Filter
Top Products
A-4
Cisco uBR7100 Series and Cisco uBR7100E Series Universal Broadband Router Hardware Installation Guide
OL-5916-01
Appendix A System Specifications
DOCSIS Upstream and Downstream Specifications
Seasonal/diurnal signal level
variation
< 8 dB < 8 dB
Carrier to second order < –50 dBc < –50 dBc
Digital Signal Levels
From cable modem (upstream) +8 to +58 dBmV (QPSK)
+8 to +55 dBmV (16 QAM)
+8 to +58 dBmV (QPSK)
+8 to +55 dBmV (16 QAM)
Input amplitude to modem card
(upstream)
–16 to +26 dBmV –10 to +25 dBmV
Signal as relative to adjacent video
signal
–6 to –10 dBc –6 to –10 dBc
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 Specifications
1
Minimum Settings
2
Your Headend Settings
System/Channel
RF channel spacing (bandwidth) 6 MHz 6 MHz
Transit delay
3
0.800 µsec 0.800 µsec
Carrier to noise ratio > 30 dB (64 QAM
4
)
5
> 35 dB (256 QAM)
5
>30 dB (64 QAM)
5
> 33 dB (256 QAM)
5
Carrier to ingress power ratio > 35 dB > 35 dB
Composite triple beat distortion < -50 dBc
6
< -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 ns
7
in 6 MHz 75 ns in 6 MHz
Micro reflections bound for dominant
echo
–10 dBc @ < 0.5 µsec
–15 dBc @ < 1.0 µsec
–20 dBc @ < 1.5 µsec
–30 dBc @ < 1.5 µsec
–10 dBc @ < 0.5 µsec
–15 dBc @ < 1.0 µsec
–20 dBc @ < 1.5 µsec
–30 dBc @ < 1.5 µsec
Carrier hum modulation < –26 dBc (5%) < –26 dBc (5%)
Burst noise < 25 µsec < 25 µsec
Seasonal/diurnal signal level variation 8 dB 8 dB
Table A-5 DOCSIS Cable Upstream RF Specifications (continued)
Specification DOCSIS Specifications
1
Minimum Settings
2
Your Headend Settings