12 | Keysight | N9923A FieldFox RF Vector Network Analyzer - Data Sheet
USB Power Sensor Measurements versus Frequency (Option 208)
This feature allows FieldFox’s source frequency to be set independently from the power sensor (receiver) frequency. With frequency-
offset using power sensor (FOPS), the frequency of both the source and receiver are swept, and the two track each other. The offset
frequency can be negative, zero, or positive.
FOPS can be used to characterize the scalar transmission response of devices such as mixers and converters. This frequency-offset
capability is necessary for conversion loss/gain measurements on frequency-translating devices, since by definition, the input and output
frequencies of the DUT are different. The FieldFox source stimulates the DUT and the power sensor is used as the measurement receiver.
Since power sensors are inherently broadband devices (not frequency-selective), the user should ensure that only the signal of
interest is present at the power sensor input and that all others signals are filtered appropriately
Setup Parameters
Source frequency
Receiver frequency
Frequency offset
Frequency step size
Number of points
Center/span or start/stop
Range determined by power sensor range
Positive offset or negative offset
30 kHz minimum
2 to 1601
Source frequency span must be equal to receiver frequency span.
Receiver sweep direction: forward (default setting) or reverse.
For some DUTs, the output frequency may sweep in a reverse direction, as compared to the source frequency. The basic relationships
between the source, receiver and offset frequencies are shown in the table below. The FieldFox analyzer includes an offset calculator
that ensures a fast measurement setup
S r c S w e e p D i r e c t i o n Rx Sweep Direction Frequency Calculations
Forward f2src > f1src Forward f2rx > f1rx
Forward f2src > f1src Reverse f2rx > f1rx
Receiver frequency = Source frequency ± Offset
Receiver frequency = Offset — Source Frequency Offset > Source frequency
Description
Measurements
Source power, gain/loss and receiver (Rx) power
Gain = Rx power / source power (memory). Source power (memory) is measured during setup
Refer to the test port output power typical data on page 3
Output power
Dynamic range
The dynamic range with FOPS is dependent on FieldFox’s output power and the power sensor’s dynamic range. Supported
USB power sensors: www.keysight.com/find/fieldfoxsupport
Pulse Measurements (Option 330)
FieldFox’s pulse measurement option can be used to characterize RF pulses such as those used in radar and electronic warfare
systems. Measurements are made using FieldFox and Keysight’s USB peak power sensors.
Performance specifications such as frequency, dynamic range and minimum pulse width depend on the peak power sensor. Sup-
portedpeak power sensors: http://www.keysight.com/find/fieldfoxsupport
Description
Setup parameters
Functions
Frequency, time (center), time/division, gating, triggering, video bandwidth, averaging
Average power, peak power, and peak to average ratio
Analog gauge display and digital display, dBm and watts
Relative/absolute measurements, offset, dB or %, minimum and maximum limits
Trace graph for pulse profiling with gating
Rise time, fall time, pulse width, pulse period, pulse repetition frequency
KEYSIGHT [ Keysight Technologies ]
