JPH0923174A - Power line carrier communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable power line carrier communication equipment even in the case of a power line in an inferior transmission environment in respect to communication data demodulation applying spread spectrum communication technology to a power line carrier communication equipment. SOLUTION: An SS communication type receiving means is constituted of plural BPFs 51 to 53 having respectively different pass frequency bands, amplifying means 61 to 63, inverse diffusion means 71 to 73 and data demodulating means 81 to 83 which correspond to the number of BPFs 51 to 53, and a majority means 9. Since each frequency band is sufficiently amplified in accordance with the levels of a signal and a noise, data corresponding to the SN ratio of the band are demodulated and the majority of the whole frequency bands is found out, accurate data demodulation can be attained even when the SN ratio of a partial frequency band with a high signal level is deteriorated and a signal level is low in other frequency bands having sufficiently high SN ratios, so that the SN ratio of the whole bands can be improved and highly reliable communication can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to data demodulation of communication in which spread spectrum communication technology is applied to a power line carrier communication device.

[0002]

2. Description of the Related Art In conventional power line carrier (hereinafter abbreviated as PLC) communication, impedance matching (hereinafter abbreviated as imp.) Is impossible in a power line (hereinafter abbreviated as PL) unlike a normal communication dedicated line. Due to a certain thing and a strong noise of a device which is arbitrarily connected to the PL, the communication reliability thereof has been remarkably lowered. Therefore, in recent years, in order to overcome the above-mentioned problems, spread spectrum (hereinafter abbreviated as SS) communication technology has been applied to PLC communication.

In SS communication, as shown in FIG. 5, on the transmission side, the spreading code generated by the spreading code generating means 2 and the input data are multiplied by the first modulating means 3, and further the second modulating means 4 is used. At the receiving side, a wideband modulated signal obtained as a result of multiplication with the carrier generated by the transmitting means 1 is transmitted, and at the receiving side, a bandpass filter (hereinafter, referred to as B
The received signal received via the PF (abbreviated as PF) 50 is amplified by the amplifying means 60 and returned to an ordinary narrow band signal by the despreading means 70, and demodulated data is obtained by the data demodulating means 80.

[0004]

However, as shown in FIG. 6 (a), the characteristics of the PL as a transmission line are such that the noise in the bright line spectrum is dominant, and in FIG. 6 (b). As illustrated, depending on the type of source, it is divided into a low frequency center, an intermediate frequency center, and a high frequency center, and the attenuation is inversely proportional to the frequency as illustrated in FIG. Simple decay and imp. Since it is a combination of frequency selective resonance attenuation due to mismatch, the S / N of the received signal is often not good as a whole, and even if the received signal is amplified, the S / N ratio is not always good.
Since / N cannot be improved, communication reliability cannot be expected to improve even though the SS method is adopted.

The present invention solves the above problems, and an object of the present invention is to provide a power line carrier communication device having high reliability even in a PL having poor characteristics.

[0006]

To achieve the above object,
The power line carrier communication device of the present invention includes a transmitting means adopting an SS communication system and a plurality of BPFs having different pass frequency bands.
And the receiving means having the same number of amplifying means, despreading means and data demodulating means as the BPF, and one majority decision means.

Further, it is assumed that the plurality of BPFs have the same cutoff frequency on the high frequency side and have different cutoff frequencies on the low frequency side, and the majority decision means is composed of an addition means and a comparison means to improve the feasibility. I am raising.

[0008]

With the above construction, sufficient amplification can be performed according to the signal and noise levels for each frequency band, and the data corresponding to the S / N can be demodulated to take the majority decision, so that some Even if the S / N is degraded in the signal level frequency band, sufficient amplification is possible and accurate data demodulation can be performed in other frequency bands with a sufficient S / N even if the signal level is low. As a result, it is equivalent to the improvement of S / N, and highly reliable communication is established.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. Since the transmitting side has the same configuration as the above-mentioned conventional example, description thereof will be omitted. On the receiving side, 5 is a BPF section, which is the first BPF 5.
1, 2nd BPF52, 3rd BPF53, 6
Is an amplifying section, which is a first amplifying means 61, a second amplifying means 62,
The third amplifying means 63 comprises a despreading section 7 which comprises a first despreading means 71, a second despreading means 72 and a third despreading means 73, and 8 a data demodulation section. The data demodulation means 81, the second data demodulation means 82, and the third data demodulation means 83, and 9 is a majority decision means.

