DE102005002522A1 - Communication and data signals e.g. analog telephone and broadband data transmission signals, transmission method, involves compensating data signal interference due to switching of communication signal transmission unit between modes - Google Patents

Communication and data signals e.g. analog telephone and broadband data transmission signals, transmission method, involves compensating data signal interference due to switching of communication signal transmission unit between modes

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Publication number
DE102005002522A1
DE102005002522A1 DE200510002522 DE102005002522A DE102005002522A1 DE 102005002522 A1 DE102005002522 A1 DE 102005002522A1 DE 200510002522 DE200510002522 DE 200510002522 DE 102005002522 A DE102005002522 A DE 102005002522A DE 102005002522 A1 DE102005002522 A1 DE 102005002522A1
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Germany
Prior art keywords
signal
transmission device
transmission
data
switching
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
DE200510002522
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German (de)
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DE102005002522B4 (en
Inventor
Thomas Ferianz
Dietmar Dr. Sträußnigg
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Lantiq Beteiligungs GmbH and Co KG
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Infineon Technologies AG
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Priority to DE200510002522 priority Critical patent/DE102005002522B4/en
Publication of DE102005002522A1 publication Critical patent/DE102005002522A1/en
Application granted granted Critical
Publication of DE102005002522B4 publication Critical patent/DE102005002522B4/en
Application status is Active legal-status Critical
Anticipated expiration legal-status Critical

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M11/00Telephonic communication systems adapted for combination with other electrical systems
    • H04M11/06Simultaneous speech and telegraphic or other data transmission over the same conductors
    • H04M11/062Simultaneous speech and telegraphic or other data transmission over the same conductors using different frequency bands for speech and other data
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/64Hybrid switching systems
    • H04L12/6418Hybrid transport
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M3/00Automatic or semi-automatic exchanges
    • H04M3/005Interface circuits for subscriber lines
    • H04M3/007Access interface units for simultaneous transmission of speech and data, e.g. digital subscriber line [DSL] access interface units
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/64Hybrid switching systems
    • H04L12/6418Hybrid transport
    • H04L2012/6478Digital subscriber line, e.g. DSL, ADSL, HDSL, XDSL, VDSL
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M3/00Automatic or semi-automatic exchanges
    • H04M3/18Automatic or semi-automatic exchanges with means for reducing interference or noise; with means for reducing effects due to line faults with means for protecting lines

Abstract

The method involves transmitting an indication signal (8) from a communication signal transmission unit (10) to a data signal transmission unit (20) when the unit (10) switches between operational modes. The signal indicates the time and the type of the switching of the unit (10) between the modes. An interference in the data signal, due to the switching between the modes, is compensated based on the indication signal. An independent claim is also included for a device for transmission of a communication signal and a data signal, where the device is designed as an integrated data and voice transmission system e.g. digital subscriber line integrated voice data system.

