This chapter is organized as follows. In Section 17.2, we give a self-contained
view of PMD concepts that are used in the remainder of the chapter. Section 17.3
describes the “hinge” model which we have found helpful in describing field test
results. In Section 17.4, we briefly review results from a series of reported field
tests and show how they can be understood in terms of the hinge model. Section
17.5 is devoted to penalties and system outages due to pure first-order PMD, which
is very important from the practical point of view. Next, in Sect ion 17.6, we review
higher PMD orders and discuss their importance in today’s systems. The ability to
evaluate systems without the burdens of full field tests has motivated PMD
emulation, and we describe ...