Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/0264—Arrangements for coupling to transmission lines
  • H04L25/0266—Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/0264—Arrangements for coupling to transmission lines
  • H04L25/0272—Arrangements for coupling to multiple lines, e.g. for differential transmission
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/12—Compensating for variations in line impedance
• • 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
  • H04M11/062—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors using different frequency bands for speech and other data

Definitions

• the invention relates to a low-pass filtering device for a private installation connected to an access network carrying narrowband services (analog or ISDN) and broadband services (xDSL or HomePNA) and private installations comprising such devices.
• narrowband services analog or ISDN
• xDSL or HomePNA broadband services
• IPC Private Client Infrastructure
• CPN Customer Premises Network
• NID network Interface Demarcation
• PABX active equipment
• this will be a telephone and data processing installation connected to the telephone network comprising one or more narrowband terminals such as telephone sets, faxes, answering machines, modems or any type of analog or digital equipment (ISDN). and one or more broadband terminals based on DSL or HomePNA technology.
• Narrowband terminals will be designated subsequently by the abbreviation TBE and broadband terminals by the abbreviation TBL.
• Broadband service means any service transmitted in a spectral band located above narrowband services (ie telephony or ISDN, frequencies above 10 KH). Typically these are the services delivered by the xDSL network, or well based on purely private systems called Home PNA, for example.
• XDSL will denote broadband services grouping together all technological families such as SDSL, ADSL, ADSL-lite.
• HomePNA is a Consortium created in 1998 in order to federate the specifications of transmission systems on telephone pairs: Home Phonelme Networking Alliance. By extension in this description, the so-called HomePNA systems will designate all telephone copper pair transmission systems, whether or not they conform to the specifications of the HomePNA Consortium.
• SG15 / Q4 G.992 determination (ADSL-lite or Spitterless modems), SG15 / Q4: determination G.996.1 (test procedures for performance evaluation of DSL systems),
• TBR21 Equipment terminal (TE); Attachment requirements for pan-European approval for connection to the analog Public Switched Téléphone Networks (PSTNs) of TE (excludmg TE supporting the voice telephony service) m which network addressmg, if provided, is by means of Dual Tone Multi Frequency (DTMF) signaling ,
• PSTNs Public Switched Téléphone Networks
• An IPC is connected to an access network. It makes it possible to deliver services to the various TBEs
• This same IPC can be used to deliver Broadband services to one or more TLBs'
• the two services ranges are transported simultaneously on the same IPC by frequency multiplexing of the corresponding signals.
• ADSL modem The entry into service of an ADSL modem conventionally requires the installation of a splitter or “splitter” of narrowband signals (analog services or ISDN) and ADSL signals (broadband services) at the entrance to a private installation. Each of the services is then routed separately over two separate infrastructures (copper pairs) to the ad-hoc TBEs or TBLs (typically ADSL modem).
• a splitter or “splitter” of narrowband signals analog services or ISDN
• ADSL signals broadband services
• FIG. 1B An example of a filter used in the prior art is illustrated in Figure 1B. It is a filter marketed by the company Excelsus.
• narrowband services must not disturb the broadband services carried by ADSL signals (for example hanging up / picking up a telephone set), and vice versa;
• the type of filter used must be independent of the number of filters installed in the customer's private installation
• an impedance mismatch between a TBE and telephone access causes a local echo phenomenon, the level of which is linked to the degree of mismatch.
• the TBE (vocal and non-vocal) can present several types of îtoe ance described in the publications of ETSI- -TBR21 and TBR37.
• the stiffness of a filter is a first approximation ⁇ e nx ⁇ dB by octave, where "n" is the order of the filter.
• First order filters do not sufficiently protect narrowband and broadband services. In terms of speech, a residual noise (breath) is then perceptible.
• a possible solution would consist in designing them in such a way that the impedance seen by each TBE is adapted to a given configuration. For example, if the customer's installation requires the use of “n” filters, it is possible to manufacture a low-pass filter suitable for this particular situation: “n” filters installed in parallel on the IPC.
• a new class of filter has also been proposed by B. Beeman - Siemens Telecom Networks.
• the objective sought for this technique consists in modifying the filter impedance Z in order to limit the variation in the level of "Return Loss" (measured here at 4 KHz) when the number of filters installed in parallel changes.
• Each filter does not individually have an impedance strictly adapted to the TBE, but the “Return Loss” varies little within the limits of some given configurations.
• the present invention overcomes these drawbacks.
