JP2003332950A - Power distribution line carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the SN ratio enough to receive in a transmission system for signals carried on power distribution lines against noise voltages leaking from power source circuits, etc., of home electronic apparatus. <P>SOLUTION: A communication signal voltage at transmitting is measured to calculate the line impedance. The output impedance for transmission signals at the transmit side is high and the calculated output impedance for noise voltages is high in general, and hence they can be received, as they are, if the calculated line impedance is low. If the calculated line impedance is high, a control switch 15 is set on to add an additional impedance 16 in electrically parallel to the line impedance to lower the line impedance, thereby lowering the noise level of a transmission line 17. This improves the S/N ratio to enable the reception. <P>COPYRIGHT: (C)2004,JPO

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 which uses a distribution line as a transmission line for communication.

[0002]

2. Description of the Related Art FIG. 11 shows, for example, Japanese Patent Laid-Open No. 2000-174.
It is a block diagram which shows the conventional distribution line conveying apparatus shown by the 731 publication. In FIG. 11, the transmitting unit is 1
Is a frame configuration unit, which is a unit that generates digital data to be transmitted according to transmission data and transmission parameters instructed by the transmission control unit 9. Reference numeral 2 denotes an error detection code addition section, which is a section for adding an error detection code to the digital data generated by the frame configuration section 1. Reference numeral 3 denotes a modulator, which is a part that converts digital data to which an error code has been added into a modulated high frequency signal for transmission to a distribution line.

Reference numeral 4 denotes a coupling circuit (light line coupling section) which connects the transmission / reception section of the distribution line carrier to a distribution line (not shown) which is a transmission line to prevent the commercial frequency from flowing in.
Has a role of passing a carrier signal. Reference numeral 6 denotes a demodulation circuit (demodulation unit) which is a circuit for demodulating the carrier signal input from the coupling circuit 4 into digital data. Reference numeral 5 is a no-response determination unit, which is a circuit that detects a response from another distribution line carrier that is communicating after transmission. An error detection unit 7 is a unit that calculates digital data input from the demodulation circuit 6 to perform presence / absence / correction of a transmission error.

Reference numeral 8 is a reception content analysis unit, which is an error detection unit 7.
It is a part that performs data analysis of digital data from and generates received data. Reference numeral 9 denotes a transmission control unit, which determines the transmission status from the data from the no-response determination unit 5, the error detection unit 7, and the transmission path state determination unit 11 and determines the transmission parameters such as the optimal transmission information frame length. is there. Reference numeral 10 denotes a transmission result storage unit, which is used for transmission errors and received data.
This is a part for storing the occurrence state of no response. Reference numeral 11 is a transmission line state determination unit, which is a unit that reads out the transmission result from the transmission result storage unit and determines whether the line state is good or bad.

Next, the operation of the conventional distribution line carrier will be described. The distribution line carrier on the transmitting side transmits a distribution line carrier signal, and when the signal arrives at another distribution line carrier device, the commercial frequency is applied to the distribution line side of the coupling circuit 4 of the other distribution line carrier device connected to the distribution line. A signal voltage superimposed on the voltage is induced.
Since the frequency of the signal is considerably higher than the commercial frequency, it passes through the coupling circuit 4 which blocks the commercial frequency. At this time, high-frequency noise leaking from the power supply circuit of home appliances to the distribution line also passes through the coupling circuit at the same time. Then, the transmission control device 9 investigates and determines the reception state of the response signal and the situation of error occurrence, and thereby changes the communication parameters such as the communication packet length to obtain a distribution line carrier device having high transmission efficiency. You can

[0006]

