Agilent Technologies E4406A, Руководство пользователя

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Chapter 4 95
Making Measurements
Making the Spectrum (Frequency Domain) Measurement
•
Auto
- Data is automatically packed. This is the default setting
and most recommended.
•
Short (16 bit)
- Data is packed by every 16 bits.
•
Medium (24 bit)
- Data is packed by every 24 bits.
•
Long (32 bit)
- Data is packed by every 32 bits.
ADC Dither
- Allows you to toggle the ADC dither function between
Auto
,
On
, and
Off
. When set to auto (the default), ADC dither will
be activated when a narrow bandwidth is being measured, and
deactivated when a wide bandwidth is being measured. “ADC
dither” refers to the introduction of noise to the digitized steps of
the analog-to-digital converter; the result is an improvement in
amplitude accuracy. Use of the ADC dither, however, reduces
dynamic range by approximately 3 dB.
Decimation
- Allows you to toggle the decimation function between
Auto
and
Man
, and to set the decimation value.
Auto
is the
preferred setting, and the only setting that guarantees alias-free
FFT spectrum measurements. If you are familiar with the
decimation feature, you can change the decimation value by
setting to
Man
, but be aware that aliasing can result in higher
values.
IF Flatness
- Allows you to toggle between
On
and
Off
. When
toggled to
On
(the default), the IF flatness feature causes
background amplitude corrections to be performed on the FFT
spectrum. The
Off
setting is used for adjustment and
troubleshooting the transmitter tester.
Changing the View
View/Trace menu keys are used to activate a view of a measurement
with preset X and Y scale parameters, called a “window”. Using the X
and Y Scale keys you can then modify these parameter settings. You
can also activate specific traces, using the
Trace Display
menu key.
Windows Available for Spectrum Measurements
The spectrum and the I/Q windows can be viewed at the same time, or
individually. You can use the
Next Window
and
Zoom
keys to move
between these different views.
Spectrum
window Select this window if you want to view frequency
and power. Changes to frequency span or power will sometimes affect
data acquisition.
I/Q Waveform
window. Select this window to view the I and Q signal
characteristics of the current measurement in parameters of voltage
and time.