JPS62139423A - Spread spectrum power line carrier communication method and its equipment - Google Patents

Abstract

PURPOSE:To remove surely a periodical impulse noise included in a receiving signal by detecting the impulse noise included in the receiving signal and cancelling the receiving signal only by its generating period on the basis of a delayed receiving signal. CONSTITUTION:Since various conditions are set up so that the delay time of one period of AC power supply flowing into a power line, receiving signals supplied from a power line interface 1 are successively outputted from a delay element 16f as delayed receiving signals C inverted at their polarity after one period of the AC power supply. The delayed receiving signal C is selected only an impulse noise detecting signal ND generating period and supplied to an adder 17b so as to be added to the receiving signal supplied from the interface 1, so that the periodical impulse noise can be removed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a spread spectrum power line carrier communication method and device that utilizes a power line as a transmission path, and particularly relates to a spread spectrum power line carrier communication method and device that utilizes a power line as a transmission path, and in particular, the influence of periodic impulse noise synchronized with AC power flowing through the power line. The present invention relates to a spread spectrum power line carrier communication method and apparatus that avoids interference.

[Prior art]

Traditionally, when transmitting data using power lines,
Various methods are used depending on the type of transmission path. For example, in the case of a power transmission line transmission line, a single sideband modulation method is used, and in the case of a distribution line transmission line, a frequency modulation method or a phase modulation method is used. Power lines are not laid with data transmission in mind, so when attempting to transmit data, various types of noise may come in, or the transmission characteristics may change significantly depending on the load situation. Has a fluctuating problem. In other words, the high-frequency characteristics of a power line, regardless of whether it is a power transmission line or a power distribution line, have large corona noise and load noise, and vary greatly depending on the load state of the power line. Therefore, it is difficult to perform data transmission with high reliability, and particularly high-speed data transmission is impossible.

By the way, research has recently been underway to actively utilize spread spectrum communication methods in various fields.
An explanation of its principles and application fields is published in the Journal of the Institute of Electronics and Communication Engineers (Showa 5).
It is disclosed on page 956 of the September 7 issue and page 1035 of the October issue. This spread spectrum communication method is characterized by a wide spectrum spectrum and correlated reception, and when used for data transmission using power lines,
Because it is less susceptible to noise and transmission characteristics,
This makes it possible to transmit high-speed data with high reliability. In other words, this spread spectrum power line carrier communication system transmits narrowband transmission data by spreading the spectrum evenly over a wide band, so zero points occur in the transmission characteristics depending on the load condition of the power line. However, it will hardly be affected.

[Problem that the invention seeks to solve]

However, with the rapid development of semiconductor switches in recent years, power supply to various devices such as electric carpets connected to power lines is controlled by phase control. Here, since the phase control is to control the conduction angle of the semiconductor switch with respect to the AC power supply, impulsive noise is generated when the semiconductor switch is turned on and mixed into the power line. Since the phase control is performed every half cycle of the AC power supply, the impulsive noise generated with this phase control has a width of, for example, 0.1 to 1 m5ec synchronized with the AC power supply when the power control is stable. It has a relatively high level of quality.

As a result, when transmitting high-speed data of, for example, 9600 baud, the width of the impulsive noise generated in synchronization with the power supply is wider than the 1-bit period, so This has the problem that incoming transmission data cannot be reliably received.

[Means for solving problems]

Therefore, the spread spectrum power line carrier communication method and apparatus according to the present invention detects the relatively high level impulse noise generation period included in the spread spectrum modulated received signal sent from the transmitting side via the power line, and generates noise. By generating a detection signal and delaying the received signal for a period that is an integer multiple of the half cycle of the AC power flowing through the power line, the phase of the periodic impulse noise included in this delayed reception signal is adjusted to the phase of the AC power. The periodic impulse noise contained in the received signal is synchronized with the periodic impulse noise contained in the received signal received at a time delayed by an integral multiple of the half period, and the delayed received signal is used only during the period in which the noise detection signal is generated. It executes calculations to cancel periodic impulse noise.

