remote control device 300 via the filter circuit 201, the communication line 401 and the communication line 402. By receiving the ASK signal, remote control device 300 can detect that the remote control device 200 has made a call start request.

  If it is determined that the call start request has been received (step S102: YES), or if the process of step S103 is completed, the control unit 204 detects the signal level of the carrier wave used for the FM (step S104). As described later, when receiving the call start request or detecting a call start operation, remote control device 300 starts output of a carrier wave used for FM. The carrier wave is transmitted through a route of FM modulation circuit 315 → FM transmission circuit 316 → filter circuit 317 → communication line 401 and communication line 402 → filter circuit 211 → FM reception circuit 212. Therefore, the level detection circuit 215 detects the signal level of the carrier wave received by the FM reception circuit 212, and supplies an analog voltage signal indicating the detected signal level to the control unit 204. The control unit 204 can detect the signal level of the carrier based on the supplied analog voltage signal. Note that in the FM modulation, the amplitude of the carrier does not change. That is, the signal level of the carrier wave used for FM is the same as the signal level of the FM signal. Therefore, the control unit 204 may detect the signal level of the FM signal instead of the signal level of the carrier wave used for the FM.

  When the process of step S104 is completed, the control unit 204 adjusts the gain according to the detected signal level (step S105). Specifically, the control unit 204 refers to the conversion table stored in the storage unit 2041, identifies a gain corresponding to the detected signal level, and sets the identified gain in the audio transmission circuit 216. The control unit 204 sets a smaller gain as the detected signal level increases, and sets a larger gain as the detected signal level decreases. The audio transmission circuit 216 amplifies the analog audio signal supplied from the interphone circuit 214 in accordance with the gain set by the control unit 204.

  When the process of step S105 is completed, the control unit 204 turns on the power of the interphone circuit 214 (step S106). When the interphone circuit 214 is powered on, the analog audio signal generated by the microphone 218 is supplied to the audio signal transmission circuit 216, and the analog audio signal demodulated by the FM demodulation circuit 213 is supplied to the speaker 219. Then, when the power of the interphone circuit 214 is turned on and the power of the interphone circuit 314 is turned on further, two-way simultaneous telephone conversation becomes possible between the remote control device 200 and the remote control device 300. In the two-way simultaneous call, the sound collected by the microphone 218 is output from the speaker 319, and the sound collected by the microphone 318 is output from the speaker 219.

  When the process of step S106 is completed, the control unit 204 determines whether or not there is a call end operation (step S107). Specifically, control unit 204 determines whether or not an operation signal instructing the end of the call is supplied from button 209.

  When determining that there is no call termination operation (step S107: NO), the control unit 204 determines whether a call termination request has been received (step S108). The call termination request is a request to terminate the call, and is a request to be notified from the remote control device on which the call termination operation has been performed to another remote control device. Here, control unit 204 determines whether or not a call termination request has been received from remote control device 300. The call end request is notified by data communication.

  If the control unit 204 determines that the call termination request has not been received (step S108: NO), the process returns to step S107. Here, when the control unit 204 determines that there is a call termination operation (step S107: YES), the control unit 204 transmits a call termination request (step S109). Similar to the call start request, the control unit 204 transmits the call end request to the remote control device 300 by data communication.

  If it is determined that the call termination request has been received (step S108: YES), or if the process of step S109 is completed, the control unit 204 powers off the interphone circuit 214 (step S110). When the interphone circuit 214 is powered off, the analog audio signal generated by the microphone 218 is not supplied to the audio signal transmission circuit 216, and the analog audio signal demodulated by the FM demodulation circuit 213 is not supplied to the speaker 219. When the power of the interphone circuit 214 is turned off or the power of the interphone circuit 314 is turned off, two-way simultaneous conversation can not be performed between the remote control device 200 and the remote control device 300. When the control unit 204 completes the process of step S110, the process returns to step S101.

  Next, the second call process executed by remote control device 300 will be described with reference to the flowchart shown in FIG. The second call process is started in response to power on of remote control device 300.

  First, the control unit 304 determines whether there is a call start operation (step S201). Specifically, control unit 304 determines whether or not an operation signal instructing start of a call is supplied from button 309.

  When determining that there is no call start operation (step S201: NO), the control unit 304 determines whether a call start request has been received (step S202). For example, control unit 204 determines whether a call start request has been received from remote control device 200 or not. The call start request is notified by data communication.

