KR19990021881A - Demultiplexers, protective switch units, networks and demultiplexing methods - Google Patents

Abstract

The present application is provided with a demultiplexer for selecting an output for a signal received at an input during a multiplexing process, a protection switch unit including one demultiplexer, and a communication network including one protection switch unit, wherein the demultiplexer is provided with an input (IN +, IN -) And at least two outputs (OUT1 +, OUT1-, OUT2 +, OUT2-). At the input, the first connection point IN1 + is connected to the first transmission line TLINE_1 to conduct the input signal there. At each output, first connection points OUT1 +, OUT2 + are connected to transmission line TLINE_1 via respective first controllable signal transmission devices Q1, Q2. Externally controllable signal switch means S1 and S2 are also connected to each output. The switch means S1 controls one of the first signal transmission devices Q1 to transmit a signal applied through the first transmission line TLINE_1 to the first connection point OUT1 + of the selected output. It is also connected to each output for forwarding a signal or at least part thereof delivered to the input to the first transmission line TLINE_1. The first transmission line TLINE_1 is connected at the output to the first connection point OUT +, where a signal of good quality is obtained.

Description

Demultiplexers, protective switch units, networks and demultiplexing methods

In a communication network, a plurality of signal lines are often connected to the exchange through the medium of each terminal access unit. The terminal access unit is a relatively expensive and complicated unit, which can sometimes be destroyed. For this reason, the network comprises at least one protective switch unit, the output of which is connected to the signal line and the input of the unit to the spare terminal access unit.

When the standard terminal access unit cannot be used for any reason or for any other reason, the exchange sends an output signal intended for the signal line connected to the normal terminal access unit which is not available via the spare terminal access unit to the demultiplexer of the protective switch unit, and The demultiplexer is controlled to cause an output signal to be sent to the signal line.

Good signal quality is required when switching or demultiplexing signals having transmission rates in the region of about 140-155 Mb / s. In this relationship, the pulse shape of the output signal is often required to be the same as the pulse shape of the input signal.

Mismatches between configuration and leads can easily occur in high-speed demultiplexers, causing significant damage to signal quality.

It is also necessary to adjust the spare terminal access unit and also the demultiplexer against errors in the protective switch unit.

Multiple standard circuits exist for demultiplexing signals having bit rates up to about 30 Mb / s in a relatively simple and inexpensive manner. At higher bit rates, line impedance, connection, termination, line operation, and configuration data place stringent requirements on the circuit. In order to keep the wire impedance as constant as possible, special care must be taken when performing the printed board assembly.

In a demultiplexer, circuits including standard circuits are expensive and consume a lot of current.

There is currently no technique to effectively demultiplex while adjusting in the above mentioned rate range.

US-A 5,146,113 describes an integrated circuit having several narrow, long strips of resistance on a circuit-board for equipping board mounted circuits with set input and / or output impedances.

US-A 5,281,934 describes a microwave multiplexer which is entirely comprised of a microstrip.

The present invention relates to a demultiplexer, a protective switch unit including the demultiplexer, a communication network including the protective switch unit, and a demultiplexing method. In particular, the present invention relates to the aforementioned apparatus and method for demultiplexing signals which are preferably single mode or differential mode signals in the form of CMI in the transmission rate range of about 100 Mbit / s or more and preferably about 140 to 155 Mb / s. It is about.

Additional objects of the present invention and the advantages provided by the same are evident from the following description of the preferred embodiments of the present invention made with reference to the accompanying drawings.

1 is a block schematic diagram of a communication system of the present invention;

2 is a circuit diagram of a demultiplexer of the present invention.

One object of the present invention is to provide a method of selecting one of several output signals as the output of a received input signal during demultiplexing to obtain good signal quality at the same time in a simple and inexpensive manner.

The object is achieved by a method in which an input signal received on an input is first conducted to a first transmission line and then selectively conducted to one of at least two outputs.

It is another object of the present invention to provide a method of selecting one of several outputs as an output of a received input signal and deciding in a simple manner the signal passed to one of the outputs during demultiplexing.

The object is also achieved by a method comprising generating a duplicate of the signal transmitted to the selected output by simultaneously inverting the input signal passing through the selected output to the third transmission line.

