Tektronix MTM400 Manual do Utilizador descarregar pdf (Página 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.

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Tektronix MTM400 Manual do Utilizador Página 160