JPS6224742A - Signal supervisory equipment of multiplex transmission system - Google Patents

Abstract

PURPOSE:To attain supervision of a signal at an optional position with simple constitution by providing a return signal monitor section reproducing a return signal and monitoring it based on a differentiation signal of a return signal induced in other signal line provided nearly to a control line. CONSTITUTION:A signal supervisory equipment A is provided with a transmission signal monitor section 8 monitoring a transmission signal sent via the control line 3 based on the voltage level detection of the control line 3 and the return signal monitor section 9 recovering and monitoring the reply signal based on the differentiation signal of the return signal induced in other signal line 4 provided nearly to the control line 3, and the return signal monitor section 9 consists of a comparator CP1 detecting the voltage level induced in the signal line 4 of an information receptacle 6 and a flip-flop FF. The signal is supervised by having only to connect the signal supervisory equipment A by plugging in a plug 7 to the information receptacle 6.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a signal monitoring device for a multiplex transmission system that multiplex transmits transmission signals, return signals, etc. between a central control unit and a plurality of terminal devices. .

[Background Art 1] Basically, this type of multiplex transmission system used as a home television 7-on system, as shown in Fig. 1, consists of a central control unit 1 equipped with a main phone function and security function, A control circuit M is connected between the terminal device 2 equipped with the function or the terminal device 2 equipped with the fire and crime prevention monitoring function.
3 and other signal lines (for example, voice lines) 4 are arranged, and the central control unit 1 is connected to each terminal device 2 via the control line #13.
, 2' to multiplex transmit (time-division multiplex transmission) the transmission signal Vs consisting of control signals such as line connection signals, abnormality notification signals, and return standby signals, and to control the control line 4 as appropriate during the return standby signal period. From the terminals 2, 2' to the central control unit ra1 by shorting through the impedance.
Return signals such as dialing signals, fire signals, security monitoring signals, etc., were sent back as current mode signals.

FIG. 2 shows the signal transmission unit 10 of the central control device 1,
An example of the configuration of the signal transmission unit and power supply section of the terminal devices 2, 2' is shown, and the signal transmission circuit 10a of the signal transmission unit 10 includes an inverter circuit I and four transistors Q.
, ~Q4, and the transmission data creation section 11
Transistors Q, ~Q, with the data signal output from
is controlled on and off, and a signal voltage with different pulse widths and alternately inverted polarity corresponding to "1" to "O" of the transmitted data is applied to the control line 3, resulting in a bipolar circuit as shown in Fig. 3. A transmission signal Vs is transmitted. An address signal AD is used to access the terminal device 2 using this transmission signal Vs.

Control signal CD for controlling the terminal device 2 and return standby signal W
is now being transmitted. On the other hand, the receiving circuit 20a of the transmission unit of the terminal device 2, 2' detects the level of the bipolar transmission signal Vs to reproduce and receive the transmitted data, and also includes a resistor R0 and a transistor. In the transmission circuit 20b consisting of Q0, the control line 4 is short-circuited via the resistor Ro during the return standby signal period Tl11 (the transistor Q is turned on by the return data output from the return data generation circuit 22). A return signal vb consisting of a current mode signal is transmitted. In addition, in the power supply section 21 of the terminal device 2, 2'',
A terminal circuit power source is obtained by stabilizing the DC voltage obtained by rectifying the transmission signal Vs by a diode bridge DB and a diode D1. The return signal vb sent back from the terminal device 2 in this way is transmitted to the central control unit W1.
The signal receiving circuit 10b of the transmission unit 1 receives the signal and sends it to the return data determining section 12.
, , R2 and a comparator CP for level detection.

By the way, in such a multiplex transmission system, information outlets 6 are provided at a plurality of locations in order to allow the terminals 2 to be moved to appropriate locations, and the terminals 2, 2 are connected to the information outlets 6 via plugs 7.゛ can be freely connected, but
When the signal monitoring device A is connected to the information outlet 7 to monitor the transmission signal Vs and the return signal vb for system maintenance etc., the transmission signal Vs, which is a voltage signal, is detected by the voltage level detection of the control circuit #i3. However, there is a problem in that the return signal vb, which is a current mode signal, cannot be easily detected.

That is, in order to detect a return signal consisting of a current mode signal, the output of the signal receiving circuit 10m of the transmission unit 10 of the central control device 1 can be taken out, or the control line 3 can be disconnected and a current transformer can be inserted to output the current transformer. However, the configuration of the return signal monitor section becomes complicated, and as shown in FIG. There was a problem in that the return signal (b) could not be detected through the normal information outlet 6 in which only T1 to T were provided, and the signal could not be monitored at any location.