  For example, remote control device 200 transmits an ASK signal generated by ASK modulating the carrier wave of the first frequency with a digital data signal indicating a call start request to remote control device 300 via communication line 401 and communication line 402. . In this case, the ASK reception circuit 302 supplies the ASK signal received via the filter circuit 301 to the ASK demodulation circuit 303. The ASK demodulation circuit 303 demodulates the supplied ASK signal to acquire a digital data signal, and supplies the acquired digital data signal to the control unit 304. The control unit 304 can detect that a call start request has been made from the remote control device 200 by being supplied with a digital data signal indicating the call start request.

  When determining that the call start request has not been received (step S202: NO), the control unit 304 returns the process to step S201. Here, when determining that there is a call start operation (step S201: YES), the control unit 304 transmits a call start request (step S203).

  For example, the control unit 304 supplies a digital data signal indicating a call start request to the ASK modulation circuit 305. On the other hand, the ASK modulation circuit 305 generates an ASK signal by ASK modulating the carrier wave of the first frequency with the supplied digital data signal, and supplies the generated ASK signal to the ASK transmission circuit 306. Then, the ASK transmission circuit 306 transmits the supplied ASK signal to the remote control device 200 via the filter circuit 301, the communication line 401 and the communication line 402. By receiving the ASK signal, remote control device 200 can detect that the remote control device 300 has made a call start request.

  When it is determined that the call start request has been received (step S202: YES), or when the process of step S203 is completed, the control unit 304 starts output of a carrier wave used for FM (step S204). For example, the control unit 304 controls the FM modulation circuit 315 to start output of a carrier wave used for FM. Then, this carrier wave is transmitted through a route of FM modulation circuit 315 → FM transmission circuit 316 → filter circuit 317 → communication line 401 and communication line 402 → filter circuit 211 → FM reception circuit 212.

  When the process of step S204 is completed, the control unit 304 turns on the power of the interphone circuit 314 (step S205). When the interphone circuit 314 is powered on, the analog audio signal generated by the microphone 318 is supplied to the FM modulation circuit 315, and the analog audio signal received by the audio signal reception circuit 312 is supplied to the speaker 319. Then, when the power of the interphone circuit 314 is turned on and the power of the interphone circuit 214 is further turned on, a two-way simultaneous call can be performed between the remote control device 200 and the remote control device 300.

  When the process of step S205 is completed, the control unit 304 determines whether or not there is a call end operation (step S206). Specifically, control unit 304 determines whether or not an operation signal instructing the end of the call is supplied from button 309.

  If the control unit 304 determines that there is no call termination operation (step S206: NO), the control unit 304 determines whether a call termination request has been received (step S207). Specifically, control unit 304 determines whether a call termination request has been received from remote control device 200 or not. The call end request is notified by data communication.

  If the control unit 304 determines that the call termination request has not been received (step S207: NO), the process returns to step S206. Here, if the control unit 304 determines that there is a call termination operation (step S206: YES), the control unit 304 transmits a call termination request (step S208). Similar to the call start request, the control unit 304 transmits the call end request to the remote control device 200 by data communication.

  If the control unit 304 determines that the call termination request has been received (step S207: YES), or if the process of step S208 is completed, the control unit 304 stops the output of the carrier wave used for the FM (step S209). For example, the control unit 304 controls the FM modulation circuit 315 to stop the output of the carrier wave used for FM.

  When the process of step S209 is completed, the control unit 304 turns off the power of the interphone circuit 314 (step S210). When the interphone circuit 314 is powered off, the analog audio signal generated by the microphone 318 is not supplied to the FM modulation circuit 315, and the analog audio signal received by the audio signal receiving circuit 312 is not supplied to the speaker 319. When the power of the interphone circuit 214 is turned off or the power of the interphone circuit 314 is turned off, two-way simultaneous conversation can not be performed between the remote control device 200 and the remote control device 300. When the control unit 304 completes the process of step S210, the process returns to step S201.

