Cisco Systems UBR7225VXR specifications Upstream RF Channel Transmission Characteristics

Appendix B RF Specifications

DOCSIS 1.0 Transmission Characteristics

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

Parameter	Value
Seasonal and diurnal signal level variation	8 dB
Maximum analog video carrier level at the cable modem	17 dBmV
input, inclusive of above signal level variation
Lowest analog video carrier level at the cable modem input,	–5 dBmV
inclusive of above signal level variation

1.For measurements above the normal operating frequency band (except hum), impairments are referenced to the highest-frequency NTSC carrier level.

2.This presumes that the digital carrier is operated at analog peak carrier level. When the digital carrier is operated below the analog peak carrier level, the carrier-to-noise ratio may be less.

3.Decibels relative to carrier, a common measurement in RF engineering to specify the power of a sideband in a modulated signal relative to the carrier in decibels.

4.For hum measurements above the normal downstream operating frequency band, a continuous-wave carrier is sent at the test frequency at the same level as the highest-frequency NTSC carrier.

Upstream RF Channel Transmission Characteristics

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

Table B-4	DOCSIS 1.0 Assumed Upstream RF Channel Transmission Characteristics
Parameter		Value
Frequency range		5 to 42 MHz edge to edge
Transit delay from the most distant cable modem to the		≤ 0.800 msec (typically much less)
nearest cable modem or CMTS
Carrier-to-noise ratio		Not less than 25 dB
Carrier-to-ingress power (the sum of discrete and broadband		Not less than 25 dB1
ingress signals) ratio
Carrier-to-interference (the sum of noise, distortion,		Not less than 25 dB
common-path distortion, and cross-modulation) ratio
Carrier hum modulation		Not greater than –23 dBc (7%)
Burst noise		Not longer than 10 μsec at a 1-kHz average rate for most
		cases2, 3
Amplitude ripple		5 to 42 MHz: 0.5 dB/MHz
Group delay ripple		5 to 42 MHz: 200 ns/MHz
Micro-reflections—single echo		–10 dBc @ ≤ 0.5 microseconds
		–20 dBc @ ≤ 1.0 microseconds
		–30 dBc @ > 1.0 microseconds
Seasonal and diurnal signal level variation		Not greater than 8 dB min to max

1.Ingress avoidance or tolerance techniques may be used to ensure operation in the presence of time varying discrete ingress signals that could be as high as 0 dBc. (CableLabs1)

2.Amplitude and frequency characteristics sufficiently strong to partially or wholly mask the data carrier.

3.Impulse noise levels more prevalent at lower frequencies (<15 MHz).

Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide

OL-17309-02 B-3