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Digital Analysis (QAM View OPT4): Quick Start

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display shows the channel, modulation format, the symbol rate, the carrier

offset (in KHz), the equalizer stress.

Press this key to view the digital DETAIL display.

Press this key to view the QAM Level display.

QAM Ingress Mode (Quick Start)

QAM INGRESS Mode provides a spectrum view of ingress noise,

CSO/CTB, and other coherent (in-band) noise occurring at levels beneath

the digital signal.

Measurement data is shown on two lines, A and B, below the graph. These

two lines show the readings of the vertical markers on the graph.

Press this key to select the active vertical marker. The dotted

line is the active marker. The solid line (other marker) does not

move. The active marker moves with the left and right diamond

keys.

Press this key to automatically place the active marker at the

frequency with the greatest amplitude.

Constellation Mode (Quick Start)

CONSTELLATION Mode shows a picture of the quality of the demodulated

digital signal. Identifying a specific constellation pattern and associating this

pattern with a specific type of impairment quickly leads to troubleshooting

options that minimize or eliminate the impairment. (A good QAM signal will

show a tight grouping of dots in the center of each square on the grid.)

Use the Zoom feature to examine the constellation in more detail. In 64

QAM, three grids are available for viewing – 8x8, 4x4, and 2x2. In 256 QAM,

four grids are available for viewing – 16x16, 8x8, 4x4, and 2x2.

Press this key to view the QAM Level display.

Press this key to enter the Zoom Submenu.

The top left quadrant of the constellation grid will be framed by a dark

outline. Use the diamond keys to move this frame to the desired quadrant.

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Wavetek 147 Especificações Página 176