Interface Configuration and Interpretation

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.

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MTM400 MPEG Transport Stream Monitor User Manual