Cisco Systems UBR900 User Manual

Cisco IOS Release 12.0(7)T

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

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

Most field measurements are of nearby 

or adjacent analog signal which is normally 
+6 to +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.)

These performance numbers are in 

laboratory-controlled conditions against 
statistically pure noise sources (AWGN). Since 
such conditions do not exist in practise, a 6 dB 
or more 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 
15 dB 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>25 dB)

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.