VeEX VePal CX350, Руководство пользователя

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Equalized and Un-equalized MER measurements
Un-equalized MER is typically measured before the adaptive equalizer and equalized MER is measured after the adaptive equalizer but often this circuitry resides in the
QAM receiver and cannot be disabled. So while the adaptive equalizer performs a great job improving MER of a QAM signal, it makes troubleshooting marginal amplifiers,
small ingress, CPD and related impairments a lot more difficult.
It is important to know how hard the adaptive equalizer is working to determine if there is any margin for system degradation. To solve this problem, the CX350’s adaptive
equalizer can be turned off, allowing a technician to easily identify, sectionalize and locate these difficult linear type distortion problems.
To proceed, first achieve Digital lock. Then tap on the Equalizer Off button. Note the icon at the top indicating the Equalizer is now off.
Equalizer Off
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7.2 Tilt Analysis
Overview
Tilt measurement is used to check the channel levels at the lowest and highest frequencies because level variations across the frequency spectrum are indicative of
distortion. Tilt measurement is also the most efficient tool for balancing distribution amplifiers. By tapping on the channel bars, the Tilt measurement will measure the two
most recently selected channels.
Typically, the same analog and digital channels which have been recommended or defined for the Scan function should be used when performing Tilt measurements. Often,
Tilt measurements are useful to identify excessive cable lengths at the customer premises that can cause high frequency roll off.
CX350 measures up to 8 analog and 8 digital channels simultaneously. You may select from the following tests:
Digital: Digital channels only
Analog: Analog channels only
A&D: Analog and Digital channels, presented on separate screens
A&D Combined: Analog and Digital channels, interleaved in one screen
Tilt Scan
Tilt Scan
CX350 e-Manual D07-00-037 RevC01 Page 29 of 81