JPS63280521A - Distribution line communication equipment - Google Patents

Abstract

PURPOSE:To prevent the production of a interference electric field to other equipment and damage to the equipment by adjusting a control gain to a low value other than at the transmission request and adjusting it to a prescribed level at the transmission request. CONSTITUTION:A signal inputted from an input terminal (a) is adjusted by an automatic gain adjusting device (AGC) 1 and the AGC 1 is adjusted by the degree of an output signal of an AGC controller (AGC-C) 1'. When no transmission request signal exists, the transmission level is controlled lower and when the transmission request signal exists conversely, the transmission level is controlled to be a prescribed level. Since no interference electric field is generated to other device and the voltage stress to the receiver is decreased, the destruction of the device is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a power distribution line communication device that performs communication using a power supply wiring network installed indoors.

(Summary of the Invention) The present invention performs automatic gain adjustment such that when there is no transmission request signal, the transmission level is rapidly controlled to a low value, and when there is a transmission request signal, the transmission level is amplified and controlled to a predetermined level. .

(Prior art and its problems) Conventionally, communication devices using indoor wiring networks are well known.
In order to improve the quality of communication, efforts are also being made to prevent fluctuations in the communication level.

For example, the distribution line communication device proposed by the present applicant in Japanese Patent Application Laid-Open No. 59-50627 includes automatic gain adjustment (AGC) means for keeping the transmission level constant at all times.

According to the previous proposal, it has the advantage of being able to effectively remove impedance fluctuations in the wiring network and noise components in the power supply frequency.

However, in the previous proposal, in order to always keep the transmission level constant, the gain of the communication device was controlled even during reception, resulting in a high gain, and the next time it transmitted, the communication level would exceed the specified level, resulting in a strong electric field from the distribution line. This could cause interference to other equipment or destroy the other party's communication equipment.

(Object of the invention) The present invention has been made in view of the above problems, and includes:
Adjust the hunt roll gain low except when requesting transmission.
Another object of the present invention is to provide a distribution line communication device that adjusts to a predetermined level when a transmission request is made.

(Structure and Effects of the Invention) In order to achieve the above object, the present invention provides an automatic gain adjustment provided in a circuit for transmitting a communication signal in a distribution line communication device that connects a communication device to an indoor wiring network to communicate. and an automatic gain adjuster controller that increases the output level of the automatic gain adjuster when there is a transmission request signal and decreases the output level of the automatic gain adjuster when there is no transmission request signal. It is characterized by this.

Since the present invention is configured as described above, there is no occurrence of an electric field that interferes with other devices, and voltage stress on the receiver is small, so that damage to the device can be prevented.

(Explanation of Examples) The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 1 is a block diagram of the transmission circuit side of the power distribution line communication device, and FIG. 2 is a wiring diagram in which the blocks of FIG. 1 are converted into a circuit.

In the figure, a is an input terminal into which a transmission signal is input, and b is an input terminal for a transmission request signal.

The signal input from input terminal a is passed through an automatic gain adjuster (A
Adjusted by GC>1, this AGCl is
It is adjusted according to the level of the output signal of an AGC controller (AGC-C>, which will be described later).

2 is a buffer, which is an impedance converter connected to the output side of AGCl, and 3 is a switching circuit that converts the output of the buffer 2 according to the degree of the output signal of the comparator of the transmission request signal, which will be described later. When there is no transmission request signal, the output of buffer 2 is passed through as is,
When there is a transmission request signal, the output of buffer 2 is set low (L
) The level can be changed as desired.

4 is a transformer driver, which is connected to the primary side of the output transformer 5 for sending a transmission signal to indoor wiring. Further, the secondary side of the output transformer 5 is connected to indoor wiring via a filter (l(PF)) 6 consisting of a capacitor (not shown) that cuts signal components of the power supply frequency.

Reference numeral 7 denotes a transmitting signal detector, which performs envelope detection of the output signal of the transformer driver 4.

8.9 and 10 are predetermined threshold values Va, respectively.

(2) It is a comparator having 9 and Vllll for comparison with the output level of the detector 7.

Of these, the output values of comparators 9 and 10 are connected via switching circuits (SW) 11 and 12 that are driven by the output values of individual comparators provided in the transmission request signal system, which will be described later. AG
It is designed to be input to the Cl controller (AGC-C) 1-.

Further, 13 is a comparator for detecting the presence or absence of a transmission request signal from the input terminal, and when there is no transmission request signal, it is at a high (H) level, and when there is no such signal, it is at an L level. There is.

Furthermore, each output has a predetermined threshold value V+4.
# Three comparators 14, 15 and 16 with V+s and V+s are connected.

Of these, the comparator 14 is connected to the switching circuit 3.
Comparator 15 and comparator 16 are connected to switching circuit 11 and switching circuit 12, respectively.

The operation of this embodiment configured as described above is explained in the third section.
This will be explained with reference to the time chart shown in the figure.

When no transmission request signal is input to the input terminal, the output of the comparator 13 is at H level, and the comparators 14, 15 and 16 connected in parallel to the output side of the comparator 13 are in an inactive state. It is.

For this reason, the switching circuit 3 requires the output of the comparator 14 to be at L level, so its output becomes L level.

