JPS60187158A - Information outlet - Google Patents

Abstract

PURPOSE:To prevent the evil influence of malfunction, etc., to be exerted upon a frequency multiplex transmission line by interposing a branching circuit between a low-pass filter and the transmission line when a base band signal is led out of or supplied to the transmission line. CONSTITUTION:The base band signal of a frequency multiplex signal inputted to an input terminal 11 is led out to a digital signal terminal 13 through a branching circuit 1' and low-pass filter 7 and an audio signal, video signal, etc., are led out to a subband FM/TV terminal 14 through a branching circuit 1. An unnecessary signal flowing from a digital signal terminal 13 never flows to an output terminal 12 because of high-frequency transformers 2 and 3 and the influence of equipment connected to the digital signal terminal 13 is therefore eliminated.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to an information outlet for injecting and extracting various signals in a home comprehensive information transmission system that fully utilizes a home TV shared listening system. It is something.

Background: Comprehensive information transmission systems for home use have become possible due to the rapid development of microelectronic technology in recent years.
This is due to home automation. As the cost of interfaces becomes lower and they can be integrated into various home appliances, information outlets will be pre-wired and installed in each new home, just like power outlets, and each The user must purchase the necessary equipment (＼
/ i"R, Port 1.Computers, AV equipment, Word processors, -', Lil 1', J equipment, Security equipment) All purchases [7, These devices only need to be connected to an outlet, making them ideal The realization of home automation will become a major goal.

Furthermore, 1.20 years later. Starting with NS (Advanced Information 11n Communication System), CAPTAIN (C
I+; eye aclt-r AndPattern Te1e
phone Access Inronn+li+)
1+ Network), information is rapidly becoming more and more diverse even in the home, and it is becoming increasingly important to centralize and transmit all information such as digital control signals, digital data signals, audio signals, and video signals. There is a great need for a transmission system for home use that can be used.

Specifically, 1) Digital control signals... Crime prevention (electronic locks, intrusion sensors, etc.) Disaster prevention (gas leak sensors, fire sensors, etc.) Home appliance control (lighting equipment).

Air conditioners, etc.) ・'II) Digital data signals, personal computers, etc. 111) Audio signals... ...Telephones, intercoms.

doorbell etc. 1v) Video signal...--On-air TV broadcast.

゛r■ Camera etc. are categorized.

Currently, the transmission medium for the system is weak radio waves and Red Sun 1.
Wireless media such as wires, coaxial cables, twisted pair wires,
Wired media such as fiber cables are being considered, but 1) the installation cost is low because most existing home public listening systems can be used in that 4 inch size. In the case of houses that are pre-wired when they are newly built, there is no need for construction or cost.

H) Frequency division multiplexing allows multiplex transmission of various signals through a single coaxial cable, so users can connect the necessary number of devices according to their preferences and extract only the necessary signals.
It is flexible, easy to expand, and allows the construction of extremely flexible systems.

Mt.) The broadband time characteristics of coaxial cables will reach 1/1 in the near future.
Captain and INS are expected to become popular.

It is also fully compatible with VR8 and satellite broadcasting.

From the viewpoint of
A frequency division multiplexing system using I-thread coaxial cables is considered optimal.

On the other hand, devices connected to the transmission system that are in high demand are considered to be sensors and actuators related to energy saving, crime prevention, and disaster prevention, and it is desirable to have a configuration in which the interface module for these control signals is the least expensive. Therefore, the digital control signal is a baseband signal that does not require modulation/demodulation or level conversion.
L (1”rans: s tcr'I'ransi
What should be transmitted at the ster Logic level? can be,
It goes without saying that on-air television broadcasts and FM radio broadcasts are transmitted in the on-air frequency band.

For example, if you want to install a camera at the entrance and monitor it on a TV, you can modulate the camera's video signal to the available TV channel Q' and transmit it. Just use the frequency band sound you are using. An example of frequency allocation is shown in FIG. In the figure, a frequency band called Sub Band is used for transmitting digital data signals and audio signals.

