JPS586200B2 - Shingokenshiyutsuhoshiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of transmitting "1", "0" information by supplying a high frequency signal to a power line in relation to the phase of an alternating current voltage such as a power transmission/distribution line. Concerning information detection methods.

As a method of collecting small amounts of information scattered at many points, such as the measurement of electricity meters, the information to be transmitted scattered at many points is set as a combination of "1" t0p, and the
A method has been proposed in which a high frequency signal is placed on the distribution line in synchronization with a portion of one cycle of the AC voltage on the distribution line depending on the state of ``0'' or ``0''.

FIG. 1 shows an example of this, and FIG. 2 shows waveforms of various parts.

A plurality of information transmission sources S and information collection sources R are coupled to a power distribution line 1 via couplers 2 and 3.

In the transmission source S, 4 is a high frequency signal oscillator, 6 is an information generation source such as a power meter, and 5 is a modulator.

The alternating current voltage a shown in FIG. 2 is applied to the modulator 5 via the line L1.
, and its phase information is extracted.

When information on t1p and aOp, such as 11, etc., arrives from an information source 6 such as a power meter, the high-frequency signal from the oscillator 4 is modulated in relation to the phase of the AC voltage using that information. This becomes the transmission signal b.

On the other hand, at the collecting end R, the high frequency signal C sent by the power transmission line 1 is received via the coupler 3, and the demodulator demodulates the high frequency signal modulated by the transmission source, and the level reaches the threshold level SL. If this is the case, it is input to the information determiner 8 as a baseband signal as shown in d.

The information determiner 8 is further inputted with an alternating current voltage, and samples the baseband signal d from the demodulator 1 by creating sampling pulses at every fixed phase position of the alternating voltage.

Depending on which phase position the sampled baseband signal is in during one cycle of the AC voltage, t1p, a0
Determine p.

In FIG. 2, when the baseband signal exists only in the positive half cycle, it is determined that the information is "1".

However, in general, power transmission and distribution lines are greatly affected by noise, and the level of the transmitted high-frequency signal varies due to the noise N when it is received at the collecting end R, as shown in FIG. 3C.

Therefore, when the level due to this noise N exceeds the threshold level SL, the paceband signal obtained from the demodulator 7 exists at all phase positions in l cycle as shown in FIG. , a0p information will not be received.

Furthermore, various loads such as motors are connected to the power distribution line 1, and the alternating current voltage varies greatly between when the loads are in operation and when they are at rest.

Particularly during operation, the AC voltage drops to become lower than the threshold level SL, making it impossible to detect high-frequency signals.

From the above, the threshold level SL is set to AC voltage,
Although it is conceivable to change the threshold level in accordance with the level or noise level, it has been difficult to appropriately change the threshold level in accordance with these level fluctuations.

In view of the above, an object of the present invention is to eliminate such problems, and the configuration of the present invention is to replace a partial period of one cycle or several cycles of the AC voltage of the electric line with the period α and other periods. The period is β, and when the information to be transmitted is 1', a high frequency signal is supplied to the electric line during the period α, and when the information to be transmitted is tOn, the high frequency signal is supplied to the electric line. Detecting the transmitted information by comparing the signal levels of periods α and β and determining that the high-frequency signal is present during the period when the signal level is high and that the high-frequency signal is not present during the period when the signal level is low. It is characterized by:

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

FIG. 4 shows an embodiment of the collecting end R using the present invention, and FIG. 5 shows a waveform diagram according to the present invention.

As mentioned above, in the data transmission method to which the method of the present invention is symmetrical, a high frequency signal is transmitted during one part of one cycle of the AC voltage, so one unit of information is a1n during one cycle of the AC voltage at the collecting end R. , t(y).

Therefore, the method of the present invention can be used for a part of each cycle of AC voltage (
In the example, the level of the high frequency signal existing in the positive half cycle) and the other period (negative half cycle) is compared, and the period with the higher level is determined to be ``1'', and the period with the smaller level is determined to be ``0''. This is to prevent errors caused by noise.

The operation is shown in FIG. 4. The information is demodulated from the power distribution line 1 through the coupler 3 consisting of a receiving filter 31, a receiving amplifier 32, etc., and is demodulated by the demodulator 7. 81, the register memory 82,
Alternatively, it is input and accumulated in 83.

It should be noted that which of the memory registers 82 and 83 is stored is controlled by the clocks CL1 and CL2. It is created in a part not shown.

That is, as shown in FIG.
The signal level of the π period is stored in the memory register 83 by the clock CL2.

Then, the comparator 84 compares which of the accumulated values in the memory registers 82 and 83 has a thicker level, and sets the larger level as "1" and the smaller one as "O", leaving the accumulated temporal relationship unchanged. It is input to the reception register 85.

The content of the receiving register 85 is a baseband signal as shown in FIG. 5d.

As described above, according to the present invention, it is noted that one unit of information is composed of two bits, 111 and tQj, in each cycle of the AC voltage, and the levels in each cycle are compared, and the larger level is set as ゜1'' and the smaller one is 0, it is possible to easily prevent reception errors due to the above-mentioned noise.

In the above explanation, an example was given in which a high frequency signal is supplied for the positive half cycle period and the negative half cycle period of the AC voltage. It is clear that there is no loss of generality.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of data transmission targeted by the method of the present invention, Figs. 2 and 3 are waveform diagrams of the conventional method, Fig. 4 is an embodiment of the receiving side using the method of the present invention, and Fig. 5 shows a waveform diagram according to the method of the present invention. In FIG. 4, reference numerals 82 and 83 denote memory registers that store the demodulated signals of each portion in a cycle, and 84 a comparator that determines the level of the demodulated signal in each portion of one cycle.

Claims (1)

[Claims] 1 A part of one cycle or several cycles of various AC voltages supplied to the electric line is a period α, and the other period is β, and when the information to be sent is “1”, the information to be sent is in the period α. In a signal detection method on the receiving side of an information transmission system that supplies a high-frequency signal to an electric line during a period β when the signal is 0, the first and second registers respectively accumulate the signals of the period α and β; The outputs of the first and second registers are connected to two input terminals respectively, and it is determined that the high-frequency signal exists during the period when the signal level is higher, and the high-frequency signal does not exist during the period when the signal level is lower. A signal detection method characterized by having a comparison circuit that outputs a transmitted signal as transmitted information.