However, in the conventional transmission apparatus for carrying a distribution line, the voltage of the transmission signal drops when the distribution line has a long line length, and when the distribution line has a low impedance (the transmission device As a transmission signal is transmitted to the distribution line carrier device, the transmission signal is divided more into the distribution line carrier device side than the distribution line, and the signal level itself transmitted to the distribution line becomes smaller, or high level high frequency Noise is the demodulation circuit 6 of the distribution line carrier (as a receiver)
In such a case, the distribution line carrier device (as a receiving device) cannot receive the distribution line carrier signal even if the communication parameter is changed by the transmission control unit 9. . Therefore, the distribution line carrier of another communication destination does not return the response signal. Further, in the conventional distribution line carrier, even if another distribution destination carrier communicates with the response signal, an event occurs in which the response signal cannot be received due to the same reason as the above-mentioned distribution line carrier. Furthermore, the impedance of the distribution line used to carry the distribution line is unspecified depending on the connection and operating conditions of home appliances, and the noise voltage leaking from the power supply circuit of home appliances is also unspecified, and the high-frequency voltage extracted from the distribution line is high. Among the components, the signal voltage is high, but the noise voltage is also high, and there is a problem that reception cannot be performed if the SN ratio is poor.

The present invention has been made in order to solve the above problems, and adds an additional impedance in parallel to a line when the line impedance is high or when the line impedance has frequency characteristics. Therefore, it is an object of the present invention to obtain a portable transmission device in which the influence of a noise source having a high output impedance and the deviation of the signal voltage due to the frequency are reduced to improve the transmission reliability.

[0008]

(1) A distribution line carrier according to claim 1 of the present invention is a distribution line carrier that transmits and receives a signal via a distribution line according to a line impedance at a frequency of a transmission signal. The impedance adding means for electrically connecting the additional impedance to the distribution line in parallel is provided to improve the S / N ratio of the received signal to noise.

(2) A distribution line carrier according to a second aspect of the present invention is the distribution line carrier according to the first aspect, wherein the impedance adding means is the additional impedance corresponding to the line impedance at the frequency of the transmission signal. Is a means for electrically charging or releasing in parallel to the distribution line.

(3) A distribution line carrier according to claim 3 of the present invention is the distribution line carrier according to claim 1 or 2, wherein the line impedance is calculated based on a transmission signal voltage at a transmission frequency. Is.

(4) A distribution line carrier according to a fourth aspect of the present invention is a distribution line carrier that transmits and receives signals of a plurality of frequencies via a distribution line, depending on the deviation of the line impedance at each frequency of the transmission signal. The impedance adding means for electrically connecting the additional impedance to the distribution line in parallel is provided to reduce the signal voltage deviation at each communication frequency.

(5) A distribution line carrier according to a fifth aspect of the present invention is the distribution line carrier according to the fourth aspect, wherein the impedance adding means has a predetermined value of deviation of the line impedance at each frequency of the transmission signal. If the deviation of the line impedance at each frequency exceeds a predetermined value, the additional impedance corresponding to the deviation is electrically connected in parallel to the distribution line.

(6) The distribution line carrier according to claim 6 of the present invention is the distribution line carrier according to claim 4 or 5, wherein the line impedance at each frequency of the transmission signal is the transmission frequency. It is calculated based on the transmission signal voltage corresponding to.

(7) A distribution line carrier according to a seventh aspect of the present invention is a distribution line carrier that transmits and receives signals of a plurality of frequencies via a distribution line, and shows the frequency characteristics of the line impedance corresponding to each of the above frequencies. Depending on the deviation, a filter adding means for receiving through a filter having a predetermined frequency characteristic such as a high-pass filter, a low-pass filter, a band filter corresponding to the deviation is provided to reduce the signal voltage deviation of each communication frequency. It is a thing.

(8) The distribution line carrier according to claim 8 of the present invention is the distribution line carrier according to claim 7, wherein the filter adding means has a predetermined frequency characteristic of the line impedance at each frequency of the transmission signal. If it is within the value, it is received directly, and if the line impedance of the transmission signal in the low frequency band of each frequency of the above transmission signal exceeds a predetermined value, it is received via a high-pass filter and the transmission signal of the high frequency band When the line impedance exceeds a predetermined value, the line impedance is received through a low-pass filter to reduce the signal voltage deviation at each communication frequency.

