Abstract: Method, arrangement and devices for calibration of a line driving device, such as a DSLAM, having a line port. The method comprises deriving of a first parameter vector, PVinf, for example Hinf. The parameter vector PVinf is derived by performing, at a first site, an echo measurement on the line driving device while the line port on said line driving device is open. The method further comprises calibrating the line driving device based on the first parameter vector PVinf and a second parameter vector PVref, which second parameter vector is based on information on echo measurements performed on at least one reference line driving device.

Abstract: Method, arrangement and network node/device for estimating a quantity related to impedance in a first frequency interval, D1, of a telecommunication transmission line where the transmission line has a length d. The method involves determining a quantity related to impedance of the telecommunication transmission line for at least two frequencies, f1D2 and f2D2, in a second frequency interval D2. The frequencies f1D2 and f2D2 should fulfil the condition that the line length d times the absolute value of the difference between a line propagation constant ?(f1)D2 and a line propagation constant, ?(f2)D2, is less than ?, i.e. abs(d*?(f1)D2?d*?(f2)D2)<?. The method further involves estimating a quantity related to impedance in the first frequency interval D1 based on the determined quantity related to impedance in the second frequency interval D2, where the estimating involves the fitting of a Puiseux series to the determined quantity related to impedance in frequency interval D2.

Abstract: The present invention concerns methods for estimating one or more transmission properties of a telecommunications transmission line. Estimates of the line input impedance, Zin at a frequency ƒ, and the line capacitance ? are made. An estimate is then made in dependence of ?, the frequency ƒ and a value ?, where ? satisfies the relationship ? coth (?)=Zin·j??, and ?=2?ƒ. Accuracy may be improved by least squares fitting a curve to a set of intermediate values and then generating an estimate from the coefficients of the curve.

Abstract: A FDR SELT measurement is made in a stop band of a DSL band plan, using a PSD allowed by the PSD mask. Further measurements may also be made in an adjacent pass band and further bands, and the results combined to create a wide-band measurement result. When transformed into the time domain (e.g. by inverse Fourier transform to produce the line impulse response) greater resolution in time (and hence greater spatial resolution) is achieved. In order to compensate for AGC calibration errors measurements using different AGC steps may be scaled to fit smoothly to each other. If measurements overlap, measurement results in the region of overlap may be combined in various ways to limit the influence of noise and to create a smooth transition from one measurement to the next.

Abstract: A method and device for estimating one or more transmission properties of a telecommunication transmission line. At least one signal is sent on the line, the at least one signal including at least two frequencies for which the absolute value of the line propagation constant times the line length is less than ?, and a resulting signal is received. An estimate of at least one transmission line property is then determined by examining the relationship between the sent and resulting signal or signals. The process may be repeated, if necessary. The estimate determination may also be repeated one or more times, with each successive estimate preferably using for the determination only those frequencies for which, as previously estimated, the absolute value of the line propagation constant times the line length is less than ?.

Abstract: Method and arrangement in a telecommunication system for estimating frequency dependent resistance of a transmission line. Insertion loss per length unit of the transmission line at a first frequency is determined. Thereupon a first resistance per length unit based on the determined insertion loss per length unit of the transmission line is calculated. Effective resistance per length unit at a second frequency based on the calculated first resistance is calculated. The calculated effective resistance could be used when estimating the insertion loss for the second frequency and all frequencies of interest.

Abstract: Embodiments of the present invention relate to an arrangement for analyzing transmission line properties. Measurement data providing means provide data of a first frequency dependent line property, line property calculation arrangement with model handling means, a Hubert transform handler and line property determination means calculate said first property based on model parameters, line resistance at 0 frequency, roc r cut-off frequency, v, line capacitance C?r and line inductance ??. The line model handling means calculates the line inductance L(J) via a Hubert transform of Q(f/v)r relating line resistance R(J) to roc such as formula (I). The Hilbert transform values are calculated using a parameterized closed form expression for the Hubert transform or they are tabulated.

Abstract: Transmission properties of a telecommunications transmission line may be estimated with improved accuracy by numerical solution for ? of Zin·j??C=?coth(?). At least one curve is adapted to ? solutions already obtained and a starting point for numerical solution is selected in dependence of the at least one curve and in dependence of an already obtained solution close in frequency. In a first frequency range, starting points for numerical solution may be calculated from a biquadratic equation. In a second frequency range, a line in the complex plane may be adapted to solutions already obtained and new starting points selected in dependence of the line and in dependence of the previous solution. In a third frequency range, two lines in the frequency plane may be adapted to solutions already obtained and new starting points selected in dependence of the lines.

Abstract: The present invention relates to a method for estimating properties of a transmission line by means of features of a noise spectrum generated by noise entering said transmission line at an intermediate location between the ends of the line. The invention provides possibility to estimate a number of properties, e.g. length of a portion of the transmission line, line attenuation of said Sine portion and even line termination.

Abstract: A system, method, and transceiver unit for determining one or more properties of a digital subscriber line (DSL) utilizing a time-variable finite impulse response (FIR) filter. The transceiver unit sends a loop test signal to the line and calculates an impulse response of a reflection of the loop test signal from the line. The calculated impulse response is filtered utilizing the time-variable FIR filter and properties of the line are determined. Characteristics of the FIR filter may be controlled by a set of parameters that vary as a function of time according to a predetermined formula. As a result, the FIR filter provides both high time resolution of closely separated pulses and amplification of far-end pulse reflections.