Description

  • The The present invention relates to a method of transmission a communication signal and a data signal via a common transmission line and a correspondingly configured device. The invention is particularly suitable for Combined or integrated data and voice transmission systems, such as Example DSL IVD systems (Digital subscriber line Integrated Voice Data Systems).
  • at Combined or integrated data and voice transmission systems in which For example, digital data transmitted by means of a DSL transmission method (digital subscriber line transmission method) and to transmit voice data by means of a plain old telephone service (POTS) transmission method are, i. with a combination of digital broadband data transmission and analogue telephony, it is common so-called splitter, via which both a transmission device for the digital broadband data transmission, e.g. a DSL modem, as also a transmission device for a analog telephone signal connected to a transmission line are. In the transmission line it is usually a so-called subscriber line, which in a central or exchange of a telephone network via a a subscriber line interface (SLIC, Subscriber Line Interface Circuit) with a network-side transmission path connected is. The splitter is usually a suitable one Combination of a high-pass filter to the one transmitted in a high frequency range Data signal, i. a digital broadband data transmission signal to couple into the transmission line or a low-pass filter to the communication signal, i.e. the analogue telephone signal, which is in a low frequency range typically transmitted below 4 kHz will, in the transmission line to couple or decouple from it.
  • For the transmission properties a transmission device is the termination impedance with which the transmission line is terminated, essential. In a transmission device for a analog telephone signal typically have different modes of operation on, each with different terminating impedances for the transmission line are connected. These modes of operation may be, for example a so-called on-hook state, a so-called off-hook state or act a so-called active state, each with different operating conditions a subscriber connected to the terminal are connected. When switching between different operations of the transmission device for the analog Phone signal becomes the change the termination impedance of the transmission line essentially by the change the impedance of a line driver of this transmission device, i. the subscriber line interface. For integrated or combined data and voice transmission systems causes the switching of the operation of the transmission device for the analog Phone signal a change the termination impedance of the entire system and thus also a change in the transmission characteristics the transmission device for the Broadband data communications signal. It therefore occur when switching the operation in the transmission device for the Data signal transient interference on which the transmission of the data signal. In particular, you can in digital data transmission checksum occur, and it can even lead to a connection break.
  • In order to keep the effects of switching the operation of the transmission device for the analog telephone signal on the transmission of the data signal as low as possible, it is currently common to design the splitter with elaborate separation filters, ie filters of high order. An example of a prior art combined data and voice transmission system is shown in FIG 3 shown schematically.
  • The combined data and voice transmission system comprises a first transmission device 10 ' for transmitting a communication signal in the form of an analog telephone signal and a second transmission device 20 ' for transmitting a data signal in the form of a broadband data transmission signal according to a DSL transmission method.
  • The first and the second transmission device 10 ' . 20 ' are located in a central office of the telephone network and are network-side with a digital transmission link 30 ' connected, via which both the first and the second transmission device 10 ' . 20 ' Exchange data in digital form with the network. This means, in particular, that the data underlying the analog telephone signal is transmitted in digital form between the first transmission device and the network. A conversion between digital data and analog telephone signals takes place in a coding-decoding unit 16 ' the first transmission device 10 ' , Furthermore, in the first transmission device 10 ' a control means 14 ' for switching between different modes of operation of the first transmission device 10 ' intended. A subscriber line interface 12 ' It is used to supply the transmission line through a pair of copper wires 2 ' . 3 ' is formed, with the analog phone signals.
  • The second transmission device 20 ' for the data signal includes digital signal processing means 26 ' , an analog frontend 24 ' and a line driver 22 ' to apply the data signal to the transmission line.
  • The connection of the first transmission device 10 ' and the second transmission device 20 ' with the transmission line via a splitter 5 ' which is a low-pass filter 5a ' over which the first transmission device 10 ' connected to the transmission line, and a high-pass filter 5b ' over which the second transmission device 20 ' is connected to the transmission line comprises. The splinter 5 ' serves in particular to avoid that the transmitted in a low frequency range analog telephone signal in the second transmission device 20 ' is coupled, and to avoid that the transmitted in a high frequency range data signal in the first transmission device 10 ' is coupled. Furthermore, the low pass filter 5a ' and the high pass filter 5b ' configured such that transient interference, which by switching the operation of the first transmission device 10 ' are not caused in the second transmission device 20 ' be coupled. For this it is necessary to use complex filters of high order.
