
resulting FSR is equal to 1/D, where D is the DGD experienced throughout the
link. As a result of this filtering effect, the spectral content of the transmitted RF
spectrum changes with DGD. As the DGD of the link increases, the RF power also
increases. Therefore, it is possible to measure variations in power level of the RF
spectrum and correlate these variations to the first-order PMD of the link. Because
the RF content is not impacted much by CD at lower RF frequencies, this
monitoring technique is relatively insensitive to CD. Besid es the dispersion insen-
sitivity, this monitoring scheme operates on very low frequencies, for example,
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