JP2002374190A - Power line communication device and power line communication system - Google Patents

Abstract

(57) [Problem] To provide a power line communication device and a power line communication system capable of transmitting data reliably and at high speed using a power line. SOLUTION: An AGC circuit 14 for amplifying an inputted OFDM modulated signal to a fixed level, an OFDM demodulating circuit 15 for demodulating the amplified OFDM modulated signal, and an OFD circuit
An OFDM modulation circuit 17 for M-modulating and outputting an OFDM modulation signal; an ALC circuit 16 for amplifying the OFDM modulation signal from the OFDM modulation circuit 17 to a required level;
And a control section 18 having a reception signal level detection circuit 19 for controlling the entire circuit including the circuit 16 and detecting the reception signal level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power line communication device and a power line communication system for performing communication via a power line.

[0002]

2. Description of the Related Art Conventionally, spread spectrum power line communication has been proposed as a method for transmitting data using a power line, and communication is always performed to a required minimum transmission power according to a change in transmission characteristics of the power line. A spread spectrum power line communication device is disclosed in Japanese Patent Application Laid-Open No. 62-92526.

FIG. 4A is a block diagram showing a spread spectrum power line communication device as a power line communication device disclosed in the official gazette, and FIG. 4B shows an ALC circuit constituting the device of FIG. It is a block diagram.

In FIG. 4, reference numeral 10 denotes a power line, 14 denotes an AGC circuit for amplifying a spread spectrum modulation signal input from the power line 10 via a coupler 22 to a predetermined level, and 16 denotes a spread spectrum signal from a spread spectrum modulation circuit 21 to be described later. ALC circuit that amplifies the modulated signal to the required level,
Reference numeral 18 denotes a control unit for controlling the whole, 20 denotes a spread spectrum demodulation circuit that demodulates a spread spectrum modulation signal output from the AGC circuit 14, and 21 denotes a spread spectrum modulation circuit that performs spread spectrum modulation on data and outputs a spread spectrum modulation signal. , 161 is an amplifier for adjusting the output level to a required level, 162 is a detection circuit for detecting a spread spectrum modulation signal from the coupler 22 to obtain a reception signal level, and 163 is a reference voltage based on an instruction from the control unit 18. The generated reference voltage generation circuit 164 detects an error between the reference voltage from the reference voltage generation circuit 163 and the level of the received signal from the detection circuit 162, and controls the output level of the amplifier 161 based on the detection error. Circuit.

[0005] In FIG. 4, as described above, the error detection circuit 164 detects an error between the reference voltage from the reference voltage generation circuit 163 and the received signal level from the detection circuit 162, and based on the detection error. Since the output level of the amplifier 161 is controlled, the ALC circuit 16
A transmission signal of a constant level corresponding to the reference voltage is output.

[0006]

However, in the above-mentioned conventional power line communication apparatus, a spread spectrum method which is considered to be strong in noise and transmission characteristics is used. However, there is a problem that high-speed transmission has a limit. In addition, transmission may be performed at a transmission power level that is not optimal depending on a change in transmission characteristics, and there is a problem that reliable communication cannot be performed. To this end, various transmission power control devices have been proposed. . However, these are generally power line communication devices for low-speed data transmission and have a problem that they are insufficient for power line communication for high-speed data transmission.

The power line communication device and the power line communication system are required to be able to transmit data reliably and at high speed using the power line.

In order to satisfy this demand, the present invention provides a power line communication device capable of transmitting data reliably and at high speed using a power line, and a power line communication capable of transmitting data reliably and at high speed using a power line. The purpose is to provide a system.

[0009]

To solve the above-mentioned problems, a power line communication apparatus according to the present invention comprises an AGC circuit for amplifying an inputted OFDM modulated signal to a fixed level, and an amplified OFC circuit.
OFDM demodulation circuit for demodulating a DM modulation signal, and OFDM for OFDM modulating data and outputting an OFDM modulation signal
A modulation circuit, an ALC circuit for amplifying the OFDM modulation signal from the OFDM modulation circuit to a required level, and a control unit having a reception signal level detection circuit for controlling the whole including the ALC circuit and detecting the reception signal level It has a configuration.

