Telefonaktiebolaget Lm Ericsson (publ)

Klas Ericson

Miguel Berg

Antoni Fertner

Per Ola Börjesson

Daniel Cederholm

Fredrik Lindqvist

Chenguang Lu

Per-Erik Eriksson

Ioanna Pappa

Aldebaro Klautau

Henrik Almeida

Stefan Höst

Joäo C Weyl Albuqerque Costa

Roberto Menezes Rodrigues

João C Weyl Albuquerque Costa

The present disclosure relates to wireline communication systems, and in particular to aspects of a method and a line estimation device for estimating a characteristic impedance of a section of a transmission medium. The method comprises determining, by a test equipment having a test port with known impedance Z, an Sscattering parameter vector S[f] of the transmission medium, indexed by frequency f. The method also comprises generating, based on Zand S[f], a model of reflection in the transmission medium corresponding to an observation of the transmission medium via a test port having a test impedance Z, and also estimating the characteristic impedance of the section as a value of Zwhich minimizes a difference between a reflection value of the model of reflection and a respective target reflection value of the section.

Estimation of impedances in a transmission medium

The present disclosure relates to a Time Duplex Division (TDD) modem and a method in such a modem for making Single Ended Line Test (SELT) measurements. The device comprises a transmitter and a receiver and it has a normal mode of TDD communication. In these devices, Time Domain Reflectometry (TDR) is used as line measurement. It has a number of drawbacks, and for overcoming said drawbacks, Frequency Domain Reflectometry (FDR) measurement techniques adapted for TDD devices are suggested.

Single ended line test methods for time duplex division devices

A method and a test device for determining communication characteristics of a metal cable suitable for use in a communication system are provided. The method comprises transmitting a wideband test signal on the metal cable; receiving a reflected signal as a result of the wideband test signal; and determining an interval of the reflected signal to be analyzed, the interval corresponding to a part of the cable length. The method further comprises approximating the reflected signal within the interval by a regression model; and determining characteristics of the metal cable based on the regression model.

Test device and a method for determining communication characteristics of a metal cable

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, r, a cut-off frequency, v, a line capacitance Cand a line inductance L. The line model handling means calculates the line inductance L(f) via a Hubert transform of a function of Q(f/v), wherein the function Q(f/v) relates the line resistance R(f) to ras R(f)=r&#xb7;Q(f/v). The Hilbert transform values are calculated using a parameterized closed form expression for the Hubert transform or they are tabulated. The line property determination means calculates the first property and criteria function application means uses the measured first property and the calculated first property for model parameters to find optimized numerical model parameter values.

Arrangement and method relating to analysis of transmission lines

The present invention relates to a method and an arrangement based on two-port network (TPN) theory that allows analytically estimating the loop transfer function from open and short-circuited input impedance measurements, e.g. single ended line transmission (SELT) measurements, by utilizing the fact that the line under test (LUT) can be considered reciprocal and by assuming that the LUT is symmetric. Hence, by using the present invention and an estimation of the noise on the line, the attainable bit rate at the customer premises can be determined by means of SELT measurements at the CO. The transfer function of a telephone copper-loop is estimated regardless of its topology by impedance measurements from the CO side. Specifically, such estimation is carried out from the calculation of the transmission parameters of loop, which are expressed only in terms of open and short-circuited input impedance measurements at the CO when reciprocity and symmetry is assumed.

Method and arrangement for a digital subscriber line

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 line portion and even line termination.

Passive single-ended line test

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.

Calibration of a line driving device

The present invention concerns methods for estimating one or more transmission properties of a telecommunications transmission line. Estimates of the line input impedance, Zat a frequency &#x192;, and the line capacitance &#x108; are made. An estimate is then made in dependence of &#x108;, the frequency &#x192; and a value &#x393;, where &#x393; satisfies the relationship &#x393; coth (&#x393;)=Z&#xb7;j&#x3c9;&#x108;, and &#x3c9;=2&#x3c0;&#x192;. 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.

Method for transmission line analysis

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.

Growing community of inventors

Alvsjo, Sweden

Klas Ericson