EXFO EXpert IPTV Test Tools (FTB-1 / 2 Pro) - Manual (Page 58)

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A.2.1.7 VQmon Markov Model (VMM)
VQmon/HD uses a four-state Markov Model to gather and report packet loss statistics for
“burst” periods (where quality is significantly degraded) and “gap” periods (periods between
each burst interval when quality is relatively unimpaired).
VQmon/HD calculates quality metrics in these burst and gap states, and then combines them
to generate the overall quality score on user experience. These calculations are based on the
results of numerous subjective voice/video quality analysis tests that indicate there is not an
instantaneous change in perceived quality when a transition between the gap and burst states
occurs, but rather that the perceived quality exponentially “decays” from one level to
another. For example, a 100-millisecond burst of “noise” is much less annoying than a 10
second burst of “noise”.
Figure 2-8 illustrates the VQmon 4-state Markov model. The VQmon 4-state Markov model is
defined as having the following states and associated transitions:
Table 2-1. VQmon 4-state Markov model state transition descriptions