Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M19/00—Current supply arrangements for telephone systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
  • H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Definitions

• the invention relates to a device for galvanically isolated ⁇ connecting a telephone line with a Signalver ⁇ processing device at the subscriber end of the telephone line according to the preamble of claim. 1
• exchangers have the disadvantage that they frequency range to other components of the modem have a large volume in pullfre ⁇ relative and in their electrical properties inherent ⁇ a relatively large statistical dispersion have. The statistical spread of the electrical properties must be compensated for by complex circuits in the modem.
• a circuit arrangement for coupling an analog transmission path to a digital transmission path has become known from EP 0 798 885.
• the analog transmission path could represent an analog telephone line, and the digital transmission path could represent a digital data bus within a modem.
• the circuit arrangement alternatively provides capacitors and optocouplers as galvanic isolating elements.
• the use of optocouplers is avoided in many applications because they are relatively expensive in comparison with the other components.
• the use of capacitors as galvanic isolating elements is fundamentally advantageous, but when this concept is implemented, it becomes apparent that a pair of capacitors must be provided for each transmission direction in order to ensure reliable data transmission over the insulation limit.
• At least four capacitors are therefore generally provided. This large number of components is undesirable for manufacturing reasons. In addition, such a circuit proves to be sensitive to common mode interference on the telephone line.
• the technical problem of the invention is therefore to provide a device for the galvanically isolated connection of a telephone line with a signal processing device. ben, which is inexpensive to manufacture and can make do with a small number of components to ⁇ .
• the device of the invention uses a transformer for electrical isolation.
• the transformer is not directly connected to the telephone line, but located just behind a hybrid circuit that the signals from the telephone line m a first signal path and a two ⁇ th signal path for the respective transmission directions separated. May be there behind the hybrid circuit the signals from the telephone line shown in a different way, to ⁇ special m a higher frequency range, it is possible to dimension different from the transmitter, ie, the transmitter can m its volume are made smaller. In such a frequency range, statistical scatter of the transmitter hardly comes into play and therefore need not be taken into account.
• the signals of the telephone line behind the hybrid circuit are a high-rate digital-analog converter or analog-digital
• the signals of the telephone line behind the hybrid circuit are demodulated by a high-frequency de-odulator or modulated by a high-frequency modulator.
• the modulation or demodulation is preferably carried out at a different frequency for the two transmission directions.
• the circuit actuator which is galvanically connected to the telephone line, preferably has an energy supply device which is alternatively fed by the telephone line or is fed by the transmitter.
• a feed from the Ubertra ger is particularly advantageous because it can be guaranteed with relatively simple means and is not subject to the fluctuations in the power supply of analog telephone lines.
• Figure 1 shows a first embodiment of the device of the invention
• Figure 2 shows a second embodiment of the device of the invention.
• a transformer 3 is shown as a galvanic separation element, the processing the galvanic Tren ⁇ voltage between the subscriber end of an analog Weg- 5 and ensures a signal processing device 6 in the form of a DSP (Digital Signal Processor).
• Line 4 symbolizes the insulation barrier that runs through the transformer 3 and is exchanged via the signals.
• the transformer 3 has a winding on each side of the insulation barrier 4. A primary winding is located on the side of the telephone line 5 and a secondary winding is located on the side of the signal processing device 6. The windings of the transmitter 3 are magnetically coupled to one another.
• the primary winding is connected to a circuit 1.
• the circuit 1 has a hybrid circuit 7 which is connected to the subscriber end of the analog telephone line 5.
• the hybrid circuit 7 carries out a two-wire-four-wire conversion and provides a signal output and a signal input on the four-wire side, which correspond to the transmission directions between the signal processing device 6 and the far end of the Phone line 5 correspond.
• an analog-digital converter is connected 19 to the hybrid circuit 7, the abta the incoming from the telephone line 5 analog signal at a high sampling rate ⁇ stet and the sampled signal values m the form of digital outputs Si ⁇ gnale.