  As described above, in the present embodiment, data communication between remote control device 200 and remote control device 300 is generated by modulating the carrier wave of the first frequency, which is equal to or lower than a predetermined upper limit frequency, with a digital data signal. The audio communication from remote control device 200 to remote control device 300 is realized by a non-modulated analog audio signal, and the audio communication from remote control device 300 to remote control device 200 is from the first frequency. This is realized by a modulated voice signal generated by modulating, with an analog voice signal, the carrier wave of the second frequency higher than the frequency of the low unmodulated analog voice signal. Therefore, according to the present embodiment, it is possible to widen the interval of the frequency used in the data communication and the voice communication while suppressing the frequency used in the data communication and the voice communication to the upper limit frequency or less. . Therefore, it is possible to separate the signal using a filter with low Q value and low order. As a result, according to the present embodiment, the delay time of the signal is reduced, and the speed of data communication and voice communication can be increased.

  In the case where it is strongly required to suppress the signal level in the frequency band of 150 kHz or more to the allowable value or less, for example, a method of suppressing the signal level to the allowable value or less can be considered. However, this method is not only vulnerable to extraneous noise, but also increases the cost due to using a receiver circuit with high reception sensitivity. In the present embodiment, since it is not necessary to keep the signal level below the allowable value, noise immunity and cost reduction can be expected.

  Further, in the present embodiment, the signal level of the non-modulated analog audio signal is corrected according to the signal level of the modulated audio signal or the carrier wave of the second frequency. Therefore, according to the present embodiment, the signal level of the non-modulated analog audio signal is not dependent on the wiring length of the communication line 401 or the communication line 402, or the size of the load connected to the communication line 401 or the communication line 402. Can be corrected to a predetermined signal level, and the output sound pressure can be maintained at a predetermined sound pressure. In addition, since the unmodulated analog audio signal is amplified before transmission, improvement in noise resistance can be expected.

  Further, in the present embodiment, the remote control device 200 that transmits an unmodulated analog audio signal includes the level detection circuit 215 and the level correction circuit (control unit 204). Therefore, according to the present embodiment, the remote control device 200 does not have to perform data communication with the remote control device 300 for detection of the signal level and correction of the signal level.

  Further, in the present embodiment, frequency modulation using a carrier wave of the second frequency is used in voice communication from remote control device 300 to remote control device 200. For this reason, according to the present embodiment, improvement in noise resistance in voice communication can be expected. Further, in frequency modulation, the amplitude of the modulated audio signal does not change. Therefore, remote control device 200 easily estimates the wiring length of communication line 401 and communication line 402 and the size of the load connected to communication line 401 and communication line 402 based on the signal level of the modulated audio signal. The signal level of the unmodulated analog audio signal can be properly corrected.

Second Embodiment
The first embodiment shows an example in which the control unit 204 sets the gain in the audio signal transmission circuit 216 based on the signal level detected by the level detection circuit 215. In the second embodiment, an example in which the control unit 304 sets a gain in the audio signal reception circuit 312 based on the signal level detected by the level detection circuit 215 will be described.

  FIG. 6 shows the configuration of a communication system 1100 according to Embodiment 2 of the present invention. The communication system 1100 includes a water heater 100, a remote control device 220, and a remote control device 320. The remote control device 220 basically has the same configuration as the remote control device 200, and the connection relationship of each configuration and the operation of each configuration are different from those of the remote control device 200. Further, remote control device 320 basically has the same configuration as remote control device 300, and the connection relationship of each configuration and the operation of each configuration are different from remote control device 300. Hereinafter, differences from the first embodiment will be mainly described.

  The control unit 204 specifies the gain to be set in the audio signal reception circuit 312 based on the signal level indicated by the analog voltage signal supplied from the level detection circuit 215. For example, the control unit 204 refers to the conversion table shown in FIG. 3 to identify the gain corresponding to the signal level. The control unit 204 specifies the gain such that the gain decreases as the signal level increases, and the gain increases as the signal level decreases.

  The control unit 204 transmits the identified gain to the remote control device 300 by data communication. For example, the control unit 204 generates a digital data signal indicating the specified gain, and supplies the generated digital data signal to the ASK modulation circuit 205. On the other hand, the ASK modulation circuit 205 generates an ASK signal by ASK modulating the carrier wave of the first frequency with the supplied digital data signal. The ASK transmission circuit 206 transmits the ASK signal supplied from the ASK modulation circuit 205 to the remote control device 300 via the filter circuit 201, the communication line 401 and the communication line 402.