The operation of the power line carrier communication apparatus configured as described above will be described with reference to the spectrum waveform diagram of FIG.

Now, assuming that the output of the transmission signal is transmitted with the spectrum waveform of the broken line in FIG. 2 (b), the signal is PL
While passing through the upper part and reaching the receiving side, the signal is attenuated to form the received signal spectrum waveform shown in the figure, and noise as shown in the figure is also added. When the sum of the attenuated signal and the noise is input to the BPF unit 5 on the receiving side, FIG.
The frequency band is 3 by the first BPF 51, the second BPF 52, and the third BPF 53 having the bandpass characteristics shown in FIG.
Then, the first amplification means 61, the second amplification means 62, and the third amplification means 63 perform appropriate amplification for each frequency band like the output of the amplification means of FIG. 2C. Then, the first despreading means 71, the second despreading means 72, and the third despreading means 73 restore the narrow band signal for each frequency band to the first data demodulating means 81. The data is demodulated by the second data demodulation means 82 and the third data demodulation means 83, and finally, the majority decision means 9
The plausible data is obtained from the demodulated data of the three systems by majority voting. In the case of the conventional example, as shown in FIG. 2B, since one data is demodulated from the received signal having a poor S / N and the sum of noise, the reliability of communication becomes poor, but according to the present embodiment. As is apparent from the output of the amplifying means of FIG. 2C, since the independent amplification, despreading and data demodulation processes are performed after the band division, the system of the first BPF 51 having a poor signal S / N ratio. The demodulated data of is likely to be incorrect, but it can be said that the demodulated data of the second BPF 52 and the third BPF 53 are correct because the S / N of the signal is good. The result will be extremely reliable.

Next, a second embodiment of the present invention will be described with reference to the block diagrams of FIGS. 3 and 4.

FIG. 3B shows an embodiment of the BPF 5, which is one high-pass filter (hereinafter abbreviated as HPF) 54, a first low-pass filter (hereinafter abbreviated as LPF) 55, a second LPF 56, and a third LPF 56. The LPF 57 is composed of three LPFs having different cutoff frequencies, and its bandpass characteristic is shown in FIG.
As shown in (a), the cutoff frequencies on the high frequency side are all the same, and the cutoff frequencies on the low frequency side are different from each other. Now, considering the noise in FIG. 6, since the noise is inversely proportional to the frequency, even if the intermediate frequency band or the high frequency band is originally allowed to pass only the low frequency band, the S / N of the system is passed. Does not have a large effect on the S / N of the system even if the high frequency band is allowed to pass where only the intermediate frequency band should be allowed to pass, and a small amount of noise is taken in. On the contrary, improvement of S / N can be expected, and the configuration becomes simple.

FIG. 4 shows an embodiment of the majority decision means 9. In FIG. 4A, 91 is an addition means and 92 is a comparison means. The demodulated data of the three systems described above are added by the adding means 91, and then the comparing means 92 determines whether the data is "0" or "1". However, the characteristic of the influence of the bright line spectrum noise on the PL on the demodulated data is that "0" and "1" of the data are not completely inverted, but the central value of the data demodulated output signal voltage is "0" or " Since each data demodulation means does not include a data determination means for determining "0" or "1" of the data, the reliability of the data after the majority decision is increased. For example, even if the center value of the data demodulation output signal voltage shifts up to 2 out of 3 systems due to noise, the data demodulation output signal voltage of the remaining 1 system is firm and the shift of the other 2 systems If there is a surplus of the above, the final data will be correct. Therefore, in consideration of this, FIG. 4A is more concretely shown in FIG. 4B. 93, 94,
Reference numeral 95 is a first, second and third resistance, 96 is a fourth LPF for adjusting the cutoff frequency to the data transmission rate, and 97 is a comparator IC. The three resistors 93, 94, 95 and the fourth LPF 96 constitute an adding means, and the added output is input to the comparator IC 97 and the result of comparison with the reference voltage 98 is output as final data. .
By doing so, it is possible to obtain the final demodulated data with a much higher reliability even with a simple configuration.

