Update to the Cisco uBR904 Cable Modem Installation and
Configuration Guide

Product Number: uBR904

This document describes the tests performed, test results, and caveats related to the Multimedia Cable Network Partners, Ltd. (MCNS) Data Over Cable Service Interface Specification (DOCIS) compatibility for the Cisco uBR904 cable modem.

Cisco uBR904 MCNS DOCSIS Compatibility

Table 1 lists the test results that were used to confirm MCNS DOCIS compatibility of the uBR904.

Note All adjacent channel interference results are measured both at the downstream receiver (demodulator) and before the tuner (at the cable plant) of Cisco uBR904 cable modems.

Table 1: **CIsco uBR904 MCNS DOCSIS Compatibility Test Matrix**
	MCNS DOCSIS Compatibility Testing (BER¹ < or = 1 x 10^-8)
	Tests Performed		Results
	PHY (RF)	End-to-End	SNR² at Downstream Receiver
			SNR		Adjacent Channel Interference
Data Rate			MCNS Specification	Actual Results	MCNS Specification	Actual Results
Downstream
256 QAM³ (5.360 Msps⁴, alpha 0.12)	X	-	30 dB	33 dB	30 dB⁵ 30.5 dB⁶ 31 dB⁷	33 dB⁵ 33.5 dB⁶ 34 dB⁷
64 QAM³ (5.057 Msps⁴, alpha 0.18)	X	X	23.5 dB	23.5 dB	23.5 dB⁸ 23.7 dB⁷	23.5 dB⁸ 23.7 dB⁷
Upstream
16 QAM³ (1.280 Msps⁴, alpha 0.25)	X	-	30 dB	30 dB	-	-
QPSK⁹ (1.280 Msps⁴, alpha 0.18)	X	-	30 dB	30 dB	-	-

¹BER = bit error rate.
²SNR = signal-to-noise ratio.
³ QAM = quadrature amplitude modulation.
⁴ Msps = Megasymbols per second. A symbol is the basic unit of modulation.
⁵ Analog or digital adjacent channel, 0 decibels relative to carrier (dBc) located at ±6 MHz from the desired channel.
⁶ Analog adjacent channel, 10 dBc located at ±6 MHz from the desired channel.
⁷ Digital adjacent channel, 10 dBc located at ±6 MHz from the desired channel.
⁸ Analog adjacent channel (10 dBc) or digital adjacent channel (0 dBc) located at ±6 MHz from the desired channel.
⁹ QPSK = quadrature phase shift keying.

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