Thus, a power line communication device capable of transmitting data reliably and at high speed using the power line can be obtained.

[0011] In order to solve the above problems, a power line communication system of the present invention is a power line communication system having a master unit and a slave unit communicating with the master unit via a power line. An AGC circuit for amplifying the OFDM modulated signal to a fixed level, and an OGC circuit for demodulating the amplified OFDM modulated signal
FDM demodulation circuit, OFDM modulates data and OFDM
An OFDM modulation circuit that outputs a modulation signal, an ALC circuit that amplifies the OFDM modulation signal from the OFDM modulation circuit to a required level, and a reception signal level detection circuit that controls the entire ALC circuit and detects a reception signal level The slave unit has an OFDM demodulation circuit for demodulating an input OFDM modulated signal, and an OFDM demodulation circuit for demodulating data.
An OFDM modulation circuit that modulates and outputs an OFDM modulation signal, an ALC circuit that amplifies the OFDM modulation signal from the OFDM modulation circuit to a required level, and a control unit that controls the whole including the ALC circuit are provided. I have.

Thus, a power line communication system capable of transmitting data reliably and at high speed using the power line can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power line communication apparatus according to a first aspect of the present invention includes an AGC circuit for amplifying an inputted OFDM modulated signal to a fixed level, an OFDM demodulating circuit for demodulating the amplified OFDM modulated signal, An OFDM modulation circuit that OFDM modulates the signal and outputs an OFDM modulation signal;
A control circuit having an ALC circuit for amplifying an OFDM modulation signal from a DM modulation circuit to a required level, and a control unit having a reception signal level detection circuit for controlling the whole including the ALC circuit and detecting a reception signal level It is.

With this configuration, the transmission output level of the OFDM modulated signal in the ALC circuit can be controlled in accordance with the received signal level.
It is possible to sufficiently cope with such a change, and it is possible to transmit data reliably and at high speed.

According to a second aspect of the present invention, in the power line communication apparatus according to the first aspect, the control unit includes an OFDM modulation circuit when the reception signal level detected by the reception signal level detection circuit is insufficient. Control the ALC circuit to increase the transmission output level of the OFDM modulated signal from
If the detected received signal level is excessive, the ALC circuit is controlled so as to lower the transmission output level of the OFDM modulation signal from the OFDM modulation circuit.

With this configuration, the transmission output level of the OFDM modulated signal is controlled according to the received signal level.
Even if the transmission characteristics change, it is possible to sufficiently cope with the change, and it is possible to transmit data reliably and at high speed.

According to a third aspect of the present invention, in the power line communication apparatus according to the first aspect, the control unit first controls the ALC so as to minimize the transmission output level of the OFDM modulation signal from the OFDM modulation circuit. Circuit, and if there is no response from the partner device, the ODM
The ALC circuit is controlled so that the transmission output level of the FDM modulation signal is increased step by step.

According to this configuration, it is possible to perform communication with the minimum necessary transmission power with respect to the fluctuation of the transmission characteristic, so that the power consumption and the unnecessary radiation can be reduced.

According to a fourth aspect of the present invention, in the power line communication apparatus according to the first aspect, the control unit first controls the ALC so as to maximize the transmission output level of the OFDM modulation signal from the OFDM modulation circuit. The circuit is controlled, and the ALC circuit is controlled so as to lower the transmission output level according to the detected reception signal level.

According to this configuration, it is possible to establish reliable communication from the beginning, and thus to quickly establish reliable communication.

According to a fifth aspect of the present invention, in the power line communication apparatus according to the first aspect, the control unit first sets the ALC so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit is intermediate. The circuit is controlled, and the ALC circuit is controlled so as to increase or decrease the transmission output level according to the detected reception signal level.

This configuration has the effect of being able to cope with fluctuations in transmission characteristics at an intermediate level where communication is likely to be established.

According to a sixth aspect of the present invention, in the power line communication apparatus according to the first aspect, the control unit determines the state of the received signal based on transmission quality such as a packet error rate, and determines a result of the determination. ODM from the OFDM modulation circuit
A so that the transmission output level of the FDM modulated signal is appropriate
This is to control the LC circuit.

