JPS62203443A - Coaxial cable network system - Google Patents

Abstract

PURPOSE:To transmit high and low frequency signals with high accuracy without being affected by the form of a network by connecting a series circuit comprising a capacitor and a resistor to plural terminations of a coaxial cable, and connecting a series circuit comprising a choke coil and a resistor to an optional one position of the coaxial cable. CONSTITUTION:A terminator 2 comprising a series circuit consisting of a capacitor 3 and a resistor 4 connected to the termination of a coaxial cable 1, a load 5 of a pulse transformer comprising a series circuit comprising a choke coil 6 and a resistor 7 connected to an optional position of the coaxial cable 1, a communication controller 8 connected to the coaxial cable 1, a controller 9, a transmitter 10 and a receiver 11 are provided. Thus, the series circuit comprising a choke coil and a resistor acts like a load of a pulse transformer of a communication controller without being affected with the termination resistor of the coaxial cable in the communication using a low frequency and only the termination resistor is made effective without being affected by the series circuit comprising a choke coil and a resistor to the communication using a high frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a coaxial cable network having a superimposed transmission function of high and low frequencies.

BACKGROUND ART FIG. 3 is a block diagram showing an example of a conventional coaxial cable network, in which 31 is a coaxial cable, which is connected to a television 34 via a termination device 32 consisting of a 75Ω resistor and a branch 33 of the coaxial cable 31. A communication control device 35 is connected to an antenna 37 via a distributor 36 of the coaxial cable 31, and the signal received by the antenna 37 is sent to the coaxial cable via the distributor 33, and the high frequency signal received by the television 34 and communication control are performed. The low frequency waves used for communication by the device 35 are transmitted over a coaxial cable.

In such a coaxial cable network, a terminating resistor that is suitable for high frequencies may not be suitable as a load resistor for a pulse transformer of a communication control device that uses low frequency signals. Therefore, when the signal waveform is unipolar, a configuration as shown in FIG. 4 has been used. This is a flywheel diode 3 on the primary side of a pulse transformer 38.
9, waveform undershoot can be suppressed without adding a load resistance to the pulse transformer 38.

In the case of a bipolar signal, a similar format is shown in FIG. 5, in which either diode 41 is turned on at the time of reception.

Therefore, the input impedance seen from the information transmission medium to the pulse transformer 4o becomes small, and the amplitude of the pulse is attenuated.

Problems to be Solved by the Invention In such conventional coaxial cable networks, the terminating resistor may act as an inappropriate load resistor for the pulse transformer of the communication control device.

In addition, the coaxial cable network type is distributed into three types.

When the number of distributions increases to four, the load on the pulse transformer also changes because the number of terminating resistors increases. Therefore, the waveform sent out from the pulse transformer is also affected by the network configuration (distribution method).

The present invention has been made in view of this point, and with a simple configuration, it is possible to use a conventional terminating resistor for high frequencies while providing an optimal load resistance for low frequencies that is unaffected by the network configuration. It is something.

Means to Solve the Problems In order to solve the above problems, the present invention connects series circuits of capacitors and resistors to multiple ends of a coaxial cable, and connects series circuits of a choke coil and a resistor to any one location of the coaxial cable. Make the connection.

Effect of the present invention With the above-described configuration, the series circuit of the choke coil and the resistor acts as a load for the pulse transformer of the communication control device without being affected by the terminating resistor of the coaxial cable for communications using low frequencies. For communication using frequency, only the terminating resistor is effective without being affected by the series circuit of the choke coil and resistor.

Embodiment FIG. 1 is a block diagram of a communication control device showing an embodiment of the present invention. In FIG. 1, 1 is a coaxial cable, 2 is a termination device consisting of a series circuit of a capacitor 3 and a resistor 4 connected to the end of the coaxial cable 1, and 5 is a choke coil connected to an arbitrary point on the coaxial cable 1. A pulse transformer load consisting of a series circuit of 6 and a resistor 7, 8 a communication control device connected to the coaxial cable 1, 9 a control device, 10
1 is a transmitting device, and 11 is a receiving device. 12 is a transistor that outputs a positive pulse to coaxial cable 1; 13
is a transistor for outputting a negative pulse to the coaxial cable 1, and is a pulse transformer 14 with a center tap.
The collector of the transistor 12 is connected to one end of the primary winding, the collector of the transistor 13 is connected to the other end,
Transistors 12 and 13>') A voltage of 6V is applied at night. 15 is a resistor, one end of which is connected to the output port of the control device 9, and the other end connected to the base of the transistor 12. Similarly, the resistor 16 is connected to the control device 9
One end is connected to the output port B of the transistor B, and the other end is connected to the base of the transistor B.

