DE2546422A1 - PROCEDURES FOR EXCHANGING DATA BETWEEN LOCAL AND REMOTE STATIONS - Google Patents

Description

MANITZ, FINSTERWALD & GRÄMKOW

Munich, the IB. QKt H75

Ur / b - ii 2065

IiOR (DHEElT ELEGTEIG COMPAIiX, LIMITED 1600 Dorchester Blvd. West Montreal, Que., Canada

Procedure for data exchange between local and remote stations

The invention relates to data transmission between a local station and a remote telephone station and in particular a device and a method that uses clock pulses present at the local station to provide timing for continuous two-way data transmission over a two-wire transmission line.

There are different types of telephone systems in telephone technology, commonly known as private business exchanges (PHX) or subscriber centers in which analog and / or digital processes are used The subscriber sets used in such systems often belong to the so-called push-button phone or push-button phone type It is well known that a touch-dial telephone has the option of using any number of telephone lines connected to it enables. Of course, this requires arbitrary

DR. G. MANITZ · DIPL.-ING. M. FINSTERWALD DIP L. - I NG. W. GRAMKOW ZENTHALKASSE BAYER. FOLK BANKS MÖNCHEN 22. ROBERT-KOCH-STRASSE I 7 STUTTGART 50 (BAD CANNSTATT) MÖNCHEN. ACCOUNT NUMBER 7270 TEL. tO89> 224211. TELEX 05-29672 PATMF SEELBERGSTR. 23/25. TEL. (0711) 56 72 61 POSTSCHECK: MÖNCHEN 77062-805

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'' Selection of lines for additional monitoring functions, such as the displays BELEGiE, EUP and WAIT. To enable some of these additional monitoring functions additional lines were required in addition to the actual telephone lines. Consequently, it is in touch-dial telephone systems A touch dial phone typically has a bundle of phone lines and monitoring lines physically connected to the phone. PBX switching device or the subscriber exchange connected. The more telephone lines and monitoring options there are, the larger the circumference of the bundle becomes.

Typically, touch-dial telephone systems are in commercial and Find business premises. In that kind of environment it is. the actual whereabouts of individuals always have something in the Flow. Hence, the remote communication facilities required by the individuals are required to travel with them. For example, some statistics show that in North America a touch-dial telephone is subject to an operational change about once every year and a half. Accordingly, this will be Line bundles assigned to a touch dial telephone are disconnected from the PBX switching equipment or the subscriber exchange with the same number of times and connected to it again. This creates an opportunity for errors to occur, at least in proportion the number of lines affected, and that in addition to the establishment and maintenance of the necessary Business telephone operations incur considerable costs.

In some modern and more sophisticated time division multiplex systems (TDM) -PBX-type, is a variety of touch dial-like Telephone sets connected to a single telephone line, which is often a coaxial cable, with communication and communication Monitoring should be done on a time gap distribution basis. BLe is the electrical circuit of each individual telephone set

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of course, far more complicated than that of a typical touch-sensitive telephone, but the copper wire savings make the ease of setup and modification and the added flexibility of operation make this system attractive. A The main disadvantage of this system is that if it is cut through or otherwise severed or severed of the cable, all telephones operated by this cable are put out of operation.

Another type of system is any telephone or touch-dial telephone operated by a telephone line with only one single voice path, as in practice there is usually only one on a telephone Conversation takes place at the same time. The individual voice path in the switchgear is like this. switched that he was the identity of somebody from a certain group of lines represented by buttons on the telephone set. A surveillance For example, the operating states or activity states of the telephone numbers connected to the touch-dial telephone is created via a four-wire monitoring connection. Two of these wires are used to send monitoring information to the telephone set and the remaining ones two wires are used to receive the monitoring information from the telephone set. This kind of System enables significant cost savings in copper material, Establishment and modification.