This configuration has the effect of improving the communication accuracy by changing the transmission power level in consideration of not only the attenuation due to the transmission path but also the influence of noise from other electric devices.

According to a seventh aspect of the present invention, in the power line communication device according to any one of the first to sixth aspects, the control unit controls the transmission output level in the ALC circuit for each packet. It was done.

According to this configuration, there is an effect that it is possible to promptly respond to the state fluctuation of the power line.

According to a power line communication apparatus described in claim 8, in the power line communication apparatus according to any one of claims 1 to 7, the control unit controls the transmission output level in the ALC circuit at an arbitrary timing. It is what it was.

This configuration has the effect of improving the communication rate in an impulse noise environment.

According to a ninth aspect of the present invention, in the power line communication apparatus according to any one of the first to eighth aspects, the control unit controls the transmission output level in the ALC circuit only for the subcarriers that need to be controlled. It was decided to do it.

This configuration has the effect of suppressing the average power of transmission.

A power line communication system according to a tenth aspect is a power line communication system having a master unit and a slave unit that communicates with the master unit via a power line, wherein the master unit transmits an input OFDM modulated signal. AGC circuit for amplifying to a certain level, OFDM demodulation circuit for demodulating the amplified OFDM modulation signal, OFDM modulation circuit for OFDM modulating data and outputting OFDM modulation signal, and OFDM modulation signal from OFDM modulation circuit at required level And a control unit having a reception signal level detection circuit for controlling the whole including the ALC circuit and detecting a reception signal level. The slave unit is an OFDM for demodulating an input OFDM modulation signal. A demodulation circuit and OFDM-modulate data
An OFDM modulation circuit that outputs an FDM modulation signal;
An ALC circuit that amplifies the OFDM modulated signal from the M modulation circuit to a required level and a control unit that controls the whole including the ALC circuit are provided.

According to this configuration, the master unit can transmit a transmission power control signal corresponding to the received signal level to the slave unit, thereby realizing a power line communication system capable of coping with fluctuations in transmission characteristics even when the slave unit has a simple configuration. Has the effect of being able to

The power line communication system according to claim 11 is the power line communication system according to claim 10,
The control unit of the master unit controls the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit becomes the maximum, and when there is no response from the slave unit, instructs the ALC circuit to stop transmission. It is decided to do.

This configuration has the effect of protecting a slave unit in an abnormal state.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a block diagram showing a power line communication apparatus according to Embodiment 1 of the present invention.

In FIG. 1, 10 is a power line, 11 is an outlet for connecting to the power line 10, 12 is a plug connected to the outlet 11, and 13 is connected to the power line 10 via the plug 12 and the outlet 11 for communication. A coupler section 14 for OFDM (Orth
ogonal Frequency Divisi-o
n Multiplex, orthogonal frequency division multiplexing) AGC circuit for amplifying a modulated signal to a fixed level, and 15 an OFDM for demodulating the OFDM modulated signal amplified by the AGC circuit 14
The demodulation circuit 16 receives an ODM signal from an OFDM modulation circuit 17 described later.
An ALC circuit that amplifies the FDM modulated signal to a required level,
Reference numeral 17 denotes an OFDM modulation circuit that performs OFDM modulation on data to output an OFDM modulation signal, and reference numeral 18 denotes a control unit that has a reception signal level detection circuit 19 that controls the entire operation including the ALC circuit 16 and detects a reception signal level.

The operation of the power line communication device thus configured will be described.

Various home appliances are connected to the power line 10, and as a result, the noise characteristics and impedance characteristics of the power line 10 are undefined. In such an environment, the power line communication signal (OFDM modulated signal) is amplified from the plug 12 to a level sufficient for demodulation by the AGC circuit 14 via the coupler unit 13, and is subjected to discrete Fourier transform by the OFDM demodulation circuit 15. Demodulated. From the demodulated result, the received signal level is obtained by the received signal level detection circuit 19, and the necessary transmission power control signal a
Passed to.

Here, FIG. 2 shows the effectiveness of the transmission power control by the OFDM method.

