Viavi OneExpert CATV User Manual page 189

Chapter 9 Test Results
Spectral results
• Channel width – specifies the width of the spectrum analyzer.
To change the channel width, select the desired width from the buttons
above the spectral display. If the 2.4 GHz spectrum is active select
10 MHZ or 40 MHz. If the 5.0 GHz spectrum is active select 10 MHZ,
40 MHz or 80 MHz.
• Max Hold – the blue line above the standard spectral line that
represents the peak value (in dBm) seen at each frequency point.
Press OK to reset the Max Hold trace and restart the measurement.
• Averages – specifies the number of samples to be used for averaging
of the real-time trace. To change the number of samples press the (+)
or (–) arrows at the end of the Averages display bar
The following are some common interferences that could show up in a
spectral measurement.
Microwave ovens can interfere with an 802.11 signal. They are most
prevalent in channels 10 and 11. If possible, it is a good idea to look at the
spectral response while the microwave is running to determine its impact.
Bluetooth devices appear as spikes and appear to "roll" through the
spectral view. They are fast moving and you may only see them
occasionally. The systems are designed to be inter-operable, but
Bluetooth will impact throughput.
Channels can "bleed over" into adjacent channels. The width of the signal
(due to RF considerations) can affect nearby channels. This bleed over is
treated as noise.
Page 166
OneExpert CATV User's Guide
22121055-001, Rev000