(9) A distribution line carrier according to claim 9 of the present invention is the distribution line carrier according to claim 7 or 8, wherein the frequency characteristic of the line impedance is:
It is calculated based on the transmission signal voltage at each transmission frequency.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.
First Embodiment FIG. 1 is a block diagram of a distribution line carrying device showing a first embodiment of the present invention. In FIG. 1, reference numerals 1, 4, 6 to 9 are the same as those described in the conventional device. 15 is an additional impedance 16 (ZT) controlled by the transmission control unit 9.
For example, a control switch that controls the insertion of a resistor,
Is the signal AC voltage between the lines (the voltage of the transmitted signal (specifically,
Corresponding to the voltage on the output side of the modulator 3), the voltage of the received signal (specifically, the input voltage of the demodulator 6), or the voltage before the power line coupling unit 4 (on the side of the modulator 3 and the demodulator 6). Is a rectifier that rectifies the voltage into a direct current, 13 is a smoother that smoothes the rectified voltage, and 12 is a comparator having a threshold value. The threshold of the comparator 12 is set in advance based on the line impedance that makes the line impedance ZL large and makes it difficult to receive the distribution line carrier signal. Reference numeral 17 is a distribution line which is a transmission line, and 18 and 19 are coupling capacitors for blocking the inflow of the commercial frequency and passing the carrier signal.

In FIG. 2, the output of the comparator is monitored at the time of transmission, and if it is determined that the line impedance ZL of the transmission line is lower than a threshold value, the additional impedance is removed to prevent the impedance of the transmission line from decreasing, and the line of the transmission line is prevented. It is a flowchart which performs control which inserts additional impedance if impedance is higher than a threshold value, and lowers line impedance to improve transmission performance.

FIG. 3 is a diagram in which a power line which is a transmission line is modeled. In FIG. 3, reference numeral 31 is a model of a home electric appliance or the like as a noise source, 37 is a virtual voltage source Vn of noise, and 35 is a virtual output impedance Zn of noise. 32 is a model of a device on the transmission side of the distribution line carrier, 38 is a virtual voltage source Vs of the transmission side device, and 36 is an output impedance Zs of the transmission side device. Reference numeral 33 is a model of a device on the transmission / reception side of the delivery / transport device, and has a high impedance (for example, several hundreds to several kΩ) that does not affect the line impedance ZL (for example, several Ω) and is induced at both ends. Voltage VL
The (reception voltage 39) is processed and reception is performed. 34 is a model of the line impedance ZL.

Here, since the signal source voltage Vs and the output impedance Zs of the modulator 3 are unique values, adjustment is made before connecting to the distribution line 17 in order to obtain the line impedance ZL of the distribution line 17 described later. It is obtained in advance by connecting to an impedance and voltmeter (not shown) for use. The line impedance ZL of the distribution line 17 is known as this voltage VL by detecting a signal voltage (transmission voltage) VL (not shown) between the lines in front of the power line coupling unit 4 during transmission of the distribution line carrier. Can be obtained from the signal source voltage Vs and the impedance Zs ((I) = V
L / ZL = Vs / Zs).

In the first embodiment, instead of directly obtaining the line impedance ZL, when a transmission signal (AC) is transmitted as shown in FIGS. 1 and 2 (step 40 in FIG. 2), this signal is changed. By rectifying with the rectifier 14, smoothing with the smoothing device 13, and comparing with the comparator 12 (step 41 in FIG. 2), it is determined whether the line impedance ZL is larger or smaller than the threshold value (step 42 in FIG. 2).
It has such a configuration. Then, in step 42,
When it is judged that the threshold of the line impedance ZL is large,
When the distribution line carrier signal is received, the control switch 15 is turned on (step 43 in FIG. 2), and when it is judged to be small, the control switch 15 is turned off when the distribution line carrier signal is received (step 44 in FIG. 2).

There are various types of noise sources 31, but the main function of producing noise is to increase the impedance seen from the distribution line 17 by inserting a noise filter or the like between the power source line and the noise generating part. hand,
It is common to reduce the conduction noise to the distribution line 17. Therefore, the virtual output impedance Zn of the noise source 31 in FIG. 3 is generally considered to be large. Further, the distribution line carrier on the transmission side reduces the output impedance Zs so that the signal voltage can be superimposed on the distribution line 17 even when the line impedance ZL becomes low impedance.

