JP2580211B2 - Communication device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device, and more particularly to a communication device that performs data transmission using a power line.

[Prior Art] Conventionally, a technique of transmitting digital data using an AC power line of 100 to several hundred volts is known. According to this method, since it is not necessary to install a line for communication, there is an advantage that equipment can be simplified. in recent years,
Application to home automation or communication between computers, which controls various electric devices by this power line transfer, is also considered.

[Problems to be solved by the invention] When digital data is serially transmitted via a power line,
Signal synchronization is important, and if signal synchronization is not accurately obtained, data errors can cause serious accidents.

For this reason, in the past, prior to data transmission, synchronization was achieved by a method such as transmitting and receiving a specific synchronization signal as a part of data using a carrier wave. The level cannot be increased, and sufficient reliability regarding signal synchronization cannot be obtained conventionally.

On the other hand, various noises such as corona noise due to discharge, induction noise of an external electromagnetic wave, and noise generated by each connected device are mixed in the power line, and there has been a problem that these disturbances cause a high probability of erroneous synchronization.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a method for reliably receiving a synchronization signal superimposed on an AC power signal and having a level much smaller than that of the AC power signal, A communication apparatus for performing data communication by superimposing a data signal including a synchronization signal modulated by a predetermined modulation method on an AC power signal based on a cycle of the AC power signal on a power line, with a view to demodulating the signal, Detecting means for detecting a predetermined level at which an AC power signal waveform on the power line is periodically generated; receiving means for performing reception processing of the synchronization signal in accordance with detection timing of the detecting means; receiving by the receiving means A configuration having demodulation means for demodulating the data signal based on the synchronization signal is adopted.

[Operation] According to the configuration described above, it is possible to reliably receive the small-level synchronization signal superimposed on the AC power signal and demodulate the data signal.

EXAMPLES Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a power line through which, for example, a power signal of a commercial AC power supply, for example, a 100 V, 50 Hz sine wave signal is transmitted. The power line 1 is connected to a power line carrier data communication device indicated by a broken line. Hereinafter, the structure of the communication device will be described.

The power line 1 is connected to a coupling unit 2 including a coupling capacitor, a coil, and the like. By this coupling part 2,
Only a carrier component modulated by a predetermined method for data transmission superimposed on the power signal is input / output.

The coupling unit 2 includes a transmission unit 9 including an amplifier, a modulation unit using a known predetermined modulation method such as frequency shift keying, frequency modulation, amplitude modulation, and single sideband modulation, and performs demodulation corresponding to the modulation method. A receiving unit 3 including a demodulating unit, an amplifying unit, and the like is connected.

In this embodiment, a predetermined portion of the power signal waveform of the power line 1 is used as a synchronization signal when transmitting and receiving data. For this reason, a transformer 4 is connected to the power line 1. The transformer 4 steps down the power signal of the power line 1 in accordance with the winding ratio and inputs it to one input terminal of the comparator 5. The other input terminal of the comparator 5 is connected to 0 V as a reference voltage. Therefore, a rectangular wave output having an edge at the zero cross of the power waveform is obtained at the output terminal of the comparator 5. The signal 6 is input to the transmission unit 9 and the reception unit 3 as a synchronization signal for data transmission.

Next, with reference to FIGS. 2 (A) and 2 (B), a transmission / reception operation performed between the apparatuses shown in FIG. 1 will be described.

FIG. 2A shows an alternating current (sine wave) waveform carried by the power line 1. Since the AC power waveform P is input to the comparator 5 of FIG. 1 via the transformer 4, the comparator 5 generates a synchronization signal 6 of a rectangular wave having a zero cross point of the power waveform P as a rising edge and a falling edge.
Is output. The synchronization signal 6 is provided to the transmission unit 9.

The transmitting unit 9 modulates the carrier with the serial digital data D0, D1,... Having a predetermined frame or packet configuration at the timing shown in FIG.
This carrier is output to the power line 1 via the coupling unit 2.

On the other hand, in the device on the receiving side, the comparator 5 similarly outputs the synchronization signal 6 synchronized with the zero cross of the power waveform P.
This signal is input to the receiver 3 and used as a synchronization signal for data reception.

According to such a configuration, it is not necessary to add a special synchronization signal to the carrier data (D0, D1,...), And the receiving side can receive the carrier data using the zero cross point of the power waveform P as a synchronization reference. Since the power waveform P has significantly higher power than the data signal to be conveyed, signal synchronization can be reliably obtained, and data having a frame or packet configuration of a predetermined size can be reliably transmitted and received every half cycle of the power signal. .