The invention provides a monitoring device and a method for monitoring touch-dial-like telephone subscriber sets created. A subscriber set is shared with one Control and switching center connected via four wires, consisting of an analog voice telephone line and a digital one Supervision line exist. DtLe telephone line provides a typical voice connection between telephone switching equipment and the remote touch-dial-like telephone subscriber set

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-H-

The supervisory line enables supervisory information to be exchanged between the telephone switching equipment and the remote keypad-like telephone subscriber set on an ongoing basis. The simplicity of this connection will reduce the cost of copper equipment and relocation created compared to the more typical common business telephone systems. In addition, the total failure susceptibility of PBX, .TDM loop systems, i.e. of systems with subscriber centers in time division multiplex operation, avoided. The invention relates to a method for data exchange between local and remote stations via a Two-wire transmission line. The method includes the step of receiving an encoded two-phase signal from the local Station to send out. The encoded two-phase signal has a first and a second section, each of which is data bits represent with first and second states. The first section contains two transitions per data bit and the second section contains four transitions per data bit. The coded two-phase signal is received in the remote station and first Signals with the Baud-Eat.e of the coded two-phase signal and synchronized with it are generated. Moreover, will second signals are generated at half the baud rate or transmission speed and in phase with the first section. The received, encoded two-phase signal is decoded in synchronization with the first and second signals in order to obtain the To derive data bits or to obtain them from them. A two-phase signal that represents the other bits of data with half that Baud-Eate or transmission speed of the coded two-phase signal, synchronized with the second signal, is sent. The two-phase signal is received at the local station by less than half the period of the baud-eat or transmission speed of the encoded two-phase signal delayed and decoded synchronously with a signal that is in phase with the first section to derive the other data bits from it.

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The invention also relates to a device for exchanging data between a local station and a remote station via a two-wire transmission line which is terminated with a hybrid circuit device. The device comprises in the local station devices for transmitting or transmitting a coded two-phase signal via the hybrid circuit device and the Sendebzw. Transmission line, said two-phase encoded signal having first and second sections each representing bits of data having first and second states; the first section has two transitions per data bit and the second section has four transitions per data bit. In the remote station, a receiving device receives the encoded two-phase signal. A generator device generates first signals with the baud rate or transmission rate of the coded two-phase signal and in synchronization with this, and generates second signals with half the baud rate of the first section and in phase with this. A decoder device decodes the encoded two-phase signal synchronously with the first and second signals in order to derive or obtain the data bits therefrom. A two-phase signal transmission or transmission device transmits or transmits, synchronized with the second signal, a two-phase signal, which represents the other data bits and is equipped with half the baud rate or transmission speed of the encoded two-phase signal, via the hybrid circuit device and the transmission - or transmission line. In the local station, a receiving device receives the two-phase signal which was delayed in transmission by less than half the period of the encoded two-phase signal. A decoder is synchronized with a signal which is in phase with the first section and derives the other binary data therefrom.

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The invention thus relates to a two-wire full duplex data transmission system. In this telephone system there is a local or local station, which is typically with a telephone switching device is connected, and a remote touch-dial telephone station is provided for monitoring. A data link between the stations has a two-wire transmission line which is completed with a hybrid circuit. In the local and in the distant Station, an electronic switching arrangement enables continuous two-way transmission of monitoring data by means of two-phase signals. An encoded two-phase signal sent or transmitted by the local station has a baud rate that is twice that of a two-phase signal sent by was sent back or transmitted to the remote station. This enables the transmission of synchronization information to the remote station. The permissible length of the transmission line between the stations is by a maximum permissible one-way delay is limited by half the period of the maximum baud rate or transmission speed.

The invention is described below by means of an exemplary embodiment explained in more detail with reference to the drawing; it shows:

1 shows a block diagram of an apparatus for carrying out the method according to the invention; and

Hg. 2 (A) through 2 (Q) are a graphical representation of the waveforms produced at various points in the I ¹ Xg. 1 can be observed during its operation.

