A Frequency Domain Identification Algorithm for Single-Ended Line Measurements (original) (raw)
Related papers
2003
A measurement set-up is proposed to measure the oneport scattering parameter of a subscriber line at the Central Office. The measurements are performed in the time domain using periodic multi-sine signals. A pre-processing algorithm will deliver the impulse response of the one-port scattering parameter. It will de-noise and de-alias the impulse response and search for the first significant reflection. It will be shown that the processed impulse response of the one-port scattering parameter reveals the most important signal features, which would otherwise remain undetectable using classic time domain reflectometry. J J J J a J J a J J a J J a J J J J
Calibration and Pre-Processing of Signals for Single-Ended Subscriber Line Identification
2003
Abstract—A preprocessing algorithm is proposed to visualize the time-domain one-port scattering parameter of a subscriber line measured at the Central Office. To overcome the high line attenuation and the mismatch between the line and the measurement instrument, a preprocessing algorithm is developed to obtain numerically the impulse response of the one-port scattering parameter. The algorithm will search for a quasi-optimal base impedance for the scattering parameter; then, it will de-noise and de-alias the impulse response and will provide an estimate for the first meaningful significant reflection. Index Terms—Impulse response, scattering parameter, time alias, time-domain reflectometry (TDR), transmission lines. I.
Channel Capacity Estimation of Digital Subscriber Lines: a Frequency Domain Approach
2007 IEEE International Conference on Communications, 2007
In order to identify if a subscriber loop is suitable for a certain Digital Subscriber Line (DSL) service, the transfer function of the loop has to be estimated. Several measurement techniques exist, however Single-Ended Line Testing (SELT) is often preferred by the telecom operators because all necessary measurements can be done at the central office. The SELT data is typically interpreted in the time domain. This paper presents a new approach by doing the identification in the frequency domain. It starts by explaining the drawbacks of the time domain approach. The paper explains how these are avoided by using a frequency domain identification algorithm. Measurement results show this is a viable alternative to the classical time domain identification.
Frequency Domain Identification
IFAC Proceedings Volumes
Techniques to identify parametric transfer functions from noisy frequency domain data are considered. A maximum-likelihood estimation method is presented which in parallel with the system transfer function also estimates a parametric noise transfer function. This leads to a consistent and efficient estimator. It is shown how the discrete Fourier transform can be applied to generate frequency domain data from sampled time domain data. For the finite data case the exact frequency domain expressions are derived relating the transfer function with the discret Fourier transformed data for both continuous and discrete time systems.
Sequence and spread spectrum time domain reflectometry for transmission line analysis
Proceedings of SPIE - The International Society for Optical Engineering, 2007
This paper describes Sequence Time Domain Reflectometry (STDR) and Spread Spectrum Time Domain Reflectometry (SSTDR), which utilizes concepts from direct sequence spread spectrum communications, as a technique for detecting impedance mismatches in telephone lines (twisted pair). The aim of this paper is to present methodologies for characterizing a subscriber loop, which is used for Digital Subscriber Line (DSL) technology, based on STDR and SSTDR tests. Those tests enable the TDR functionality to be incorporated into a DSL transceiver integrated circuit eliminating the need for costly test equipment. In addition to the cost savings, the characteristics of the STDR and SSTDR offer improved spectral compatibility, interference immunity and fault resolvability.
Accuracy in time domain transmission line measurements
1994
This paper examines time domain methods for characterizing signal propagation in uniform transmission lines. The impact of the limitations associated with time domain instrumentation and methodologies are examined and guidelines for minimizing errors are presented.
All the standard frequency sources, except the primary standards, have to be calibrated. The majority of the standard outputs of these standard sources are either or a combination of 1MHz, 5MHz, or 10MHz. to determine the frequency offset of these outputs they have to be down converted by either a frequency division or frequency multiplication. In this article we study the effect of removing the frequency divider and calibrating directly the high frequency of these standard frequency sources in the time domain using the Phase Comparison Method.
This application note will introduce time domain and distance-to-fault (DTF) measurement techniques for identifying the location and relative amplitudes of discontinuities while operating in the field. This application note will describe the relationship between frequency domain measurements and time domain transforms and their relationships to time resolution and range. Also shown will be VNA configurations for characterizing band-limited devices such as couplers, filters, antennas and waveguide components, and broadband devices such as cables and connectors. This note will also discuss time domain "gating", a powerful feature that effectively isolates discontinuities in the time domain just as a filter would isolate signal energy in the frequency domain. Measurement examples will be provided using the Agilent FieldFox vector network analyzer.
Sequence Time Domain Reflectometry for Transmission Line Analysis
Anais do XXV Simpósio Brasileiro de Telecomunicações, 2007
This paper describes Sequence Time Domain Reflectometry (STDR), which utilizes concepts from direct sequence spread spectrum communications, as a technique for detecting impedance mismatches in telephone lines (twisted pair). The aim of this paper is to present methodologies for characterizing a subscriber loop, which is used for Digital Subscriber Line (DSL) technology, based on STDR tests. Those tests enable the TDR functionality to be incorporated into a DSL transceiver integrated circuit eliminating the need for costly test equipment. In addition to the cost savings, the characteristics of the STDR offer improved spectral compatibility, interference immunity and fault resolvability.