Cisco UBR7225VXR, Руководство по установке оборудования

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B-5
Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide
OL-17309-01
Appendix B RF Specifications
EuroDOCSIS Transmission Characteristics
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.
EuroDOCSIS Transmission Characteristics
The following tables provide information on the assumed RF channel transmission characteristics for
EuroDOCSIS.
Table B-6 DOCSIS 1.1 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
nearest cable modem or CMTS
≤
0.800 msec (typically much less)
Carrier-to-interference plus ingress (the sum of noise,
distortion, common-path distortion, and cross-modulation
and the sum of discrete and broadband ingress signals,
impulse noise excluded) ratio Not less than 25 dB
1
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 10 dBc. Ratios are guaranteed only within the digital carrier channels.
Carrier hum modulation Not greater than –23 dBc (7%)
Burst noise Not longer than 10 microseconds at a 1-kHz average rate for
most cases
2, 3
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).
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 reverse gain (loss) variation Not greater than 14 dB min to max