Cisco Systems UBR7100E manual Table A-6 Docsis Cable Downstream RF Specifications

Appendix A System Specifications

DOCSIS Upstream and Downstream Specifications

Table A-5 DOCSIS Cable Upstream RF Specifications (continued)

Specification	DOCSIS Specifications1	Minimum Settings2	Your Headend Settings
Seasonal/diurnal signal level	< 8 dB	< 8 dB
variation
Carrier to second order	< –50 dBc	< –50 dBc
Digital Signal Levels
From cable modem (upstream)	+8 to +58 dBmV (QPSK)	+8 to +58 dBmV (QPSK)
	+8 to +55 dBmV (16 QAM)	+8 to +55 dBmV (16 QAM)
Input amplitude to modem card	–16 to +26 dBmV	–10 to +25 dBmV
(upstream)
Signal as relative to adjacent video	–6 to –10 dBc	–6 to –10 dBc
signal

1.DOCSIS specifications are baseline settings for a DOCSIS-compliant, two-way data-over-cable system.

2.Minimum settings are slightly different than the DOCSIS settings to account for cable system variations over time and temperature. Using these settings should increase the reliability of DOCSIS-compliant, two-way data-over-cable systems.

3.QPSK = Quadrature Phase-Shift Keying: a method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits.

4.These settings are measured relative to the digital carrier. Add 6 or 10 dB, as determined by your company’s policy and derived from the initial cable network setup, relative to the analog video signal.

5.QAM = Quadrature Amplitude Modulation: a method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding.

6.dBc = decibels relative to carrier.

Table A-6 DOCSIS Cable Downstream RF Specifications

Specification		DOCSIS Specifications1	Minimum Settings2	Your Headend Settings
System/Channel
RF channel spacing (bandwidth)		6 MHz	6 MHz
Transit delay3		0.800 ∝sec	0.800 ∝sec
Carrier to noise ratio		> 30 dB (64 QAM4)5	>30 dB (64 QAM)5
		> 35 dB (256 QAM)5	> 33 dB (256 QAM)5
Carrier to ingress power ratio		> 35 dB	> 35 dB
Composite triple beat distortion		< -50 dBc6	< -50 dBc
Carrier to second order		< –50 dBc	< –50 dBc
Cross-modulation level		< –40 dBc	< –40 dBc
Amplitude ripple		0.5 dB in 6 MHz	0.5 dB in 6 MHz
Group delay		75 ns7 in 6 MHz	75 ns in 6 MHz
Micro reflections bound for dominant		–10 dBc @ < 0.5 ∝sec	–10 dBc @ < 0.5 ∝sec
echo		–15 dBc @ < 1.0 ∝sec	–15 dBc @ < 1.0 ∝sec
		–20 dBc @ < 1.5 ∝sec	–20 dBc @ < 1.5 ∝sec
		–30 dBc @ < 1.5 ∝sec	–30 dBc @ < 1.5 ∝sec
Carrier hum modulation		< –26 dBc (5%)	< –26 dBc (5%)
Burst noise		< 25 ∝sec	< 25 ∝sec
Seasonal/diurnal signal level variation		8 dB	8 dB
	Cisco uBR7100 Series and Cisco uBR7100E Series Universal Broadband Router Hardware Installation Guide
A-4				OL-5916-01