• a digital to analog converter 20 is provided, the m is the processing device of the Signalverarbei ⁇ 6 derived digital signals into analog signals in order to provide information on the hybrid circuit 7 to the telephone line. 5
• the analog to digital converter 19 and the digital-to-analog converter 20 are connected to a digital Si- gnalmultiplexer 17, which is in turn connected to two Wick ⁇ lungsabgriffen the primary winding of the transformer 3 is connected.
• the digital signal multiplexer 17 operates for at ⁇ Ubertragungs ⁇ chtitch in time division multiplex, that is, it sends to the transmitter 3, or receives from the transmitter 3 alternately signals m a Pmg-pong method.
• the circuit 1 is opposite a circuit 2 on the other side of the insulation barrier 4. This is connected on the one hand to the transmitter 3 and on the other hand to a signal processing device 6.
• a digital signal multiplexer 18 is provided in the circuit 2 and operates in a manner similar to that of the digital signal multiplexer 17 in the circuit 1. Accordingly, the digital signal multiplexer 18 sends signals to the secondary winding of the transmitter 3 and receives them Signals from the secondary winding of the transformer 3 alternately in a Pmg-Pong method by time division multiplexing.
• the digital signal multiplexer 18 sends and receives in each case bit-serially.
• the serial bit stream to be sent or received is controlled by a frequency generator 14 which is connected to the digital signal multiplexer 18.
• the frequency generator 14 is in turn connected to a quartz oscillator 15, which is arranged outside the circuit 2.
• the circuit 2 also has a digital filter and Control circuit 16, which means between the signal processing ⁇ 6 and the digital signal multiplexer tet 18 maral ⁇ .
• the digital filter and control circuit 16 effects a preprocessing of the digital data to be sent to the transmitter 3 or to be received by the transmitter 3.
• the digital filter and control circuit 16 is also clocked by the frequency generator 14 for this purpose.
• a switch 9 provided for example in the form of a relay Re ⁇ within the circuit 1, which is actuated by the circuit 1 by means of the ditialen signal multiplexer.
• This switch 9 can also be implemented and integrated by a transistor.
• the switch 9 is closed when the signal processing device 6 of the circuit 1 signals via the transmitter 3 that a telephone connection is to be established.
• the bell signal can be received by the circuit 1 via its own line.
• the ringing signal is derived from the protective circuit 30 in a voltage-limited manner in order to signal the circuit 1 an incoming connection request.
• the circuit 1 then causes the switch 9 to be closed.
• the wires a and b of the telephone line 5 are also connected to a rectifier and current regulating circuit 8, which is also controlled by the circuit 1.
• the circuit 8 on the one hand, rectifies the signals on the telephone line 5 and, on the other hand, regulates the current through the wires a and b of the telephone line 5 in accordance with the regulations of the respective network operator of the telephone line 5, in order to signal a pickup or hanging up.
• Circuit 1 receives its supply voltage from two
• the node between the diode 12, the diode 31 and the capacitor 13 is connected to a voltage regulating unit 10 m of the circuit 1, which provides a regulated voltage to the other parts of the circuit 1.
• the voltage regulating unit 10 could be connected to the telephone line 5.
• Many network operators provide a limited supply of energy for the terminal connected to the subscriber line.
• the special feature of the invention is that the transmitter 3 is not connected directly to the wires a and b of the telephone line 5, but that the hybrid circuit 7 is connected between the telephone line 5 and the transmitter 3.
• the exchange of signals over the isolation barrier 4 takes place by means of high-rate bit streams in the Pmg-Pong method. Due to the high frequency of the bit streams, a high frequency transmitter can be used. Lower demands can be placed on these with regard to the latency and phase distortion, as is the case with the known low-frequency transmitters which are connected directly to the telephone line 5.
• the circuit has its own reference potential 11, which is independent of a reference potential m of the circuit 2 or m of the signal processing device 6.
• the circuits 1 and 2 are preferably each integrated on a semiconductor chip.
• the rectifier and current regulation circuit 8, the protective circuit 30, the diodes 12, 31 and the capacitor 13 and parts of the circuit 10 are preferably discrete components which are connected to the circuit 1 designed as an integrated semiconductor circuit.
• the quartz oscillator is also a discrete component 15 which is connected to the circuit 2.
• the digital signal multiplexer 17 m of the circuit 1 is above about, a Taktregene ⁇ réellessclien on, re zugewmnen around from the frequency generator 14 of the circuit m 2 produced, and in the transmitted bit stream clock contained the circuit m, and the local circuit parts, particularly the digital signal multiplexer 17 to provide the analog-to-digital converter 19 and the digital-to-analog converter 20.
