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as the center frequency of the channel and the channel's bandwidth. The
UCD provides other information to the cable modems such as burst type
and burst descriptor. Refer to the Cable Modem Termination System 1000
Administration and Operations Manual for a detailed description of the
UCD.
After a CM 100 learns how to receive (Scanning) and acquires a down-
stream channel, it can then learn how to transmit (Ranging). The cable
modem, after learning how to receive and transmit, listens for UCDs and
MAPs.
You set the input power level to where you want the CMTS 1000 to
receive, based on the transmission rates at which you want the CM 100
cable modems to transmit. The CMTS 1000 transmits Upstream Channel
Descriptors periodically informing all CM 100s in its operating frequencies
of all the upstream channel characteristics, including transmit power.
Table 2-1 shows the CMTS 1000 input power level ranges for each of the
five symbol rates and both modulation modes.
Table 2-1 CMTS 1000 Upstream Demodulator Input Power Characteristics
Symbol Rate
Ksym/sec
1,280
2,560
Perform the following procedure to set the CMTS 1000 input power level.
Setting the CMTS 1000 input power level is accomplished via an SNMP
MIB variable or the Command Line Interface. Both procedures are not
available as of this printing.
302693-B Rev 00
Modulation Format
QPSK
16 QAM
Kbits/sec
Kbits/sec
160
320
320
640
640
1,280
2,560
5,120
Channel Width
KHz
640
1,280
2,560
5,120
1,600
10,240
3,200
Hardware Installation
Power Range
dBmV
200
-16 to +14
400
-13 to +17
800
-10 to +20
-7 to +23
-4 to +26
2-7
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