FIG. 2 is a graph showing an OFDM spectrum in which a plurality of subcarriers are arranged.
The vertical axis indicates amplitude, and the horizontal axis indicates frequency. The transmission state of the power line 10 is indefinite, but the attenuation is generally larger in a higher frequency range. That is, the reception level of # N25 is lower than that of # N10. Therefore, by increasing the transmission power in the higher frequency range, efficient power control becomes possible. Naturally, it is possible to control an arbitrary subcarrier in the state of the power line 10 without being limited to the high frequency region.

As described above, according to the present embodiment, the AGC circuit 14 amplifies the input OFDM modulated signal to a certain level, and the OFD circuit demodulates the amplified OFDM modulated signal.
M demodulation circuit 15 and OFDM-modulate data to OFDM
An OFDM modulation circuit 17 for outputting a modulation signal;
It has an ALC circuit 16 for amplifying the OFDM modulation signal from the modulation circuit 17 to a required level, and a control unit 18 having a reception signal level detection circuit 19 for controlling the whole including the ALC circuit 16 and detecting the reception signal level. This makes it possible to control the transmission output level of the OFDM modulated signal in the ALC circuit 16 in accordance with the received signal level. Can be transmitted.

When the received signal level detected by the received signal level detection circuit 19 is insufficient, the control unit 18 controls the ALC circuit 16 to increase the transmission output level of the OFDM modulation signal from the OFDM modulation circuit 17. If the ALC circuit 16 is controlled to lower the transmission output level of the OFDM modulation signal from the OFDM modulation circuit 17 when the detected reception signal level is excessive, the OFDM modulation signal is controlled according to the reception signal level. Is controlled, so that even if the transmission characteristics change, it is possible to sufficiently cope with the change and to transmit data reliably and at high speed.

Further, the control unit 18 controls the ALC circuit 16 so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit 17 is minimized at first. O from circuit 17
If the ALC circuit 16 is controlled so as to gradually increase the transmission output level of the FDM modulation signal in a stepwise manner, communication can be performed with a minimum necessary transmission power with respect to fluctuations in transmission characteristics. Power and unnecessary radiation can be reduced.

Further, the control unit 18 controls the ALC circuit 16 so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit 17 is maximized at first, and changes the transmission output level according to the detected reception signal level. A to lower
If the LC circuit 16 is controlled, reliable communication can be established from the beginning, and thus quick communication can be reliably established.

Further, the control unit 18 controls the ALC circuit 16 so that the transmission output level of the OFDM modulated signal from the OFDM modulation circuit 17 is initially set at an intermediate level, and adjusts the transmission output level according to the detected received signal level. If the ALC circuit 16 is controlled to move up and down, it is possible to cope with fluctuations in the transmission characteristics at an intermediate level at which communication is likely to be established.

Further, the control unit 18 determines the state of the received signal based on the transmission quality such as the packet error rate, and the transmission output level of the OFDM modulation signal from the OFDM modulation circuit 17 becomes appropriate according to the determination result. If the ALC circuit 16 is controlled as described above, it is possible to improve the communication accuracy by changing the transmission power level in consideration of not only the attenuation due to the transmission path but also the influence of noise from other electric devices.

Further, if the control section 18 controls the transmission output level in the ALC circuit 16 for each packet, it can quickly respond to a power line state change.

Further, if the control section 18 controls the transmission output level in the ALC circuit 16 at an arbitrary timing, the communication rate in an impulsive noise environment can be improved.

Furthermore, if the control section 18 controls the transmission output level in the ALC circuit 16 only for the necessary subcarriers, it is possible to suppress the average transmission power.

(Embodiment 2) FIG. 3 is a block diagram showing a power line communication system according to Embodiment 2 of the present invention.

In FIG. 3, the power line 10, the outlet 1
1, plug 12, coupler section 13, AGC circuit 14, OF
The DM demodulation circuit 15, the ALC circuit 16, the OFDM modulation circuit 17, the control unit 18, and the reception signal level detection circuit 19 are shown in FIG.
Therefore, the same reference numerals are given and the description is omitted. Reference numeral 1 denotes a master unit, and 2 denotes a slave unit that communicates with the master unit 1 via the power line 10.