• the rectified data clock on the circuit 1 side can serve as an energy source.
• the diodes 12, 31, the capacitor 13 and the voltage regulation unit 10 are provided.
• FIG. 2 shows a second exemplary embodiment of the invention. Elements that perform a function similar to elements m in the exemplary embodiment in FIG. 1 are identified in FIGS. 1 and 2 by the same reference numerals. Therefore, for a more detailed explanation Guided Tours to the exemplary embodiment of Figure 1, reference is made to the education ⁇ .
• the exemplary embodiment of FIG. 2 differs from that of FIG. 1 in that instead of high-rate bit streams, analog high-frequency signals are transmitted via the transmitter 3.
• a modulator 23 is provided in circuit 1, which modulates the signal coming from hybrid circuit 7 onto a high-frequency carrier with frequency RF1. The carrier signal thus modulated becomes an analog
• Signal mixer 21 supplied.
• a demodulator 25 is provided between the analog signal mixer 21 and the hybrid circuit 7, which is controlled with a high-frequency carrier signal with the frequency RF2.
• the analog signal mixer 21 sends that coming from the modulator 23
• the carrier frequencies RF1 and RF2 are sufficiently spaced so that there is no superimposition of the modulated signals.
• the respective transmission directions are separated from one another by the transmission filter and the reception filter.
• an analog signal mixer 22 is provided m the circuit 2 of Figure 2, which also has a Sen ⁇ Defilter and a Empfangsfllter.
• the received from the transmitter 3 signal that has been modulated in the modulator 23 with the Tragerfre acid sequence RF1 is demodulated m 2 of the circuit by means of a De odulators 26, which also operates on the Tra ⁇ gerfrequenz RF1.
• a modulator 24 is provided which operates at the carrier frequency RF2.
• the output signal of the modulator 24 is fed to the transmitter 3 via the analog signal mixer 22.
• the analog signal mixer 21 m of the circuit 1 receives this signal and feeds it to the demodulator 25, which demodulates it with the same carrier frequency RF2.
• an analog-digital converter 27 is provided in the circuit 2, which converts the received analog signal m into a digital signal and feeds it to a digital filter and control circuit 29.
• digital signals from the digital filter and control circuit 29 are fed to a digital-to-analog converter 28, which supplies the modulator 24 with an analog transmit signal.
• a frequency separation method is used for transmitting bidirectional signals via the transmitter 3. Since high-frequency signals are transmitted via the transmitter 3, the same requirements apply to the transmitter 3 of FIG. 2 as for the transmitter 3 of FIG. 1.
• the hybrid circuit is used to implement the frequency separation method between the transmitter 3 and the telephone line 5 7 switched.
• the circuit 1 receives the voltage supply from special taps of the primary winding of the transformer 3 via the diodes 12, 31 and a capacitor 13.
• the switch 9 is controlled entirely within the circuit 1. Both exemplary embodiments combine the advantages of lower costs and a lower form factor compared to previous solutions.
• the circuit 1 Since the power supply of the circuit 1 takes place via the transformer 3, a network operator-specific From ⁇ interpretation of the circuit 1 is not required.
• the circuit 1 is therefore also insensitive to disturbances and fluctuations in the DC voltage on the wires a and b of the telephone line 5.
• the switch 9 is advantageously controlled in the circuit 1.
• the caller ID (Caller ID) contained in an incoming connection request can be programmed by programming the digital filter and control circuit 16 and 29 m of the circuit 2 are determined and transmitted to the signal processing device 6. Any interference voltages present on the analog telephone line 5 are suppressed by the proposed transmission techniques. This enables a very high data rate to be achieved via the analog telephone line 5.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Telephonic Communication Services (AREA)
• Telephone Function (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

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Family Applications (1)

Country Status (7)

Families Citing this family (2)

Family Cites Families (10)

• 1998
  • 1998-09-30 DE DE19845123A patent/DE19845123B4/de not_active Expired - Fee Related
• 1999
  • 1999-09-14 US US09/786,897 patent/US6978013B1/en not_active Expired - Fee Related
  • 1999-09-14 JP JP2000573065A patent/JP2002526986A/ja active Pending
  • 1999-09-14 KR KR1020017004038A patent/KR20010079958A/ko active IP Right Grant
  • 1999-09-14 WO PCT/DE1999/002911 patent/WO2000019689A1/de active IP Right Grant
  • 1999-09-14 CN CN99811563A patent/CN1320319A/zh not_active Withdrawn
  • 1999-09-14 EP EP99955691A patent/EP1118201A1/de not_active Withdrawn

Non-Patent Citations (1)

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