Now, an information outlet is a two-bit unit necessary for extracting or injecting a desired signal from a coaxial cable, which is an information transmission path.For example, a control signal α:! Each terminal is provided with terminals such as a J connector and an audio signal terminal, and in the future, it will be necessary to pre-wire and install it next to a power outlet when constructing a house. The information outlet must be of such circuitry that it does not interfere with the transmission of signals by connecting to cables, or inject one signal that interferes with other signals.

<Prior Art> FIG. 9 shows an example of the circuit configuration of an information outlet according to the prior art. J is the existing public listening switch,
It is a hybrid connection of two high frequency transformers 2 and 3, 4 is a resistor, and 5° and 6 are capacitors to prevent the cable from being short-circuited. Dimension 7 is a low-pass filter that prevents harmonic components of the baseband digital signal from interfering with signals above the subband, θ and 9 are its inductors, and I
O indicates a capacitor.

+1 is the input terminal, 12 is the output 1'L; 1 child, 13 is the baseband digital signal terminal, 14 is the subband and I''M・'r■ terminal.Low pass filter 7
The cutoff wave number must be set so that waveform distortion of the baseband digital signal is kept within permissible limits, and its harmonics are sufficiently attenuated in the lunar subband frequency band.

By the way, in such a system, the signals handled span a high frequency band, so in the high frequency region above the subband,
The entire transmission path including the information concentrator must be well matched to 750. This is because if the degree of matching is poor, standing waves will be generated due to reflection, and the transmission characteristics will deteriorate, such as the generation of ghosts in television receivers, for example. Therefore, it is necessary to take precautions such as terminating unused terminals of sub-band or higher, but considering that these are widely used in ordinary households, they may not always be used correctly. Information outlets require measures to prevent them from affecting the main line due to incorrect usage or failure of connected equipment.

Ideally, the input impedance of the low-pass filter 7 in FIG. 9 increases as the frequency increases, and at frequencies above the subband, it should be considered almost unloaded when viewed from the cable, that is, nothing is connected. I can do it. However, in reality, the inductors 8 and 9, which are the components of the filter 7, have a distributed capacitance 15, as shown in the equivalent circuit of FIG. 10, and the equivalent inductance 16 decreases as the frequency increases. , above a certain frequency (self-resonant frequency), it cannot be considered an inductor and becomes a capacitor. After all, the equivalent circuit in the high frequency region of the low-pass filter 7 portion of the information outlet shown in FIG. 9 can be expressed as shown in FIG. 11. From the figure, it is clear that the transmission line is short-circuited at high frequencies, and it is impossible to maintain a sufficient degree of matching.

<Object of the Invention> In view of the above-mentioned points, it is an object of the present invention to provide four information outlets that can ensure sufficient consistency even in the high frequency range. In other words, in a transmission system in which multiple signals are transmitted through frequency division multiplexing, baseband signals may be completely lost from the transmission line or may be caused by the non-ideal characteristics of the constituent parts of the information outlet to be injected. It improves the deterioration of mismatch loss characteristics and completely eliminates the negative effects on the main transmission path due to malfunction of connected equipment or incorrect usage by the user.

<Embodiments> Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 7.

FIG. 1 schematically shows an embodiment of the present invention, and the feature of the present invention is that a branch 1' is fully expanded between the transmission line and the low-pass filter 70.

The operation of the turnout will now be explained using FIG. 2.

The splitter 1' is structurally similar to the public listening splitter 1 shown in FIG. A signal is applied to the input terminal 18, and the high frequency transformer 2
When an electric current fA'+, ■1 flows through the primary coil 28 of the
In this case, a portion of the energy of the input signal can be taken out, and most of the human signal energy flows to the output width 1 element 19.

When an unnecessary signal 3 flows from the branch terminal 20, ]3 flows to the primary side 3a of the high frequency transformer 3.
) 77s 20:) Secondary [112bVclAUrel 1
5 VC/IL, and furthermore, [4 causes 16 to flow into the secondary of the high frequency transformer 3 (Ill 8 a, and the input j
E terminal 18 VC reverse 11L current ■7 and output terminal 1
Electric current flowing out to ff11.9. 'Divided into IB. on the other hand,
■5 causes current to flow to the primary side 2a of the high frequency transformer 2■9
1 is generated, but its direction is opposite to that of 18, and its amplitude is approximately the same, so that they cancel each other out by /-7, so that 11 does not flow to the output terminal 19.