As shown in Fig. 1, a local station and a remote telephone station are communicated with each other through a communication line 10, which is designed as a twisted pair

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and via a twisted pair line, which is called an analog Stinun transmission line 11 is used, interconnected. Typically the local station is one off a group of local stations which are arranged together in connection with a switching device. Optionally, the local station can be located remotely from the switching device and connected to it by any appropriate device, e.g. by a time division multiplex loop and a corresponding matching circuit.

The transmission line ends in the remote telephone station 11 in the case of the voice circuit (not shown) in a telephone subscriber set 12 similar to touch dialing. The subscriber set 12 includes various buttons and light indicators (not shown) associated with the monitoring circuitry 13 are connected.

In the local station, monitoring data are applied to the connection 5 by the switching device. At the connection 3 clock pulses are applied and a flip-flop 4, which acts as a divider by two and which is connected to the clock terminal 3 is, delivers clock pulses with half the repetition frequency at its outputs Q and Q.

In the following, the circuit structure is illustrated by the description of the operations or the functional sequences of the circuit shown in FIG illustrated device, explained in more detail with reference to the waveforms shown in FIG. Each of the as Switching elements designated flip-flop has a data input D, a clock input CL and complementary outputs Q. and Q not on. Output Q assumes the status during operation of input D when there is a positive pulse edge at input OL. The term "two-phase signal" • is intended to denote a coded signal in the following, whose

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average DC value halfway between the opposite extreme excursions of the signal waveform lies. The term "two-phase binary signal" is intended to denote a two-phase signal "as it typically comes from a digital circuit would be obtained operating between the DC supply voltage and the ground potential. Accordingly, that takes Two-phase binary signal at any point in time one of two states, which essentially correspond to the mass.epotential or im essentially correspond to the DC supply voltage.

Those shown in Fig. 2 (A), as mentioned above, the clock pulse to the terminal 3 supplied clock pulses are through the flip-flop 4 and appear at its output Q, as shown in Fig. 2 (B). The clock pulses of Fig. 2 (A) 'have a Period of about 210 microseconds and those of Fig. 2 (B) have a period of about 420 microseconds. Monitoring binary data, for example, as shown in Fig. 2 (C), from the switching device / to the input of a NAND gate

20 created. The clock pulses with half the repetition frequency of Fig. 2 (B) are applied to a further input of the NAND gate 20 and deliver a signal at its output that corresponds to the representation of the Fig. 2 (D) corresponds to the input D of a flip-flop

21 is created. The clock pulses of Fig. 2 (A) are inverted by an inverting amplifier 22 and applied to the input CL of the flip-flop 21 placed. The resulting signal appears at the output Q of the flip-flop 21 and corresponds to the signal shown in Fig. (D), but it is inverted and with the half cycle of the clock pulse repetition rate, i.e. 105 microseconds, is delayed as shown in Fig. 2 (E). This signal is applied to an input of an exclusive OE gate 23; the clock pulses are fed to another one of its inputs. The result of the exclusive OR operation produces a coded two-phase binary signal X as shown in Fig. 2 (F). A comparison of FIGS. 2 (0) and 2 (F) shows that the encoded two-phase signal has a baud rate or transmission speed which is twice the baud

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Rate that is required to carry or transmit the binary data bit rate. Those sections of the signal representing the low portions of the binary data of the Pig. 2 (C) correspond to the clock pulses of Fig. 2 (A) and have twice the baud rate of those sections containing the high-altitude sections of the data in the Fig. 2 (C) and correspond to the signals with half the pulse repetition frequency from the flip-hop 4 (lig.2 (B)).

