Cisco CableCARD, Руководство по эксплуатации

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QPSK Requirements
734375 Rev H 49
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 Forward Path Levels
Current FDC: Level -16 to +15 dBmV
Current FDC: S/N > 21 dB
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 Forward Path Levels Reverse Path Levels
Analog/Digital Ratio at DHCT < 10 dB Not applicable
Amplitude Response in 1 MHz < 1 dB < 1 dB
Delay Response in 1 MHz < 100 ns <100 ns