Therefore, the output port connected to the resistor 16 of the control device 9 is L.
When the voltage reaches the OW level, the transistor 12 is turned on, a current flows in the direction A through the primary winding of the pulse transformer 14, a pulse voltage is generated in the secondary winding, and a positive pulse signal can be transmitted to the coaxial cable 1. Similarly, when the output port connected to the resistor 1θ of the control device 9 becomes low level, the transistor 1
3 is turned on, a current flows in the direction of A in the primary winding of the pulse transformer 14, a pulse voltage is generated in the secondary winding, and a negative pulse signal can be transmitted to the coaxial cable 1. Reference numerals 17 and 18 are transistors whose collectors are connected to the input port of the emitter control device 9 and grounded. A resistor 19 has one end connected to the base of the transistor 17 and the other end connected to one end of the primary winding of the pulse transformer 14 . The other end of the pulse transformer 14 is connected to one end of the resistor 20,
The other end of the resistor 2o is connected to the base of the transistor 18. 21 is a pull-up resistor for setting the input port of the control device 9 to a high level. When the transistor 12 is turned on or when there is a positive pulse on the coaxial cable 1, a base current flows through the transistor 17 and the control device 9
0 input port becomes low level. Also, when the transistor 13 is turned on or when there is a negative pulse on the coaxial cable 1, a pace current flows through the transistor 18, and the input port of the control device 9 becomes low level, and the monitor during transmission and the coaxial cable 1 Can receive certain data.

FIG. 2 is a block diagram of a coaxial cable network showing one embodiment of the present invention. 1 to 8 are the same as 1 to 8 in FIG. 8' is similar to the communication control device 8;
It is connected to the coaxial cable 1 via a branch 22.

23 is connected to the coaxial cable 1 via the TV branch 22. 24 coaxially sends the television signal received by the antenna via a distributor 26.

First, when viewing the television 23 in this configuration, a television signal received from the antenna 24 is transmitted via the coaxial cable 1. In the case of such a high frequency, the coil 6 exhibits high impedance and does not work, so it is not affected by the load 5, and only the termination device 2 suitable for high frequency transmission works.

Next, communication between the communication control devices 8 and 8', that is, communication at a low frequency will be explained. Since the capacitor 3 does not conduct current for low frequencies, there is no effect on the pulse transformer by the terminating device 2, and if the wavelength of the low frequency is sufficiently long compared to the total length of the coaxial cable 1, the reflection of low frequencies can be ignored. By applying a load 6 suitable for communication using a low frequency, normal human MI communication can be performed.

Similarly, even if the network configuration increases to 3-4 distribution, only the load 5 works without being affected by the terminating resistor 4.
Optimal load can be applied to low frequencies.

In other words, it becomes possible to provide resistance suitable for both high and low frequencies, regardless of the form of the network.

In this embodiment, the load 5 is directly connected to the coaxial cable, but when a DC power source is superimposed on the coaxial cable, the load 5 is connected to the coaxial cable via a large capacity capacitor such as an electrolytic capacitor.

As described above, the present invention has an extremely simple configuration,
Accurate transmission of high and low frequencies can be achieved without being affected by the network configuration, and is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a communication control device for a home bus system according to an embodiment of the present invention, FIG. 2 is a block diagram of a coaxial cable network for a home bus system according to an embodiment of the present invention, and FIG. 3 is a conventional Block diagram of a coaxial cable network for an example home bus system, Part 4
6 and 6 are configuration diagrams of a conventional pulse transformer. 1... Coaxial cable, 2... Termination device, 3... Capacitor, 4... Resistor, 5
...Load, 6...Choke coil, 7
......Resistance, 8...Communication control device, 9.
...Control device, 10...Transmission device, 11
・・・・・・A receiving device. Name of agent: Patent attorney Toshio Nakao and one other person
Li

Claims (1)

[Claims] A communication control device that transmits and receives information packets via a coaxial cable, a pulse transformer whose primary side is connected to the communication control device and whose secondary side is connected to the coaxial cable, and which converts and amplifies the output signal of the communication control device. a transmitting device that controls the current in the primary coil of the pulse transformer; a receiving device that receives a transmission signal superimposed on the coaxial cable via the pulse transformer and converts it into a signal that can be input to the communication control device; A plurality of termination devices consisting of a series circuit of a capacitor and a resistor connected to a plurality of ends of the coaxial cable, and a series circuit of a choke coil and a resistor connected to an arbitrary point of the coaxial cable as a load of the pulse transformer. A coaxial cable network system comprising: