Measuring The Rf Signal At The Forward Test Point On A Laser Transmitter - Cisco 7246 - uBR Router Hardware Installation Manual

Chapter 4 Connecting the Cisco uBR7200 Series Router to the Cable Headend
The slight "ramp-up" at the beginning of the preamble when viewed in this mode is attributed to the time
Note
required to charge the spectrum analyzer's detector circuit.
Figure 4-55
a very fast burst upstream carrier. You can compare the measurements obtained using a spectrum
analyzer with those of specialized test equipment. In general, the readings from the spectrum analyzer
will be within 1 to 2 dB of the (more expensive) specialized equipment. Because 1 to 2 dB is well within
the calibration accuracy of spectrum analyzers, you can reliably use these procedures in the cable
headend environment.
Measuring the RF Signal at the Forward Test Point on a Laser
Transmitter
This section describes RF signal measurements that should be taken with a spectrum analyzer at the
downstream forward test point on the fiber-optic laser transmitter. (See
location of the downstream forward test point.)
Use the following steps to measure the downstream forward test point on the fiber-optic laser
transmitter:
Connect the spectrum analyzer to the downstream forward test point on the fiber-optic laser transmitter.
Step 1
Figure 4-56
Figure 4-56
Using the spectrum analyzer zoom feature, zoom the display on the first individual video channel. In the
Step 2
example in
OL-5421-03
shows a smooth and easily measured signal amplitude, providing accurate measurement of
shows a typical measurement of the downstream forward test point.
Measuring the RF Signal at the Downstream Forward Test Point on the
Laser Transmitter
Figure 4-57, the first video channel is channel 48.
Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide

Measuring the RF Signal at the Forward Test Point on a Laser Transmitter

Figure 4-14 on page 4-15 for the
4-49