[For production]

In the spread spectrum power line carrier communication method and device of the present invention, by delaying a spread spectrum modulated received signal sent from the transmitting side via a power line, periodic impulse noise contained in the delayed received signal is The delayed reception signal is used only during the generation period of the impulse noise detection signal, which detects the impulse noise contained in the reception signal and indicates the generation period. An operation is being performed to cancel the received signal. Therefore, the waveforms of the periodic impulse noise in the delayed received signal and the periodic impulse noise in the received signal match, and the waveforms of the periodic impulse noise in the received signal also match with a delay of a predetermined period. To this end, in the calculation section, only during the generation period of the impulse noise detection signal, the received signal and the delayed received signal are added with their polarities reversed, or the delayed received signal of the same polarity is subtracted from the received signal, etc. By performing the calculation, it becomes possible to reliably cancel the periodic impulse noise contained in the received signal with the periodic impulse noise contained in the delayed received signal. In this case, since the signal used to cancel the periodic impulse noise included in the received signal is generated by the predetermined periodic light under the same conditions, it is assumed that the waveform is sufficiently similar. This makes the cancellation operation more reliable.

After canceling the periodic impulse noise contained in the received signal in this way, by performing spectrum despread modulation on this received signal, it is possible to reliably extract the data sent from the transmitting side. Become.

〔Example〕

FIG. 1 is an overall configuration diagram for explaining an embodiment of a spread spectrum power line carrier communication method and apparatus according to the present invention. In the figure, reference numeral 1 denotes a power line interface connected to a power line 2 used as a communication path, which extracts spectrum and spread modulated signals supplied via the power line 2 as received signals, and transmits data through spread spectrum modulation. The transmitted signal is supplied to the power line as a transmission signal. Reference numeral 3 denotes an impulse noise canceling unit, which cancels periodic impulse noise synchronized with the AC power flowing through the power line 2 from among the impulse noise included in the received signal output from the power line interface 1. . 4 is a receiving amplifier that amplifies the received signal from which periodic impulse noise synchronized with the AC power source outputted from the impulse noise canceling unit 3 has been canceled; 5 is a receiving amplifier that demodulates the received signal outputted from the receiving amplifier 4 by spectrum despreading. A demodulator extracts received data A by determining the correlation between the M-sequence code M whose code pattern and phase match the M-sequence code used when modulating the received signal and the received signal supplied from the receiving amplifier 4. It is composed of a correlator 6. Reference numeral 7 denotes a synchronous M-sequence code generation unit that generates an M-sequence code M having a code pattern and phase matching the M-sequence code used during spread spectrum modulation on the transmitting side, and which generates a correlation state generated from the correlator 6. a synchronization control section 9 that controls the phase of the clock pulse CP generated from the clock pulse generation section 8 according to a level signal corresponding to the clock pulse generation section 8; The M-sequence code generator 10 generates an M-sequence code M having the same code pattern as the M-sequence code. Reference numeral 11 denotes a data processing unit that performs various processing on the reception data A output from the correlator 6 and sends out the transmission data B, and includes, for example, a central processing unit (
CPU). 12 is a modulation unit that performs spread spectrum modulation on the transmission data B sent out from the data processing unit 11 to generate a transmission signal,
It is constituted by a multiplier 13 that multiplies transmission data B and M-sequence code M. 14 is a transmission amplifier that amplifies the transmission signal sent out from the modulation section 12 and supplies it to the power line interface l.

FIG. 2 is a circuit diagram showing a specific example of the impulse noise canceling section 3 shown in FIG. 1. In the same figure, the impulse noise canceling unit 3 has a power line interface l.
an impulse noise detection section 15 that detects impulse noise contained in a received signal supplied from the 1000 MHz signal and outputs an impulse noise detection signal ND indicating the period of occurrence of the impulse noise; A delayed received signal C delayed for a period that is an integer multiple of and a calculation unit 17 that performs a calculation to cancel the delayed reception signal from the reception signal supplied from the power line interface 1 when the impulse noise detection signal ND is generated. ing.

The impulse noise detection section 15 includes an average detection circuit 15a that detects the average level of the received signal, and a variable resistor 15b that receives an average level signal output from the average detection circuit 15a. an adder 15C that adds the set value E to generate a reference value F obtained by level-shifting the average level signal by the set value E, a double-wave rectifier circuit 15d that double-wave rectifies the received signal, and the double-wave rectifier. circuit 1
and a comparator 15e which outputs an impulse noise detection signal ND when the output signal G of 5d exceeds the reference value E.