  • Around to reduce the expense of designing the splitter, It is known to use so-called reduced splinters, which essentially based on first order filters. Due to interference the switching between operations of the transmission device for the analog However, in this case, it is necessary to in the low-pass filter of the splitter to use a correspondingly large inductance. However, this creates problems in the realization of the country-specific Terminating impedance for the transmission line, which then compared to conventional ones Splinter with filters higher Order can no longer be programmed with a high degree of flexibility. It is therefore usually for different countries also different equipment variants needed. Furthermore, the use of a large inductance causes one additional Cost of materials and additional Costs.
  • The The object of the present invention is therefore to enable the occurrence of transient disorders when switching the operation of a transmission device for a communication signal in another transmission device for transmission to avoid a data signal in a simple and effective way in particular without a splitter having a complex filter arrangement for this purpose would be required.
  • These Task is solved by a method having the features of independent claim 1 and by a device having the features of independent claim 11. Defining the dependent claims preferred and advantageous embodiments the invention.
  • According to the present Invention, it is provided that for the transmission of a communication signal, e.g. an analog telephone signal, and a data signal, e.g. a digital broadband data transmission signal, via a common transmission line a first transmission device for transmission the communication signal and a second transmission device for transmission the data signal are used, wherein the first transmission device for transmission of the communication signal via has several modes of operation, between which a switch can be made. To disturbances in the data signal of the second transmission device, which by the switching between the modes of operation of the first transmission device caused to avoid or compensate, it is in accordance with the present Invention provided that when switching between the modes the first transmission device an indication signal from the first transmission device to the transmitted second transmission device will, and the disorder, which is caused in the data signal by the switching, depending on the display signal is compensated. That way, the use can of complex filter arrangements in a splitter, through which the coupling of caused by switching operations transient disorders from the first transmission device to the second transmission device should be avoided avoided.
  • Preferably, the indication signal of the second transmission device indicates the timing and / or the manner of switching between the modes. The type of switching between the modes of operation is to be understood in particular that is displayed between which modes of switching, since with each mode of operation in general a different terminating impedance of a line driver of the first transmission device is connected and thus a different pronounced pulse-like disturbance in the data signal is to be expected, though is switched between different modes of operation. If the timing and type of switching between the operations in the second transmission device is known, the disturbance in the data signal can be compensated. This can be done, for example, by the glitch, for example by means of a finite impulse response filter, a so-called FIR filter, replicated and subtracted from the data signal.
  • The for the Replica of the interference pulse required filter coefficients can be based on a Fourier transform or be determined on the basis of an adaptation process. Continue the relative timing of the impulse noise to a data symbol of the Data signal determined to be based on the occurrence of the impulse noise the spectral interferences, i.e. to calculate the coefficients for the simulation of the interference pulse.
  • If the second device defines data symbols of the data signal Is time transfers It is particularly advantageous to switch between the modes the first transmission device in terms of the defined times for transmission synchronize the data symbols. This is preferably done by a synchronization signal from the second transmission device transmitted to the first transmission device becomes.
  • By the synchronization is achieved that switching between the operations of the first transmission device always in a fixed time relation to the transmission a data symbol of the data signal takes place. This will be the Compensating the disturbance caused by the switching operation the second transmission device considerably simplified. In particular, it is not necessary to spectral interference components to recalculate at each switching operation, since the timing of the disorder in terms of of the data symbol is fixed and thus the nachzubildende glitch depends only on the type of switching operation.
  • Farther is it possible in this case the interfering signal not by simulating the interference pulse, i.e. in the time domain, but in the frequency domain to compensate. Compensation in the frequency domain offers the particular advantage that not just impulsive disturbances can be compensated, but also periodic disturbances, e.g. a so-called external ringing. As in DSL data transmission systems the transfer of the data signal is based on discrete single tones, has a signal processing means the appropriately designed transmission device usually via means to carry out a fast Fourier transform (FFT). The spectral interferences to compensate for the caused by a switching process disorder in the data signal thus in a particularly simple way by means of already existing Means of implementation be won an FFT.
