JPH0563614A - Distribution line carrier - Google Patents

Abstract

PURPOSE:To improve the noise proofing property in a distribution line carrier using a distribution line for a transmission line so as to send data. CONSTITUTION:A transmitter side converts data to be sent by one cycle into a transmission signal, and the cycle when the transmission signal is superimposed and a non-signal cycle are repeated for each cycle of a commercial power supply frequency. A reception side uses a comb-line filter provided to an input section to eliminate the fundamental wave frequency of the commercial power supply frequency and its harmonic component. Since the transmission signal is superimposed for each cycle of the commercial power supply frequency, the transmission signal is not deformed by the comb-line filter at the reception side and the fundamental wave frequency of the commercial power supply frequency and its harmonic component only are cancelled. Thus, the transmission signal is demodulated at a very high S/N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution line carrier device for carrying a signal through a distribution line as a transmission line.

[0002]

2. Description of the Related Art As one of distribution line carrier devices for performing data transmission using a distribution line as a transmission line, a spread spectrum communication system based on a direct spread system of baseband signals is adopted.

This spread spectrum communication system spreads the spectrum by modulating a transmission signal with a pseudo noise code, and demodulates the same with the same pseudo noise code on the receiving side. It has characteristics that are not easily affected.

[0004]

However, not only in the communication system that does not perform spread spectrum, but also in the above-mentioned spread spectrum communication system, if the power supply noise level such as the harmonic noise superimposed on the distribution line is high, the effect of the power supply noise level is high. Receive. In the case of the spread spectrum communication system, since the sampling cycle is asynchronous before the synchronization detection, the received noise and the spread code sequence may be stochastically correlated and data demodulation may be erroneous. Since the distribution line carrier is installed at various locations on the distribution line and has various noise characteristics, communication performance cannot be improved by uniform noise countermeasure processing.

An object of the present invention is to solve the above-mentioned problems and to provide a distribution line carrier apparatus capable of performing reliable data transmission even when the power supply noise level is high.

[0006]

Most of the power source noise is noise (harmonic noise) that is an integral multiple of the fundamental wave, and these are always present and their fluctuations are gradual. Therefore, if these noises can be removed, the S / N ratio can be dramatically improved. To remove harmonic noise, a comb filter that blocks frequency components that are integral multiples of the fundamental wave is effective. The comb filter is constructed by inverting a signal delayed by one cycle of the fundamental wave and adding it to the original signal. However, if the signal delayed by one cycle of the fundamental wave is simply inverted and added to the original signal, the superimposed signal is also filtered and the superimposed signal waveform is destroyed.

Therefore, the present invention provides a distribution line carrier comprising a transmitter for superimposing a transmission signal on a distribution line to transmit data, and a receiver for extracting the superimposed signal on the distribution line and demodulating the data. A transmitter is provided with transmission means for converting data to be transmitted for one cycle of the commercial power frequency into a transmission signal and superimposing it on a distribution line, and transmission timing control means for operating the transmission means for each cycle of the commercial power frequency. It is characterized in that the input signal is delayed by one cycle of the commercial power supply frequency and a comb filter for obtaining a difference component from the input signal is provided in the signal input section of the receiver.

[0008]

In the distribution line carrier according to the present invention, the transmission means provided on the transmitter side converts data to be transmitted for one cycle of the commercial power frequency into a transmission signal and superimposes it on the distribution line for transmission. The timing control means actuates the transmission means for each cycle of the commercial power frequency. As a result, for each cycle of the commercial power frequency, the data to be transmitted for one cycle is converted into a transmission signal and superimposed on the distribution line. Therefore, the signal superposition cycle and the non-signal cycle alternately appear for each cycle of the commercial power frequency. On the other hand, the signal input section of the receiver is provided with a comb filter that delays the input signal by one cycle of the commercial power supply frequency to obtain the difference component from the input signal.
Therefore, the fundamental wave component of the commercial power supply frequency and its harmonic component are removed very efficiently. In addition, since the signal for data transmission is not superimposed on the signal for one cycle for obtaining the difference component in the comb filter, the signal for data transmission is not filtered and the signal does not collapse. Therefore, reliable data transmission becomes possible with a very high S / N ratio.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a distribution line carrier according to an embodiment of the present invention is shown in FIGS.

