Cisco Systems UBR7225VXR specifications Downstream RF Channel Transmission Characteristics

Appendix B RF Specifications

EuroDOCSIS Transmission Characteristics

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 CENELEC 50083-7 documentation.

Table B-7 EuroDOCSIS Assumed Downstream RF Channel Transmission Characteristics for Analog TV and Sound Signals

Parameter	Value
Frequency range1	Cable system normal downstream operating range is from
	47 MHz to as high as 862 MHz. However, the operating range
	for data communication is from 108 to 862 MHz. The use of
	frequencies between 108 and 136 MHz may be forbidden due
	to national regulation with regard to interference with
	aeronautical navigation frequencies.
RF channel spacing (design bandwidth)	7/8 MHz, 8 MHz channels are used for data communication
Transit delay from headend to most distant customer	≤ 0.800 msec (typically much less)
Carrier-to-noise ratio in a 8-MHz band (analog video level)	Not less than 44 dB2
Carrier-to-interference ratio for total power (discrete and	Not less than 52 dB within the design bandwidth
broadband ingress signals)
Composite triple beat distortion for analog modulated carriers	PAL—Not greater than –57 dBc within the design bandwidth
	SECAM—Not greater than –52 dBc within the design
	bandwidth.
Composite second order distortion for analog modulated	PAL—Not greater than –57 dBc within the design bandwidth.
carriers	SECAM—Not greater than –52 dBc within the design
	bandwidth.
Cross-modulation level	Under consideration
Amplitude ripple	2.5 dB in 8 MHz
Group delay ripple in the spectrum occupied by the CMTS	100 ns over frequency range 0.5 to 4.43 MHz
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 modulation3	Not greater than –46 dBc (5%)
Burst noise	Not longer than 25 microseconds at a 10-Hz average rate
Signal level slope, 85–862 MHz	12 dB
Seasonal and diurnal signal level variation	8 dB
Maximum analog video carrier level at the system outlet,	PAL: 77 dBmicroV
inclusive of above signal level variation	SECAM: 74 dBmicroV
Lowest analog video carrier level at the system outlet,	PAL: 60 dBmicroV
inclusive of above signal level variation	SECAM: 57 dBmicroV

1.For measurements shown, the normal downstream operating frequency band (except hum), impairments are referenced to the highest-frequency PAL/SECAM 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.

Cisco uBR7225VXR Universal Broadband Router Hardware Installation Guide

B-6 OL-17309-02