JPS6113722A - Signal transmitter device - Google Patents

Abstract

PURPOSE:To increase the signal transmitting distance without giving any limitation to the terminal units by stopping the signal transmission to a remote repeater station when it is decided that the signal on a signal transmission line is equal to a loop-back signal sent from the remote repeater station at a repeater station of the center side. CONSTITUTION:A repeater station 5 and a remote repeater station 6 connected to each other by repeating signal lines (4a and 4b) are set between the signals lines 2 (2a and 2b) at the side of a center unit 1 connected to a terminal unit 10 and a signal lines 3 (3a and 3b) for extension connected to a terminal unit 11. A differential amplifier 52 which supplies the signals on the lines 2 and the both- terminal voltage of a resistor R51 is added to the station 5 together with a comparator 54 which compares the output of the amplifier 52 with the comparison voltage VS2 and a logical circuit which calculates the outputs of comparators 53 and 54. Then the station 5 discriminates the loop-back signal sent from the station 6, and the transmission of signals is stopped to the station 6 when a loop-back signal is discriminated. Thus the signal transmitting distance is extended without giving any limitation to the unit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a signal transmission device applied to, for example, a remote control system that exchanges digital information and controls equipment etc. by multiplex transmission.

[Prior art and its problems]

The inventors of the present application have proposed, as one of the signal transmission devices, the following transmission system in which a plurality of terminals and a center unit are connected via a transmission path, in which the plurality of terminals are connected relative to each other. a plurality of sets of transmitting terminals and receiving terminals, the transmitting terminal is configured to output a transmission confirmation signal at a first location in the data format when transmitting data, and the receiving terminal is configured to output a transmission confirmation signal at a first location in the data format when receiving data. The receiver is configured to output a reception confirmation signal at a second location in the receiver, and the plurality of sets of transmitting terminals and receiving terminals are divided into blocks for each predetermined number of sets, and each block is assigned an address separately. Then, the address is sequentially transmitted from the center unit to designate a block, and for each designated block, data transmission from the transmitting terminal in the designated block to the opposing receiving terminal is performed in accordance with the data format. let it be done,
Time division multiplex transmission characterized in that the transmission confirmation signal and the reception confirmation signal are checked in either the center unit or the terminal performing data transmission, and if either one is missing, an alarm operation is performed. system (Japanese Patent Application No. 58-73191).

The basic signal transmission configuration of this time division multiplex transmission system is shown in FIG. FIG. 1 is simplified to the extent necessary for the discussion herein, and only the signal transmission portion is shown. The center unit l performs communication control for time division multiplex transmission, and by turning on and off the transistor TRI in accordance with the input signal QO, a voltage is applied from the voltage VC to the signal paths 2a and 2b via the resistor R1. Transmits signals by changing voltage. Similarly, the terminal unit to
, ii also turn on transistors TR2 and TR5,
By turning OFF, the voltage applied between the signal paths 2a and 2b is changed, thereby transmitting the signal.
And center unit) 1. m-terminal unit) 10,11
In this case, signals are received by detecting the voltage between signal paths 2a and 2b (these structures are not shown).

In such a transmission system, by extending the distance between the terminals 10 and 11, the field of application of the transmission device expands, so there is a great need for increasing the distance.

However, in the configuration shown in FIG. 1, when the distance of the signal path 2 is extended, the impedance of the signal path causes the remote terminal unit 11 to
Since the value of the "H" level of the signal at signal path 2 decreases, problems occur such as the longer the signal path 2 becomes, the more difficult it becomes to binarize the transmitted signal with a fixed threshold value Vs. Communication becomes impossible (as shown in FIG. 2, communication becomes impossible at a distance due to the distance s).

Therefore, there has been a desire for an inexpensive signal path extension device for expanding the communication distance. In addition, when a signal path is provided outdoors, the electromagnetic environment is poor and there is a risk of various types of noise entering, so it has been desired to use optical fibers to improve noise resistance.

FIG. 3 is a block diagram showing an example of the configuration of a conventional extension device designed to realize such a request. Third
As shown in the figure, between the signal path 2 on the center unit side to which the terminal unit 1° is connected and the extension signal path 3 to which the terminal unit 11 is connected, the center unit side relay station 5 and the remote relay A station 6 and a relay signal path 4 are provided. Here, it is assumed that the relay signal path 4 is composed of an optical fiber 4a and an optical fiber 4b. The center unit l supplies a current to the signal path 2 via a resistor R1 connected to the power supply Vc in order to send the transmission data "0" or "1" to the signal path 2. In addition, in order to create a communication control signal, the transistor TRI is turned on with the signal QO.
Or turn it off.