The hybrid circuit 24 in the local station and the Hybrid 30 are in the remote telephone station well known. The encoded two-phase binary signal from the output of the exclusive OR gate 23 is to the input terminal the hybrid circuit 24 placed and consequently appears on the Transmission line 10 as a two-phase signal with no direct current component. The encoded two-phase signal from hybrid circuit 24 is applied to the hybrid's transmission line connector 30 received and passed in a known manner to their output terminal. The coded two-phase signal passes through a low-pass filter 31 and is operated by a pulse shaper circuit 32 brought into a rectangular shape and with a DC voltage component Mistake. The waveform of the signal at the output of the pulse shaper circuit is similar to that in Pig. 2 (G) shown and slightly delayed with respect to the waveform at the output of the exclusive OR gate 23 · The maximum permissible Transmission delay is less than half the cycle of the clock frequency. The coded two-phase binary signal the pulse shaper circuit 32 is connected to the negative (-) and positive (+) inputs of a non-retriggerable monostable multivibrator or monoflop 34 · via a control circuit 33 created. The timing period or the time constant of the monoflop 34- is more than half the period of the clock frequency, but less than the entire period. The signal at the output of the monoflop 34 is similar

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that shown in Fig. 2 (H). The repetition rate or the repetition frequency is the same as that of the clock signal (! Pig. 2 (A)), since it is due to the received When the two-phase signal is regenerated, it is equally delayed.

The regenerated signal from the output of the monostable circuit 34 is applied to the OL input of a flip-5 ¹ Iop 36 via an inverting amplifier 35. The encoded two-phase signal from the pulse shaping circuit 32 is also applied to the D input of the flip-flop 36. The flip-flop 36 supplies a partially decoded signal at its Q output, for example as shown in FIG. 2 (K). The signal at this point has already been partially decoded.

An OR gate 37 and a flip-flop 38 also provide signals half the clock frequency in phase with the section of the low baud rate or transmission speed of the encoded Two-phase signal. The regenerated clock pulse signals from The output of the monostable circuit 34- are connected to the CL input of the flip-flop 38 connected; in this flip-flop these will be Signals divided to provide half-clock frequency signals as shown in Fig. 2 (J). The exit Q of the flip-flop 36 is linked to the output of the inverting amplifier 35 via an OR function by a To deliver Jerksetζ signal, as it is for example in the Fig. 2 (M) is shown. The Jerksetζ signal is with a rucks et ζ input R of the flip-flop 38 and connected causes the flip-flop 38 to be reset when it is not in phase with the low baud rate section of the encoded two-phase signal should be as this could occur during an interruption in the power supply.

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The partially decoded signal from flip-flop 36 is on placed the input D of a flip-flop 39, where it is synchronized with the signals holder clock frequency from the flip-flop 38, which are applied to the input CL, is completely decoded. This puts the binary data at the Q output of the flip-flop 39 (Fig. 2 (L)) for further use in the Monitoring circuit 13

In addition to receiving continuous monitoring data the monitoring circuit 13 also generates monitoring data for use in the associated switching device. The monitoring data generated are applied in binary form to the input D of a flip-flop 40 while regenerated clock signals with half the repetition frequency from the flip-flop 38 (FIG. 2 (J)) are applied to the input CL of the flip-flop 40 are. The output signal resulting at the output Q of the flip-flop 40, for example in FIG. 2 (N) is shown with an exclusive OR function with the regenerated Clock signal of half the repetition frequency linked by an exclusive OR gate 41 to form a two-phase binary signal with the lower baud rate, as shown for example in FIG. 2 (0). This two-phase signal is via the hybrid circuit 30, the transmission line 10, the hybrid circuit 24 and a low-pass filter 51 on a pulse shaper circuit 52 is transmitted. The pulse shaper circuit 52 has recently added a DC voltage level to the signal and converts the signal into a square wave form To create a signal such as that shown in Figure 2 (P) Waveform is similar to the two-phase binary data Y. This signal is applied to input D of a flip-flop 53 and is synchronous with the clock signals applied to input CL decoded by half the repetition frequency from the flip-flop 4 to the monitoring information (Fig. 2 (Q)) at a terminal to deliver.

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Provide the low pass filters between the output terminals of the respective hybrid circuits and the pulse shaping circuits an isolation from voltage peaks caused by the steep edges of the signals applied to the input ports and which tend to be caused by the typical telephone hybrid to be transferred.