  On the other hand, remote control device 300 receives the ASK signal transmitted from remote control device 200. Specifically, the ASK receiving circuit 302 receives an ASK signal via the filter circuit 301. Then, the ASK demodulation circuit 303 demodulates the ASK signal received by the ASK reception circuit 302 to generate a digital data signal. Here, the control unit 304 obtains the digital data signal generated by the ASK demodulation circuit 303, and specifies the gain indicated by the digital data signal. Then, the control unit 304 sets the identified gain in the audio signal reception circuit 312. The audio signal receiving circuit 312 amplifies the unmodulated analog audio signal supplied from the filter circuit 311 in accordance with the gain set by the control unit 304, and supplies the amplified unmodulated analog audio signal to the interphone circuit 314.

  As described above, in the present embodiment, the signal level of the unmodulated analog audio signal after reception is corrected according to the signal level of the modulated audio signal or the carrier wave of the second frequency. Therefore, according to the present embodiment, the unmodulated analog audio signal after reception is not dependent on the wire lengths of the communication line 401 or the communication line 402, or the size of the load connected to the communication line 401 or the communication line 402. Can be corrected to a predetermined signal level, and the output sound pressure can be maintained at a predetermined sound pressure.

(Embodiment 3)
In the first embodiment, the example in which the remote control device 200 includes the level detection circuit 215 has been described. In the third embodiment, an example in which the remote control device 300 includes the level detection circuit 215 will be described.

  FIG. 7 shows the configuration of a communication system 1200 according to Embodiment 3 of the present invention. The communication system 1200 includes a water heater 100, a remote control device 230, and a remote control device 330. The remote control device 230 basically has the same configuration as the remote control device 200 except that the level detection circuit 215 is not provided. Further, remote control device 330 basically has the same configuration as remote control device 300 except that level detection circuit 215 is provided. Hereinafter, differences from the first embodiment will be mainly described. The present embodiment is preferably applied to the case where the drop of the audio signal by the FM transmission circuit 316 is dominant and the audio signal is significantly attenuated by the FM transmission circuit 316 than the communication line 401 and the communication line 402. is there.

  The level detection circuit 215 detects the signal level of the carrier wave or FM signal of the second frequency output from the FM transmission circuit 316, and supplies an analog voltage signal indicating the detected signal level to the control unit 304. When the output impedance of the FM transmission circuit 316 is large, the carrier wave or FM signal of the second frequency output from the FM transmission circuit 316 is greatly attenuated.

  The control unit 304 transmits the signal level indicated by the analog voltage signal supplied from the level detection circuit 215 to the remote control device 230 by data communication. For example, the control unit 304 generates a digital data signal indicating the signal level indicated by the analog voltage signal, and supplies the generated digital data signal to the ASK modulation circuit 305. On the other hand, the ASK modulation circuit 305 generates an ASK signal by ASK modulating the carrier wave of the first frequency with the supplied digital data signal. The ASK transmission circuit 306 transmits the ASK signal supplied from the ASK modulation circuit 305 to the remote control device 230 via the filter circuit 301, the communication line 401 and the communication line 402.

  On the other hand, remote control device 230 receives the ASK signal transmitted from remote control device 330. Specifically, the ASK receiving circuit 202 receives an ASK signal via the filter circuit 201. Then, the ASK demodulation circuit 203 demodulates the ASK signal received by the ASK reception circuit 202 to generate a digital data signal. Here, the control unit 204 obtains the digital data signal generated by the ASK demodulation circuit 203, and specifies the signal level indicated by the digital data signal.

  Here, the control unit 204 specifies the gain to be set in the audio signal transmission circuit 216 based on the specified signal level. For example, the control unit 204 refers to the conversion table shown in FIG. 3 to identify the gain corresponding to the signal level. The control unit 204 specifies the gain such that the gain decreases as the signal level increases, and the gain increases as the signal level decreases. Then, the control unit 204 sets the identified gain in the audio signal transmission circuit 216. The audio signal transmission circuit 216 amplifies the unmodulated analog audio signal supplied from the interphone circuit 214 in accordance with the gain set by the control unit 204, and supplies the amplified unmodulated analog audio signal to the filter circuit 217.

