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QAM Requirements
QAM Forward Path Levels
The following table provides the QAM staging area RF requirements that can be
checked from Page 5 of the DHCT diagnostic screens.
Item
Current QAM: Level
Current QAM: S/N
* Relative to QAM power
The following table provides the QAM staging area RF requirements that can be
checked using the procedures in the NCTA Recommended Practices for Measurements
on Cable Television Systems.
Item
Analog/Digital Difference
at DHCT
Amplitude Response of 6
MHz Channel
CTB, CSO, CM
** NCTA method relative to analog
Recommended Frequencies for Improved CVT Download Performance
During the CVT download process, the DHCT scans a set of recommended
frequencies. If the DHCT does not initially find the recommended frequency, it then
searches all frequencies.
This section provides the recommended download frequencies for the following
frequency plans:
Standard frequency (STD)
Incrementally related carrier (IRC)
Harmonically related carrier (HRC)
734375 Rev H
Modulation Rate
64 QAM
256 QAM
64 QAM
256 QAM
Modulation Rate
64 QAM
256 QAM
64 QAM
256 QAM
64 QAM
256 QAM
QAM Level
-20 to +14 dBmV
-14 to +14 dBmV
> 27 dB*
> 31 dB*
QAM Level
6 to 10 dB down**
3 to 6 db down**
< 5 dB
< 5dB
< -50 dB**
< -53 dB**
QAM Requirements
47
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