JPS643381B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a power line transport device.

2. Description of the Related Art Power line transport systems are known that communicate data, voice, etc. by superimposing signals on power lines.

However, since various loads are connected to the power line, a lot of noise is superimposed on the power line, and this noise may be harmful to power line transport.

This type of noise is often generated from loads,
Further, the noise occurs in synchronization with the alternating current phase, and often occurs at the wave height, that is, at the peak of the alternating current wave. For these reasons, conventional power line carriers have used a method of prohibiting data transmission near the 90°, 180°, and 270° phases of commercial AC waves. However, in reality, noise may occur in phases other than those mentioned above depending on the load condition.
The method of prohibiting data transmission only with a specific fixed phase, as in conventional devices, has the disadvantage that data and noise overlap.

The present invention was made in order to eliminate the above-mentioned drawbacks, and provides a power line carrier that stores the phase in which noise occurs and selects a phase with no noise to transmit a signal without error. The purpose is to provide

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

In Fig. 1, 1 is a commercial AC power line, 2 is a transformer connected to the AC power line 1 and extracts an AC power signal, and 3 is a transformer that removes the fundamental wave of the AC power signal from the output of the transformer 2 and converts it into a data signal. A high-pass filter extracts the noise component, 4 is an amplifier that amplifies the output voltage of the high-pass filter 3, and 5 is a level detector that detects that the noise component is above a certain value L ₀ .

6 is a shift register that stores detected noise in correspondence with the phase of the AC power signal. If the shift register 6 is to transmit predetermined data using a 50 Hz power signal, and if the reference timing signal Ts for operating the shift register is a signal with one cycle of 500 μsec, then Since the cycle is 20 msec, 20×10 ^-3 /500×10 ^-6 =
40, and a 40-bit shift register is used.

That is, one cycle of the power signal is divided into 40 parts, and if there is noise in each divided part, a "1" signal is stored in the stage corresponding to that phase.

The outputs of the first and second stages 6-1 and 6-2 of the shift register 6 are read out via the OR gate 7, and the output of the OR gate 7 is sent to the communication control circuit 8.
If the output of the OR gate 7 is "1", data transmission is prohibited in the corresponding phase and the phase is expanded by one bit.

The output of the communication control circuit 8 is connected to the commercial AC power line 1 via a coupler 9.

In the above configuration, for example, the second
As shown in Figure A, the AC power signal f ₀ has phases P ₁ ,
When noise N _{1 ,} N ₂ , N ₃ is superimposed on P 2 and P ₃ ,
When this noise level is higher than the discrimination level L ₀ , the output of the level detector 5 becomes "1" at the phases P ₁ , P ₂ and P ₃ (FIG. 2D).

On the other hand, shift register 6 is a reference timing signal
Every time Ts is applied, the output of the level detector 5 is read into the shift register.

Note that the reference timing signal Ts is synchronized with the power signal so that one cycle of the AC power signal is divided into 40 equal parts. Therefore, in the above example, in the Nth cycle, the 0th to ( _P1-1 )th stages of the shift register have 0, the _P1st stage has "1", and (P1 ₊₁ ) or “0” for the stages up to (P _2-1 )th, “1” for the P _second stage, “0” for the (P ₂₊₁ ) to (P _3-1 )th stages, P “1” for _{the third} stage, (P ₃₊₁ )
"0" is stored in the 40th stage to 40th stage.

Then, in the next N+1 cycle of the AC power signal, the contents of this shift register 6 are transferred to the right one stage at a time and read out sequentially from the leading bit 6-1. That is, the output of the shift register 6 is "0" in the current phase from 0th to (P _1-2 ) of the power signal, and no inhibition is applied to the communication control device 8, so that data is not transmitted during this period. When the data is sent, the data is injected from the coupler 9 to the commercial AC power line 1. Note that in this N+1 cycle as well, the power signal and noise are detected and written in the shift register in the same manner as described above.

On the other hand, at the (P _1-1 )th phase, the second stage 6-2 of the shift register 6 becomes “1”, and this “1” signal is applied to the communication control circuit 8 via the OR gate 7. .

Further, in the P1 _- th phase, the first stage 6-1 of the shift register 6 is "1", so the output of the OR gate 7 is "1".

Therefore, the communication control circuit 8 enters the prohibited state in the (P _1-1 )th phase and the _P1th phase. Therefore, even if data is being applied to the communication control circuit 8 during this time, the transmission of that data is prohibited.

Thereafter, the output of the OR gate 7 becomes "0" again from the P1 _+1st phase, the prohibition of the communication control circuit 8 is released, and data transmission is resumed. Phase P ₂ ,
A similar operation is performed at _P3 .

As mentioned above, by calculating the logical sum of the signals of the first stage and the second stage of the shift register 6, a period that is 1 bit longer than the period in which the noise occurs is obtained, as shown by the dotted line in FIG. Can be banned.

Noise in an electric power system is often caused by loads connected to the system, and statistically speaking, noise generated from one load occurs in approximately the same phase in each cycle. Therefore, as mentioned above, due to the noise generated at the phase of P ₁ in n cycles, n+1
cycle, by inhibiting the transmission of data in phase P ₁ , the phase of this n+1 cycle
The noise N ₁ ' generated at P ₁ is no longer injected into the data, and only pure data can be injected into the power signal in the phase where the noise N ₁ ' is eliminated.

In addition, in this type of data transmission, the length of data sent during one cycle of the power signal is shorter than the time of one cycle of the power signal, and the data includes the start code, transmitter station, and data. , end code, etc. are sent as one set, so even if the transmission phase shifts due to the above-described operation, the receiving side can identify the data.

Note that in the present invention, it is also possible to use the RAM of a microcomputer instead of the shift register.

As detailed above, the present invention stores the phase of noise that occurs during one cycle of an AC power signal, and prohibits injection of data into the power signal in the above phase in subsequent cycles. It is possible to prohibit data transmission in a state that suits the actual condition of the power line being used, or in other words, it is possible to automatically select a noise-free timing and perform accurate data transmission.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is an output waveform diagram of a main part of the embodiment of FIG. 1...Commercial AC power line, 2...Transformer, 3...
...High pass filter, 4...Amplifier, 5...Level detector, 6...Shift register, 7...OR gate, 8...Communication control circuit, 9...Coupler, _N1 ,
N ₂ , N ₃ ... Noise, P ₁ , P ₂ , P ₃ ... Phase where noise occurs.

Claims (1)

[Claims] 1. In a power line carrier device that performs communication by superimposing a high-frequency carrier wave on a power signal, there is an introduction means for introducing an AC signal of the power line, and a fundamental wave of the AC power signal introduced by this introduction means is removed. a filter means for amplifying the signal passed through the filter means, a detection means for detecting that the amplified signal is noise of a certain value or more, and one cycle introduced by the introduction means. dividing means for dividing the power signal into a plurality of phases using a predetermined timing signal; storage means for storing, for each cycle of AC power, a phase in which noise is detected by the detection means at the divided timing; Based on the memory information of the cycle,
A power line transport device comprising: control means for controlling transmission of transport data by selecting a noise-free phase at the (n+1)th cycle.