The terminal unit 10 has a resistor R and a transistor TR2 for outputting data to the signal path 2, and by controlling the transistor TR2 ON/OFF using the output signal QIO, the signal Q10 is output as shown in FIG. is at the rHJ level during the period QI0,4-QI0,5, and the transistor TR2 is turned on, thereby causing the signal path 2 to pass through the resistor R to the period Vin,4-V in the signal Vin.
The period between in and 5 is set to the "L" level, thus creating data "1" (or data "0") in section #2.

As shown in FIG. 4, in the interval #l of the transmission signal Vin, the transistor TR2 is turned off, and data "0" (or data "1") is generated in this interval #1←4 (the signal Vin is , a binary signal (data 1 and data O) is expressed by the length of the rlJ level pulse width in each section.
A comparator 53 compares in and comparison voltage VSI, and the output Q1 of the comparator 53 is transmitted to the optical fiber 4a. E10
It has a converter 58, an O/E converter 57 that converts the signal from the relay signal path (optical fiber) 4b to obtain a loopback signal Q7, and a transistor TR3 for transmitting the signal Q7 to the signal path 2. There is.

The remote relay station 6 includes an O/E converter 67, a power supply VC, a resistor R1, a transistor TR4, and an extension signal path 3a for transmitting the signal from the optical fiber 4a to the extension signal path 3.
From there, it has a comparator 83 and an E10 converter 66 for transmitting a signal to a relay signal path (optical fiber 4b).

The data rlJ of the signal Q1 created by turning on the transistor TR2 of the terminal unit 10 is transmitted to the extension signal path 3 via the relay station 5, the optical fiber 4a, and the remote relay station 6, and is sent to the terminal unit 11. reach Conversely, the data "1" signal on the extension signal path 3 created by turning on the transistor TR5 of the terminal unit 11 is transmitted to the transistor block via the remote relay station 6, the optical fiber 4b, and the relay station 5. R3 is turned ON and the signal is transmitted to signal path 2.

However, in the above extension device, transistor TR5 is ONL, and transistor TR3 is ONL.
Then, the output Q1 of the comparator 53 becomes "L", and the "L" level state of the signal Q1 is again transmitted to the extension signal path 3 via the relay station 5, the optical fiber 4a, and the remote relay station 6.
In order to set the upper signal Vin to the "L" level, the transistor TR5 is turned off, so that even if a data "0" signal is sent, the signals on the signal path 2 and the extension signal path 3 remain at the "L" level. will be retained. Therefore, in the past, in order to prevent the above-mentioned troubles caused by loopback signals, only a terminal unit (11) was used, which only had a reception function that did not require loopback signals, which restricted the application and was very inconvenient. there were.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a signal transmission device that solves the above-mentioned problems and can extend the distance of a transmission line without being subject to restrictions on usage.

[Key points of the invention]

In the present invention, a relay station on the center unit side determines whether the level of a signal path is due to a loopback signal or not, and if the level is due to a loopback signal, the transmission of the signal to the relay signal path is stopped. This is what I did.

[Embodiments of the invention]

FIG. 6 shows a block diagram of a configuration in which the present invention is applied to a time division multiplex transmission system. Since FIG. 6 is the same as the configuration example of FIG. 3 except for relay station 5, the configuration of only relay station 5 will be described.

A relay station 5 is connected between the signal path 2 and the relay signal path 4. The signal from the signal path 2 becomes one input to the comparator 53, and its level is compared with the comparison voltage Vsl to become an output signal Q1, which becomes one of the inputs to the AND circuit 55. On the other hand, the voltage Vx across the resistor R51 is transmitted to the differential amplifier 52, and the output signal C changes depending on the magnitude of the voltage Vx, becomes one input of the comparator 54, and compares the level with the comparison voltage Vs2. As a result, the signal Q2 becomes the other input of the AND circuit 55. The output signal Q3 of the AND circuit 55 is transmitted to the signal path 4a via the E10 converter 56 and transmitted to the remote relay station 6.

