Tektronix MTM400 - Manual (Page 160)

Interface Configuration and Interpretation
3-116 MTM400 MPEG Transport Stream Monitor User Manual
Front End Lock If full lock is acquired onto the channel and it is receiving the
signal correctly, the Front End Lock (FEL) indicator will light
up green. When a signal is present but no lock is achieved the
indicator is red. When no signal is found, the indicator is gray.
(Refer to the MTM400 MPEG Transport Stream Monitor Technical Reference for
more details about the QAM interfaces.)
Input Card Screen - QAM (Annex A and Annex C)
Figure 3-41: Input card screen - QAM (Annex A and Annex C)
The constellation display in the graphing area is a representation of the digitally
modulated carrier's instantaneous phase and amplitude for each transmitted
symbol. A good constellation will have well-defined dot clusters in tight
formations; each cluster should be centered in a grid overlay square. The overall
shape of the dot clusters should form a square as represented by the outer edges of
the grid.
Grid
Size This selection will be dictated by the installed interface card. If
the Auto checkbox is selected, the grid size can be selected from
the drop-down list.