An additional object of the present invention is to provide a method for selecting one of several outputs as an output for a received input signal during demultiplexing, so that the distortion of the signal obtained on the selected output and the replica of the signal is easily at a later stage. Can be reduced.

The object is that the input signal comprises two parts and two parts of the input signal are respectively inverted to each of the first and second transmission lines, and then selectively at each of the first and second connection points at the selected output, Conducted to the third and fourth transmission lines.

It is another object of the present invention to have a demultiplexer, a protective switch unit comprising one demultiplexer, and a communication network comprising one protective switch unit, wherein a good signal quality is provided for the received input signal. When selected as an output, it is obtained in a simple and inexpensive way.

The object consists of a demultiplexer, a protective switch unit and a communication network, in which the demultiplexer comprises an input and at least two outputs, where the connection point at the input is connected to each first controllable signal transmission lead means at each output. It is connected to the first transmission line which is connected via.

It is a further object of the invention to have a demultiplexer, a protective switch unit comprising one of the demultiplexers, and a communication network comprising one of the protective switch units, wherein the function of the demultiplexer and a unit connected to the input of the multiplexer are provided. The function can be easily adjusted.

The object is achieved by a demultiplexer, a protective switch unit and a communication network, where each first signal transmission lead means is connected to a third transmission line.

It is another object of the present invention to have a demultiplexer, a protective switch unit comprising one of the demultiplexers, and a communication network comprising one of the protective switch units, wherein the distortion obtained in the output signal from the demultiplexer is subjected to a later stage. Can be reduced easily.

The object consists of a demultiplexer, a protective switch unit and a communication network, wherein a second connection point of the demultiplexer input is alternately connected to the second connection terminal of each output via each second controllable signal transmission lead and connected to the fourth transmission line. It is also connected to a second transmission line that is selectively connected.

1 is a block schematic diagram of a communication system operating with a CMI signal transmitted at a transmission rate in the range of about 140-155 Mb / s. The system includes an exchange 1 in communication with a plurality of signal leads. Each signal lead is connected to a protection unit 2 (PU = Protection Unit). Although only eight protection units are shown in FIG. 1, the units may be fewer or more. Signals entering and exiting the protection unit 2 are indicated by arrows pointing towards and leaving each unit 2. Each protection unit 2 is connected to the exchanger 1 via each terminal access unit 3 (TAU) and there are actually 16 such units, but only eight of them are shown. The modus operandi of the terminal access unit 3 does not play a role in the present invention and is well known to those skilled in the art and therefore need not be described in more detail. However, the terminal access unit 3 is relatively complicated and expensive and has a high error frequency in order to require some form of protective switch. To avoid unused signal leads, a spare terminal access unit 5 is provided which is switched in to replace the unit when one of the regular terminal access units 3 is deactivated. The spare terminal unit 5 is connected between the exchanger 1 and the protective switch unit 4 (PSU).

The protective switch unit is connected to each protective unit 2. The main duty of the protection unit 2 converts the single mode signal coming into the protection switch unit 4 into a differential mode signal, and converts the differential mode signal exiting from the exchanger 1 into the terminal access unit 3 and the protection switch unit 4. The signal is converted into a single mode signal via). The protective switch unit 4 comprises a multiplexer or selector and a demultiplexer. The multiplexer functions to receive all incoming signals on the lead and to selectively transmit one of the signals, and the demultiplexer receives the outgoing signal from the exchange 1 and transmits the signal to the selected signal lead.

2 illustrates an embodiment of the demultiplexer of the present invention, where it is understood that the demultiplexer usually has multiple outputs, but only two inputs are shown for simplicity. The first input has first and second connection points OUT1 + and OUT-. The first connection point OUT1 + of the first output is connected to the first signal transmission lead means Q1 via a resistor R1, which means Q1 is connected to an RF transistor in the case illustrated. Resistor R1 is connected to the emitter of transistor Q1 in the illustrated case. The transistor base is connected to the first transmission line TLINE_1 through the resistor R8. One end of the transmission line TLINE_1 is terminated with a resistor R5 connected to the voltage source VBB.