Signal Q6 from remote relay station 6 is transmitted to O/E converter 57 in relay station 5 via E10 converter 66 and signal path 4b, becomes signal Q7, and is used for switching transistor TR3.

Next, the operation will be explained.

First, we will explain the part corresponding to the timing of section #l in FIG. 7, the transistor T in the center unit 1.
In the section Q0,1-Q0,2 where RI is OWL, the value of the input signal Vin(Ql) of the relay station 5 is close to Ov and smaller than the comparison voltage Vsl, and the value of the output signal Ql of the comparator 53 is close to Ov. is the rHJ level. Also, the voltage V! across the resistor R51! also has a value close to Ov, the output signal C of the differential amplifier 52 is smaller than the comparison voltage Vs2, and the output signal Q2 is at the rHJ level. Therefore, the output signal Q3 of the AND circuit 55 becomes rI (J level) during the period Q3,1-Q3,2, and is transmitted to the remote relay station 6 via the E10 converter 5B and the signal path 4a. Q3,1-
At 03.2, the output signal Q4 of the O/E converter B7 in the far relay station 6 also becomes rHJ level, and the transistor TR
4 is OWL, and the voltage Q5 of the extension signal path 3 is the period Q5,1.
-Q5,2 becomes rLJ level, and the state of signal path 2 is transmitted to extension signal path 3.

Even when the transistor TR2 of the terminal unit IO is ONL, the "L" level state of the signal path 2 is transmitted to the extension signal path 3, similarly to the above.

When the transistor of the center unit 1 turns from ON to OFF in periods Q0, 2-10, 3, the signal Vin of the relay station 5 increases and becomes larger than the comparison voltage Vsl, and the output signal Q1 of the comparator 53 becomes "L". ” level, AND
The output signal Q3 of the circuit 55 becomes "L" level. Therefore, the signal Q4 from the remote relay station 6 also goes to the rLJ level, and the transistor TR4 turns OFF t, the voltage Q5 on the signal path 3.
is at the rHJ level in the section Q5,2-Q5.3, which matches the state of signal path 2.

Therefore, by appropriately selecting the ON and OFF periods of the transistors TRI and TR2, the binary information of data "0" or rlJ can be transmitted from the signal path 2 side to the extension signal path 3.

Next, the part of one period #2, that is, the signal transmission in the opposite direction will be explained. 'Transistor T of terminal unit 11
When R5 is turned on during the period Qll, 4-Qll, 5, the voltage Q5 of the signal path 3 becomes rLJ level during the period Q5, 4-Q5, 5, and the comparison voltage Vs of the comparator 83
3, so the output signal QB is at the rHJ level, which is connected to E10 converter 68 and signal path 4b.
The output signal Q7 is transmitted to the O/E converter 57 of the relay station 5 through the period Q7.3-Q7.5, and the output signal Q7 becomes rHJ level, and the transistor TR3 is turned on. At this time,
When the transistor TRI of the center unit 1 and the transistor TR2 of the terminal unit 10 are off, the voltage across the resistor R51 is V! is given by equation (1).

[ix: Current flowing through resistor R51.

However, here, the resistance of the signal path, the collector-emitter voltage of the transistor TR3, etc. are ignored for the sake of simplicity, but the same can be said when they are taken into consideration. R1))R51) Also, transistor TRI or transistor TR2 is O
When NI is on, the voltage is V! is given by equation (2).

Note that due to the drop voltage of the resistor R51 and the transistor TR3, the voltage V! If there is a risk of Vx occurring, insert a diode or a fixed voltage diode τ in series with the resistor R51 of the relay station 5, as shown in Figure 8, to prevent Vx from occurring due to the drop voltage of the resistor R or transistor. It can be done.

Therefore, in the differential amplifier 52, the output signal C is set to be larger than the comparison voltage v2 for the value of Vx shown in equation (1), and for the value of Vx shown in equation (2), , by setting the signal C to be smaller than the comparison voltage Vs2, the output signal Q2 of the comparator 54 can be controlled in accordance with the value of vx. That is, as shown in FIG. 7, in the period 04-05, the transistors TRI,
When only the transistor TR3 is ON among TR2 and TR3, the value of the voltage Vx is the same as the period V! , 4-VL
5, the output signal Q2 of the comparator 54 is
2,4-Q2,5, and the output signal Q3 of the AND circuit 55 can be set to the rLJ level in the period Q3,4-Q3,8, which can be seen in the configuration example of FIG. It is possible to prevent communication failures caused by loopback signals.