FIG. 1 is a block diagram on the transmitter side. Figure 1
1 is a register for temporarily storing data to be transmitted. The modulation circuit 2 modulates the data serially output from the register 1 with the pseudo noise code output from the PN code generation circuit 3. The gate circuit 4 controls the output / stop of the modulation signal based on the signal output from the frequency dividing circuit 9. The output circuit 5 amplifies the transmission signal. Coupling circuit 6
Is, for example, an LC circuit that passes the frequency band of the superimposed signal. The power supply frequency clock generation circuit 8 generates a clock signal b synchronized with the commercial power supply frequency from the signal a extracted from the instrument transformer 7. The frequency dividing circuit 9 divides this power supply frequency clock signal by 1/2 and outputs the output / stop control signal c to the gate circuit 4 and the AND gate 11. The PLL circuit 10 multiplies the power supply frequency clock signal b and supplies a clock signal d having a constant cycle to the AND gate 11. AND
The gate 11 supplies the clock signal d output from the PLL circuit 10 to the register 1 as a read clock signal when the output signal of the frequency dividing circuit 9 is at "H" level.

Here, FIG. 3 shows the signal waveform of each part shown in FIG. In this way, the clock signal b synchronized with the power supply frequency signal a is generated, and based on this, the ½ frequency-divided signal c and the multiplied signal d are obtained.

With the above configuration, the register 1 shown in FIG. 1 is supplied with a read clock at, for example, an odd cycle of the commercial power supply frequency and stopped at an even cycle. Further, since the gate circuit 4 is controlled to open and close in synchronization with this, the transmission signal of the transmission data to be transmitted for one cycle is superimposed on the distribution line for each cycle of the commercial power frequency.

FIG. 2 is a block diagram of the receiver. In FIG. 2, the input circuit 21 detects a current signal from the distribution line. Reference numeral 24 is a comb filter including a delay circuit 22 and an adder circuit 23. The delay circuit 22 delays the input signal by one cycle of the commercial power frequency. The adder circuit 23 subtracts the delayed signal from the original signal to obtain the difference component. The bandpass filter 25 band-limits the received signal. A / D
The converter 26 samples the band-limited signal with a sampling clock that is doubled with the commercial power supply frequency and converts the signal into digital data. Correlator 27
Is correlated with the pseudo noise code generated by the PN code generation circuit 28, and is synchronized with the timing at which the correlation value reaches a peak. The demodulation circuit 29 demodulates data from the correlation value output.

FIG. 4 shows the relationship between the operation of the comb filter 24 shown in FIG. 2 and the demodulated data.

As described above, by subtracting the delayed signal delayed by one cycle from the original signal, the fundamental wave component of the commercial power supply frequency and the higher harmonic wave component are canceled and only the superimposed signal remains, and the data can be demodulated from this. it can. At this time, the polarity of the superimposed signal is inverted every cycle, but this does not affect the data demodulation, and either cycle may be adopted.

[0016]

According to the present invention, stationary power source noise such as harmonic noise superimposed on a distribution line is effectively removed, and a transmission signal is not broken. Therefore, data is transmitted in an extremely high SN ratio state. Can be demodulated, and reliable data transmission becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram on a transmitter side of a distribution line carrier which is an embodiment of the present invention.

FIG. 2 is a block diagram on the receiver side of the distribution line carrier device according to the embodiment of the present invention.

FIG. 3 is a waveform chart of each part in FIG.

FIG. 4 is a diagram showing a relationship between a signal in a comb filter and demodulated data.

[Explanation of symbols]

 24-comb filter

Claims (1)

[Claims] 1. A distribution line carrier comprising a transmitter that superimposes a transmission signal on a distribution line to transmit data, and a receiver that extracts the superimposed signal on the distribution line and demodulates the data. Transmission means for converting data to be transmitted in one cycle into a transmission signal and superimposing it on a distribution line;
The transmitter is provided with transmission timing control means for operating the transmission means for each cycle of the commercial power frequency, and the input signal is delayed by one cycle of the commercial power frequency,
A distribution line carrier, wherein a comb-shaped filter for determining a difference component from an input signal is provided in a signal input section of a receiver.