Appendix B RF Specifications

DOCSIS 1.0 Transmission Characteristics

Table B-2

Upstream Channel Data Rates (continued)

 

 

 

 

 

 

 

 

 

 

 

Channel

QPSK Raw

QPSK Nominal

QAM-16 Raw

QAM-16

Symbol Rate,

 

Bandwidth,

Data Rate,

Data Rate,

Data Rate,

Nominal Data

ksym/sec

 

MHz

Mbps

Mbps

Mbps

Rate, Mbps

 

 

 

 

 

 

 

1280

 

1.60

2.56

~2.3

5.12

~4.6

 

 

 

 

 

 

 

2560

 

3.20

5.12

~4.6

10.24

~9.0

 

 

 

 

 

 

 

DOCSIS 1.0 Transmission Characteristics

The following tables provide information on the assumed downstream RF channel transmission characteristics for DOCSIS 1.0.

Downstream RF Channel Transmission Characteristics

Transmission is from the headend combiner to the cable modem input at the customer location. Measurement methods are defined in NCTA or CableLabs2 documentation.

Go to the following URL: http://www.ncta.com/. Search on “transmission”.

Go to the following URL: http://www.cablelabs.com/.

Table B-3 DOCSIS 1.0 Assumed Downstream RF Channel Transmission Characteristics

 

Parameter

Value

 

 

 

 

Frequency range1

Cable system normal downstream operating range is from 50

 

 

 

 

MHz to as high as 860 MHz. However, the values in this table

 

 

 

 

apply only at frequencies 88 MHz.

 

 

 

 

RF channel spacing (design bandwidth)

6 MHz

 

 

 

 

Transit delay from headend to most distant customer

0.800 msec (typically much less)

 

 

 

 

Carrier-to-noise ratio in a 6-MHz band (analog video level)

Not less than 35 dB2

 

Carrier-to-interference ratio for total power (discrete and

Not less than 35 dB within the design bandwidth

 

broadband ingress signals)

 

 

 

 

 

 

Composite triple beat distortion for analog modulated carriers

Not greater than –50 dBc3 within the design bandwidth

 

Composite second-order distortion for analog modulated

Not greater than –50 dBc within the design bandwidth

 

carriers

 

 

 

 

 

 

Cross-modulation level

Not greater than –40 dBc within the design bandwidth

 

 

 

 

Amplitude ripple

0.5 dB within the design bandwidth

 

 

 

 

Group delay ripple in the spectrum occupied by the CMTS

75 ns within the design bandwidth

 

 

 

 

Micro-reflections bound for dominant echo

–10 dBc @ 0.5 microseconds

 

 

 

 

–15 dBc @ 1.0 microseconds

 

 

 

 

–20 dBc @ 1.5 microseconds

 

 

 

 

–30 dBc @ >1.5 microseconds

 

 

 

 

Carrier hum modulation4

Not greater than –26 dBc (5%)

 

Burst noise

Not longer than 25 μsec at a 10-Hz average rate

 

 

 

 

Signal level slope, 50-750 MHz

16 dB

 

 

 

 

 

 

 

 

Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide

 

 

 

 

 

 

 

 

 

 

B-2

 

 

OL-17309-02

 

 

 

 

 

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Cisco Systems UBR7225VXR Docsis 1.0 Transmission Characteristics, Downstream RF Channel Transmission Characteristics