• narrowband services analog or ISDN
• xDSL or HomePNA broadband services
• the filtering and isolation means can be functionally distinct.
• the filtering means may include one or more separate low-pass filters.
• the isolation means comprise head-to-tail switching diodes arranged in parallel.
• the isolation means comprise head-to-tail Zener diodes arranged in series.
• the filtering means comprises an LC type filter, and the isolation means are placed at the inputs of said filter.
• the filtering means comprise an LC type filter and the isolation means are placed between the inductors and the capacitor of said filter.
• the filtering and isolation means can be functionally nested.
• the filtering and isolation means comprise a low pass filter, a diode bridge and at least one relay.
• the filtering means comprise an LC filter of order 2
• the isolation means (I) are placed on either side of the capacitor of said filter
• the device further comprising at least two other capacitors (C) each being placed in parallel on the assembly formed by the isolation means and the filter capacitor.
• the filtering means comprise a LC filter of order 2 of high impedance, placed at the input of the device on the private installation side and a second filter coupled to the first of which activation depends directly on the means of isolation.
• the second filter comprises a capacity in parallel with the capacity of the LC filter, said capacity being placed in the isolation means or after said isolation means.
• the isolation means are placed after the LC filter capacitor, the capacity of the second filter is placed in the isolation device and the other two capacitors are placed, each in parallel on the assembly formed by the means of insulation and the capacitor of the second filter.
• the invention also relates to a private installation comprising at least one narrowband terminal, at least one broadband terminal, connected to an access network carrying narrowband services and broadband services, characterized in that '' it comprises at least one filtering device comprising low-pass filtering means and isolation means allowing the device to have a high input impedance the insulation of the installation when the narrow band terminal is hung up while leaving pass the ring signal.
• the filtering device is placed at the input of the narrow-band terminal on the access to the network or on the cord connecting the terminal to the network.
• the device is placed in the narrow-band terminal.
• FIG. 1A represents the diagram of a private installation equipped with filters distributed according to the etdt of the technical
• FIG. 1B represents the diagram of a low pass filter according to the state of the art (sold by the company Excelsus)
• FIG. 2A represents the diagram of a private installation comprising broadband terminals, equipped with filtering devices according to the present invention
• FIG. 2B represents the diagram of a private installation comprising "HomePNA" systems, equipped with filtering according to the present invention
• FIGS. 3A and 3B represent the block diagram of the device according to the invention, the diagram of FIG. 3B being a variant of the principle represented in FIG. 3A
• FIG. 1A represents the diagram of a private installation equipped with filters distributed according to the etdt of the technical
• FIG. 1B represents the diagram of a low pass filter according to the state of the art (sold by the company Excelsus)
• FIG. 2A represents the diagram of a private installation comprising broadband terminals, equipped with filtering devices according to the present invention
• FIG. 4 represents the diagram of operation of the device when the narrow band terminal (TBE) is hung up
• FIG. 5 represents the operating diagram of the device when the narrow band terminal (TBE) is off the hook
• FIG. 6 represents a diagram of an installation equipped with the device according to the invention in if all narrowband terminals are hung up
• Figure 7 shows a diagram of an installation fitted of the device according to the invention in the case where a narrow band terminal is off-hook
• FIG. 8A represents a diagram according to a first embodiment of the device of the invention in a first variant
• - FIG. 8B represents an alternative embodiment according to FIG. A
• FIG. 9 represents a diagram according to the first mode in a second variant
• FIG. 10 represents a diagram of a variant embodiment of the insulator
• FIG. 11A represents a diagram according to the first embodiment, of a third variant
• FIG. 11B represents a diagram according to the first embodiment, of a fourth variant
• FIG. 12 represents a diagram of a second embodiment of the device
• FIG. 13 represents a second variant of the second embodiment
• FIGS. 14 and 15 represent a third embodiment adapted respectively to the first and second modes
• FIG. 1G represents an exemplary embodiment according to FIG. 14,
• FIG. 17 represents a diagram illustrating the adaptation weakening in two distinct cases of the prior art and in a variant of the invention
• FIG. 18 represents a diagram illustrating the input impedance curves of the filters in the case of the state of the art and in a variant of the invention
• FIG. 19 represents a diagram illustrating the noise curves at the output of the filters
• FIG. 20 represents a preferred embodiment combining the second variant of the second mode (FIG. 13) and the third embodiment (FIG. 15).