In the above description it has been shown that the device enables continuous two-way data transmission over a hybrid terminated two-wire transmission line is achieved. In the local station, clock signals are used to generate a separate transmission signal, which is used in the remote telephone station for both data and time control information. Consequently the remote telephone station works delayed and synchronized with the clock signals in the local station. The one from the remote station received signals are using the original timing information in the local station decoded in order to derive the returning monitoring data from it, provided that the synchronization of these signals when they are transmitted back and forth is less than the full period of the original clock rate is delayed.

The requirement that the Delay on the way there and back is less than a certain value, sets a certain limit on the length the transmission line used in a particular system. In a system with a maximum baud rate or transmission speed of, for example, 4.8 kilobits per second, which uses typical twisted pair telephone wires with copper conductors for indoor use, changes The maximum usable distance between the local station and the remote station is primarily determined by the wire diameter or conductor diameter, as shown in the following table:

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Wire diameter American Wire Usable values in knives / mm gauge distance / m feet

0.4 26 1370 4500

0.51 24 1610 5300

0.64 22 1920 6300

It has been found that there is a reduction in the capacitance between the conductors, as for example through use from typical telephone lines for outdoor use, the usable distance increases considerably will. Of course, if the baud hate or the transmission speed is reduced, the maximum will also be usable distance increased accordingly.

The hybrid circuits given in this example were common, typical voice path telephone fork transformers. To avoid a Significant interference transmission through the fork transmitters are simple resistor-capacitor filters (31 and 51) are used.

- I & withdrawal entitlements -

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Claims (3)

