System information

BSR 64000 Configuration and Management Guide
6-12
Configuring a Downstream Channel
A downstream channel is configured to control the data flow from the cable interface
to the user CM. This section is divided into two parts. The downstream parameters
that must be configured for the minimal operation of the downstream port are
discussed in the Initial Downstream Configuration Tasks section. The downstream
parameters that are configured to manage the downstream channel operation are
discussed in the Managing the Downstream Channel section.
Table 6-1 contains the downstream parameters.
Table 6-1 Downstream Parameters
Parameter Identification Default Value
Frequency
Range
Radio frequency carrier center
frequency
555,000,000 Hz 93,000,000 to
855,000,000 Hz
Insertion
Interval
Time available for CM initial
channel request
2,000
milliseconds
100 to 2,000
milliseconds
Interleave Depth Depth to provide protection from
noise
32 8, 12, 16, 32,
64, 128,
Modulation Rate Data traffic speed 256 QAM 64 QAM (6 bits)
or 256 QAM (8
bits) per symbol
MPEG Framing
Format
Annex A (European) standard
Annex B (North American)
standard
BA or B
Power Level Downstream transmit power level 55 dBmV 45 to 65
decibels per
millivolt (dBmV)
SYNC Interval Interval between SYNC message
transmissions
200 1 to 200
milliseconds