Agilent Technologies 83487A User Manual page 77

C A U T I O N
ment was less without the attenuator, then you had compression during the
initial measurement; the second measurement with the attenuator and associ-
ated offset adjustment is the accurate measurement.
Using the fixed 5 dB attenuator
The Agilent 83487A is shipped with a nominal 5 dB attenuator (±1.5 dB),
which will provide correct attenuation for most signals up to –5 dBm average
power (the current allowable standard). Follow the procedure outlined above
to use this attenuator and enter in the correct offset value.
For many signals, the easiest way to proceed is to always use the attenuator
with the correct offset. A couple of exceptions to this recommendation are:
• when you are splitting the signal for multiple tests or if there is already an-
other source of attenuation in front of the Agilent 83480/Agilent 83487A, or
• when you know there is no high frequency ringing associated with the device
under test and you want to use the high sensitivity of the Agilent 83487A.
The fiber-optic connectors on the 5 dB attenuator, like all fiber-optic
connectors, are easily damaged when connected to dirty or damaged cables
and accessories. Before making any connections to the attenuator, refer to
"Cleaning Connections for Accurate Measurements" on page 5-14.
Summary
The Agilent 83480A with the Agilent 83487A plug-in module was designed for
high sensitivity and has excellent waveform fidelity for signals with peak pow-
ers less than 400 µW (–4 dBm). For signals with peak powers greater than
400 µW (–4 dBm), a multimode attenuator is used to maintain high waveform
fidelity. By using the right attenuator, and entering the correct attenuation
factor into the external scale variable, the Agilent 83480A/Agilent 83487A
makes true Fibre Channel and Gigabit Ethernet compliance measurements
throughout the entire power range specified by the standards.
For more information, see Measuring High Power Waveforms with the
Agilent 83480/83487A, Product Note 83480-1. This is available through your
local Agilent Technologies sales office or at www.agilent.com/go/lightwave.
Measuring High Power Waveforms
Reference
5-9