Tektronix MTM400 Manuel d'utilisateur télécharger pdf (Page 164)

Interface Configuration and Interpretation

3-120 MTM400 MPEG Transport Stream Monitor User Manual

Input Card Screen - QAM Annex B II

Figure 3-43: Input card screen - QAM Annex B II (example)

Two LED indicators are available on the Readings section of the screen:

FEC Lock

Forward Error Correction Lock, which displays the status of the

deinterleaver and Reed Solomon decoder.

RF Lock

If full lock is acquired onto the channel and it is receiving the

signal correctly, the RF Lock 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.

The following graphs, which can be selected from the Graph drop-down list, are

available when the QAM (Annex B) interface card is installed:

RF Constellation I and Q data are collected from the QAM front end and

displayed as a conventional constellation of 256 points by 256

points. The samples collected are not real time, so there is some

dwell (delay) before a complete constellation is displayed. The

persistence of the display can be varied using the Persist slider

control at the bottom of the graph.

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Tektronix MTM400 Manuel d'utilisateur Page 164