• the filtering device can be independent equipment to be inserted in the private IPC installation in front of a narrow band terminal TBE1, TBE2, TBE3 (for example between the PI wall socket and the connector Cl of TBE1), or be directly integrated into TBE (for example in the example cord: TBE3, D3 or integrated into the terminal exp: TBE4).
• the device can also be installed so as to isolate several narrowband terminals which would be connected simultaneously to this same device.
• the filtering devices according to the invention make it possible to isolate the narrow band terminal TBE1 from the installation with respect to the broadband signals of the “HomePNA” systems TLB1 and
• a private installation may include, as illustrated in FIGS. 2A and 2B, a plurality of low-pass filtering devices with integrated isolator, placed in front of (or in) one or more terminals TBE of this private installation
• the filtering device combines a low-pass filtering function F and an isolation function I of the filter when the associated terminal TBE is in an on-hook state.
• the filtering and isolation functions can be physically distinct, which corresponds to a first embodiment of the invention (FIGS. 8A,
• the device behaves like a low-pass filter for the frequencies of the narrow band service considered
• the device When the TBE is hung up, the device isolates the filtering function. - When the TBE is hung up, the device does not prohibit the transmission of ringing current to the TBE (it is transparent to the ringing signal). The system therefore guarantees transparency between narrowband services and broadband services (xDSL) regardless of the number of terminals installed in the private IPC installation.
• xDSL narrowband services and broadband services
• the device according to the invention does not call into question the type of configuration associated with the distributed filtering.
• the device can possibly be set up by the customer himself according to the three alternatives already mentioned:
• terminal TBE 1 the independent device is connected to the telephone socket;
• the device In the case of the TBE 2 terminal: the device is inserted into the terminal cord; In the case of the TBE 3 terminal: the device is integrated into the terminal.
• FIGS. 3A, 4 and 5 illustrating the functional diagrams of a filtering device Dn according to the invention.
• the device Dn is connected to an access Cn of the telephone network (IPC).
• IPC telephone network
• the device comprises an isolator I associated with the low-pass filter F, leaving a channel for the passage of the ringing signal S.
• FIG. 4 The state of the device when the terminal TBEn is hung up is illustrated in FIG. 4:
• the device isolates the low-pass filter from the rest of the IPC installation.
• the resulting impedance of the installation is therefore not affected by the presence of one (or more) device (s)
• the device does not disturb the ringing current.
• the state of the device when the terminal TBEn is off-hook is shown in FIG. 5.
• the device behaves like a low-pass filter for the frequencies of the narrowband service considered (analog or ISDN).
• the device has a suitable impedance on the TBEn terminal side for the same frequencies.
• the device remains transparent to the ring signal.
• the isolator acts globally on all of the low-pass filters Fzl and Fz2 which are attached to it: transparent when at least one TBE is off the hook, and insulating when all TBEs are hung up.
• Low pass filters can have separate or similar impedances. It is therefore possible to connect a TBE to each output of the device, as soon as the impedance between the TBE is adapted to that presented by the output of the low-pass filter considered.
• the TBEs deployed are likely to be classified according to several types of impedance, for example telephone sets with impedance 600 Ohms, and those with impe ⁇ ance Complex (ex conforming to TBR21).
• This mode of presentation therefore makes it possible to design a 'dual' device: that is to say having two low-pass filtering outputs whose output impedances would be representative of the majority of TBEs existing in the country considered.
• the user would then be invited to connect it to the appropriate output of the device: for example the adapted output 600 Ohms, or the output adapted for a complex impedance.
• the same concept can also apply to the case of a device having several outputs corresponding to different types of low-pass filters (e.g.
• FIGS. 8A and 11A do not take up this concept, although they are suitable for such an embodiment.
• the second embodiment shown in FIGS. 12 and 13 does not allow this.
• FIG. 6 shows a diagram illustrating the connection of several terminals TBE1-TBEn in the case where all the terminals are hung up In this case, the resulting impedance of several hung-up devices is high and does not depend on the number of devices.
• FIG. 7 illustrates an installation as shown in FIG. 6 but in which a terminal is lifted, for example the terminal TBEn.
• the associated Du device acts as a suitable low-pass filter while the other Dl-Dn-1 devices behave as isolators.
• FIGS. 8A, 8B, 9, 10, 11A, 11B illustrate these different possible variants of a first embodiment.
• the device comprises an isolator I with switching diodes D head-spades and a low-pass filter F of order greater than 1.
• the device can be produced by using any type of LC low-pass filter of order greater than 1 or of a different design.
