Data Specifications - Cisco uBR905 Installation Manual

Data Specifications

Data Specifications
Table A-2 lists the specifications for the Cisco uBR905 cable access router's data ports.
Table A-2 Cisco uBR905 Cable Access Router Data Specifications
Description
Frequency Range
Modulation
Data Rate
Bandwidth
FEC
Signal-to-Noise Ratio
(SNR)
One Channel
Cisco uBR905 Router Hardware Installation Guide
A-2
Downstream Values
88 to 860 MHz
64 QAM
256 QAM
64 QAM—30 Mbps (27 Mbit/sec after FEC
overhead)
/256 QAM—42.8 Mbps (36 Mbit/sec after
FEC overhead)
6 MHz
RS (122, 128) Trellis
64 QAM:
>23.5 dB @ BER<10^-8
256 QAM*:
>30 dB @ BER <10^-8
(For input level between +15 and -6 dBmV,
SNR must be greater than 30 dB. For input
level between -6 and -15 dBmV, SNR must be
greater than 33 dB.)
These performance numbers are in
Note
laboratory-controlled conditions,
against statistically pure noise
sources (AWGN). Since such
conditions do not exist in practice, a
6 or more dB SNR margin is required
for reliable operation. Check with
your local system guidelines.
Receive level of digital signal
-15 to +15 dBmV
Most field measurements are of
Note
nearby or adjacent analog signal,
which is normally +6 to +10 dB
(system specific) above the digital
signal level.
Appendix A
Upstream Values
5 to 42 MHz
QPSK
16 QAM
QPSK—320 Kbit/sec to 5 Mbit/sec
16 QAM—640 Kbit/sec to 10 Mbit/sec
200K, 400K, 800K, 1.6M, 3.2 MHz
QPSK:
>15 dB @ BER<10^-8
(QPSK works at 98% successful ping rate for
SNR>13 dB. An SNR of 15 dB is needed to get
almost optimal packets per minute transition.)
16 QAM:
>22 dB @ BER <10^-8
(For 16 QAM, an SNR>22 dB provides only a
98% ping efficiency. To get good packet rate, you
need SNR>25 dB)
Note These measurements were done for 0 and
-10 dBmV input to the CMTS, 1280
ksym/sec and 64 bytes packet size with
laboratory-controlled conditions.
QPSK— +8 to +58 dBmV
16 QAM— +8 to +55 dBmV
Technical Specifications
OL-0598-01 (9/2000)