Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B3/00—Line transmission systems
  • H04B3/02—Details
  • H04B3/30—Reducing interference caused by unbalanced currents in a normally balanced line

Definitions

• the invention relates to a method of operating a system for transmitting signals from a transmitter to a receiver.
• the invention relates to a computer-readable medium. Furthermore, the invention relates to a program element. Furthermore, the invention relates to a transmitter.
• the invention relates to a receiver. Furthermore, the invention relates to a signal transmission system.
• the hybrid has a balance network that dynamically alters its impedance to closely balance with the two wire line impedance. Residual common mode signals are cancelled. Resistors are connected to the wires and the circuit generates a high impedance to differential mode signals and a virtual ground to common mode signals.
• a method of operating a system for transmitting signals from a transmitter to a receiver in an environment in which an interference signal may be present comprising the steps of muting the transmitter, adjusting a receiver transfer function of the receiver so that an output signal of the receiver is minimized, and setting a transmitter transfer function of the transmitter to be inverse to the adjusted receiver transfer function.
• a computer-readable medium e.g. a CD, a DVD, a USB stick, a floppy disk or a hard disk
• a computer program for transmitting signals from a transmitter to a receiver in an environment in which an interference signal may be present is stored which, when being executed by a processor, is adapted to control or carry out a method having the above mentioned features.
• a program element for transmitting signals from a transmitter to a receiver in an environment in which an interference signal may be present is provided, which program element, when being executed by a processor, is adapted to control or carry out a method having the above mentioned features.
• a transmitter for a system for transmitting signals from the transmitter to a receiver in an environment in which an interference signal may be present comprising a muting unit adapted for muting the transmitter, and a setting unit adapted for setting a transmitter transfer function of the transmitter to be inverse to a receiver transfer function.
• a receiver for a system for transmitting signals from a transmitter to the receiver in an environment in which an interference signal may be present comprising an adjustment unit for adjusting a receiver transfer function of the receiver in a mute state of the transmitter so that an output signal of the receiver is minimized, and a transfer unit for transferring the adjusted receiver transfer function to the transmitter to enable the transmitter to set a transmitter transfer function of the transmitter to be inverse to the adjusted receiver transfer function.
• a signal transmission system comprising an inventive transmitter for transmitting signals to an inventive receiver.
• a system for calibrating a communication arrangement in which interference signals (or disturbing signals) are efficiently suppressed.
• a sender is brought into a silent non-transmitting state.
• a transfer function of a receiver is adjusted in a manner to reduce an output signal of the receiver originating from interference signals in the environment as much as possible.
• the transmitter is adjusted in such a way that its transfer function is essentially inverse to the transfer function of the receiver.
• the transmission channel can be wire based (for instance via a cable, for example in a similar manner as in a USB communication), or based on wireless communication according to a corresponding wireless data transmission protocol (for instance using a 13.56 MHz frequency of an RFID system, using a Bluetooth system, using infrared communication, etc.).
• signal processing and data communication calibration for suppressing interference signals and for improving the signal quality can be realized by a computer program, that is by software, or by using one or more special electronic optimization circuits, that is in hardware, or in hybrid form, that is by means of software components and hardware components.
• the term "transfer function" particularly denotes a (mathematical filter) function describing a ratio between an output signal and an input signal of a signal manipulating unit, particularly in a time invariant system. The transfer function describes an impact of a signal manipulating unit on a signal to be processed by this signal manipulating unit.
• inverting a transfer function particularly denotes modifying the transfer function in a manner that the effect of the original transfer function is compensated by the inverted transfer function. In the case of a scalar transfer function, inverting is equal to a multiplication with a factor of - 1.
• interference signal particularly denotes any signal which influences a useful signal, which is transmitted over a transmission channel, in an undesired or unintended manner.
• the method comprises the step of transmitting the signals from the transmitter to the receiver after having adjusted the receiver transfer function and after having set the transmitter transfer function.