In recent years, the waveform and frequency of the power signal carried on the power line have been significantly improved in accuracy by computer control or the like, and in the above configuration, the possibility that the error of the power signal affects the synchronization signal is extremely low.

The portion of the power waveform is not limited to the above zero cross point,
Various sites may be used. Further, a predetermined portion in a predetermined signal obtained from the power waveform may be used as a synchronization reference. For example, when the synchronization signal 6 is obtained by the comparator 5, in order to cut off various noises superimposed on the power waveform,
It is conceivable to insert a low-pass filter, that is, an integrator at the position indicated by reference numeral 10 in FIG.

In such a case, the signal input to the comparator 5 has an integrated waveform as shown in FIG. Then, as shown in FIG. 2 (D), the data D0, D1... May be transmitted and received at the transmitting side and the receiving side using the zero cross points t0 ′, t1 ′. According to this configuration, since the synchronization signal is formed from the power waveform from which the noise component has been removed by the low-pass filter, more reliable synchronization can be obtained, and the reliability of data transmission can be improved.

Second Embodiment FIGS. 3A to 3E and FIG. 4 show a second embodiment of the present invention. 3 (A) to 3 (E) show signal synchronization in the present embodiment, and FIG. 4 shows a configuration of a communication device corresponding to FIG.

In this embodiment, in order to perform more reliable data transmission,
As shown in FIG. 3B, headers H0, H1,... Are added to the head of data D0, D1,. Have a predetermined configuration including an identification code of the data D0, D1,... Immediately after the header H0, H1,..., Or a synchronization component used when demodulating the data D0, D1,.

Further, in the present embodiment, reliable transmission can be performed even when the power waveform P has a jitter, that is, a phase difference. Therefore, as shown in FIGS. 3 (A) and (B),
The heads of the headers H0, H1,... Are not completely synchronized with the zero cross of the power waveform P, but are each synchronized with a delay time of τ0.

The delay times τ0 are equal and set to a time sufficiently longer than the expected jitter of the power waveform P.

In order to perform such delay synchronization, the synchronization signal 6 output from the comparator 5 may be input to the synchronization signal 6 via a delay circuit 12 for delaying the synchronization signal 6 by the time τ0 as shown in FIG.

On the other hand, on the receiving side, it is conceivable that the zero-cross timing of the power waveform P changes as shown in FIG. 3C due to the jitter.

Therefore, in synchronization with the zero-cross timings t0 ', t1',.
13, the strobe pulse S as shown in FIG.
0, S1 ... are formed. The pulse generation circuit 13 can be composed of a mono multivibrator or the like. The time τ1 is a length obtained by adding the time width of the headers H0, H1,.

The strobe pulses S0, S1,...
By taking the logical product of the header and the data signal transmitted at the timing as shown in FIG.
H1 ... can be extracted.

By using such a method, it is possible to reliably demodulate data even when there is interference due to phase delay such as jitter as compared with the first embodiment. Further, by adding header information, there is an excellent advantage that frame synchronization, bit synchronization, or data identification can be reliably performed, and the reliability of data communication can be improved.

In each of the above embodiments, a device having both a transmitting and receiving unit has been described. However, it is needless to say that a similar technology can be implemented in a device provided with only one of them.

[Effects of the Invention] As is clear from the above, according to the present invention, a predetermined level at which an AC power signal waveform on a power line periodically occurs is detected, and a synchronization signal receiving process is performed according to the detection timing. , Since the data signal is demodulated based on the synchronization signal received in this reception process,
The data signal can be demodulated by reliably receiving the small-level synchronization signal superimposed on the AC power signal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the structure of a communication device employing the present invention, FIGS. 2 (A) to 2 (D) are waveform diagrams showing the operation of the device in FIG. 1, and FIGS. (E) is a waveform diagram showing an operation in a different embodiment, and FIG. 4 is a block diagram showing a device configuration for realizing the operation of FIG. DESCRIPTION OF SYMBOLS 1 ... Power line 2 ... Coupling part 3 ... Receiving part 4 ... Transformer 5 ... Comparator 6 ... Synchronous signal 9 ... Transmission part 12 ... Delay circuit, 13 ... Pulse generation circuit

Claims (1)

(57) [Claims] 1. A communication device for performing data communication by superimposing a data signal containing a synchronization signal modulated by a predetermined modulation method on an AC power signal based on a cycle of the AC power signal on the power line, comprising: Detecting means for detecting a predetermined level at which an AC power signal waveform is periodically generated; receiving means for performing a receiving process of the synchronization signal in accordance with detection timing of the detecting means; and the synchronization signal received by the receiving means On the basis of,
A communication device comprising demodulation means for demodulating the data signal.