Keysight Technologies C Series - About I;Q Analyzer (IQA) Measurements; Setting the IF Path

298 Keysight N9915-90020 User’s Guide
IQ Analyzer (IQA) – Option 351
About I/Q Analyzer (IQA) Measurements
About I/Q Analyzer (IQA) Measurements
The I/Q Analyzer Mode makes general purpose frequency domain and time
domain measurements. The mode enables two types of I/Q measurements:
— frequency domain and
— time domain measurements
In order to ensure consistent results between frequency domain and time
domain, spectrum measurement and waveform measurement are based on the
same I/Q acquisition. The following acquisition parameters are automatically
calculated to satisfy these requirements:
1. RBW and IF BW specified in Spectrum measurement BW (BW 2
) menu.
2. Start time and Stop time specified in Waveform measurement Sweep
(Sweep 3) menu and IF BW specified in Waveform measurement BW
(BW 2
) menu.
3. I/Q signal capture related parameters specified in the Measurement Setup
(Meas Setup 4
) menu.
Some measurement parameters are auto-coupled and are not user-settable.
Setting the IF Path
How to check or set the IF Path. By default the IF Path is set to Auto.
1. Press Meas Setup 4
2. Press BW 2
.
3. Then
IF Path The underlined setting is the current setting. Choose Auto,
10 MHz, or 100 MHz (100 MHz requires Option B04 or B10 and either
Option 350 RTSA or Option 351 IQ Analyzer).
Optional: After you click 100 MHz, you can use the Freq/Dist hard key and
the number pad or using the numeric keypad, the arrows, to increase
your IF path bandwidth to 120 MHz.
Noise level in time-domain measurements are higher for IF-BW >100 MHz
due to raised noise levels at the edges of the 120 MHz bandwidth.
When in full span, ADC dither raises the noise floor at the edges of the
120 MHz.