The transistor collector is connected to a third transmission line TLINE_3 included in the demultiplexer circuit board, and the third transmission line is terminated at each end by respective resistors R13 and R12 connected to the voltage source VCC. A first connection point SUP + is provided at the end of the third transmission line TLINE_3 with a signal at the regulation output.

The second transmission line mounted on the demultiplexer circuit board via the resistors R3 and RF transistor Q4 and the additional resistor R10 similarly to the first connection point OUT1 + of the first input point OUT1 +. Is connected to (TLINE_2). One end of TLINE_2 is terminated with a resistor R6 connected to the voltage source VBB. The collector of transistor Q4 is connected to a fourth transmission line TLINE_4 mounted on a demultiplexer circuit board, and the fourth transmission line is connected in one stage as the resistor R14 and in the other in a manner similar to the third transmission line TLINE_3. Is terminated with resistor R7 at which the resistor is connected to a voltage source VCC. The second connection point is obtained at one end of the fourth transmission line TLINE_4 at the control signal output.

Each emitter of the first and second transistors Q1 and Q4 is connected to one end of the first externally controlled switch means S1 via resistors R29 and R31 respectively. The other end of the switch S1 is connected to ground.

The connection points OUT2 + and OUT2- of the second output are exactly the same via resistor R2, transistor Q2 and resistor R9 and via resistor R4, transistor Q3 and resistor R11. Are connected to the first and second transmission lines TLINE_1 and TLINE_2. Each collector of transistors Q2 and Q3 is connected to each of third and fourth transmission lines TLINE_3 and TLINE_4. Each emitter of transistors Q2 and Q3 is connected to a second externally controlled switch S2 via resistors R30 and R32 in exactly the same way as the first output, which switch S2 is connected to switch S1. Similarly connected to ground.

Transistors Q1, Q2, Q3 and Q4 and associated configurations are located along transmission lines TLINE_1, TLINE_2, TLINE_3 and TLINE_4 so that mismatches and reflections are minimal. In fact, additional transistors for additional outputs are correspondingly located along the transmission lines TLINE_1, TLINE_2, TLINE_3 and TLINE_4.

The differential amplifier D_AMP has one output and is connected to the first transmission line TLINE_1 at the first connection point (+0) and to the second transmission line TLINE_2 at the second connection point (-0). The amplifier D_AMP has an input with two connection points (+ I and -I) respectively connected to respective connection points IN + and IN- at the input.

Resistors terminating the ends of each of the first and second transmission lines TLINE_1 and TLINE_2 connecting the amplifier D_AMP are included in the amplifier and also connected to the source VBB, which is also connected to the amplifier D_AMP at the end of the transmission line. And therefore not shown in the figures.

In a preferred embodiment, each transmission line TLINE_1, TLINE_2, TLINE_3 and TLINE_4 has the form of a microchip included in the board circuit and a transistor is connected thereto. The microchips are preferably straight, have the same length and are essentially single width. However, an important feature of this embodiment is that two transistors at each output have an equally long path to the junctions (+0 and -0) at the output of the amplifier D_AMP. The transmission lines TLINE_1, TLINE_2, TLINE_3 and TLINE_4 are optionally slightly narrowed in that the transistors are connected to match the impedance of the microstrip to the additional capacitance supplied by the passive transistors. Alternatively, the impedance of each transmission line is matched to the capacitance of the passive transistor by selecting the value of the termination resistors R5, R6, R7 and R12, R13 and R14 to correspond to the transmission lines with additional distribution capacitance supplied by the transistor. Can be.

Another achievable variant of the transmission line is a parallel plane line (stripline) disposed in the middle layer of the circuit board. However, the transmission line embodiment requires the transistor to be connected to the line by bushings or throughlets, which makes it slightly more difficult to solve the matching problem than when the transistor is connected to the microstrip. However, the input and output of the demultiplexer are often configured in the form of parallel plane lines through the interior of the circuit board.

The demultiplexer illustrated in FIG. 2 functions as a differential mode signal, and as a result, the distortion of the signal leaving the demultiplexer is reduced. The demultiplexer operates as follows: The input signal is received on the inputs IN + and IN- and amplified to the appropriate level in the amplifier D_AMP. The amplified input signal is transmitted to the output selected by the first and second transmission lines TLINE_1 and TLINE_2. Amplification of the amplifier D_AMP is chosen to essentially compensate for the resulting losses due to output impedance and load.