On the other hand, the received signal delay unit 16 includes an inverting amplifier 16a that inverts the polarity of the received signal, and a part of the AC power supply that supplies the received signal H whose polarity has been inverted by the inverting amplifier 16a to the power line 2.
and a delay circuit 16b which outputs a delayed received signal C by delaying it over a period of time. The delay circuit 16b includes a pulse oscillator 16d,
The direct output of this pulse oscillation circuit 16d and the inverter 16
e and the signal inverted by 1.e. Second clock φ1.
The delay element 16f such as a CCD or BBD sequentially shifts an input signal as φ2. and,
In this delay circuit 16b, as is generally known, when the oscillation frequency of the pulse oscillator 16d is fc and the number of stages of the delay elements 16f is N, the delay time t is as follows. Therefore, the delay element 16 whose stage number N is 4096
When the power supply frequency (50 C/S) is set to 1 using f, from the above (11), it is sufficient to set the oscillation frequency fc of the pulse oscillator 16d to =102.4 KHz.

On the other hand, the calculation unit 17 normally outputs a zero signal (earth level).
The analog switch 17a selects the delayed reception signal outputted from the reception signal delay unit 16 when the impulse noise detection signal ND is supplied, and outputs it as a cancellation signal ■, and the reception signal and the cancellation signal (2) and an adder 17b that adds .

In the device configured in this manner, for example, an AC power of 50 C/S as shown in FIG. When control is performed by phase control, periodic impulse noises N+, Nz, Nx synchronized with the phase of the AC power source are generated as shown in Figure 3(a).
. . . will be mixed into the AC power supply at a relatively high level.

In such a state, when a spread spectrum modulated signal is sent from the partner station (not shown) via the power line 2, the power line interface 1 receives this spread spectrum modulated signal as a received signal as shown in FIG. 3(b). Remove as shown. And the impulse noise N, contained in the AC power supply.

Nt, N3, . . . will also be mixed into the received signal extracted by the power line interface 1.

Here, in the impulse noise canceling section 3,
The average value detection circuit 15a shown in FIG. 2 performs average value detection on the received signal shown in FIG. By adding the set value E supplied from the variable resistor 15b, a reference value F whose level is shifted to a level sufficiently higher than the normal signal level is output. is for level-shifting the average level signal to a reference value F as an impulse noise detection level higher than the normal signal level.

The double-wave rectifier circuit 15d generates the output signal G shown in FIG. The signal is inverted from "L" to "H" and the impulse noise detection signal ND shown in FIG. A signal G exceeding the reference value F is determined to be a portion affected by impulse noise.

On the other hand, the inverting amplifier 162 provided in the received signal delay section 16 inverts and amplifies the polarity of the received signal, thereby supplying the received signal H to the delay circuit 16b. In the delay circuit 16b, the delay element 16f divides the direct output of the pulse oscillator 16d and the signal inverted by the inverter 16e into two.
Phase clock φ1. Since it is input as φ2, this 2
Phase clock φ1. Every time φ2 is supplied, the received signal H
are taken in sequentially and shifted. By repeating such operations, the delay time shown in the above equation (11) can be obtained with high accuracy.In this case,
20m5e, which is one cycle period of AC power flowing through power line 2
Since various conditions are set so that a delay time of c is obtained, the received signal supplied from the power line interface 1 is output from the delay element 16f as a delayed received signal C whose polarity is inverted after one cycle of the AC power supply. They will be output sequentially. The delayed reception signal C extracted in this manner is selected by the analog switch 17a only during the generation period of the impulse noise detection signal ND, and is sent to the adder 17b.
and is added to the received signal supplied from the power line interface 1.

Here, looking at the relationship between the impulse noise detection signal ND and the cancellation signal (■) output from the analog switch 17a, for example, the impulse detection section 15 detects the impulse noise N3 in FIG. 3(C) and outputs the impulse detection signal ND3. When the delayed reception signal C is generated from the reception signal delay unit 16, the delay time of the delay circuit 16 is equal to the length of one cycle (two half cycles) of the AC power flowing through the power line 2.
Impulse noise N3
This means that the impulse noise N1 just one cycle before is outputted with a reverse polar phase. As a result, when the analog switch 17a is switched by the noise detection signal ND3 only during the generation period of this signal, only the impulse noise N1 included in the delayed reception signal C generated from the delay circuit 16c has a reverse polarity. , it becomes a warning that it is output as a cancel signal I. Then, this cancellation signal ■ is sent to the adder 1
By being added to the received signal in step 7b, this cancellation signal I has the same waveform as the impulse noise signal N periodically included in the received signal in synchronization with the AC power supply, but only the polarity is reversed. Therefore, the two cancel each other out, and the received signal output from the adder 17b has periodic impulse noise removed.