The signal voltage extracted from the distribution line 17 by the distribution line carrier on the receiving side is a voltage obtained by dividing the voltage of the signal source Vs of the distribution line carrier on the transmitting side by the internal impedance Zs of the transmitter and the line impedance ZL. Is. Similarly, the noise voltage extracted from the distribution line 17 in the reception side device is a voltage obtained by dividing the voltage of the virtual voltage source Vn of the noise source 31 by the virtual internal impedance Zn of the noise source 31 and the line impedance ZL.

From these facts, the line impedance Z
When L becomes high, the voltage divided into the virtual output impedance Zn in the noise source 31 decreases, and the noise voltage Vn is easily induced between the power supply lines. On the other hand, in the distribution line carrier on the transmission side, since the output impedance Zs is small, when the line impedance ZL becomes high to some extent, the voltage divided by the internal output impedance Zs almost disappears, and the line signal voltage becomes almost constant.

For example, the signal voltage detected at the receiving point is V
When rs and the noise voltage are Vrn, the following formulas are established. Vrs = Vs × ZL / (Zs + ZL) Vrn = Vn × ZL / (Zn + ZL) Here, if the line impedance ZL is high, the SN ratio at the receiving point is calculated. Vs = Vn = V, Zn = ZL = 150Ω, Zs = 10Ω
Then, Vrs = V / 2, Vrn = 15V / 16, Vrs = 15V / 16, Vrn = V / 2, and the SN ratio at that time is S / N = Vrs / Vrn = 1.86.
= 5.4 dB. If the distribution line carrier device requires an S / N of 10 dB for stable reception, it cannot be received.

Therefore, the additional impedance 16 (ZT)
It is assumed that the line impedance ZL is matched to the output impedance Zs by adding (that is, the line impedance ZL = 10Ω (to match the same as Zs)).
14 Ω), Vs = Vn = V, Zn = 150 Ω, ZL = 10 Ω, Zs
= 10Ω, Vrs = V / 2 and Vrn = V / 16, and the SN ratio at that time is S / N = Vrs / Vrn = 8 = 18 dB. It can be received sufficiently stably by a distribution line carrier which requires an S / N of 10 dB for stable reception.

In the distribution line carrier constructed as described above, the fact that the impedance ZL of the distribution line becomes high is detected by the flow of FIG. 2, and the control switch 15 in FIG. (ZT) is inserted in parallel to the distribution line to reduce the line impedance ZL to a level larger than the output impedance Zs of the transmission line carrier on the transmission side, whereby the line impedance ZL from the noise source 31 is divided. The noise voltage is sufficiently reduced, the signal voltage of the transmission side distribution line carrier device with a small output impedance Zs has little effect, the SN ratio is substantially improved, and stable communication is possible even on a distribution line that could not be conventionally communicated. It can be carried out.

Further, the transmission signal voltage (the signal voltage between the lines in front of the power line coupling section 4) is determined by the rectifier 14, the smoothing device 13 and the comparator 12 to determine the magnitude of the line impedance ZL. It is not necessary to directly measure and the circuit configuration can be simple. Further, if the output of the comparator 12 is directly input to the control switch 15, the transmission unit including the frame configuration unit 1, the modulation unit 3, the transmission control unit 9 and the like, the demodulation unit 6, and the reception content analysis unit 8 are provided. , A transmission control unit 9, etc.
The analog circuit of the rectifier 14, the smoothing device 13, the comparator 12, the control switch 15, and the analog circuit of the additional impedance 16 may be added to the one-chip IC for carrying the distribution line configured by C. It can be applied to devices and the like.

In the above description, an example in which the magnitude of the line impedance ZL is judged by the analog circuit composed of the rectifier 14, the smoothing device 13 and the comparator 12 has been explained, but the demodulation unit 6 or the signal detection unit of the reception unit is described. It is also possible to directly calculate the transmission signal voltage using, calculate the line impedance ZL from this calculation result, and compare it with a threshold value to control ON / OFF of the control switch 15. In this case, the signal detection unit decodes this data after AD conversion of the reception signal by the demodulation unit 6 or the reception unit (or, in the case of distribution line transportation using a plurality of frequencies, FFT (Fast Fourier Transform)). Conversion)
The line impedance ZL is obtained by separating the carrier signal for each frequency and decoding the digital data thereof, and is compared with a threshold value to control ON / OFF of the control switch 15. By the way, since the distribution line carrier device originally has a function of decoding the received carrier wave signal, a small improvement has been made to the software for decoding the carrier wave signal (the line impedance ZL is obtained, compared with a threshold value, and controlled). Switch 15
There is a merit that it is only necessary to add (improvement of ON / OFF control of).

