| 1. |
- Fertner, Antoni, et al.
(författare)
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Applications of Backscattering for the Study of Twisted Pair Transmission Lines
- 2018
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 66:12, s. 5230-5237
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Tidskriftsartikel (refereegranskat)abstract
- The phenomenon of backscattering in copper cables has been recently observed and initially explicated. It can provide promising techniques to address the problem of loop diagnostic and maintenance. The backscattering is analyzed both in frequency and time domains. To demonstrate the practical use of the phenomenon, we estimate certain properties of the loop using wideband, high-frequency $\selevenf(f)$ measurements performed in the laboratory on real cables. The results corroborate the usefulness and accuracy of the investigated method.
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| 2. |
- Fertner, Antoni, et al.
(författare)
-
Backscattering in Twisted-Pair Nonhomogeneous Transmission Lines
- 2018
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 66:6, s. 2674-2682
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Tidskriftsartikel (refereegranskat)abstract
- The development of the communication networks tends gradually toward exploiting higher frequencies, sometimes even reaching the lowest microwave band (P-band). As the signal bandwidth used for transmission over twisted-pairs increases, as recommended by G.fast and other broadband systems, new phenomenon was observed, namely, backscattering. Motivated by the measurements of copper cables in frequency band up to 400 MHz, we propose a novel backscattering model. It may be productively applied to the problem of loop diagnostics. The methods to accurately and reliable determine the relevant transmission-line parameters are sine qua non condition to appropriately exploit the potential of short-to-medium range access lines. In this paper, a recursive formulation of the frequency-domain response of the backscattering is used for a space-time characterization. To confirm the practical use of the finding, we evaluate the properties of a loop using wideband, high-frequency S₁₁ measurements of the real cables. These laboratory results confirm the effectiveness and accuracy of the proposed method.
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| 3. |
- Fertner, Antoni, et al.
(författare)
-
Determination of the Propagation Constant From Single-Ended Line Test Data
- 2012
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456. ; 61:9, s. 2422-2427
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a numerical method, here, called recursive obliquely moving approximation (ROMA), for determining the propagation constant from single-ended line test measurements. The method is based on deriving an equation binding the input impedance of the open-ended transmission line and the characteristic impedance with the line propagation constant. The algorithm solving this equation relies on a recursive Newton-Raphson-type procedure. Initial guesses are generated using oblique least squares on the complex plane for the extrapolation of previous data while moving toward higher frequencies. For residential access, the loops often consist of multiple sections. In those scenarios, the ROMA algorithm gives a less accurate and more difficult-to-interpret estimate of the propagation constant than for single-segment loops. Nevertheless, it still enables a quick and credible estimation of the loop capacity. ROMA provides these estimates without a priori information; it is insensitive to local solutions, and it has low numerical complexity. Moreover, for single-segment loops, common in, e. g., mobile backhaul applications, the algorithm gives a highly accurate estimation of the propagation constant.
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| 4. |
- Höst, Stefan, et al.
(författare)
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Low complexity computation of the BT0 Hilbert twisted pair cable model
- 2010
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Ingår i: [Host publication title missing]. ; , s. 195-199
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Konferensbidrag (refereegranskat)abstract
- By use of the Hilbert transform the standardized BT0 twisted pair cable model can be rederived as a causal model with lower order, denoted BT0$_H$. In the present contribution the computational complexity of the BT0$_H$ model is decreased as the Hilbert transform is approximated with a look-up table implemented as a polynomial approximation. This results in a model of lower complexity than BT0$_H$ and lower order than the original BT0 model. Finally a comparison on causality of the considered models is presented.
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| 5. |
- Lindqvist, Fredrik, et al.
(författare)
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Detection and localization of load coils from one-port measurements
- 2010
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456. ; 59:7, s. 1972-1982
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThis paper deals with detection and localization of load coils in the copper access network. The load coil is a legacy device that must be removed before deploying broadband services on twisted-pair transmission lines. The proposed methods do not require dedicated hardware but utilize the already installed transceivers for one-port measurements of the line input impedance. The number of load coils is detected by counting the number of resonance peaks in the line impedance spectrum. An approximative model of the symmetric loaded line is presented, from which a low-complexity load coil locator is derived. For nonsymmetric lines, a load coil locator using model-based optimization is proposed. The two methods are compared and evaluated by computer simulations and by laboratory measurements on real transmission lines. The estimation results indicate that up to five load coils can be robustly detected and located with the proposed methods.
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| 6. |
- Lindqvist, Fredrik, et al.
(författare)
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Estimation of Nonhomogeneous and Multi-Section Twisted-Pair Transmission-Line Parameters
- 2015
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 63:11, s. 3568-3578
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Tidskriftsartikel (refereegranskat)abstract
- In emerging and future copper access networks, the trend goes towards exploiting higher transmission bandwidths on shorter twisted-pair cables. Methods to accurately determine relevant transmission-line parameters are a prerequisite to exploit the potential of these short-to-medium range access lines. In this paper, we propose a model-based space-frequency optimization approach initially developed for microwave applications. By utilizing the concept of capacitive length, two major advances are achieved. First, we overcome the requirement of a priori information of physical line length. Second, the number of parameters is reduced compared to prior art. We introduce two estimators to illustrate the concept. A low-complexity estimator with only two parameters per spatial unit primarily targets higher frequencies. A wideband estimator with three parameters per spatial unit extends to the lower frequencies used by operational digital subscriber line services. Performance and limitations of the approach are illustrated by both computer simulations and measurements.
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| 7. |
- Santos, Reginaldo, et al.
(författare)
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Binder Identification Using Pattern Recognition on Phantom Measurements
- 2016
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456. ; 65:3, s. 522-534
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes an automatic method for the identification of twisted pairs (TPs) sharing the same binder, based on the analysis of phantom circuit measurements. This type of circuit is often used for improving data transmission rates in communication systems, but in this paper, phantoming is used to reveal if a four-wire loop composed of two TPs is close enough and well balanced in order to be considered in the same binder. The method uses four features extracted from scattering parameter measures in phantom-mode between two TPs. These features are related to the presence of periodicities and impedance mismatch between the measurement device and the four-wire transmission line. The identification is done via application of two pattern recognition techniques, support vector machines and K-means, on scattering parameter obtained from the phantom-mode measurement of two TPs. This paper also describes a method to determine the length of the two TPs that share the same binder. Laboratory results confirm the accuracy of the proposed methods.
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