In this way, the received signal from which periodic impulse noise has been removed is sent to the demodulator 5 shown in FIG. 1 via the receiving amplifier 4.
By supplying the received data A to the correlator 6 constituting the synchronous M-sequence code generating section 7, the correlation with the M-sequence code M supplied from the synchronous M-sequence code generating section 7 is determined, and spectrum despread demodulation is performed, thereby extracting the received data A. and is supplied to the data processing section 11. Further, the correlator 6 generates a signal indicating the correlation state between the received signal and the M-sequence code M, and supplies it to the synchronization control section 9. The synchronization control section 9 variably controls the oscillation frequency of the clock generation section 8 in accordance with the signal supplied from the correlator 6 so that the correlator 6 is in a completely correlated state. Here, when the frequency of the clock pulse CP generated by the clock generator 8 is varied, the M-sequence code generator 8 varies the phase of the M-sequence code M generated in accordance with the supply of this clock pulse CP. . Since such operations are repeated by closed-loop control, the generated M-sequence code is automatically synchronized with the M-sequence code used when modulating the received signal, and independent synchronization is established.

It should be noted that even for single impulse noise, the impulse noise detection signal N is output from the impulse noise detection circuit 15.
Since D is generated, the analog switch 17a is switched accordingly, and the signal that does not match the unity impulse noise is sent to the adder 17b as a cancellation signal ■.
Therefore, the received signal output from the adder 17b will be affected by the cancellation signal I, but the demodulation operation in the demodulation section involves finding the correlation with the receiving M-sequence code. Since the received data is taken out by the delay circuit 16b, there is no correlation between the cancellation signal delayed by the delay circuit 16b and the receiving M-sequence code M, and there is no influence due to this.

Next, when the data processing unit 11 confirms that the received data A does not exist, that is, that the receiving operation is not in progress (;11),
After switching to the transmission mode, the transmission data B is sent to the multiplier 13.
supply to. Here, in the transmission mode, the frequency of the clock pulse CP generated from the clock generation section 8 is fixed to a predetermined value, and the frequency of the clock pulse CP generated from the clock pulse CP is fixed at a predetermined value. An M-sequence code according to the conditions is generated and supplied to the multiplier 13. Therefore, the modulation section 12 constituted by the multiplier 13
outputs the narrowband transmission data B as a spectrum signal spread over a wide band by multiplying the transmission data B and the M-sequence code M. This spread spectrum modulation signal is amplified to a predetermined level in the transmission amplifier 14 as a transmission signal by spread spectrum communication, and then supplied to the power line 2 via the power line interface 1, thereby connecting the power line 2 to the transmission line. It is transmitted to the other party in a state where it is used as a

In the above embodiment, a case has been described in which the delay circuit 16b delays the received signal over one cycle period of the AC power flowing through the power line, but by delaying the received signal, periodic impulse noise contained therein is It is sufficient if the periodic impulse noise contained in the subsequent received signal is synchronized with the periodic impulse noise contained in the subsequent received signal. Therefore, when removing periodic impulse noise that is periodically generated every half cycle of the AC power supply, the minimum It is only necessary to delay the signal over a half cycle f, ljLJ, and in short, it is sufficient that the delay time is an integer multiple of the half cycle of the AC power supply.

Furthermore, in the above embodiment, a case has been described in which the received signal delay section 16 is provided with an inverting amplification section 16a, and the polarity of the delayed received signal C outputted from the received signal delay section 16 and the received signal are reversed. , they may have the same polarity as long as the arithmetic unit 17 performs subtraction processing and cancels them (,
Furthermore, when the delay time of the delay circuit 16b is set to half a cycle of the AC power supply, the polarity of the periodic impulse noise included in the received signal is inverted every half cycle, so the inverting amplifier 1
Even if 6a is not provided, the periodic impulse noise contained in the received signal and the analog switch 17a are activated in synchronization with the periodic impulse noise contained in the received signal.
The cancellation signal (periodic impulse noise included in the delayed reception signal) outputted from the signal (2) has opposite polarity. Furthermore, in the above embodiment, the inverting amplifier 16a,
Although the delay circuit 16b and the analog switch 17a are connected in this order, they may be connected in any order.