  • at the synchronization signal is preferably a frame synchronization signal, which usually in accordance with a DSL transmission method working transmission devices is used. The indication signal and / or the synchronization signal can, for example, via a separately provided control line or via a general interface transmit the transmission devices become.
  • The inventive device for transmission a communication signal and a data signal via a common transmission line is preferable to carry out of the method described above and includes for this Purpose in particular a first transmission device for transmission the communication signal and a second transmission device for transmission the data signal, wherein the first transmission device via a Control means for switching between several modes of operation has. The Device is configured to switch between the operations of the first transmission device an indication signal from the first transmission device to the second transmission device to convey. The second transmission device comprises signal processing means which are designed to a caused by the switching between the modes disorder dependent from the indication signal.
  • Farther includes the device according to the invention preferably a low-pass filter, via which the first transmission device with the transmission line is connected and a high-pass filter, via which the second transmission device with the transmission line connected is. By inventively provided compensation from by switching operations caused disturbances Is it possible, to design the filters in a simplified form, for example as a first order filter. This results in a comparison with conventional Data and voice transmission systems clearly less implementation effort, which not least to a saving of costs leads.
  • following The present invention is based on preferred embodiments and with reference to the accompanying drawings.
  • 1 schematically shows a data and voice transmission system according to an embodiment of the invention;
  • 2 schematically shows a data and voice transmission system according to another embodiment of the invention; and
  • 3 schematically shows a data and voice transmission system according to the prior art.
  • 1 schematically shows a data and voice transmission system. The data and voice transmission system comprises a first transmission device 10 for transmitting a communication signal in the form of an analog telephone signal. Furthermore, the data and voice transmission system comprises a second transmission device 20 for transmitting a data signal in the form of a digital broadband data transmission signal according to a DSL transmission method. The first data transmission device 10 and the second data transmission device 20 are network side with a digital transmission link 30 connected via which both the analog telephone signal underlying data in digital form to or from the first transmission device 10 as well as the data signal underlying data in digital form to or from the second transmission device 20 be transmitted. The connection to the digital transmission medium 30 can be accomplished, for example, via a backplane of a cabinet, in which the first transmission device 10 and the second transmission device 20 inserted as separate cards or as an integrated card.
  • Participant side are the first transmission device 10 and the second transmission device 20 over a splinter 5 connected to a transmission line. In particular, the transmission line may represent a subscriber line in a telephone network, which, as is customary, through a pair of copper lines 2 . 3 is formed. The splinter 5 includes a low pass filter 5a which has a simplified structure and is preferably formed by a first-order filter. The low pass filter 5a connects the first transmission device 10 with the transmission line and ensures the transmission of the communication signal between the first transmission device 10 and the transmission line in a low frequency range below 4 kHz. The splitter also includes a high pass filter 5b , which is the second transmission device 20 connects to the transmission line. The high pass filter 5b ensures the transmission of the data signal between the second transmission device 20 and the transmission line in a high frequency range above 4 kHz. The high pass filter 5b also includes a transformer for coupling the data signal into the transmission line.
  • The first transmission device 20 comprises a coding-decoding unit 16 which decodes network-side received digital data and, based thereon, generates the communication signal transmitted over the transmission line. Likewise, the encode-decode unit encodes 16 the received from the transmission line communication signal in digital form, to then over the digital transmission path 30 to the network.
  • The coding-decoding unit 16 includes synchronization means 18 which is a control means 14 for switching between several modes of operation of the first transmission device 10 controls. In particular, by the control means a switching of a subscriber line interface 12 between different modes of operation, which may correspond, for example, to an on-hook state, an off-hook state, or an active state.
  • The second transmission device 20 includes digital signal processing means 26 , an analog frontend 24 and a line driver 22 for charging the transmission line with the data signal. The signal processing means 26 or the analog frontend 24 generate a synchronization signal 9 which may in particular be derived from a frame synchronization signal of the DSL transmission method. The synchronization signal 9 is the coding-decoding unit 16 the first transmission device 10 fed.
  • For transmission of the data signal are from the second transmission device 20 Receive or generate data symbols of finite duration at defined times.