• a calibration phase is performed, in which the receiver transfer function and the transmitter transfer functions are adjusted for an efficient suppression of an influence of interfering signals on the data transmission line.
• data communication is performed with proper data transmission quality.
• the method comprises the step of transmitting the signals via a multi channel (particularly multi-wire) communication from the transmitter to the receiver.
• the signals are transmitted via two or more wires, for instance in a differential manner.
• a interference signal couples into the different communication paths in a different manner.
• the interference signal suppression scheme according to an exemplary embodiment of the invention allows for a proper transmission quality even under such harsh circumstances.
• the method comprises the step of adjusting the receiver transfer function by adjusting a gain and/or a phase parameter of the receiver characteristic.
• the gain and the phase are two proper (filter) parameters which can be modified so as to suppress the influence of interference signals appropriately.
• the method also comprises the step of adjusting the receiver transfer function by adjusting a plurality of stages of the receiver.
• the receiver has two input stages, and the transmitter has two output stages.
• the transfer functions being indicative of the performance of the individual stages are adjusted individually, thereby improving accuracy of the adjustment.
• the sender is muted and then the receiver transfer functions is determined by adjusting the input stages of the receiver (e.g. in gain and phase) so that the output signal is a minimum.
• the sender transfer functions is set to the inverse receiver transfer functions, and the data transmission is started.
• the method also comprises the step of setting the transmitter transfer function by adjusting a plurality of stages of the transmitter to be inverse to a respective one of the plurality of stages of the receiver. Therefore, each state of the transmitter has an associated stage of the receiver, or vice versa.
• a fine tuning of the transmission properties can be carried out.
• the method also comprises the step of adjusting the receiver transfer function in a frequency dependent manner.
• a transfer function of a disturbing channel may be emulated, and interference signals may be compensated, in a sophisticated manner.
• the subtraction of signals in a differential data transmission scheme may be performed frequency-dependent.
• the frequency denotes a frequency of data signals to be transmitted.
• the signal transmission system comprises a signal transmission channel for transmitting the signals from the transmitter to the receiver and comprises a (separate) transfer function transfer channel for transferring the adjusted receiver transfer function from the receiver to the transmitter.
• the signal transmission channel is the channel over which data or signals are transmitted.
• the transfer function transfer channel is a communication channel over which the receiver sends adjusted transfer function parameters to the transmitter as a basis for the inverse transfer function adjustment there, for instance via a feedback loop. Then, the transmitter adjusts its transfer function so that it is inverse to the one of the receiver.
• the transmitter and the receiver is located within one and the same apparatus, for instance a transceiver.
• An example for such an embodiment is an RFID reader, in which the originally emitted radio frequency signal and the radio frequency signal modulated or damped by a present RFID tag forms the signal to be transmitted.
• a wired or wireless data communication line between the receiver and the transmitter in the apparatus transmits the adjusted transfer function parameters from the receiver to the transmitter.
• the transmitter and the emitter are components of two different devices.
• a separate data communication channel for transmitting the transfer functions from the transmitter to the receiver may be advantageous or necessary.
• Such a system may include a periphery device connected to a computer via some kind of USB connection.
• one of the communication partners serves as the transmitter and the other one as the receiver.
• Examples for the signal transmission system are an RFID reader, a contactless chip card reader, a USB data transmission system, or a telephone signal transmission system.
• the signal transmission system may be formed as a part of the base station reading a (for instance mobile/wireless) transponder.
• a reader may be a base station cooperating with a radio frequency identification tag (RFID tag) or with a (for instance contactless) smart card.
• RFID tag radio frequency identification tag
• An RFID tag usually comprises a semiconductor chip (having an integrated circuit) in which data is stored, and a high frequency antenna matched to an operation frequency band used (for example 13.56 MHz).
• an RFID system comprises a read/write device (i.e. a base station - simply, also referred to as "reader") and a system antenna enabling a bi-directional wireless data communication between the RFID tag and the read/write device (e.g. a loop antenna, a monopole antenna, or a dipole antenna).