Further, in the above description, the frequency of the communication signal was explained as one frequency, but it may be a communication signal of a plurality of frequencies. In the case of a communication signal having a plurality of frequencies, the present invention is applied to each of the plurality of frequencies.

Embodiment 2. In the first embodiment described above, the distribution line carrier device that mainly uses a single frequency has been described. , ZL2, ...
, ZLn: 1, 2, ..., N corresponds to the number of frequencies), there is a deviation in the transmission signal voltage between the transmission frequencies, and the demodulation unit 6 on the receiving side outputs the signal. When detected, a deviation occurs in the voltage of each frequency component.

The signal amplitude obtained by synthesizing the signal voltage of each frequency is input to the internal analog circuit of the demodulation unit 6, but the input voltage range of the internal analog circuit (the input range of the AD converter) is limited. The high-voltage frequency signal becomes dominant, and the low-voltage frequency signal may be lost due to circuit noise or the like. Therefore, the difference in the line impedance ZL for each communication frequency (same as the distribution line carrier frequency) is detected, and if the deviation between the communication frequencies of the line impedance ZL is equal to or more than the specified value, the additional impedance ZT is added, The deviation of the line impedance ZL can be reduced and the deviation of the reception voltage can be reduced.

FIG. 4 is a block diagram of a distribution line carrier which uses, for example, two communication frequencies. 2, the filter 20 (filter 1) corresponding to the communication frequency,
Two systems of a filter 21 (filter 2), a smoother following it, and a comparator are provided. That is, the filter 20 (filter 1) is a filter that mainly passes one communication frequency, and the filter 21 (filter 2) is a filter that mainly passes other communication frequencies. In the configuration of FIG. 4, a signal in which voltages of two communication frequencies are combined is transmitted from the modulator 3 during transmission. The line impedances ZL (ZL1, ZL2) at the two communication frequencies are the same as in the first embodiment, respectively, at the time of transmitting the distribution line signal, the signal source voltages Vs (Vs1, Vs2) that are known for each of the two signal frequencies.
And the output impedance Zs (Zs1, Zs2) and the signal voltage V between the lines in front of the power line coupling section 4 which is output to the distribution line 17.
L (VL1, VL2) is filtered and rectified for each signal frequency.
It can be obtained by smoothing and comparing. In addition, the voltage detection circuit of each signal frequency of the demodulation unit 6 is used during transmission to
It is likewise possible to measure the transmitted signal voltage at one communication frequency.

For example, let Vrs1 and Vrs2 be signal voltages of two frequencies detected on the side of the modulation unit 3 and the demodulation unit 6 of the power line coupling unit 4 of the distribution line carrier on the receiving side, and set the line impedances of the two frequencies to Vs1 and Vrs2. If ZL1 and ZL2 are set, the following formula is established. Vrs1 = Vs1 × ZL1 / (Zs1 + ZL1) Vrs2 = Vs2 × ZL2 / (Zs2 + ZL2) Here, if the line impedance ZL1 is high and the line impedance ZL2 is low, the signal voltage ratio of two communication frequencies at the receiving point is calculated. . Vs1 = Vs2 = V, ZL1 = 150Ω, ZL2 = Zs
When 1 = Zs2 = 10Ω, Vrs1 = 15V / 16, Vrs2 = V / 2, and Vrs1 / Vrs2 = 1.86.

Here, if an additional impedance ZT having no frequency characteristic and an impedance of 10Ω is added in parallel to the line, ZL1 = 9.4Ω and ZL2 = 5Ω. Vr
s1 = 49V / 97 and Vrs2 = V / 3. Vrs
It is relaxed to 1 / Vrs2 = 1.52.

