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QPSK Requirements
QPSK Recommendations
The RF requirements for the QPSK modulator are as follows:
The available spectrum of 1 MHz must be within the range of 70 MHz to 130
MHz.
The selected spectrum must be free of ingress, spurious, and spillover signals
from other services.
The center frequency can be set at 0.25 MHz increments starting with 70 MHz.
QPSK Forward and Reverse Path Levels
The following table provides QPSK signal level requirements that can be checked on
page 5 of the DHCT diagnostic screens.
Item
Current FDC: Level
Current FDC: S/N
The following table provides QPSK signal level requirements that can be checked
using procedures in the NCTA Recommended Practices for Measurements on Cable
Television Systems.
Item
Analog/Digital Ratio at DHCT
Amplitude Response in 1 MHz
Delay Response in 1 MHz
734375 Rev H
Forward Path Levels
-16 to +15 dBmV
> 21 dB
Forward Path Levels Reverse Path Levels
< 10 dB
< 1 dB
< 100 ns
QPSK Requirements
Not applicable
< 1 dB
<100 ns
49
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