Claims \\ jj Method for data exchange between local and remote stations via a two-wire transmission line, characterized in that (a) a coded two-phase signal is transmitted in the local station, which has first and second sections, each representing data bits in first and second states, with the first sections having two transitions per data bit and the second sections have four transitions per data bit, (b) the coded two-phase signal is received in the remote station, (c) from the received, coded two-phase signal first
Signals are generated with the baud rate of the coded two-phase signal and synchronized with it, as well as second signals with half the baud rate and in phase with the first sections, (d) the received encoded two-phase signal in synchronism with
the first and second signals are decoded in order to derive the data bits therefrom, (e) a two-phase signal representing the other data bits at half the baud rate of the encoded two-phase signal and is synchronized with the second signal, sent, (f) in the local station, the two-phase signal by less than half the period of the baud rate of the encoded two-phase signal is received with a delay, and that (g) the two-phase signal synchronous with one with the first Sections of the in-phase signal is decoded in order to derive the other data bits therefrom. 2. Device for data exchange between a local station and a remote telephone station via a two-wire transmission line terminated with a hybrid circuit device, characterized in that in 6 0 9817/0943 the local station facilities for the transmission of a encoded two-phase signal provided via the hybrid circuit devices (24-, 3O) and the transmission line are, the encoded two-phase signal having first and second sections each having data bits in first and represent second states, and the first section two transitions per data bit and the second section four transitions per data bit that in the remote station means (31,32) for receiving the coded two-phase signal are provided, devices (33 »39) which respond to the received, coded two-phase signal, for generating of first signals at the baud rate of the encoded two-phase signal and synchronous with it, and for generation of second signals with half of this baud eat and in phase with the first sections, and for decoding of the received, coded two-phase signal, synchronized with the first and second signals, to generate the data bits therefrom derive, as well as means for transmitting (40,4-1) a two-phase signal which represents the other data bits, with half the baud rate of the coded two-phase signal and synchronized with the second signal * that in the local Station means for receiving (51,52) the two-phase signal are provided that by less than half the period of the baud rate of the encoded two-phase signal is delayed, and that in the local station facilities (53) are provided with one in phase with the first section are synchronized to decode the two-phase signal to derive the other Derive data bits. 3. Procedure for data exchange between a local station and a remote telephone station, each station coupled to a two-wire transmission line via hybrid circuitry and the local station ■ to which is coupled to a first source of clock pulses and a second source of clock pulses, which is half * via the hybrid circuit and the two-wire transmission line 609817/0943 Have repetition frequency and with the first clock pulse source are synchronized, characterized in that (a) A coded two-phase binary signal is generated at the local station by dividing the bits with one of two States of the two-phase binary signal representing the first binary data bits from the local station correspond to the first clock pulses, and the bits with the other of two states of the first binary data bits from the local station representing two-phase binary signals correspond to the second clock pulses, where the first two-phase binary signal to one of the hybrid circuit devices is applied to the transmission of an encoded two-phase signal over the transmission line to enable (b) at the remote telephone station, the coded two-phase signal is received by the other hybrid circuit device by less than half the period the repetition frequency of the first clock pulse signals at the Transmission from the local station is delayed, and the coded two-phase binary signal is regenerated out will, (c) Clock pulse signals from the regenerated in method step (b) Signal can be regenerated, (d) Clock pulse signals with half the repetition frequency as a function from the regenerated clock pulse signals and synchronously with the bits of the regenerated in step (b) Signals are generated which represent the other of the two states, (e) the signal regenerated in step (b) synchronously with the regenerated clock pulse signals and the generated Clock pulse signals of half the repetition frequency are decoded in order to derive the first binary data bits, (f) a two-phase binary signal in synchronism with the generated Clock pulse signals of half the repetition frequency is generated, 60981 7/0943 -M- represents the second binary data bit, and the two-phase binary signal to the other of the hybrid circuit devices is applied to the transmission of a two-phase signal to effect over the transmission line, (g) at the local station, the two-phase signal is received from the one hybrid circuit that is to less than half the period of the repetition frequency the first clock pulse is delayed in transmission from the remote telephone station, and from this one Two-phase binary signal is regenerated, and (h) the two-phase binary signal in synchronism with the second clock pulse signal en is decoded in order to derive the second binary data bits from it. 4-. Device for carrying out a data exchange between a local station and a remote telephone station via a two-wire transmission line, characterized in that facilities in the local station (20,23) are provided which are based on first clock pulses and second clock pulses that are at half the repetition frequency of the first clock pulses and occur synchronously with them, respond to generate an encoded two-phase binary signal by bits of the encoded two-phase binary signals representing the first binary data bits of one of two states from the local station, correspond to the first clock pulses, and the bits of the encoded two-phase binary signal that make up the first binary r Data bits represent the other of the two states corresponding to the second clock pulses that first hybrid circuit means (24) with an output connection, an input connection for supplying the coded two-phase binary signal and a transmission line connection connected to the transmission line is provided for the transmission of coded Two-phase signals and for receiving two-phase signals, as well as devices responsive to the second clock signals (53) for decoding the second two-phase signals which are sent to the output terminal of the first fork circuit device 609817/0943 occur and when transmitting from the remote telephone station by less than half the period of the pulse repetition frequency of the first clock pulses are delayed to derive second binary data bits from that in the removed Telephone station responding to binary data bits and regenerated clock pulse signals with half repetition frequency (4-0,41) are intended to generate a two-phase binary signal, and second hybrid circuit devices (30) having an output connection, an input connection for Supply of the two-phase binary signal and a transmission line connection for the transmission of the two-phase signals and for receiving the coded two-phase signals that further devices (33, 34) are provided which respond to the am Output connection of the second fork switching device appearing, address coded two-phase signals, for the regeneration of clock pulses, devices (35,38), the on the regenerated clock pulse signals and the encoded Two-phase signals that are transmitted by less than half the period of the repetition frequency of the first Clock pulse signals are delayed, respond to the regeneration of the clock pulse signals with half the repetition frequency, facilities (36 »39), based on the regenerated clock pulse signals and the regenerated clock pulse signals with half the repetition frequency respond, to decode the output terminal of the second hybrid circuit device responding occurring first two-phase signals to the first binary data bits derive from it. 609817/0943 Blank page