The operation of the power line communication system thus configured will be described.

As shown in FIG. 3, in the present embodiment, for simplification of the circuit, the AGC circuit 14 and the control unit 18 are connected to the opposing device (here, the slave unit 2 opposed to the master unit 1). The transmission power control signal a is transmitted from the base unit 1 without receiving the reception signal level detection circuit 19, and the transmission power control signal b output from the control unit 18 receives the transmission power control signal a. Perform control. Thereby, it is possible to cope with the fluctuation of the transmission characteristics with a simple circuit.

As described above, the slave unit 2 has the AGC circuit 1
4 and the received signal level detection circuit 19 are not mounted, and transmit the required transmission power instructed by the base unit 1. Handset 2
, The link is ideally established once, but when calling from the base unit 1, a plurality of times are required to optimize the transmission power level in the slave unit 2. Despite this, the circuit can be simplified.

As described above, according to the present embodiment, a power line communication system including master device 1 and slave device 2 that communicates with master device 1 via power line 10 is provided. AGC circuit 14 for amplifying input OFDM modulated signal to a fixed level, and OFD for demodulating amplified OFDM modulated signal
M demodulation circuit 15 and OFDM-modulate data to OFDM
An OFDM modulation circuit 17 for outputting a modulation signal;
An ALC circuit 16 for amplifying the OFDM modulation signal from the modulation circuit 17 to a required level, and a control unit 18 having a reception signal level detection circuit 19 for controlling the whole including the ALC circuit 16 and detecting the reception signal level are provided. The handset 2 requires an OFDM demodulation circuit 15 for demodulating the input OFDM modulation signal, an OFDM modulation circuit 17 for OFDM modulating data and outputting an OFDM modulation signal, and an OFDM modulation signal from the OFDM modulation circuit 17. By having the ALC circuit 16 that amplifies the level up to the level and the control unit 18 that controls the whole including the ALC circuit 16, the base unit 1 transmits the transmission power control signal a corresponding to the received signal level to the slave unit 2. Therefore, it is possible to realize a power line communication system capable of coping with fluctuations in transmission characteristics even when the slave unit 2 has a simple configuration.

The control unit 18 of the base unit 1 controls the ALC circuit 16 so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit 17 is maximized. Instructs the ALC circuit 16 to stop transmission, so that the slave unit 2 in an abnormal state can be protected.

[0058]

As described above, according to the power line communication apparatus of the first aspect of the present invention, an AGC circuit for amplifying an input OFDM modulated signal to a fixed level, and an amplified ODM circuit.
OFDM demodulation circuit for demodulating an FDM modulated signal and OFD for OFDM modulating data and outputting an OFDM modulated signal
An MLC circuit, an ALC circuit for amplifying the OFDM modulated signal from the OFDM modulator circuit to a required level, and a control unit having a received signal level detection circuit for controlling the whole including the ALC circuit and detecting the received signal level. By having this, the transmission output level of the OFDM modulated signal in the ALC circuit can be controlled according to the received signal level, so that even if the transmission characteristics change, it is possible to sufficiently cope with the change, and to achieve a reliable and high-speed operation. This has the advantageous effect that data can be transmitted to a computer.

According to the power line communication device of the second aspect, in the power line communication device of the first aspect, the control unit is configured to perform the OFDM operation when the reception signal level detected by the reception signal level detection circuit is insufficient. OFDM from modulation circuit
The ALC circuit is controlled so as to increase the transmission output level of the modulation signal. If the detected reception signal level is excessive, OFD
By controlling the ALC circuit to lower the transmission output level of the OFDM modulation signal from the M modulation circuit, the transmission output level of the OFDM modulation signal is controlled in accordance with the reception signal level. , It is possible to sufficiently cope with the change, and it is possible to obtain an advantageous effect that data can be transmitted reliably and at high speed.

According to the power line communication device of the third aspect, in the power line communication device of the first aspect, the control unit first minimizes the transmission output level of the OFDM modulation signal from the OFDM modulation circuit. Control the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit is gradually increased in a stepwise manner when there is no response from the partner device. Since the communication can be performed with the minimum necessary transmission power with respect to the fluctuation, the advantageous effect that the power consumption and the unnecessary radiation can be reduced can be obtained.