  • By means of the synchronization signal 9 These are defined times of the first transmission device 10 displayed so that the synchronization means 18 the control means 14 for switching between the operations of the first transmission device 10 such that the switching operations between the modes of operation with respect to the defined points in time to which the data symbols of the data signal in the second transmission device 20 be generated or received, is synchronized. This means that a fixed time relationship between the transmission of a data symbol by the second transmission device 20 and the switching operation between the operations of the first transmission device 10 consists.
  • When switching between the operations of the first transmission device 10 generates the first transmission device 10 ie the coding-decoding unit 16 an indication signal 8th , which is the second transmission device 20 shows the time and type of switching. Thus, the second transmission device 20 based on the display signal 8th not only recognize when a switchover occurs, but also determine the nature of the switching process.
  • Depending on the indication signal 8th is in the second transmission device 20 the disturbance occurring in the data signal by the switching operation between the operations of the first transmission device 10 caused, compensated. The compensation is done by the signal processing means 26 accomplished in the frequency domain or in the time domain. Approaches to compensate for transient disturbances, which in the present case are suitable for compensating for the disturbance, are described, for example, in the publication "New Approach to Time-Domain Equalization and Frequency-Domain Transient Compensation for a DMT-based ADSL System" by D. Sträußnigg A. Kozarev, H. Schenk and J. Bodner, IEEE, Eurocon'2001.
  • In the usual DSL transmission methods, the data signal comprises a number of discrete single tones. To compensate for the interference in the frequency domain, the corresponding spectral interference components of the interference are therefore determined and subtracted from the corresponding spectral components of the data signal in order to compensate for the interference. The spectral interference components can be determined in a simple manner by means of a fast Fourier transformation (FFT), which in any case belongs to the functional scope of a signal processing means for data signals composed of discrete individual tones, and thus in the signal processing means 26 must not be provided separately for the purpose of compensating the disturbances.
  • The Compensation of impulsive disturbances can also occur in the time domain take place, wherein the pulse-like disorder, for example by means of a finite impulse response filter, i. a FIR filter, is reproduced. The corresponding coefficients of the FIR filter can be determined by means of an FFT or by an adaptation process. For the Adaptation process is carried out a certain number of switching operations and the filter coefficients of the FIR filter are adjusted so that the minimized disturbance in the data signal caused by the switching operation becomes. The compensation in the time domain then takes place by the imitated disorder is subtracted from the data signal.
  • The above-described compensation of the disturbance in the data signal is simplified in particular in that the disturbance occurs in a fixed time relationship to the data symbols of the data signal. This is achieved in that the switching operation between the operations of the first transmission device 10 based on the synchronization signal 9 with the times at which data symbols are transmitted in the data signal is synchronized.
  • However, it is also possible to synchronize the switching operations in the first transmission device 10 to renounce. A corresponding example of a data and voice transmission system is schematically shown in FIG 2 shown. The data and voice transmission system of 2 corresponds essentially to that of 1 but does not have the synchronization means 18 , Furthermore, the second transmission device generates 20 of the data and voice transmission system of 2 no synchronization signal to the first transmission device 10 ,
  • In the data and voice transmission system of 2 Thus, only the timing and the type of switching operation of the first transmission device 10 to the second transmission device 20 transmitted. This is done by means of the display signal 8th , Also in this configuration, it is possible to compensate for a pulse-like disturbance in the data signal caused by the switching operation. This can be done in the time domain. For this purpose, the pulse-like disturbance is simulated, for example, by means of an FIR filter, wherein the required filter coefficients can be determined on the basis of an FFT or by an adaptation process. However, the compensation process is more complex than the example described above. In particular, the relative timing of the pulse-like disturbance with respect to a data symbol of the data signal is not fixed, so that the signal processing means 26 must first determine the relative timing of the pulse-like disorder with respect to the data symbol. This can be done internally, for example, on the basis of the frame synchronization signal of the DSL transmission method. Based on the relative timing, the filter coefficients required to simulate the pulse-like disturbance are then calculated for the FIR filter when the pulse-like disturbance occurs. Since the relative timing of the pulse-like disturbance with respect to a data symbol may differ for each switching operation, the spectral noise components must be recalculated for each switching operation.
  • The transmission of the indication signal 8th or the synchronization signal 9 between the first transmission device 10 and the second over tragungsvorrichtung 20 can be done in different ways. For example, it is possible to provide a separate control line or a possibly already existing microcontroller interface of the first transmission device 10 and the second transmission device 20 can be used.

