Tektronix MTM400 - Manual (Page 161)

Interface Configuration and Interpretation
MTM400 MPEG Transport Stream Monitor User Manual 3-117
Clear Points Clears all points from the display grid.
Readings
MER (dB) (Modulation Error Ratio) Provides a single 'figure of merit' for
received signal. It is the ratio of 'ideal signal vectors' to 'errored
signal vectors' expressed in dB. MER is similar to a
signal-to-noise measurement (ref: TR 101 290).
EVM (%) (Error Vector Magnitude) Closely related to, and can normally
be calculated from, MER. It is a ratio of 'errored signal vectors'
to maximum signal amplitude expressed as a percentage
(ref: TR 101 290 Annex).
BER (Bit Error Rate) Provides an indication of the Forward Error
Correction workload.
TEFs (Transport Error Flag or TEI transport error indicator) Indicates
the Forward Error Correction failure.
Lock If the QAM interface is able to acquire full lock onto the channel
and is receiving the signal correctly, the Lock indicator will
light up green. Red indicates that lock cannot be achieved. Gray
indicates that a signal is not present.
Settings
Update (s) Allows the period in seconds between samples of the incoming
signal to be set.
Persist Allows the time that the dots persist on the grid display to be set.
Log
File Constellation data can be written to the file identified in this
field; data is saved in csv format.