One of the inputs, for example a first output, is operated by a first externally controlled switch S1 which activates transistors Q1 and Q4 connected to the input when the input is closed. The second input is passive, ie the second switch S2 is turned off.

The switch has any one of a number of different designs known to those skilled in the art, for example in the form of a transistor. The switches S1 and S2 are controlled by a control circuit arranged in the protective switch unit, and function to close the switch depending on which of the above-mentioned terminal access units is deactivated. The switching function can also be performed directly from the above mentioned exchanger. When the switch S1 is closed, the transistors Q1 and Q4 are biased and the amplified input signal is transmitted from the transmission lines TLINE_1 and TLINE_2 to the connection points OUT1 + and OUT1- of the first output via the transistors Q1 and Q4. Is inverted.

The demultiplexer is used to also conduct the output signal to the third and fourth transmission lines TLINE_3 and TLINE_4 as soon as the output signal is obtained on the output. That means that a duplicate of the input signal is also obtained. The duplication is obtained at the connection points SUP + and SUP- of the regulating output and processed in the regulating circuit included in the protective switch unit. The demultiplexer also includes a second differential amplifier that amplifies the control signal. By analyzing the signal, it can be set whether or not the spare access unit has been destroyed. Signal analysis reveals that the demultiplexer works in the intended way. It would otherwise save the additional control circuitry required.

Connection of transmission lines means that some reflections are quickly distinguished. Transmission lines are arranged so that the third and fourth transmission lines TLINE_3 and TLINE_4 have approximately half the impedance of the first and second transmission lines TLINE_1 and TLINE_2. This is done by choosing the width of the transmission line and its respective distance to the ground plane. As a result of that choice, the collector voltage of the transistor is lower than the emitter and base voltages. Crosstalk from the collector to the base has only a very minor impact on signal quality. The predetermined degree of crosstalk occurs in the weak direction, but the quality of the control signal is not as important as the quality of the output signal. Since the collector voltage is low compared to the base and emitter voltages, the transistor can be considered as emitter follower. It gives high input impedance and thereby has little influence on the first and second transmission lines TLINE_1 and TLINE_2, which only has a minor effect on the pulse shape.

The amplifier D_AMP may alternatively be connected to opposite ends of the first and second transmission lines TLINE_1 and TLINE_2. The control signal output may also be located at opposite ends of the third and fourth transmission lines TLINE_3 and TLINE_4.

Claims (29)