• an input/output device for instance a computer is used to control the read/write device.
• RFID systems Different types are known, namely battery-assisted (powered by a battery, wherein a back modulation usually is done by using load modulation (RF) or back scatter (microwaves)), active RFID systems (powered by a battery, wherein a back modulation is performed actively) and passive RFID systems (powered via the RF field emitted by a reader, wherein a back modulation is done by using load modulation (RF) or back scatter (microwaves)).
• RF load modulation
• microwaves passive RFID systems
• semi-active (semi-passive) systems which are passively activated and in which a battery is used on demand (for instance for transmitting data), are available.
• a smart card or chip card usually is a tiny secure crypto processor embedded within a credit card-sized card or within an even smaller card, like a GSM card.
• a smart card normally does not contain a battery, but power is supplied by a card reader/writer, that is to say by a read and/or write device for controlling the functionality of the smart card by reading data from the smart card or by writing data to the smart card.
• a smart card device is commonly used in the areas of finance, security access and transportation. Smart cards normally contain high security processors that function as a security storage of data like card holder data (for instance name, account numbers, a number of collected loyalty points). Access to these data is only possible when the card is inserted in or coupled to a read/write terminal.
• the calibration and data transmission scheme as described hereinbefore is also used for suppressing distortions (like ripples) in a voltage generated by a voltage supply unit.
• distortions like ripples
• the system may be used in amplifiers in order to regulate a signal when signal distortions are measured.
• a voltage may be smoothed by performing a frequency-dependent suppression of interference signals.
• Fig. 1 and Fig. 2 show signal transmission systems according to exemplary embodiments of the invention.
• Fig. 1 shows a signal transmission system 100 according to an embodiment of the invention.
• the signal transmission system 100 comprises a transmitter device 101 for transmitting a first signal Si via a first data transmission channel 102 and for transmitting a second signal S 2 via a second data transmission channel 103 to a receiver device 104.
• the signals Si and S2 may be differential signals.
• An input signal s m is supplied to an input of the transmitter 101.
• This input signal s m is processed within the transmitter 101 to generate the pair of differential signals Si and S2 having opposite phase.
• a source of interference 105 acts on the signals Si and S2 during transmission over data transmission lines 102 and 103.
• the interference signal is denoted with S3.
• the influence of the interference signal S3 on the first signal Si is described by a transfer function A3, which differs from a transfer function A4 indicative of an influence of the interference signal S3 on the second signal s 2 .
• A3 is considered to be identical to A4. However, in many cases, this is just a rough approximation yielding an improper data transmission quality due to the different impact of the interference signal S3 on the signals Si and S 2 .
• the received signals are processed again, particularly in accordance with a transfer function of the receiver 104, and an output signal s ou t is output by the receiver 104.
• the influence of the interference signal S 3 on the signals Si (described by A3) and S 2 (described by A4) is suppressed by a corresponding method which will be explained hereinafter in more detail.
• the system 100 is operated in a manner that the transmitter 101 is first brought to a silent or mute state. In such a mute state, essentially no signal is emitted from the transmitter 101 over the communication channels 102 and 103.
• the receiver transfer function of the receiver 104 is adjusted in such a manner that the output signal s ou t of the receiver 104 is made acceptable small or is even minimized.
• Corresponding optimization algorithms are known by the skilled person. For example, gain and/or phase parameters are incremented or decremented, and the response of the system is monitored. If this change improves the quality and reduces the output signal s ou t, it is accepted, otherwise it is rejected. By such an iterative procedure, an optimum transfer function can be obtained. Namely, when no useful signal is transmitted from the transmitter 101 to the receiver 104, s ou t should be "0" in an ideal case.
