Feature Overview
6Cisco IOS Release 12.0(7)T
Note Interactive games are the exception. Although low latency is required in gaming applications,

high upstream data throughput is not demanded since the volume of data transmitted upstream is

typically small.

Data Specifications
Table1 Cisco uBR900 Series Cable Access Router Data Specifications
Description Downstream Values Upstream Values
Frequency Range 88 to 860 MHz 5 to 42 MHz
Modulation 64 QAM
256 QAM
QPSK
16 QAM
Data Rate 30 Mbps/64 QAM
(27 Mbit/sec after FEC overhead)
42.8 Mbps/256 QAM
(36 Mbit/sec after FEC overhead)
QPSK—320 Kbit/sec to 5 Mbit/sec
16 QAM—640 Kbit/sec to 10 Mbit/sec
Bandwidth 6 MHz 200K, 400K, 800K, 1.6M,
3.2 MHz
FEC RS (122, 128) Trellis Reed Solomon
One Channel Receive level of digital signal
-15 to +15 dBmV
Note Most field measurements are of nearby
or adjacent analog signal which is normally
+6to +10 dB (system specific) above the
digital signal level
QPSK— +8 to +58 dBmV
16 QAM— +8 to +55 dBmV
Signal-to-Noise Ratio
(SNR)
64 QAM:
>23.5 dB @ BER<10^8
256 QAM*:
>30 dB @ BER <10^-8
(For input level between +15 and -8 dBmV,
SNR must be greater than 30 dB. For input
level between -8 and -15 dBmV, SNR must be
greater than 33 dB.)
Note These performance numbers are in
laboratory-controlled conditions against
statistically pure noise sources (AWGN). Since
such conditions do not exist in practise, a 6dB
ormore SNR margin is required for reliable
operation. Check with your local system
guidelines.
QPSK:
>15 dB @ BER<10^-8
(QPSK will work at 98% successful
ping rate for SNR>13 dB. A SNR of
15dB will be needed to get almost
optimal packets per minute transition.)
16 QAM:
>22 dB @ BER <10^-8
(For 16 QAM, a SNR>22 dB makes the
grade for 98% ping efficiency. To get
good packet rate, you need
SNR>25dB)
Note These measurements were made
for 0 and -10 dBmV input to the CMTS,
1280 ksym/sec and 64 bytes packet size
with a Cisco uBR904 cable access router
and laboratory-controlled conditions.