In the demultiplexing method, which is a method of selecting one of several outputs as an output for an input signal received on an input (IN +, IN-), Conducting an input signal or at least a first portion thereof from a first connection point (IN +) of the input to a first transmission line (TLINE_1); At least two outputs OUT1 +, on the demultiplexer as an output signal of high signal quality or a first portion of the output signal via the first controllable signal transmission device Q1 from the first transmission line or its first portion. And selectively conducting to one of the first connection points (OUT1 +) of OUT1-, OUT2 +, and OUT2-. The input signal or the first portion thereof of claim 1, wherein an input signal or a first portion thereof is conducted to the first connection point OUT1 + at an output to produce an output signal or a first replica of the first portion thereof. And conducting a third transmission line (TLINE_3) to the third transmission line (TLINE_3). The input signal according to claim 1 or 2, wherein the input signal comprises a first part and a second part, wherein the first part of the input signal is the first signal from the second connection point IN- of the input to the second transmission line TLINE_2. Demultiplexing, characterized in that it is conducted simultaneously with the negative, and then the second part is conducted from the second transmission line to the second connection point OUT1- of the one output via the second controllable signal transmission device Q4. Way. The method of claim 3, wherein the second portion is conducted to the second connection point OUT1-1 to generate a second copy of the second portion of the output signal, and at the same time, the second portion of the input signal is transferred to a fourth transmission line ( TLINE_4). A method according to any one of the preceding claims, comprising amplifying an input signal prior to conducting the signal to transmission lines (TLINE_1, TLINE_2) which bind the inputs together to the one output. In a demultiplexer having inputs IN +, IN- and at least two outputs OUT1 +, OUT1-, OUT2 +, OUT2-, the first connection points OUT1 +, OUT2 + of each input are each first controllable signal transmitter Q1. Is connected to common line TLINE_1 via Q2), and the first connection point of each output transmits a signal or a first portion of an applied signal to the first connection point of the output via the common line. 1. In a demultiplexer connected to externally controlled switches S1 and S2, which serve to control a signal transmission device, Demultiplexer, characterized in that the common line is a first transmission line (TLINE_1) which is also connected to the first connection point (IN +) at the output. 7. The demultiplexer according to claim 6, wherein each of the first signal transmission devices (Q1, Q2) is also connected to the third transmission line (TLINE_3) to generate a control signal or a first portion of the control signal. The method according to claim 6 or 7, wherein at each input, the second connection points OUT1-, OUT2- are connected to the second transmission line TLINE_2 via the respective second controllable signal transmission devices Q4, Q3, A demultiplexer, characterized in that a transmission line is connected at the input to a second connection point (IN-) and the switches (S1, S2) also control the second signal transmission device. 9. The demultiplexer according to claim 8, wherein each second signal transmission device (Q3, Q4) is also connected to a fourth transmission line (TLINE_4) to generate a second portion of the adjustment signal. 10. The demultiplexer according to any one of claims 6 to 9, wherein each of the transmission lines (TLINE_1, TLINE_2, TLINE_3, TLINE_4) is a microstrip mounted on a demultiplexer circuit board. 10. The demultiplexer according to any one of claims 6 to 9, wherein each of the transmission lines (TLINE_1, TLINE_2, TLINE_3, TLINE_4) is a parallel plane conductor mounted on a demultiplexer circuit board. 12. The amplifier according to any one of claims 6 to 11, having an amplifier connected between the inputs IN1 +, IN1- and the transmission lines TLINE_1 and TLINE_2 connecting the inputs as respective outputs OUT1 +, OUT1-, OUT2 +, OUT2-. Demultiplexer characterized in that. The signal transmitting apparatuses Q1, Q4, Q2, and Q3 are transistors, and the emitters are outputs OUT1 +, OUT1-, OUT2 +, and OUT2 via resistors R1, R3, R2, and R4. At-), the base is connected to the transmission lines (TLINE_1 and TLINE_2) connecting the inputs (IN +, IN-) to each output, and the collector is connected to the transmission lines (TLINE_3, TLINE_4) to generate a control signal. Demultiplexer characterized by. The demultiplexer according to any one of claims 6 to 13, wherein the transmission lines (TLINE_1, TLINE_2, TLINE3, TLINE4) are terminated with respective resistors (R5, R6, R12, R13, R7, R14). In a protective switch unit 4 comprising a demultiplexer having an input IN +, IN- and at least two outputs OUT1 +, OUT1-, OUT2 +, OUT2-, the first connection point of each input (OUT1 +, OUT2 +) on the demultiplexer Connected to the common line TLINE_1 via each of the first controllable signal transmission devices Q1 and Q2, and transmitting the signal or the first portion of the signal applied through the common line or the conductor to the first connection point of the output. In the protection switch unit 4, in which externally controllable switch means S1 and S2, which function to control the first signal transmission device, are also connected to each output, The protective switch unit (4), characterized in that the common line (TLINE_1) is a first transmission line which is also connected to the first connection point (IN +) at the input of the demultiplexer. The protection switch unit (4) according to claim 15, wherein each of the first signal transmission devices (Q1, Q2) is also connected to the third transmission line (TLINE_3) to generate a control signal or a first part of the control signal. The method according to claim 15 or 16, wherein at each demultiplexer output, second connection points OUT1-, OUT2- are connected to a second transmission line TLINE_2 via respective second controllable signal transmission devices Q4, Q3, A protective switch unit (4), characterized in that the transmission line is connected at the input to a second connection point (IN-), said switch (S1, S2) means also controlling said second signal transmission device. The protection switch unit (4) according to claim 17, wherein each second signal transmission device (Q3, Q4) is also connected to a fourth transmission line (TLINE_4) to generate a second portion of the adjustment signal. 