  As described above, in the present embodiment, the signal level of the unmodulated analog audio signal before reception is corrected according to the signal level of the modulated audio signal or the carrier wave of the second frequency. Therefore, according to the present embodiment, the unmodulated analog audio signal before reception is not dependent on the wiring length of the communication line 401 or the communication line 402, or the size of the load connected to the communication line 401 or the communication line 402. Can be corrected to a predetermined signal level, and the output sound pressure can be maintained at a predetermined sound pressure. In addition, since the unmodulated analog audio signal is amplified before transmission, improvement in noise resistance can be expected.

(Modification)
As mentioned above, although embodiment of this invention was described, in implementation of this invention, the deformation | transformation and application by various forms are possible.

  In the present invention, which part of the configuration, function, and operation described in the above embodiment is adopted is optional. Further, in the present invention, in addition to the above-described configurations, functions, and operations, further configurations, functions, and operations may be adopted. The configurations, functions, and operations described in the above embodiments can be combined as appropriate.

  For example, in the first embodiment, the example in which the control unit 204 stores the conversion table has been described. In the present invention, the control unit 304 may store the conversion table. In this case, for example, when remote control device 200 includes level detection circuit 215, remote control device 200 transmits the signal level detected by level detection circuit 215 to remote control device 300 by data communication. Further, for example, when the remote control device 200 includes a circuit whose gain is adjusted, the remote control device 300 transmits the gain specified based on the signal level and the conversion table to the remote control device 200 by data communication.

  In the first embodiment, an example in which the detected signal level is converted into the gain to be set using the conversion table has been described. In the present invention, the method of obtaining the gain to be set from the detected signal level is not limited to this example. For example, the gain to be set may be determined by multiplying the inverse of the detected signal level by a predetermined coefficient. According to this method, memory saving can be expected. This method is particularly effective, for example, when the degree of attenuation of the signal component of the second frequency and the degree of attenuation of the signal component of the third frequency are the same. In this case, for example, the level detection circuit 215 is provided with an arithmetic unit (divider, multiplier) for outputting the gain to be set, and the level detection circuit 215 does not go through the control unit 204 but It may be set.

  In the first embodiment, an example in which FM is adopted as a modulation method used for voice communication has been described. In the present invention, various analog modulation schemes can be adopted as modulation schemes used for voice communication. For example, AM (Amplitude Modulation) can be adopted as a modulation method used for voice communication. In this case, an AM reception circuit, an AM demodulation circuit, an AM modulation circuit, and an AM transmission circuit are provided in place of the FM reception circuit 212, the FM demodulation circuit 213, the FM modulation circuit 315, and the FM transmission circuit 316, respectively. Then, when detecting the signal level, an AM signal having a predetermined amplitude is transmitted from the AM transmission circuit, and the signal level of the AM signal received by the AM reception circuit is detected.

  In the first embodiment, an example in which ASK modulation is adopted as a modulation method used for data communication has been described. In the present invention, various digital modulation schemes can be adopted as a modulation scheme used for data communication. For example, frequency shift keying (FSK) can be adopted as a modulation method used for data communication.

  In the above embodiment, the present invention is applied to a hot water supply system. The present invention can be applied to any communication system that communicates via a communication line shared by half duplex communication data communication and full duplex communication voice communication.

  By applying an operation program that defines operations of the water heater 100, the remote control device 200, and the remote control device 300 according to the present invention to an existing personal computer or information terminal device, the personal computer etc. is the water heater 100 according to the present invention, It is also possible to function as remote control device 200 and remote control device 300.

  Also, the distribution method of such a program is arbitrary, and for example, it is stored by being stored in a computer readable recording medium such as a CD-ROM (Compact Disk Read-Only Memory), a DVD (Digital Versatile Disk), or a memory card. It may be distributed via a communication network such as the Internet.

  The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the present invention. In addition, the embodiment described above is for describing the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the claims. And, various modifications applied within the scope of the claims and the meaning of the invention are considered to be within the scope of the present invention.

  The present invention is applicable to a communication system in which communication is performed via a communication line shared by data communication by a half duplex communication scheme and voice communication by a full duplex communication scheme.