According to the power line communication device of the fourth aspect, in the power line communication device of the first aspect, the control unit first sets the transmission output level of the OFDM modulation signal from the OFDM modulation circuit to the maximum. By controlling the ALC circuit and controlling the ALC circuit to lower the transmission output level according to the detected received signal level, reliable communication can be established from the beginning, and thus quick communication can be reliably established. The advantageous effect that it can be obtained is obtained.

According to the power line communication device of the fifth aspect, in the power line communication device of the first aspect, the control unit first sets the transmission output level of the OFDM modulation signal from the OFDM modulation circuit to an intermediate level. By controlling the ALC circuit and controlling the ALC circuit to raise or lower the transmission output level in accordance with the detected received signal level, it is possible to cope with fluctuations in transmission characteristics at an intermediate level where communication is likely to be established. An advantageous effect is obtained.

According to the power line communication device of the sixth aspect, in the power line communication device of the first aspect, the control unit determines the state of the received signal based on transmission quality such as a packet error rate and determines the state. By controlling the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit becomes appropriate in accordance with the result, not only the attenuation due to the transmission path but also the influence of noise from other electric devices is taken into account. An advantageous effect that the accuracy of communication can be improved by changing the transmission power level is obtained.

According to the power line communication device described in claim 7, in the power line communication device according to any one of claims 1 to 6, the control unit controls the transmission output level in the ALC circuit for each packet. Thereby, an advantageous effect that it is possible to quickly respond to the state fluctuation of the power line can be obtained.

According to the power line communication device described in claim 8, in the power line communication device according to any one of claims 1 to 7, the control unit controls the transmission output level in the ALC circuit at an arbitrary timing. By doing so, the advantageous effect that the communication rate in an impulse noise environment can be improved can be obtained.

According to the power line communication apparatus of the ninth aspect, in the power line communication apparatus of any one of the first to eighth aspects, the control unit may be configured to control the sub-carrier required to control the transmission output level in the ALC circuit. By performing the above operation on only the average transmission power, an advantageous effect of suppressing the average power of transmission can be obtained.

According to a tenth aspect of the present invention, there is provided a power line communication system including a master unit and a slave unit communicating with the master unit via a power line, wherein the master unit receives the input OFDM modulation. An AGC circuit for amplifying the signal to a certain level, an OFDM demodulation circuit for demodulating the amplified OFDM modulation signal, an OFDM modulation circuit for OFDM modulating data and outputting an OFDM modulation signal, and an OFDM modulation signal from the OFDM modulation circuit. The slave unit has an ALC circuit that amplifies the signal to a required level, and a control unit that controls the entire circuit including the ALC circuit and has a reception signal level detection circuit that detects a reception signal level. An OFDM demodulation circuit for performing OFDM modulation on data and outputting an OFDM modulation signal;
By having an ALC circuit for amplifying the OFDM modulation signal from the DM modulation circuit to a required level and a control unit for controlling the whole including the ALC circuit, the master unit can transmit a transmission power control signal according to the reception signal level. Since it is possible to transmit to a mobile device, there is an advantageous effect that a power line communication system capable of coping with fluctuations in transmission characteristics can be realized even with a simple configuration of a mobile device.

According to the power line communication system of the eleventh aspect, in the power line communication system of the tenth aspect, the control unit of the master unit transmits the OFDM signal from the OFDM modulation circuit.
If there is no response from the slave unit even if the ALC circuit is controlled so that the transmission output level of the modulation signal is maximized, protect the slave unit in an abnormal state by instructing the ALC circuit to stop transmission. This has the advantageous effect of being able to perform.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a power line communication device according to a first embodiment of the present invention.

FIG. 2 is an OFDM in which a plurality of subcarriers are arranged.
Graph showing the spectrum of the scheme

FIG. 3 is a block diagram showing a power line communication system according to a second embodiment of the present invention.