• the transfer function of the receiver 104 is adjusted. Via a feedback line 106, the adjusted receiver transfer function parameters are transmitted to the transmitter 101. Based on these data, a transmitter transfer function of the transmitter 101 is adjusted to be inverse to the adjusted receiver transfer function of the receiver 104. Subsequently, data communication is started. By adjusting the transfer functions of the transmitter 101 and of the receiver 104, the signal transmission quality is improved or optimized, since the influence of the source of interference 105 is suppressed.
• the transmitter 101 comprises a muting unit 110 adapted for muting the transmitter 101 , that is to say to bring the transmitter 101 in an operation state in which it is silent and does not emit a signal.
• a setting unit 120 of the transmitter 101 is adapted for setting a transmitter transfer function of the transmitter 101 to be inverse to a receiver transfer function of the receiver 104 which has been adjusted before so that the output signal s ou t of the receiver 104 is minimized.
• the receiver 104 comprises an adjustment unit 130 for adjusting a receiver transfer function of the receiver 104 in a mute state of the transmitter 101 so that an output signal s ou t of the receiver 104 is minimized.
• a transfer unit 140 is provided for transferring the adjusted receiver transfer function to the transmitter 101 via the feedback loop 106 to enable the transmitter 101 to set the transmitter transfer function of the transmitter 101 to an inverse to the adjusted receiver transfer function.
• Fig. 1 shows a transmitter 101 which is accommodated in a different device than the receiver 104.
• Fig. 2 shows an RFID system 200 (which is one particular example for a wireless transmission system), wherein a transmitter 206 and the receiver 207 are accommodated in one and the same device, namely in an RFID reader 201.
• the transmitter 206 emits a signal 202 (e.g. via a transmission coil) which subsequently is modulated by an RFID tag 203 so that a receiver 207 (e.g. via a receiving coil) can detect a modulated signal 204.
• a control unit (for instance a central processing unit, CPU) 205 is provided to control the signal transmission via the transmitter 206 and the signal reception via the receiver 207. Furthermore, signals are processed by the CPU 205. Moreover, a transfer function to suppress interfering signals, which function has been adjusted in the receiver 207, is conveyed from the receiver 207 via the control unit 205 to the transmitter 206 so that the transfer function in the transmitter 206 the inverse of the one of the receiver 207.
• CPU central processing unit
• the transmitter 206 amplifies the input signal S 1n , creates the two signals Si and S2 with the opposite phase, and transmits them over the two transmission channels 102, 103.
• the signals are subtracted and the result s ou t should be identical with the input signal S 1n .
• the source of interference 105 couples the interference signal S3 in both transmission channels 102, 103. If the signals A 3 S3 and A 4 S3 are equal in magnitude and phase, they are canceled out by the subtraction in the receiver 104. These coherences may be written with the aid of Laplace transfer functions.
• the signals coupled into the two transmission channels 102, 103 are as follows:
• the coupling transfer functions of the interference signal, A3 and A4 are considered to be equal. Under these circumstances, the common mode interference is erased by the subtraction in the receiver 104.
• the interference transfer functions A3 and A4 are unequal why the common mode interference is not canceled out by the subtraction in the receiver 104.
• the following approach can be used.
• the receiver 104 uses to input stages A RI(S) and A R2(S ), and the transmitter 101 uses two output stages A T i (s ) and A T2(S ).
• the transmitter 206 is turned silent. Hence, only the interference signals are received. Now the two input stages A RI(S) and A R2(S) , are adjusted in gain and phase so that the output signal is a minimum.
• the transmitter transfer functions are made the inverse transfer functions of the receiver 104 in a second step
• the transmission of the signals can start.
• the common mode interference is suppressed by the different transmitter and receiver transfer functions.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
• Transmitters (AREA)
• Noise Elimination (AREA)

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• 2007
  • 2007-11-23 EP EP20070849232 patent/EP2087607A2/de not_active Withdrawn
  • 2007-11-23 WO PCT/IB2007/054760 patent/WO2008062380A2/en not_active Ceased
  • 2007-11-23 CN CN200780043497.3A patent/CN101542927B/zh not_active Expired - Fee Related

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