[0016]

As described above, according to the present invention, the transmitting means adopting the SS communication system and the plurality of B's having different pass frequency bands are provided.
It is basically composed of a PF, a receiving means having a same number of amplifying means, despreading means and data demodulating means as the BPF, and one majority decision means. Furthermore, a plurality of BPFs have cutoff frequencies on the high frequency side. It is assumed that all are the same but have different cut-off frequencies on the low frequency side, and the majority means is composed of an adding means and a comparing means, so that S /
It is possible to realize an excellent power line carrier communication device capable of obtaining demodulated data with sufficiently high reliability even from a received signal with a poor N.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a signal spectrum waveform diagram for explaining the first embodiment. FIG. 2A is a bandpass characteristic diagram of the bandpass filter of the first embodiment. FIG. 2B is a transmission signal and reception of the first embodiment. Signal diagram (c) is an output diagram of each amplifying means of the first embodiment.

FIG. 3A is a bandpass characteristic diagram of the bandpass filter of the second embodiment. FIG. 3B is a block diagram of the bandpass filter of the second embodiment.

FIG. 4A is a block diagram of a majority decision means of the second embodiment, and FIG. 4B is a circuit diagram of a majority decision means of the second embodiment.

FIG. 5 is a block diagram showing an example of a conventional SS communication type power line carrier communication device.

FIG. 6A is a noise spectrum waveform diagram on the power line, and FIG. 6B is a noise distribution diagram by source on the power line.

FIG. 7 is a signal transmission characteristic diagram of a power line.

[Explanation of symbols]

 1 Transmitting Means 2 Spreading Code Generating Means 3 First Modulating Means 4 Second Modulating Means 5 Bandpass Filters 6 Amplifiers 7 Despreaders 8 Data Demodulators 9 Majority Means 50 Bandpass Filters 51 First Bandpass Filters 52 Second Band Pass Filter 53 Third Band Pass Filter 54 High Pass Filter 55 First Low Pass Filter 56 Second Low Pass Filter 57 Third Low Pass Filter 60 Amplifying Means 61 First Amplifying Means 62 Second Amplifying Means 63 third amplification means 70 despreading means 71 first despreading means 72 second despreading means 73 third despreading means 81 data demodulating means 82 first data demodulating means 83 second data demodulating means 84 Third data demodulation means 91 Addition means 92 Comparison means 93 First resistance 94 Second resistance 95 Third resistance Resistor 96 Fourth low-pass filter 97 Comparator IC 98 Reference voltage

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Satoshi Shinozaki Satoshi Shinozaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Incorporated (72) Inventor Satoru Yoneya 3-22 Nakanoshima, Kita-ku, Osaka, Osaka Prefecture 3-22 Kansai Electric Power Co., Inc. Masaya Takashima 3-22 Nakanoshima, Kita-ku, Osaka, Osaka Kansai Electric Power Co., Inc.

Claims (4)

[Claims] 1. A power line carrier communication device that shares a power line as a transmission medium for high-frequency signals, comprising: a transmitting means using a spread spectrum communication system; and a receiving means for extracting and demodulating a spread spectrum information signal from the power line. The receiving means comprises a plurality of bandpass filters having different pass frequency bands, and a plurality of amplifying means for amplifying the output signals of the plurality of bandpass filters according to the pass frequency bands of the respective bandpass filters. , A plurality of despreading means for despreading the output signals of the plurality of amplification means, a plurality of demodulation means for demodulating the output signals of the plurality of despreading means, and a majority decision of the output signals of the plurality of demodulation means And a majority decision unit for outputting one demodulated data as a power line carrier communication device. 2. A power line carrier communication device that shares a power line as a transmission medium for high frequency signals, comprising: receiving means for extracting and demodulating a spectrum spread information signal from the power line, wherein the receiving means is a pass frequency band. A plurality of different bandpass filters, a plurality of amplification means for amplifying the output signals of the plurality of bandpass filters according to the pass frequency band of each bandpass filter, and despreading the output signals of the plurality of amplification means A plurality of despreading means, a plurality of demodulation means for demodulating the output signals of the plurality of despreading means, and a majority decision means for taking a majority decision of the output signals of the plurality of demodulation means and outputting one demodulated data. An electric power line carrier communication device having. 3. The power line carrier communication device according to claim 1, wherein the plurality of bandpass filters have the same cutoff frequency on the high frequency side and have different cutoff frequencies on the low frequency side. . 4. The majority decision means includes an addition means for adding the output signals of a plurality of demodulation means, and a comparison means for comparing the output signal of the addition means with a predetermined reference signal. The power line carrier communication device according to 1, 2, or 3.