Tektronix MTM400 - Manual (Page 165)

Interface Configuration and Interpretation
MTM400 MPEG Transport Stream Monitor User Manual 3-121
MER and EVM calculations are performed on the constellation
data according to the formulas given in ETR290-101.
SNR after equalizer
This graph represents the signal-to-noise ratio over time,
typically over 256 seconds. It is useful for examining signal-to-
noise trends; for example, if an alarm condition has been
breached, the graph can be used to examine trends in the signal-
to-noise performance before the alarm occurred.
Equalizer This graph shows the status of the equalizer taps, and gives an
estimate of the channel state. If there are echoes or other time
related distortions on the signal, the Equalizer display will
display the amplitude of the corresponding tap correction values
versus time.
NOTE. The Equalizer graph amplitude values are only
approximate.
MER This graph gives a time record of MER over the last 255
seconds.
Select the graph to be displayed from the Graph drop-down menu.