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DOCSIS 1.1 Transmission Characteristics
DOCSIS 1.1 Transmission Characteristics
The following tables provide information on the assumed downstream RF channel transmission
characteristics for DOCSIS 1.1.
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:
Table B-5
DOCSIS 1.1 Assumed Downstream RF Channel Transmission Characteristics
Parameter
Frequency range
RF channel spacing (design bandwidth)
Transit delay from headend to most distant customer
Carrier-to-noise ratio in a 6-MHz band
Carrier-to-composite triple beat distortion ratio
Carrier-to-composite second order distortion ratio
Carrier-to-cross-modulation ratio
Carrier-to-any other discrete interference (ingress)
Amplitude ripple
Group delay ripple in the spectrum occupied by the CMTS
Micro-reflections bound for dominant echo
Carrier hum modulation
Burst noise
Maximum analog video carrier level at the cable modem input 17 dBmV
Maximum number of analog carriers
1. Measured relative to a QAM signal that is equal to the nominal video level in the plant.
Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide
B-4
http://www.cablelabs.com/.
Value
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.
6 MHz
≤ 0.800 msec (typically much less)
Not less than 35 dB
Not less than 41 dB
Not less than 41 dB
Not less than 41 dB
Not less than 41 dB
3 dB within the design bandwidth
75 ns within the design bandwidth
–10 dBc @ ≤ 0.5 microseconds
–15 dBc @ ≤ 1.0 microseconds
–20 dBc @ ≤ 1.5 microseconds
–30 dBc @ >1.5 microseconds
Not greater than –26 dBc (5%)
Not longer than 25 microseconds at a 10-Hz average rate
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Appendix B
1
1
1
1
1
RF Specifications
OL-17309-01
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