In other words, 13 is mostly in ■4 direction? AE, resistance 4
Energy was consumed and V was reduced by the branch loss 17
The circuit operates in such a way that the current only flows back to the input terminal I8 and does not appear at the output terminal 19. Therefore, the branch terminal 2o and the output terminal 19 are isolated, and the reverse coupling loss is about 35 dB in the configuration shown in the figure.

FIG. 7 shows the branch terminal 20 in the switch shown in FIG.
This figure shows the result of determining the effect on the output terminal 18 when the terminal is closed and when it is opened. The loss (I) in the same figure shows the mismatch loss of the output terminal 19 for one day. Each scale of the vertical axis is 5cl13,
Center of horizontal axis C 400 M IIz frequency span C 800
MIIZ T a.

Ru.

The greater the mismatch loss, the better the degree of matching, and at the input terminal (Fig. 7(a))
Even if i11 (' 2 Of) is opened, the mismatch loss will be extremely worsened, but there is no effect at all in the output width of 1 child ((+) in FIG. 7). In this way, the branch terminal 20
Because it is isolated from the main line, it has the characteristic that the influence of circuits and equipment connected to the branch terminal is less likely to appear on the transmission path, and all information outlets are connected to the circuit 1'+V as shown in Figure 1.
When the low-pass filter 7 alone has insufficient characteristics as described above, i.e., the harmonics of the digital 1lijl signal are Not only can it make up for the drawback of not being able to fully prevent it, but
It is clear that this is a measure against malfunctions of connected devices or misuse by users.

FIG. 3 shows a specific example of the configuration of FIG. 1.

In FIG. 3, for example, an audio signal 17j7.1 can be obtained by adding a distribution hybrid or a branching filter for extracting a desired signal to the subband and FM, ']'V filter I4. Figures 1 and 4 show an example of the information outlet with the circuit configuration shown in Figure 3. Powerful filter++
Examples of what was done are shown below. 21 in Figure 4 is a matching transformer, 22 is a splitting device/lance, 25 and 26 in Figure 5
For example, the demultiplexing filter C123゜24 is for the audio signal 01.
61 child, this is a terminal derived as Eizo Shinsouzui-r.

From a similar method Cτ, Kami no? It is not always possible to add more terminals.

FIG. 6 is a perspective view of the information outlet.

An input IYfM element 11 and an output terminal 12 which are laterally connected to the main line. National message letter Q on both sides in the vertical direction, 17iAiko 2
3 and video signal terminals 24 and 21) digital control "1"
71f 了 13 ゜ 13 is derived symmetrically.

<Effects of the Invention> As described above, the information outlet of the present invention improves the isolation characteristics between the baseband digital control signal terminal and the main line, and eliminates mismatching due to irrational or imaginary characteristics of the component parts. The invention is highly effective because it can further reduce the effects on the trunk line of deterioration of loss, malfunction of connected equipment, and incorrect usage by users.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing an actual mu example of the present invention.
Fig. 2 is a diagram for explaining the main circuit configuration and its operation in Fig. 1, Fig. 3 is a specific circuit configuration diagram of Fig. 1, and Fig. 4
5 is a circuit configuration diagram showing another embodiment of the present invention, FIG. 6 is a circuit diagram showing still another embodiment of the invention, and FIG. 6 is a diagram illustrating the characteristics of the circuit shown in FIG. 2. Fig. 7 is a perspective view of the external appearance, Fig. 8 is a diagram showing an example of the frequency division of . Figure 11 is an equivalent circuit diagram in the same high frequency region. 1' Branch, 7] Friend band pass filter, 11 'Input 0u'; Child, 12 Output terminal, 13 Digital signal Terminal, 14, Zabband, 1, ゛ to 4, 'I''V terminal. Representative P Patent attorney Yoshihiko Fukushi (and 2 others) Fig. 1 Fig. 2 Prisoner 4/3/3 Fig. 8

Claims (1)

[Claims] 1. In an information outlet connected to a transmission system in which Kmh signals are transmitted by frequency division multiplexing and for extracting or injecting a desired signal from the transmission path, -C, installed corresponding to the base band signal. The information outlet is characterized in that a branch circuit is inserted between the low-pass filter and the transmission line.