Claims (15)

  1. Method for transmitting a communication signal and a data signal via a common transmission line ( 2 . 3 ) by means of a first transmission device ( 10 ) for transmitting the communication signal and a second transmission device ( 20 ) for transmitting the data signal, wherein the first transmission device ( 10 ) has a plurality of modes of operation between which switching can be initiated, characterized in that the method comprises: - transmitting an indication signal ( 8th ) from the first transmission device ( 10 to the second transmission device when switching between the modes of operation, and - compensating for a disturbance in the data signal caused by the switching between the modes as a function of the indication signal ( 8th ).
  2. Method according to claim 1, characterized in that the indication signal ( 8th ) indicates the time of switching between modes.
  3. Method according to claim 1 or 2, characterized in that the indication signal ( 8th ) indicates the type of switching between the modes of operation.
  4. Method according to one of the preceding claims, characterized in that the second transmission device ( 20 ) Transmits data symbols of the data signal at defined times, the method comprising: - synchronizing the switching between the modes of operation with respect to the defined times for the transmission of the data symbols.
  5. A method according to claim 4, characterized in that the method comprises: - transmitting a synchronization signal ( 9 ) from the second transmission device ( 20 ) to the first transmission device ( 10 ), where the synchronization signal ( 9 ) indicates the defined times for transmitting the data symbols.
  6. Method according to claim 4 or 5, characterized that compensating the disorder includes compensation in the frequency domain.
  7. Method according to one of the preceding claims, characterized characterized in that compensating the disturbance is a compensation in the time domain includes.
  8. Method according to one of the preceding claims, characterized characterized in that the communication signal and the data signal be transmitted in different frequency ranges.
  9. Method according to one of the preceding claims, thereby in that compensating for the disturbance comprises: - Determine of spectral noise components the disorder in the data signal based on a fast Fourier transform.
  10. Method according to one of the preceding claims, thereby in that it is the communication signal to an analog telephone signal is, and that it is at the Data signal to a broadband data transmission signal is.
  11. Device for transmitting a communication signal and a data signal via a common transmission line, comprising: - a first transmission device ( 10 ) for transmitting the communication signal, and - a second transmission device ( 20 ) for transmitting the data signal, wherein the first transmission device ( 10 ) has a plurality of operating modes, between which a switchover can be initiated, characterized in that the device is designed to switch over between the modes of operation an indication signal ( 8th ) from the first transmission device ( 10 ) to the second transmission device ( 20 ), and that the second transmission device ( 20 ) Signal processing means ( 26 ), which are adapted to a disturbance caused by the switching between the modes depending on the indication signal ( 8th ) to compensate.
  12. Apparatus according to claim 11, characterized by a low-pass filter ( 5a ), via which the first transmission device ( 10 ) is connected to the transmission line, and a high-pass filter ( 5b ), via which the second transmission device ( 20 ) with the transmission line is connected.
  13. Apparatus according to claim 12, characterized in that the low-pass filter ( 5a ) is designed as a filter of the first order.
  14. Device according to one of claims 11 to 13, characterized that the device is carrying of the method according to any one of claims 1 to 10 is configured.
  15. Device according to one of claims 11 to 14, characterized that the device as an integrated data and voice transmission system is designed.
DE200510002522 2005-01-19 2005-01-19 Method and device for transmitting a communication signal and a data signal Active DE102005002522B4 (en)

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DE102005002522A1 true DE102005002522A1 (en) 2006-07-27
DE102005002522B4 DE102005002522B4 (en) 2007-02-08

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999020027A2 (en) * 1997-10-10 1999-04-22 Aware, Inc. Splitterless multicarrier modem
US6269154B1 (en) * 1998-02-04 2001-07-31 Texas Instruments Incorporated Splitterless modem with integrated off-hook detector

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999020027A2 (en) * 1997-10-10 1999-04-22 Aware, Inc. Splitterless multicarrier modem
US6269154B1 (en) * 1998-02-04 2001-07-31 Texas Instruments Incorporated Splitterless modem with integrated off-hook detector

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