• the filter F is an LC filter of order 2 (the references L correspond to inductances and C to capacitors). Inductors can be placed between the access
• IPC and the isolator in this case, either they replace the first series of filter chokes, or they are added to this first series.
• Each switching diode of the 1N4148 type has a threshold voltage of approximately 0.6 V.
• the set of series of 2 x 5 diodes in parallel then makes it possible to filter all signals of amplitude less than 3 V peak to peak when they are not polarized (that is to say when the TBE is hung up).
• the inductors L used have a value of 10 mH (milli-Henry)
• the capacitance C has a value of 4.7 nF (nano-Farad).
• the embodiment shown in FIG. 9 corresponds to the cascading of a filter F ′ of LC type of order 1, followed by the isolator I with diodes for switching head to tail, followed by the filter of type LC d ′ order 4.
• the assembly behaves like an LC filter of order 5.
• FIG. 10 illustrates an alternative embodiment for the insulator consisting of putting several diodes in series in order to increase the threshold voltage if necessary. resulting.
• the isolator has a bridge of head-to-tail switching diodes on each input of the filter.
• Figure 11A The isolator consists of head-to-tail Zener diodes arranged in series
• Zener diodes it is also possible to insert only one pair of Zener diodes as soon as they are arranged head to tail (both on the same wire or one on each wire).
• Figure 11B This device implements inductances of 10 mH, a capacity of 14.7 nF, and Zener BZX85C diodes of reverse threshold voltage 8.2 V. Other values could have been used.
• the amplitude of the residual signal emitted by the broadband system is involved in the choice of the type of diodes.
• the pairs of Zener diodes are inserted between the inductors and the capacitor, in a similar way to the case of FIG. 9 (filter of order 1 placed before the isolator), in order to reduce the noise at high frequency
• the Zener diodes are mounted head to tail on each wire of the telephone pair in order to take account of the polarity of the line. They can be arranged anode against anode or cathode against cathode indifferently on each of the wires.
• the device comprises: an isolator I constitutes of a bridge of diodes P (of switching diodes D) and of B u at least one relay R; and a low-pass filter F of order 2 comprising at least one capacitor C.
• the diode bridge P makes it possible to polarize the current at the level of the relay R: -
• the relay R opens the circuit of the capacity C of the filter F of the type LC of order 2 when the terminal TBEn is hung up.
• the device Dn then behaves like a filter of order 1.
• the relay R closes the circuit at the level of the capacitance C of the filter LC of order 2.
• the device then behaves like a filter d 'order 2.
• capacitors Cp for the diode bridge of 1 microFarad we took capacitors Cp for the diode bridge of 1 microFarad.
• the diodes are 0.6V 1N4148 diodes.
• the filter inductances are 10 mH, the filter capacitor C is 14.7 nanoFarad.
• the LC filter is of order higher than 2, it comprises several capacitors, the same concept using a relay R can then be extended to each of the capacitors of the LC filter.
• FIG. 13 A second variant of the second embodiment of the device is shown in FIG. 13. It more specifically allows the following problem to be answered:
• Some operators have developed specific service ranges relating to telephony. These are, for example, message notification or caller identification services, based on a V23 type format for example (called Class services by the applicant France Telecom). The data transmission of such services is distinguished by the fact that it occurs in the on-hook phase of the TBE.
• the filtering and isolation means of the device in question must be transparent to the transmission of messages associated with these services, while remaining consistent with the characteristics of the device.
• the filtering means comprise an LC filter of order 2
• the isolation means are placed on either side of the capacitor C1 of said filter, and at least two other capacitors C are placed in parallel with the together.
• the values of the capacities C are calculated so as to remain transparent to the signals of the specific services considered (V23) for example).
• the capacitors C are transparent to the signals of the services considered, while the diodes isolate the capacitance Cl of the filter
• the embodiments presented include diodes (for example ⁇ chotky diodes, or Zener diodes see FIGS. 8A, 8B, 9, 10, 11A, 11B, 12 and 13). It has hitherto been assumed that such diodes have negligible residual capacitances (for example less than lOpF, or a few tens of pF). In reality, it is possible or even likely that the components used have significant residual capacities.
• diodes for example ⁇ chotky diodes, or Zener diodes see FIGS. 8A, 8B, 9, 10, 11A, 11B, 12 and 13. It has hitherto been assumed that such diodes have negligible residual capacitances (for example less than lOpF, or a few tens of pF). In reality, it is possible or even likely that the components used have significant residual capacities.