Abstract: A system and method for using loop topology identification to investigate a transmission line having a plurality of cable segments. At a measurement plane for each segment, a probing signal is transmitted into the cable. A reflected signal is detected, and an equivalent total input impedance is calculated. The system iteratively calculates the distance between the measurement planes as well as the length, characteristic impedance, and the propagation constant of each segment. A model is used to calculate the respective equivalent input impedance of each segment using the calculated characteristic impedance, propagation constant, and length of the preceding segment. The equivalent total input impedance is then calculated from the iteratively calculated segment values.

Abstract: A FDR SELT measurement is made in a stop band of a DSL band plan, using a PSD allowed by the PSD mask. Further measurements may also be made in an adjacent pass band and further bands, and the results combined to create a wide-band measurement result. When transformed into the time domain (e.g. by inverse Fourier transform to produce the line impulse response) greater resolution in time (and hence greater spatial resolution) is achieved. In order to compensate for AGC calibration errors measurements using different AGC steps may be scaled to fit smoothly to each other. If measurements overlap, measurement results in the region of overlap may be combined in various ways to limit the influence of noise and to create a smooth transition from one measurement to the next.

Abstract: The present invention concerns methods for estimating one or more transmission properties of a telecommunications transmission line. Estimates of the line input impedance, Zin at a frequency f, and the line capacitance ? are made. An estimate is then made in dependence of ?, the frequency f and a value ?, where ? satisfies the relationship ? coth (?)=Zin·j??, and ?=2?f. Accuracy may be improved by least squares fitting a curve to a set of intermediate values and then generating an estimate from the coefficients of the curve.

Abstract: A system, method, and transceiver unit for determining one or more properties of a digital subscriber line (DSL) utilizing a time-variable finite impulse response (FIR) filter. The transceiver unit sends a loop test signal to the line and calculates an impulse response of a reflection of the loop test signal from the line. The calculated impulse response is filtered utilizing the time-variable FIR filter and properties of the line are determined. Characteristics of the FIR filter may be controlled by a set of parameters that vary as a function of time according to a predetermined formula. As a result, the FIR filter provides both high time resolution of closely separated pulses and amplification of far-end pulse reflections.

Abstract: A method and device for estimating one or more transmission properties of a telecommunication transmission line. At least one signal is sent on the line, the at least one signal including at least two frequencies for which the absolute value of the line propagation constant times the line length is less than ?, and a resulting signal is received. An estimate of at least one transmission line property is then determined by examining the relationship between the sent and resulting signal or signals. The process may be repeated, if necessary. The estimate determination may also be repeated one or more times, with each successive estimate preferably using for the determination only those frequencies for which, as previously estimated, the absolute value of the line propagation constant times the line length is less than ?.

Abstract: A system and method for using loop topology identification to investigate a transmission line having a plurality of cable segments. At a measurement plane for each segment, a probing signal is transmitted into the cable. A reflected signal is detected, and an equivalent total input impedance is calculated. The system iteratively calculates the distance between the measurement planes as well as the length, characteristic impedance, and the propagation constant of each segment. A model is used to calculate the respective equivalent input impedance of each segment using the calculated characteristic impedance, propagation constant, and length of the preceding segment. The equivalent total input impedance is then calculated from the iteratively calculated segment values.

Abstract: A method is described herein that can be used to detect the presence of a load coil within a transmission line. The method can also be used to determine the number of load coil(s) present within the transmission line. In addition, the method can be used to determine the distance to the first load coil.

Abstract: The invention refers to single-ended test of a loop with the aid of a transceiver, wherein an input impedance (Zin(ƒ)) of the loop is generated. The transceiver has a digital part, a codec and an analog part and is connected to the loop. With the aid of a transmitted and a reflected broadband signal (vin, vout) an echo transfer function Hecho(ƒ)=V(f)out/Vin(f) is generated, which also can be expressed as H echo ? ( f ) = H ? ? ( f ) ? Z in ? ( f ) + Z h0 ? ( f ) Z in ? ( f ) + Z hyb ? ( f ) . Here Zh0(ƒ), Zhyb(ƒ) and H?(ƒ) are model values for the transceiver. In a calibration process a test transceiver, with the same type of hardware as the transceiver, is connected to known impedances, replacing the loop. Hecho(ƒ)=V(f)out/Vin(f) is generated for the known impedances and the model values are generated and are stored in a memory in the transceiver.

Abstract: A RFI canceller, for use in a subscriber line system using multi-carrier modulation, measures a RFI disturbance in carriers falling within a band of frequencies causing the RFI. The RFI ingress into carriers outside the band of frequencies is estimated, and an error correcting signal derived from the estimation of the RFI ingress is subtracted from a received signal. The subscriber line system may be a VDSL system and the multi-carrier modulation may be DMT. The RFI canceller includes a demodulator for demodulating an incoming data stream to provide a first parallel data stream. A parallel to serial convertor converts the first parallel data stream to a first serial data stream. A digital to analogue convertor converts the first serial data stream to a first analogue signal. An analogue RFI canceller circuit combines the analogue signal with an analogue error correcting signal, to produce a second analogue signal.

Abstract: A circuit, for digitizing an analogue signal includes an analogue to digital converter, a clip processor adapted to estimate a value for clipped digital signal samples, and a buffer adapted to dynamically store a plurality of digitized samples produced by the analogue to digital converter. The clip processor is adapted to read digitized samples from the buffer and replace clipped digitized samples with the estimated values, thereby mitigating the effects of clipping in an output of the circuit.