Defining modulation profiles, Guard time – ADC CUDA 3 User Manual

Page 420

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ADC Telecommunications, Inc.

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Defining Modulation Profiles

Modulation profiles contain the profile properties of the CMTS upstream
data stream channels. The CMTS supports two profiles for the four upstream
channels. Each profile consists of a burst descriptor for the following Interval
Usage Codes:

Request: Interval when a request on bandwidth can be sent by the
modem.

Initial Maintenance: Interval when new modems can start establishing a
connection with CMTS with Initial Ranging Requests.

Station Maintenance: Interval when modems perform periodic ranging
with periodic ranging for adjusting power, timing and frequency.

Short Data: Interval when a modem can send upstream PDU (Protocol
Data Unit), which is less than one maximum burst size.

Long Data: Interval when the modem can send upstream PDU, when
one burst size exceeds one maximum burst size on the short data interval.

For each above-mentioned Usage Code, you must define eleven profile
parameters as described in the following sections.

Caution: Profiles affect the physical layer. Changes to profile properties
affects the performance and function of the CMTS. It is recommended that
an expert-level user perform Modulation Profile configuration.

Guard Time

The Guard Time parameter is the number of symbol-times that must follow
the end of this channel's burst. Note that this parameter is read-only.

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