Furthermore, if the transistor ↑R5 of the terminal 22) 11 is turned from ON to OFF after timing Qll, 5, both the signal path 2 and the extension signal path 3 will be in the rHJ level state.

As explained above, in FIG. 7, sections #1 and #
2 means data “O” and “1” (or “1”) of the transmission signal
” and “0”), relay stations 5 and 6
It is clear that communication between the terminal units 10 and 11'' is taking place normally via the terminal units 10 and 11''.

As already mentioned, in this embodiment, the so-called pulse width modulation method, in which a binary signal is expressed by the length of the pulse width at the rLJ level, is adopted as the form of the transmission signal. It is clear that it can be used as a signal path relay device for general data transmission systems such as duplex and full-duplex communication systems. That is, although FIG. 6 shows an example of application to pulse width modulation, it goes without saying that it can also be applied to cases where H/L of a signal line is transmitted in a synchronous or asynchronous manner.

Furthermore, in Fig. 6, a resistor R51 is inserted into a circuit that sends data back to the signal path using a loopback signal, and the terminal voltages are compared. It is also possible to determine whether the signal on the signal path is due to a loopback signal.

In addition, if the system configuration is simple with a small number of connected terminals, the value of the resistance H in the terminal 10 and the resistance R in the relay station 5
By changing the value of 51 and determining the magnitude of the voltage of the signal path, for example, by making the resistance value in the relay station larger than the resistance value of other terminals or the center unit, and using only the loopback signal, It is very easy to determine whether the voltage on the signal path is changing.

In this way, whether the signal level of a signal path is determined only by the loopback signal, or by the center unit or other terminals connected to the signal path, depends on the voltage level of the signal path, The direction of the current flowing through the relay station,
Alternatively, it is easy to make a determination using a local potential difference within the relay station.

Furthermore, if an optical fiber is used for the relay signal path, high-speed transmission can be achieved, and noise resistance can also be improved.

〔Effect of the invention〕

- As explained above, according to the present invention, the relay station on the center unit side determines whether the signal on the signal path is a loopback signal from a distant relay station.
．． If the signal is due to a loopback signal, the transmission of the signal to the distant relay station is stopped, so the signal transmission distance can be extended without restricting the terminal unit connected to the extension signal path. I can do it.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of a conventional transmission system. Figure 2 is a diagram showing the signal level transmission distance characteristics of the transmission system in Figure 1. Figure 3 is an example of the configuration of an extension device. Block diagram; FIG. 4 is a timing chart of transmission signals of the transmission system of FIG. 1; FIG. 5 is a timing chart of transmission signals of the transmission system of FIG. 3; FIG. 6 is a transmission device according to the present invention. 7 is a timing chart of transmission signals of the transmission system of FIG. 6, and FIG. 8 is a configuration of a relay station of a transmission device according to the present invention. It is a block diagram showing an example. l...center unit, 2...signal path, 3...
Extension signal path, 4... Relay phase signal path, 5... Relay station, 6... Distant relay station, 10.11...
・Terminal unit. ＾ Cwa 8 〉cr:o″) Button) Shout To (1011 To~ Rumor L/) -鵠 (I) Toθ ・C(Years 6 (-Totori)

Claims (1)

[Scope of Claims] A signal transmission device in which a center unit and a plurality of terminal units are connected via a signal path and signals are transmitted between the center unit and the terminal units or between the terminal units, comprising: A signal path is connected to a center unit side signal path with one end connected to the center unit, a center unit side relay station connected to the other end of the center unit side signal path, a far relay station provided far away, and both relays. It is extended by a relay signal path that connects the stations and an extension signal path that is connected to the remote relay station, and the center unit side relay station has a “1” or “0” signal path on the center unit side signal path. means for detecting a level; means for transmitting a signal corresponding to the level detected by the detecting means to the relay signal path; means for changing the level of the signal path on the center unit side to "1" or "0" by changing the level of the signal path on the center unit side; and means for detecting a change in the level by the changing means and stopping the transmission of the transmitting means; means for changing the level of the extension signal path to "1" or "0" in accordance with the signal sent from the center unit side relay station via the relay signal path; A signal transmission device comprising: means for detecting a level of “1” or “0”; and means for transmitting a signal corresponding to the level detected by the detecting means to the relay signal path. .