Furthermore, since the switching circuit 11 acts to increase the output level of AGC-CI-, and the switching circuit 12 acts so as not to limit the output of AGC-CI-, the output level of AGC-C1- increases. Is high.

On the other hand, AGCI is AGC when AGC-01- is high output.
Since the output of AGC1 is lowered, the output of AGC1 is maintained at the lowest level.

Now, when the transmission request signal is input to the input terminal at time To, the output of the comparator 13 goes to L level, and as a result, the outputs of the comparators 14, 15 and 16 connected to the output side of the comparator 13 are t
level condition.

By the way, when the transmission request signal is input, comparator 1
4 becomes H level, and the switching circuit 3 switches to the buffer 2.
It moves to output the output as is. Also, comparator 10 has a lower threshold than other comparators 8 and 9.
111, the output of the comparator 10 is output to the AGC-01- via the switching circuit 12, and the output level of the AGC-C1' is rapidly lowered. Therefore, AGC-C1'' acts to increase the level of the output of AGCl, and the level of the transmission signal input from input terminal a increases.

When the level of the transmission signal increases and the level of the detection circuit 7 reaches VIG, which is higher than VIO, the comparator 10 stops outputting (To to T+ in FIG. 3).

After that, due to the large time constant of comparator 8, AGC
l is controlled to provide a transmission signal of a predetermined level. That is, the comparator 8 has a threshold value at which a predetermined detection level v8 is reached, and when it becomes lower than this threshold value Vn, the output of the AGC-01' is lowered and the threshold value v8 is lowered.
If it becomes higher, it works to increase the output of AGC-C1-.

By the way, when the impedance of the distribution line increases rapidly, the level of the detection circuit 7 becomes V3 or higher, so the comparator 9 becomes inactive, and therefore the output level of AGC-C1'' becomes H, and the output level of AGC-C1'' becomes H. On the other hand, when the level of the detection circuit 7 drops to V, - lower than V9, the comparator 9 operates again and returns the output level of AGC-C1= to the predetermined level. The transmission signal shall be

Also, when the impedance of the distribution line suddenly decreases, the output value of the detection circuit 7 becomes V4, which operates the comparator 10 to decrease the output of AGC-C1', thereby increasing the output of AGCl. . On the other hand, when the output value of the detection circuit 7 becomes V4- which is higher than V4, the output of the comparator 10 is stopped.

Roughly speaking, if the transmission request signal from the input terminal is cut off,
The output of the comparator 13 becomes H level, and thereby each of the comparators 14, 15, and 16 connected in parallel to the output side of the comparator 13 becomes L level. Therefore, due to the non-operation of the comparator 15, the switching circuit 11 is activated, and the output of the comparator 9 becomes AGC-0.
1” output rapidly becomes H level, which causes the AGC
will result in low output.

Further, the output of the switching circuit 3 becomes L level, the transformer driver 4 stops operating because there is no input signal, and the transmission signal rapidly attenuates.

Fig. 4 compares the disconnection effects of the distribution line communication device according to the present invention and the conventional distribution line communication device, and shows the state of impedance increase/decrease from the start of communication until reaching a steady state and during communication. I have something to eat.

In the steady state, the communication i1D is connected to the communication device A via the power distribution line.
When transmission starts at point B, in the conventional device, the transmission level rises rapidly and reaches a predetermined value, but in the present invention, the transmission level can gradually reach the predetermined level without reaching the predetermined level or higher.

Furthermore, when communication device B is removed from the steady state and the impedance after wiring increases, the transmission level increases with the increase in impedance in both the conventional device and the present invention, but in this case, in the present invention, the transmission level increases more rapidly than in the conventional device. can reach a certain level.

On the other hand, when the communication device C is further added and the wiring impedance is reduced, the transmission level drops below the predetermined level in both the conventional and inventive devices, but the inventive device reaches the predetermined level more rapidly. I know it will recover.

According to the embodiment described above, when there is no transmission request signal, the transmission level is rapidly controlled to a low value, and when there is a transmission request signal, the transmission level can be rapidly controlled to a predetermined level. It does not generate an interfering electric field to other devices, and the voltage stress on the receiver side can be reduced, which prevents damage to the device and also prevents unnecessary power consumption at the rise time when starting transmission. can.

Furthermore, high-quality communication can be achieved even if there are changes in the impedance of the power distribution line. Moreover, communication efficiency is excellent because the transmission level can quickly reach a predetermined level.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram of the transmission side of the distribution line communication device according to the present invention, and FIG. 2 is an example of a circuit in which the block diagram of FIG. 1 is converted into a circuit. FIG. 3 is a time chart 1 showing the connection state of the predetermined blocks in FIG. 1, and FIG. 4 is an explanatory diagram illustrating the operation of the present invention in comparison with the conventional one. 1... Automatic column 1q regulator (AGC) 2... Buffer 1 3.11.12... Switching circuit 4... Transformer driver 5... 1-Lance 7... Detection circuit 8.9 .10.13, 14.15.16...Comparator meter...Input terminal for transmission signal b...Input terminal for transmission request

Claims (1)

[Claims] (1) In a distribution line communication device that communicates by connecting a communication device to an indoor wiring network, an automatic gain adjuster provided in a circuit that sends a communication signal; A power distribution line communication device comprising an automatic gain adjuster controller that increases the output level and decreases the output level of the automatic gain adjuster when there is no transmission request signal.