| 摘要 |
<p>Estimation of line insertion loss (IL (f) ) of a customer transmission line. For a number of different reference transmission lines the insertion loss is laboratory measured at a number of frequencies in double- ended line tests, giving insertion loss values (L11...L14,..., L51...L54). For the same reference transmission lines single-ended laboratory tests are performed, giving one calibration quantity (PV1...PV5) per transmission line, representing the amplitude of a far-end TDR reflection. A relationship is formed between the loss values (L11 L54) and the calibration quantity (PV1...PV5), shown as one straight line (Lf1...Lf4) per frequency (f1...f4). A field single-ended line test is performed on the unknown customer transmission line, giving a calibration quantity (PVX). The insertion loss (IL';(f) ) is read as values (LX1...LX4) for the different frequencies (f1 f4). The calibration quantity (PV1 PV5; PVX) can be measured via a line card or by connecting to the transmission line. For one transmission line different relationships can be set up depending on the termination impedance of the transmission line. Accurate customer transmission line insertion loss is generated.</p> |