• the device is therefore likely to have a minimum impedance in the frequency band of broadband services. This would result in a decrease in their performance.
• a first LC filter of order 2 of high impedance called input filter Fe.
• the filtering means are then modified in that they are now split into two components: On the one hand the input filter Fe, and on the other hand complementary filtering means Fc which depend directly on the insulation means.
• Figures 14 and 15 respectively represent the case relating to the first embodiment
• the device when the TBE is hung up, the device behaves like a LC filter of order 2 of high impedance, calculated so that the resonance frequency is typically located between that of broadband services and that narrowband services. It is assumed that the value of the capacitor C2 of the input filter is much higher than that of the residual capacitances of the components. The residual capacities of the various components of the device are thus masked, and in general the complementary filter Fc as well as the TBE.
• FIG. 16 shows an example based on the fourth variant of the first embodiment. An input filter has been added to this previous example.
• the complementary filter is a simple capacitor Cl.
• the device then behaves like an LC filter of order 2, adding the capacities Cl and C2.
• Embodiment with Zener diodes Figure 11B
• Embodiment with diode bridge and relays Figure 12.
• filters supplied by Alcatel filters of order 1, single inductance
• L 7 mH filters provided by Cisco: filters of order 2 adapted 600 Ohms
• the device conforms to the supposed behavior: when the associated TBE is hung up, it behaves like a filter of order 1 (like the one supplied by Alcatel). The number of devices in the CPI does not affect the Return-loss. When the TBE is unhooked, the device of the variant Figure 12 behaves like a filter of order 2.
• the device of the variant Figure 11B represents to date a good compromise in terms of embodiment: cost and simplicity of manufacture (addition of 4 Zener diodes only), reliability (no relay %), performance equivalent to the variant Figure 8B. It also has a lower electrical noise.
• the measurement is carried out on a 600 Ohm trunk and on a short line length (75m).
• Figure 17 shows the evolution of the adaptation loss when the number of device or filter goes from 1 to 4.
• the line length of the access network part is 3400 m in 4/10 cable. Note that the curve corresponding to the variant produced with five diodes does not change, while the weakening of the filter A (Excelsus
• the input impedance of the Figure 8B variant is very high and has no resonant frequency. It has real insulation in the frequency band below 1 Hz.
• the input impedance of the Figure 11A variant is similar to that of the Figure 8B variant
• the device according to the invention makes it possible to offer a low-pass filtering solution meeting the objectives set and recalled below:
• the characteristics or specifications of each device are identical regardless of the number to be installed on the IPC installation; 2. the filtering between narrowband (analog or ISDN services) and broadband (xDSL and HomePNA) signals does not depend on the number of devices installed on the IPC. 3. the levels of the parameters qualifying the narrow-band and broadband services do not depend on the number of devices installed on the IPC.
• FIG. 19 gives a spectral record of the electrical noise at the output of the device of the invention produced with five diodes and of the filter A (Excelsus) in the 0-10 kHz band.
• the embodiment of FIG. 11A has an electrical noise lower than that of the embodiment of FIG. 8B and practically identical to that of the filter A (Excelsus).
• the “Dn Class device” is transparent to specific services (caller identification, message notification, etc.). It does not degrade the performance of broadband services, and generally remains consistent with all of the characteristics formulated above.
• the table below gives the adaptation attenuation measurements (in dB at the input of the IPC), in the case where there is one device Dn (according to figure 20) and four devices (according to figure 20 ) in parallel in front of each of the terminals (see Figures 6 and 7).

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Power Engineering (AREA)
• Telephonic Communication Services (AREA)
• Filters And Equalizers (AREA)

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• 1999
  • 1999-07-01 FR FR9908509A patent/FR2793633B1/fr not_active Expired - Fee Related
• 2000
  • 2000-04-21 WO PCT/FR2000/001071 patent/WO2000065819A1/fr not_active Ceased
  • 2000-04-21 US US10/009,398 patent/US6980645B1/en not_active Expired - Fee Related
  • 2000-04-21 CA CA002367434A patent/CA2367434A1/fr not_active Abandoned
  • 2000-04-21 EP EP00922723A patent/EP1171991A1/de not_active Ceased
  • 2000-04-21 AU AU43025/00A patent/AU4302500A/en not_active Abandoned
  • 2000-04-21 JP JP2000614644A patent/JP4289799B2/ja not_active Expired - Fee Related

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