As shown in the flow chart of the second embodiment shown in FIG. 5, when the signal is being transmitted in step 50,
In step 51, the outputs of the comparator 1 and the comparator 2 are verified, and in the case where the outputs of the comparator 1 and the comparator 2 are different from each other by a predetermined value or more in step 52, the control is connected to the additional impedance 16 (ZT) at the time of reception in step 53. By turning on the switch 15 and inserting the additional impedance 16 (ZT) in parallel with the line impedance ZL, the deviation of the impedance ZL of the distribution line 17 is mitigated, the deviation of the received voltage due to the frequency is reduced, and the comparator 1 and the comparator 2 If the output of is not more than the predetermined value, the control switch 15 connected to the additional impedance 16 (ZT) is turned off at the time of reception in step 54,
Additional impedance 1 in parallel with line impedance ZL
Line impedance Z without 6 (ZT)
L is lowered so that the absolute value of the reception voltage is not lowered. As a result, the deviation of the line impedance ZL (ZL1, ZL2) between the frequencies to be communicated can be mitigated, and the deviation of the reception voltage can be mitigated.

Embodiment 3. FIG. 6 is a block diagram of a distribution line carrier that uses two frequencies to realize the function of the third embodiment, and FIG. 7 is a control flowchart thereof. In FIG. 6, reference numerals 62 and 63 denote additional impedances ZT1 and ZT2 having frequency characteristics, which have characteristics different from those of the additional impedance 16 (ZT) having a resistance component as a main component described in the first and second embodiments. As illustrated in FIG. 8, the additional impedance having the frequency characteristic is the coil 9
It is composed of a parallel circuit of 0 and a capacitor 91, and impedance decreases at a specific frequency due to parallel resonance generated by a combination of the value of the coil 90 and the value of the capacitor 91 inside. 62 has a frequency characteristic such that the line impedance ZL1 at only one communication frequency decreases, and 63 has a frequency characteristic such that the line impedance ZL2 at another communication frequency only decreases. Is. Reference numerals 60 and 61 are control switches for additional impedances 62 (ZT1) and 63 (ZT2), respectively.

Next, the operation will be described. In FIG. 7, as in the second embodiment, the transmission of the communication signal is confirmed in step 70, and if the communication signal is being transmitted, the outputs of the comparator 1 and the comparator 2 are verified in step 71. In step 72, the comparator 1 evaluates whether the voltage is higher than the specified value. Thereby, the level of the line impedance ZL1 at one communication frequency can be determined. If the evaluation result is true, the control switch 60 (switch 1) connected to ZT1 at the time of reception is turned on in step 73, and one line impedance ZL1 (= ZL1 ×) of the communication frequency is turned on.
If ZT1 / (ZL1 + ZT1)) is lowered and the evaluation result is false, the control switch 60 (switch 1) is turned off in step 74, and the line impedance ZL1 (= ZL).
Keep 1).

Similarly, in step 75, the comparator 2 evaluates whether the voltage is higher than the specified value. This allows
Line impedance ZL at another communication frequency
You can judge the high and low of 2. If the evaluation result is true, in step 76, the control switch 61 (switch 2) connected to ZT2 at the time of reception is turned on, and another line impedance ZL2 (= ZL2 × ZT2 / (ZL2
+ ZT2)) is lowered and the evaluation result is false, the control switch 61 (switch 2) is turned off in step 77 to maintain the line impedance ZL2 (= ZL2).

As a result, the deviation of the line impedance at each communication frequency can be alleviated more effectively than in the second embodiment, and the deviation of the received voltage at each communication frequency can be alleviated.

Fourth Embodiment FIG. 9 is a block diagram of a distribution line carrier that uses two frequencies to realize the function of the fourth embodiment, and FIG. 10 is a control flowchart thereof.
The additional impedance 62 described in the third embodiment
(ZT1) and 63 (ZT2) are used to level the line impedance ZL (ZL1 and ZL2), which is different from the method of leveling the signal voltages of a plurality of frequencies. By switching the filters 92 and 93 to be placed, the signal voltages of a plurality of frequencies are leveled.