4A is a block diagram showing a spread spectrum power line communication device as a power line communication device disclosed in the official gazette; FIG. 4B is a block diagram showing an ALC circuit constituting the device in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base unit 2 Remote unit 10 Power line 11 Outlet 12 Plug 13 Coupler 14 AGC circuit 15 OFDM demodulation circuit 16 ALC circuit 17 OFDM modulation circuit 18 Control unit 19 Received signal level detection circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taisuke Konishi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Noritaka Kodama 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 1006 Kadoma, Kadoma, Osaka Prefecture F-term (reference) Matsushita Electric Industrial Co., Ltd. 5K022 DD01 DD11 DD24 DD34 5K046 AA03 BA06 BB05 DD01 DD02 DD13 DD15 DD29 PS03 PS31

Claims (11)

[Claims] An AGC circuit for amplifying an inputted OFDM modulated signal to a fixed level, an OFDM demodulator for demodulating the amplified OFDM modulated signal, an OFDM modulating circuit for OFDM modulating data and outputting an OFDM modulated signal. ,
An ALC circuit for amplifying the OFDM modulation signal from the OFDM modulation circuit to a required level; and a control unit having a reception signal level detection circuit for controlling the whole including the ALC circuit and detecting a reception signal level. Characteristic power line communication device. 2. The control unit according to claim 1, wherein the ALC circuit increases the transmission output level of the OFDM modulation signal from the OFDM modulation circuit when the reception signal level detected by the reception signal level detection circuit is insufficient. 2. The power line communication according to claim 1, wherein the ALC circuit is controlled so as to reduce a transmission output level of the OFDM modulation signal from the OFDM modulation circuit when the detected reception signal level is excessive. 3. apparatus. 3. The control unit controls the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit is minimized at first, and when there is no response from a partner apparatus, the control unit controls the ALC circuit. 2. The ALC circuit according to claim 1, wherein the ALC circuit is controlled so as to gradually increase the transmission output level of the OFDM modulation signal from the modulation circuit.
A power line communication device according to item 1. 4. The control unit controls the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit is maximized at first, and controls the transmission output level in accordance with the detected reception signal level. The power line communication device according to claim 1, wherein the ALC circuit is controlled to lower a level. 5. The control section controls the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit is set at an intermediate level, and the control section controls the transmission output level in accordance with the detected reception signal level. The power line communication device according to claim 1, wherein the ALC circuit is controlled so as to increase or decrease a level. 6. The control section judges the state of a received signal based on transmission quality such as a packet error rate, and the transmission output level of the OFDM modulated signal from the OFDM modulating circuit becomes appropriate in accordance with the result of the judgment. The power line communication device according to claim 1, wherein the ALC circuit is controlled as described above. 7. The power line communication device according to claim 1, wherein the control unit controls the transmission output level in the ALC circuit for each packet. 8. The power line communication device according to claim 1, wherein the control unit controls the transmission output level in the ALC circuit at an arbitrary timing. 9. The power line communication device according to claim 1, wherein the control unit controls the transmission output level in the ALC circuit only for a necessary subcarrier. 10. A power line communication system having a master unit and a slave unit communicating with the master unit via a power line, wherein the master unit amplifies an input OFDM modulated signal to a predetermined level. An OFDM demodulation circuit for demodulating the amplified OFDM modulation signal, an OFDM modulation circuit for OFDM modulating data and outputting an OFDM modulation signal,
An ALC circuit that amplifies the OFDM modulation signal from the OFDM modulation circuit to a required level, and a control unit that has a reception signal level detection circuit that controls the whole including the ALC circuit and detects a reception signal level, The slave unit is configured to demodulate the input OFDM modulated signal.
The whole control including a DM demodulation circuit, an OFDM modulation circuit that OFDM modulates data and outputs an OFDM modulation signal, an ALC circuit that amplifies the OFDM modulation signal from the OFDM modulation circuit to a required level, and the ALC circuit A power line communication system, comprising: 11. The control unit of the master unit controls the ALC circuit so that the transmission output level of the OFDM modulation signal from the OFDM modulation circuit is maximized, and when there is no response from the slave unit, The power line communication system according to claim 10, wherein a transmission stop instruction is issued to the ALC circuit.