Keysight Technologies FieldFox A Series, User Manual

Page: 156 / 756

156 Keysight N9927-90001 User’s Guide
SA (Spectrum Analyzer) Mode
SA Mode Settings
Check for Compressed Measurements
Compression occurs when too much power into an amplifier causes it to no
longer amplify in a linear manner. When too much power goes into the
FieldFox RF Input connector, the amplifiers in the SA receiver compress and
signal power will not be displayed accurately. This can occur even if ADC Over
Range is not displayed because devices other than the ADC, such as the mixer,
might be compressed. Increase the RF Attenuation value to prevent the SA
receiver from being compressed.
How to Check for a Compressed Measurement
— Using a marker at the signal peak, make note of the signal power level.
— Increase the RF Attenuation level by 5 dB.
—If the signal level does NOT change, then NO compression exists. This
indicates that the signal is in the linear region of the FieldFox
receiver.
—If the signal level DOES increase, then the receiver was compressed.
Set the RF Attenuation value at the setting when further increases no
longer result in an increase in the displayed power level.
Field Strength Measurements
To measure the strength of any signal transmitted through the air, an antenna
must be connected to the FieldFox. The Field Strength feature allows you to
enter the frequency response of the receiving antenna (the Antenna Factor)
and associated cabling, and then have amplitude corrections automatically
compensate the displayed trace for that response.
Field Strength Measurements
Trace 1
- Corrected trace with antenna factor. (Antenna = ON, Apply Corr =
ON)