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Cisco uBR10012 Universal Broadband Router Software Configuration Guide
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Chapter6 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 page15
•“Configuring PRBS Test Signals” section on page15
•“Verifying Test Signal Output” section on page15

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
Step1 Router(config-if# cable downstream
if-output continuous-wave Generates an unmodulated continuous wave signal on the
downstream channel. The interface is shut down.
Step2 Router(config-if# no cable downstream
if-output Stops sending test signals.
Note Remember to reenable the interface to resume normal
operations.
Command Purpose
Step1 Router(config-if# cable downstream
if-output prbs Generates a PRBS test signal on the downstream channel. The
interface is shut down.
Step2 Router(config-if# no cable downstream
if-output Stops sending test signals.
Note Remember to reenable the interface to resume normal
operations.