In FIG. 9, 92 is a high-pass filter (H
PF), which has a characteristic of passing a high-frequency signal voltage better than a low-frequency signal voltage, and preferably has a filtering band equivalent to that of the filter 20 (filter 1). A low-pass filter (LPF) 93 has a characteristic of passing a low-frequency signal voltage better than a high-frequency signal voltage, and preferably has a filtering band equivalent to that of the filter 21 (filter 2). . Reference numeral 95 denotes a control switch which precedes the high-pass filter 92 in front of the demodulation section 6 and is controlled by the transmission control section 9. Reference numeral 96 denotes a control switch which precedes the low-pass filter 93 in front of the demodulator 6 and is controlled by the transmission controller 9.
Reference numeral 94 is a control switch that guides the signal voltage from the distribution line 17 to the demodulation unit 6 without passing through the filters 92 and 93.

Next, the operation will be described. In FIG. 10, step 80 is performed as in the second and third embodiments.
In step 81, the output of the comparator 1 which detects the voltage of the low communication frequency and the output of the comparator 2 which detects the voltage of the high communication frequency are verified. Comparator 1 in step 82
And whether the output of the comparator 2 differs by a predetermined value or more (that is, whether ZL1 and ZL2 differ by a predetermined value or more) is evaluated. This makes it possible to determine whether or not the line impedance ZL (ZL1, ZL2) at the two communication frequencies has frequency characteristics.

If the evaluation result is false, in step 83 the control switch 94 (switch 1) for passing the received signal from the distribution line is turned on and input to the demodulation section 6. If the evaluation result is true, it is higher in step 84. Evaluate whether the level of communication frequency is high. If the evaluation result is true, in step 85, the received signal from the distribution line 17 is passed through the high-pass filter 92.
The control switch 95 (switch 2) is turned on in order to input the signal passed to the demodulation unit 6. Similarly, if the evaluation result is false, in step 86, the control switch 96 (switch 3) is turned on in order to input the signal obtained by passing the received signal from the distribution line 17 through the low pass filter to the demodulation unit 6.

As a result, the deviation of the reception voltage for each communication frequency can be reduced without affecting the impedance ZL of the distribution line 17 as compared with the third embodiment.

[0046]

(1) According to claim 1 or claim 2 of the present invention, since the additional impedance according to the line impedance at the frequency of the transmission signal is added, the line impedance is lowered and the impedance is high. By reducing the voltage of the noise source, the SN ratio can be substantially improved, and stable communication can be performed.

(2) According to claim 3 of the present invention, the line impedance can be calculated based on the transmission signal voltage at the transmission frequency.

(3) Claim 4 or Claim 5 of the present invention
According to the above, when transmitting and receiving a signal of a plurality of frequencies, since the additional impedance according to the deviation of the line impedance at each frequency of the transmission signal is added, the reception voltage deviation of the communication frequency of the line impedance decreases, Can communicate stably.

(4) According to the sixth aspect of the present invention, the line impedance at each frequency of the transmission signal can be calculated based on the transmission signal voltage corresponding to each transmission frequency.

(5) Claim 7 or Claim 8 of the present invention
According to the above, according to the deviation of the frequency characteristic of the line impedance corresponding to each frequency of the transmission signal, the signal is received through a filter having a predetermined frequency characteristic corresponding to the deviation. Reduce the deviation,
Can communicate stably.

(6) According to the ninth aspect of the present invention, the frequency characteristic of the line impedance can be calculated based on the transmission signal voltage at each transmission frequency.

[Brief description of drawings]

FIG. 1 is a block diagram of a distribution line carrier according to a first embodiment of the present invention.

FIG. 2 is a diagram of a control procedure for removing noise according to the first embodiment of the present invention.

FIG. 3 is a schematic view of a line in which a noise source is connected to a transmission side distribution line carrier and a reception side distribution line carrier according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a distribution line carrier according to a second embodiment of the present invention.

FIG. 5 is a diagram of a control procedure for removing noise according to the second embodiment of the present invention.

FIG. 6 is a block diagram of a distribution line carrier according to a third embodiment of the present invention.

FIG. 7 is a diagram of a control procedure for leveling a signal voltage according to the third embodiment of the present invention.

FIG. 8 is an equivalent circuit diagram showing an additional impedance having a low impedance at a specific frequency according to the third embodiment of the present invention.

