08 | Keysight | FieldFox Handheld Analyzers - Configuration Guide
FAQs – Applicable To All FieldFox RF and Microwave Analyzers
Question Answer
1. What USB 
power sensors
work with 
Option 302?
All Keysight U2000x Series USB power sensors are supported with FieldFox. 
Visit: www.keysight.com/find/fieldfoxsupport for an up-to-date listing.
2. What is the 
difference 
between USB 
power sensor 
(Option 302) 
and built-in 
power meter 
(Option 310)?
Option 302
USB power sensor
Option 310
Built-in power meter (or channel power meter)
Description Option 302 allows users to connect a 
USB power sensor to FieldFox’s USB 
port and make broadband power 
measurements.
Option 310 is a channelized power measurement capability built 
into FieldFox analyzers. Maximum bandwidth is 100 MHz.
External hardware USB power sensor required None. Uses internal receiver.
Power measurement Broadband diode detector, measures 
all frequencies
Tuned receiver, so measures frequencies within defined channel 
bandwidth
Frequency range Depends on USB sensor Frequency range of the analyzer
Settings Set CW frequency Set CW frequency, Set channel width/span
Power range Depends on USB sensor Depends on channel width and attenuator setting. 
Warm-up time 30 minutes to meet accuracy 
specifications
No warm-up time required
Accuracy Depends on USB sensor InstAlign accuracy: ± 0.5 dB typical for a CW signal. Since the 
measurement is within a certain frequency channel or bandwidth, 
to make an accurate measurement, the user needs to know the 
exact center frequency and the signal’s bandwidth and set those 
accurately.
Programmable Yes, via SCPI Yes, via SCPI
Physical connection The power sensor can easily be 
moved to the measurement point, 
with a USB cable connecting the 
detector to FieldFox.
The measurement point needs to be connected to FieldFox’s RF 
input port. If a RF jumper cable is used, the user needs to account 
for the loss of the cable with an offset value (can be entered into 
the analyzer).
FieldFox source control Yes, on/off, and nominal power level 
control
No access to FieldFox’s source from the built-in power meter mode