[Object of the Invention] The present invention has been made in view of the above points, and its object is to simplify the configuration of the return signal monitor section,
Moreover, it is an object of the present invention to provide a signal monitoring device for a multiplex transmission system that can monitor signals at any location.

[Disclosure of the Invention] (Embodiment) FIG. 5 shows an embodiment of the present invention, in which a transmission signal VS transmitted via a control line 3 is used in a signal monitoring device A of a multiplex transmission system similar to the conventional example. based on the differential signal of the return signal Vb induced by the transmission signal monitor unit 8 which monitors the voltage level by detecting the voltage level of the control circuit #13 and another signal port #14 disposed close to the control circuit #i3. return signal vb
The return signal monitor section 9 includes a comparator CP1 that detects the voltage level induced at the signal port #I4 of the information center, and a 7-lip 70-tube. It is formed with FF. Note that the voltage induced at signal port #14 is
As shown in the figure, this is obtained by the capacitance component between the control line 3 and the signal line 4, which are arranged close to each other, and both lines 3 and 4 are close to each other over a long section within the conduit. When appropriate capacitive coupling is achieved and the impedance of the signal line 4 is appropriately high (sufficiently high in the case of a voice line), the return signal v
A differential signal synchronized with the rise and fall of b is obtained.

The operation of the embodiment will be described below. Now, when a return signal vb as shown in FIG. 6(a) is being transmitted via the control line 3, the signal line 4 has a signal as shown in FIG.
A differential signal Vb' of the return signal vb as shown in b) is obtained, and the level of this differential signal Vb' is at a predetermined level V.
,, Comparator CP determines whether it is greater than or equal to V2 or less.
, and each time the comparator CP
A reproduced signal vb'' of the return signal vb as shown in FIG. 6(e) is output as the 0-tube FF output. The return signal monitor section 9 can be configured without using a transformer or the like,
The configuration can be simplified compared to the conventional example, and it is also possible to take out signals from the central control unit 1 and control circuit #i.
There is no need to insert a current transformer in series to the information outlet 6, and signal monitoring can be performed simply by connecting the signal monitoring device A to the information outlet 6 with the plug 7, so signal monitoring can be performed at any position. It is now possible to do so.

[Effects of the Invention] As described above, the present invention arranges a control line and other signal lines between a central control device and a plurality of terminal devices, and connects the central control device to each terminal device via the control line. By multiplexing transmission signals consisting of a control signal and a return standby signal, and short-circuiting the control line through an appropriate impedance during the return standby signal period, the return signal is sent from the terminal to the central control unit as a current mode signal. A signal monitoring device for a multiplex transmission system configured to send back signals, which includes a transmission signal monitor unit that monitors transmission signals transmitted via a control line by detecting the voltage level of the control line, and a signal monitoring unit disposed near the control line. The system is equipped with a return signal monitor section that reproduces and monitors the return signal based on the differential signal of the return signal induced in other signal lines installed, and as in the conventional example, the signal from the central control unit 1 is Since there is no need to take out the current signal or insert a current transformer in series in the control line to detect the current signal, the configuration of the return signal monitor section is simple, and it can be installed at any location via an information outlet, for example. This has the advantage that it is possible to provide a signal monitoring device that can perform signal monitoring.

[Brief explanation of the drawing]

FIG. 1 is a multiplex transmission system according to the present invention, FIG. 2 is a circuit diagram of the same essential parts, FIG. 3 is an explanatory diagram of the operation of the same, FIG. FIG. 6 is a circuit diagram of an embodiment of the present invention, and is an explanatory diagram of the same operation. 1 is a central control VC location, 2 and 2° are terminals, 3 is a control line, 4 is another signal line, 8 is a transmission signal monitor section, and 9 is a return signal monitor section. Agent Patent Attorney Ishi 1) Chief Figure 7 6

Claims (1)

[Claims] (1) A control line and other signal lines are arranged between the central control unit and a plurality of terminal devices, and transmission of control signals and return standby signals from the central control unit to each terminal unit via the control line A signal of a multiplex transmission system in which the signals are multiplexed and the control line is short-circuited through an appropriate impedance during the return standby signal period, so that the return signal is returned from the terminal to the central control unit in the form of a current mode signal. The monitoring device includes a transmission signal monitor section that monitors the transmission signal transmitted through the control line by detecting the voltage level of the control line, and a transmission signal monitor section that monitors the transmission signal transmitted through the control line by detecting the voltage level of the control line, and a transmission signal monitor section that monitors the transmission signal transmitted through the control line by detecting the voltage level of the control line. A signal monitoring device for a multiplex transmission system, comprising: a return signal monitor unit that reproduces and monitors a return signal based on a differential signal of the return signal.