FIG. 9 is a block diagram of a distribution line carrier according to a fourth embodiment of the present invention.

FIG. 10 is a diagram of a control procedure for reducing deviations of received voltages of a plurality of communication frequencies and performing leveling according to the fourth embodiment of the present invention.

FIG. 11 is a block of a conventional distribution line carrier.

[Explanation of symbols]

1 frame configuration section, 3 modulation section, 4 power line coupling section, 6 demodulation section, 8 received content analysis section, 9 transmission control section, 10 transmission result storage section, 12 comparator, 13
Smoother, 14 rectifier, 15 control switch, 16
Additional impedance, 17 Distribution line, 18 Coupling capacitor 1, 19 Coupling capacitor 2, 20 Filters 1, 2
1 Filter 2, 22 Comparator 2, 23 Smoother 2, 24 Rectifier 2, 25 Rectifier 1, 26 Smoother 1, 27 Comparator 1, 31 Noise source, 32 Transmitting side device, 33 Receiving side device, 34 Line impedance, 60 Control switch 1,61 Control switch 2,6
2 Additional impedance 1, 63 Additional impedance 2, 90 Coil, 91 Capacitor, 92 High pass filter, 93 Low pass filter, 94 Control switch 1, 95 Control switch 2, 96 Control switch 3

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mutsumi Ishii             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F-term (reference) 5K046 AA03 BA05 BB05 CC08 CC09                       PS50 PS51 YY02

Claims (9)

[Claims] 1. A distribution line carrier for transmitting and receiving a signal via a distribution line, comprising impedance adding means for electrically connecting an additional impedance according to a line impedance at a frequency of a transmission signal to the distribution line in parallel. , A distribution line carrier characterized by improving the S / N ratio of a received signal with respect to noise. 2. The distribution line carrier according to claim 1, wherein the impedance adding means electrically connects or disconnects the additional impedance corresponding to the line impedance at the frequency of the transmission signal to the distribution line in parallel. A distribution line carrier device characterized by being a means. 3. The distribution line carrier according to claim 1 or 2, wherein the line impedance is calculated based on a transmission signal voltage at a transmission frequency. 4. In a distribution line carrier for transmitting and receiving signals of a plurality of frequencies via a distribution line, an additional impedance corresponding to the deviation of the line impedance at each frequency of the transmission signal is electrically connected in parallel to the distribution line. The distribution line carrier device is characterized in that it is provided with impedance adding means for reducing the signal voltage deviation of each communication frequency. 5. The distribution line carrier according to claim 4, wherein the impedance adding means directly receives the line impedance deviation at each frequency of the transmission signal if the deviation is within a predetermined value, and detects the line impedance at each frequency. A distribution line conveying device, characterized in that, when the deviation exceeds a predetermined value, a means for electrically connecting an additional impedance corresponding to the deviation to the distribution line in parallel is provided. 6. The distribution line carrier according to claim 4 or 5, wherein the line impedance at each frequency of the transmission signal is calculated based on a transmission signal voltage corresponding to each transmission frequency. Distribution line carrier. 7. A distribution line carrier for transmitting and receiving signals of a plurality of frequencies via a distribution line, in accordance with a deviation of frequency characteristics of line impedance corresponding to each of the above frequencies, a high-pass filter corresponding to the deviation, and a low-pass filter. A distribution line carrier, characterized in that filter addition means for receiving through a filter having a predetermined frequency characteristic such as a bandpass filter and a bandpass filter is provided to reduce a signal voltage deviation of each communication frequency. 8. The distribution line carrier according to claim 7, wherein the filter adding means directly receives if the frequency characteristic of the line impedance at each frequency of the transmission signal is within a predetermined value, and receives each frequency of the transmission signal. If the route impedance of the transmission signal in the low frequency band exceeds the specified value, it is received via the high-pass filter, and if the route impedance of the transmission signal in the high frequency band exceeds the specified value, it is received via the low pass filter Means for reducing the signal voltage deviation of each communication frequency. 9. The distribution line carrier device according to claim 7, wherein the frequency characteristic of the line impedance is calculated based on a transmission signal voltage at each transmission frequency.