VeEX VePal CX350, Руководство пользователя

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Results:
During the test, a status indicator is displayed. Once completed, the yellow square is replaced by a green square if the measurements meet the location based thresholds, or
a red square if the measurements fail to meet the location based thresholds. Once the measurements are completed, the user can display detailed information about each
channel by tapping on the magnifying glass at the bottom right of the summary screen
The selected channels for the installation check test need to be active on the selected channel table. The installation check derives the pass and fail criteria by comparing
the measured values to pre-selected thresholds (locations). If no parameter has been selected on the active location, a warning message will be displayed.
Analog Channels:
The following measurements are performed for each channel:
Video Power Level in dBmV/dBuV
Audio1 Power Level in dBmV/dBuV
V/A1 Ratio in dB
Audio2 Power Level in dBmV/dBuV
Video/Audio2 Delta in dB
Max Adjacent Channel Delta in dB
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Digital Channels:
The following measurements are performed for each channel:
QAM Power Level in dBmV/dBuV
MER in dB
Pre-BER
Post-BER
Max Adjacent Channel Delta in dB
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7.8 Advanced Tools
7.8.1 Return Path Analysis
Overview:
The return path performance of an HFC system is very susceptible to ingress, noise, operating power level of the cable modem, and attenuation of the return signal. These
impairments are all capable of producing poor BER or MER, which can result in packet loss.
When a cable modem receives packets with errors, they are re-transmitted to ensure all the data is correct. Re-transmitting data can be occur in the forward as well as
return path. Modems that continuously resend data cause the overall data throughput for all of the modems to drop. This problem may be not significant with low data traffic
or a small number of cable modems on a system; however, when the traffic load increases, the system can fail.
HFC Test Points - Return Path
CX350 e-Manual D07-00-037 RevC01 Page 41 of 81