Further, in the above embodiment, the case where the impulse noise canceling section 3 is provided between the power line interface 1 and the receiving amplifier 4 has been described, but it can be placed at any position between the power line interface 1 and the demodulator 5. It's okay to have one.

〔Effect of the invention〕

As described above, the spread spectrum power line carrier communication method and apparatus according to the present invention delay the spread spectrum modulated received signal sent from the transmitting side via the power line, thereby reducing the amount of information contained in the delayed received signal. The phase of the periodic impulse noise contained in the received signal is matched with the periodic impulse noise contained in the received signal, and the delayed received signal is used only during the generation period of the impulse noise detection signal indicating the period of occurrence of the impulse noise contained in the received signal. The calculation is performed to cancel the received signal. Therefore, during the period in which the impulse noise detection signal is generated, the waveform and phase of the periodic impulse noise included in the received signal and the periodic impulse noise included in the delayed received signal match, so that both signals are mutually separated by arithmetic processing. Since the periodic impulse noise contained in the received signal can be reliably removed by canceling the periodic impulse noise, the periodic impulse noise mixed in from the power line can be removed by performing spectrum despread demodulation of the received signal from which this periodic impulse noise has been removed. This has an excellent effect of reliably extracting received data without being affected by impulse noise.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining an embodiment of the spread spectrum power line carrier communication method and apparatus according to the present invention, FIG. 2 is a circuit diagram showing an example of the impulse noise canceling section shown in FIG. 1, and FIG. (a) to (d+ are shown in Figure 1 and Figure 2.
FIG. 4 is a waveform chart showing the operation of each part for explaining the operation of the circuit shown in the figure. DESCRIPTION OF SYMBOLS 1... Power line interface circuit, 2... Power line, 3... Impulse noise canceling section, 4... Receiving amplifier, 5... Demodulating section, 6... Correlator, 7...
Synchronous M-series code generation section, 8... Clock generation section, 9.
...Synchronization control section, 10...M sequence code generation section, 11.
. . . Data processing section, 12 . . . Modulation section, 13 . . . Multiplier, 14 . . . Transmission amplifier, 15 .
Variable resistor, 15c... Adder, 15d... Double wave rectifier circuit, 15e... Comparator, 16... Received signal delay unit, 16a... Inverting amplifier, 16b... Delay circuit,
17... Arithmetic unit, 17a... Analog switch, 1
7b... Adder.

Claims (2)

[Claims] (1) A transmitting side and a receiving side are connected via a power line, and the transmitting side transmits a spread spectrum modulated signal to the receiving side via the power line, and the receiving side transmits a spread spectrum modulated signal to the receiving side. In spread spectrum power line carrier communication in which received data is extracted by spectrum despread demodulation of an incoming received signal, the receiving side delays the received signal extracted from the power line to eliminate periodic impulse noise contained in the delayed received signal. and periodic impulse noise included in the received signal, and cancel the received signal using the delayed received signal only during the period in which the impulse noise included in the received signal occurs. A spread spectrum power line carrier communication method characterized by performing spectrum despread demodulation after removing periodic impulse noise contained in a signal. (2) Consists of a transmitting device and a receiving device connected via a power line, the transmitting device transmits a signal spread spectrum modulated on transmission data to the receiving device via the power line, and the receiving device In a spread spectrum power line carrier communication device, the spread spectrum power line carrier communication device extracts a spread spectrum modulated reception signal sent from a transmitting device via an interface, and then performs spectrum despread demodulation in a demodulation section to extract reception data. and the demodulation unit, and a reception signal delay unit that delays the reception signal and matches the phase of the periodic impulse noise included in the delayed reception signal and the periodic impulse noise included in the reception signal. and a process of canceling periodic impulse noise included in the received signal using the delayed received signal output from the received signal delay unit during a period in which the impulse noise detection signal is output from the impulse noise detector. What is claimed is: 1. A spread spectrum power line carrier communication device, comprising: an impulse noise canceling section constituted by a calculating section;