19. The amplifier according to any one of claims 15 to 18, having an amplifier connected between the inputs IN1 +, IN1- and the transmission lines TLINE_1, TLINE_2 connecting the inputs as respective demultiplexer outputs OUT1 +, OUT1-, OUT2 +, OUT2-. A protective switch unit, characterized in that. 19. The signal transmitters Q1, Q4, Q2, and Q3 are transistors, wherein the emitters are each output OUT1 +, via the resistors R1, R3, R2, R4. Connected to the connection points of OUT1-, OUT2 +, and OUT2-, the base is connected to the transmission lines TLINE_1 and TLINE_2 connecting the inputs (IN +, IN-) to the respective outputs, and the collector is connected to the transmission lines (TLINE_3 and TLINE_4) A protective switch unit (4), characterized by generating an adjustment signal. 21. The protection switch unit according to any one of claims 15 to 20, wherein the transmission lines TLINE_1, TLINE_2, TLINE_3, TLINE_4 of the demultiplexer are terminated with respective resistors R5, R6, R12, R13, R7, and R14. 4). In a communication network comprising two or more lines connected to an exchange 1 via each terminal access unit 3, a protective switch unit 4 in which each line is alternately connected to the exchange via a spare terminal access unit 5 ), And the protective switch unit comprises a demultiplexer having inputs (IN +, IN1-) and at least two outputs (OUT1 +, OUT1-, OUT2 +, OUT2-) and at each demultiplexer output a first connection point (OUT1 +, OUT2 + is connected to the common line TLINE_1 via each controllable signal transmitter Q1, Q2, and each output transmits a signal or a first portion of the signal to which the first connection point is applied via the common line. In a communication network also connected to externally controlled switch means (S1, S2) for controlling the first signal transmission device, And wherein the common line (TLINE_1) is a first transmission line which is also connected to the first connection point (IN +) at the demultiplexer input. 23. A communication network according to claim 22, wherein each first signal transmission device (Q1, Q2) is also connected to a third transmission line (TLINE_3) to generate a control signal or a first part of the control signal. 24. The device according to claim 22 or 23, via each of the second controllable signal transmitters Q4, Q3 at which the second connection point OUT1-, OUT2- at the output of the demultiplexer is connected to the second connection point IN- at the input. A communication network connected to a second transmission line (TLINE_2), said switch means (S1, S2) also controlling said second signal transmission device. 25. A communication network according to claim 24, wherein each second signal transmission device (Q3, Q4) is also connected to a fourth transmission line (TLINE_4) to generate a second portion of the adjustment signal. A demultiplexing method for selecting one of a plurality of outputs as an output for an input signal received on an input, the demultiplexing method comprising: Conducting an input signal or at least a first portion of the signal from a first connection point of the input to a first transmission line; One of the at least two demultiplexer outputs as an output signal for the first portion of the output signal with high signal quality via a first controllable signal transmission device for the input signal for the first portion of the signal from the first transmission line And conducting to the first connection point. A demultiplexer having an input and at least two outputs, the first connection point of each input being connected to a common line via each first controllable signal transmission device; Externally controlled switch means, connected to each output, for controlling a first signal transmission device for transmitting a signal or a first portion of the signal applied through a common line to a first connection point of the output; And wherein the common line is a first transmission line which is also connected at the input to the first connection point. A protective switch unit having a demultiplexer having an input and at least two outputs, the protective switch unit comprising: a first connection point at each demultiplexer output is connected to a common line via each first controllable signal transmission device; Externally controllable switch means, also connected to each output, for controlling the first signal transmission device for transmitting a signal or a first portion of the signal applied through a common line to a first connection point of the output; And wherein the common line is a first transmission line which is also connected to the first connection point at the input of the demultiplexer. In a communication network comprising two or more lines connected to an exchange via each terminal access unit, each line is also connected to a protective switch unit alternately connected to the exchange via a spare terminal access unit, the protective switch unit being A demultiplexer having an input and at least two outputs, wherein at each demultiplexer output a first connection point is connected to the common line via each first controllable signal transmission device, the first of the signal or signal being applied through the common line An externally controlled switch means for controlling the first signal transmission device for transmitting a portion to a first connection point of the output is also connected to each output and the common line is a first transmission line that is also connected to the first connection point at the demultiplexer input. A communication network, characterized in that.