DESCRIPTION OF SYMBOLS 100 Water heater, 101, 201, 211, 217, 301, 311, 317 Filter circuit, 102, 202, 302 ASK receiving circuit, 103, 203, 303 ASK demodulation circuit, 104, 204, 304 Control part, 105, 205, 305 ASK modulation circuit 106, 206, 306 ASK transmission circuit 107 DC power supply 108 power feeding circuit 200 220 230 300 300 320 330 remote control device 207 307 power supply circuit 208 308 power receiving circuit 209 309 button, 212 FM reception circuit, 213 FM demodulation circuit, 214, 314 interphone circuit, 215 level detection circuit, 216 audio signal transmission circuit, 218, 318 microphone, 219, 319 speaker, 312 audio signal reception circuit, 315 FM modulation circuit , 16 FM transmitter circuit, 1000,1100,1200 communication system, 2041 storage unit

Claims (7)

A communication system comprising a first communication device and a second communication device that mutually communicate via a communication line shared by data communication by a half duplex communication scheme and voice communication by a full duplex communication system,
The first communication device is
A data signal transmission circuit for transmitting a modulated data signal generated by modulating a carrier wave of a first frequency not higher than a predetermined upper limit frequency with a digital data signal to the second communication apparatus;
A data signal receiving circuit for receiving the modulated data signal transmitted by the second communication device;
An audio signal transmission circuit for transmitting an unmodulated analog audio signal to the second communication device;
A modulated voice signal transmitted by the second communication device and generated by modulating a carrier wave of a second frequency lower than the first frequency and higher than the frequency of the unmodulated analog voice signal with an analog voice signal An audio signal receiving circuit for receiving;
The second communication device is
A data signal transmission circuit that transmits a modulated data signal received by a data signal reception circuit included in the first communication device to the first communication device;
A data signal receiving circuit that receives the modulated data signal transmitted by the data signal transmitting circuit included in the first communication device;
An audio signal transmission circuit for transmitting the modulated audio signal to the first communication device;
An audio signal receiving circuit for receiving the unmodulated analog audio signal.
Communications system. A level detection circuit that detects the signal level of the modulated audio signal or the carrier wave of the second frequency;
And a level correction circuit that corrects the signal level of the unmodulated analog audio signal according to the signal level detected by the level detection circuit.
The communication system according to claim 1. The first communication device includes the level detection circuit and the level correction circuit.
The communication system according to claim 2. The modulated audio signal is a signal generated by frequency-modulating the carrier of the second frequency with the analog audio signal.
The communication system according to any one of claims 1 to 3. A communication apparatus which mutually communicates with another communication apparatus via a communication line shared by data communication by a half duplex communication method and voice communication by a full duplex communication method,
A data signal transmission circuit for transmitting a modulated data signal generated by modulating a carrier wave of a first frequency equal to or lower than a predetermined upper limit frequency with a digital data signal to the other communication device;
A data signal receiving circuit for receiving the modulated data signal transmitted by the other communication device;
An audio signal transmission circuit for transmitting an unmodulated analog audio signal to the other communication device;
A modulated voice signal transmitted by the other communication device and generated by modulating a carrier wave of a second frequency lower than the first frequency and higher than the frequency of the unmodulated analog voice signal with an analog voice signal An audio signal receiving circuit for receiving;
Communication device. A communication apparatus which mutually communicates with another communication apparatus via a communication line shared by data communication by a half duplex communication method and voice communication by a full duplex communication method,
A data signal transmission circuit for transmitting a modulated data signal generated by modulating a carrier wave of a first frequency equal to or lower than a predetermined upper limit frequency with a digital data signal to the other communication device;
A data signal receiving circuit for receiving the modulated data signal transmitted by the other communication device;
An audio signal for transmitting to another communication device a modulated audio signal generated by modulating a carrier wave of a second frequency lower than the first frequency and higher than the frequency of an unmodulated analog audio signal with an analog audio signal A transmitter circuit,
An audio signal receiving circuit for receiving an unmodulated analog audio signal transmitted by the other communication device;
Communication device. A communication method executed by a communication system including a first communication device and a second communication device mutually communicating via a communication line shared by data communication by half duplex communication method and voice communication by full duplex communication method There,
The first communication device and the second communication device mutually transmit data using the modulated data signal generated by modulating the carrier wave of the first frequency, which is equal to or lower than a predetermined upper limit frequency, with a digital data signal. Communicate and
The first communication device transmits an unmodulated analog audio signal to the second communication device.
The second communication apparatus is configured to modulate the modulated voice signal generated by modulating a carrier wave of a second frequency lower than the first frequency and higher than the frequency of the unmodulated analog voice signal with an analog voice signal. 1 Send to communication device,
Communication method.

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