6-15
Cisco uBR10012 Universal Broadband Router Software Configuration Guide
OL-1520-05
Chapter 6 Troubleshooting the System
Setting Downstream Test Signals
Setting Downstream Test Signals
This feature provides configuration commands that allow you to create downstream test signals. Both
pseudo random bit stream (PRBS) and unmodulated carrier test signals are now supported.
A PRBS test signal is a random data pattern that has been modulated to look like a real data stream. An
unmodulated test signal is a continuous sine wave that looks like a carrier wave on the downstream
transmission.
See the following sections for the required tasks to create PRBS and unmodulated carrier test signals:
•
“Configuring Unmodulated Test Signals” section on page 6-15
•
“Configuring PRBS Test Signals” section on page 6-15
•
“Verifying Test Signal Output” section on page 6-15
Configuring Unmodulated Test Signals
Configuring PRBS Test Signals
Verifying Test Signal Output
To verify the output of a continuous wave test signal or the output of a PRBS test signal, use a spectrum
analyzer on the downstream channel. The downstream carrier is enabled as a default.
The standard mode of operation is modulated signal output and the interface is active. For PRBS and
continuous wave output, the selected interface is shut down.
The functioning of the
no cable downstream if-output
command has not changed. The interface is shut
down.
Command
Purpose
Step 1
Router(config-if#
cable downstream
if-output continuous-wave
Generates an unmodulated continuous wave signal on the
downstream channel. The interface is shut down.
Step 2
Router(config-if#
no cable downstream
if-output
Stops sending test signals.
Note
Remember to reenable the interface to resume normal
operations.
Command
Purpose
Step 1
Router(config-if#
cable downstream
if-output prbs
Generates a PRBS test signal on the downstream channel. The
interface is shut down.
Step 2
Router(config-if#
no cable downstream
if-output
Stops sending test signals.
Note
Remember to reenable the interface to resume normal
operations.