Digital subscriber line (DSL) technology is used to provide high speed Internet access and, more recently, video services over twisted pair lines. Telephone lines have impairments that hinder DSL transmission, and some examples are coils and bridge taps that were introduced to aid voice telephony. Other faults are caused by physical damage that results in open circuits, short circuits or water in the line. Telephone companies have to locate and repair these faults to enable high-speed data services. It is also useful to qualify lines for future DSL service so that a new customer can be promptly informed whether high-speed service can be supplied. <p>This thesis proposes a novel technique called Wideband frequency domain reflectometry (W-FDR) to accurately locate impairments in telephone lines and estimate the reflection magnitude caused by faults. The measurement produces a result similar to the well-known time domain reflectometer (TDR), however, digital signal processing techniques are now applied to provide enhanced resolution and range. In addition to magnitude, the new technique is able to measure reflection angle which can help to determine the nature of the fault (wire in the cable, broken wires, etc). <p>The measurement technique consists of energizing the line with a sinusoid that increases from 50 kHz to 1300 kHz in discrete frequency steps after coherent detection. The amplitude of the reflected signal is recorded as a function of frequency for 2500 equally spaced frequencies. The Fourier transform and some signal processing are then used to estimate the complex reflection coefficient location of the faults in the telephone line. Lines with up to 4 reflection points have been accurately analyzed. <p>Results show distance measurement accuracy better than 1% and phase measurement accuracy better than 10 degrees for line lengths up to 5 km. These measurements exceed the performance of currently available TDR instruments.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-07052006-094509 |
| Date | 07 July 2006 |
| Creators | Celaya de la Torre, Bernardo |
| Contributors | Dodds, David E. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-07052006-094509/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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