Keysight Technologies U9361C User manual

Keysight Technologies
U9361C/F/G/M RCal Receiver Calibrator
Measurement
Guide

Notices
© Copyright 2021-2022 Keysight Technologies, Inc.
The information contained in this document is subject to change without notice.
Keysight Technologies makes no warranty of any kind with regard to this material, including but
not limited to, the implied warranties of merchantability and fitness for a particular purpose.
Keysight Technologies shall not be liable for errors contained herein or for incidental or
consequential damages in connection with the furnishing, performance, or use of this material.
Manual Part Number
U9361-90003
Edition
Edition 1, October 2022
Supersedes: February 2022
Printed in USA
Published by:
Keysight Technologies, Inc.
1400 Fountaingrove Parkway
Santa Rosa, CA 95403

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 3
What you will find in this Measurement Guide
What you will find in this Measurement Guide
Overview of RCal ........................................................................................................... page 4
RCal I/O ......................................................................................................................... page 5
USB Power & Control ............................................................................................... page 5
External 10 MHz Reference ..................................................................................... page 5
RF Output..................................................................................................................page 6
LED Indicators on RCal Module.....................................................................................page 7
RCal Software – Configuration ..................................................................................... page 8
Left-Panel Controls.................................................................................................. page 9
Configuration Table Overview................................................................................ page 10
RCal Configuration Table – Parameters................................................................ page 11
RCal Software – Calibration and Application............................................................. page 15
Running a Calibration ............................................................................................ page 15
Applying a Calibration ........................................................................................... page 16
Errors, Warnings, and Status................................................................................. page 17
Correcting State Mismatches ................................................................................ page 17
Best RCal Configuration Practices ........................................................................ page 17
Multiple SA Input Ports and RCal Modules........................................................... page 18
How to Utilize Match State.................................................................................... page 18
Multiple Rows, Overlap, and Dual Corrections ..................................................... page 18
Key Steps for Every RCal Calibration .................................................................... page 19
Demonstrations ........................................................................................................... page 20
Demo #1 – Simple Magnitude Calibration............................................................ page 22
Demo #2 – Magnitude Cal with Source Control, Multiple States ........................ page 28
Demo #3 – Complex Cal: Improving EVM in a 128 QAM Signal .......................... page 36
Demo #4 - Using RCal with the 89600 VSA Software.......................................... page 43
Demo #5 - RCal vs. Power Sensor Accuracy........................................................ page 47
Demo #6 - Using RCal as a CW Source and Comb Generator............................ page 54
Programming with MATLAB page 57
Magnitude Calibration and Comparison with Use Current Meas ........................ page 57
Calibration Table Setup for VMA ........................................................................... page 58
Appendix: Connector Care.......................................................................................... page 61
Resources .................................................................................................................... page 63

4 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
Overview of RCal
Overview of RCal
The U9361x RCal Receiver Calibrator provides accurate signal analysis at a remote measurement
plane when using an X-Series Signal Analyzer. This integrated solution allows you to correct for
signal path and analyzer magnitude and phase errors to provide a more accurate measurement of
your transmitter under test. This measurement guide provides the following resources for best
success when using RCal:
— Initial RCal setup, including connector care and an overview of RCal’s I/O.
—OverviewoftheRCalCalibration graphical user interface (GUI).
— Demonstrations of both magnitude and complex corrections that highlight the most important
RCal measurement practices.
— MATLAB scripts for RCal configuration and application.
Requirements
— X-Series Signal Analyzer Software Rev A.27.05 or higher (A.29.01 or higher recommended)
— U9361Y_RCL license installed on X-Series Signal Analyzer (two licenses come with each RCal
unit, and additional upgrade options are available as U9361YU_RCL)
— X-Series Signal Analyzer (N9020B, N9021B, N9030B, N9032B, N9040B, N9041B, N9042B) To
use the N9020B with RCal, you will need option DP2, MPB, or B40.
— Various signal generators. You can perform all demonstrations using either an N5173B, N5183B,
or any model of the N519xA UXG. Additional models can be used for demos 1, 3, 4, 5, and 6.
Refer to each Demo for specific requirements.
— Option CPX adds magnitude/phase for IF flatness calibration.
Available RCal Models and Options
Model Frequency Range Connector Type
U9361C 10 MHz – 26.5 GHz 3.5 mm male (option MMM) or
3.5 mm female (option MMF)
U9361F 10 MHz – 50 GHz 2.4 mm male (option MMM) or
2.4 mm female (option MMF)
U9361G 10 MHz - 67 GHz 1.85 mm male (option MMM) or
1.85 mm female (option MMF)
U9361M 10 MHz – 110 GHz 1.0 mm male (option MMM)

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 5
RCal I/O
RCal I/O
The typical RCal use case requires three connections: USB Power & Control, Ext Ref In, and RF Out.
USB Power & Control
RCal has a USB Type-C connector, which must be connected to the signal analyzer for both power
and control. Since RCal needs ample current to operate correctly, be sure to use one of the
following ports:
— The signal analyzer front-panel USB 2.0 port, marked with a lightning bolt symbol (bottom front
panel USB connector closest to RF input connector) or marked in blue (for the N9042B).
— A signal analyzer rear-panel USB 3.0 port, identified with “SS” or having a blue connector.
When plugged in, the RCal module will boot up, accompanied by an LED boot sequence. When
boot-up is complete, the LEDs will settle to Status = Green. For more information about RCal’s LED
codes, see “LED Indicators on RCal Module” on page 7.
External 10 MHz Reference
RCal’s signals are synthesized from an internal 100 MHz clock. For the best possible measurement
accuracy, it is recommended that RCal be connected to the external 10 MHz Ref Out from the
signal analyzer, or another reference that both RCal and the analyzer are locked to. The default
setting of the RCal is Ref = External.

6 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal I/O
RF Output
The RF Output connector on the RCal module is the physical point where the calibration data
applies.
An adapter may be needed between the RCal output and test port where calibration is desired. Use
the shortest and highest quality connectors possible. Mismatch errors can be reduced with small
fixed attenuators, such as a 6 dB attenuator.
Higher frequencies require smaller connector geometries, such as 1 mm. To avoid damaging these
fragile connectors, please follow the recommendations in “Appendix: Connector Care” on page 61.

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 7
LED Indicators on RCal Module
LED Indicators on RCal Module
At startup, all LEDs on the RCal will blink with the firmware revision code and sequence through
three colors. If problems occur on startup, the LED pattern may indicate self-test codes for use by
support experts. Contact Keysight customer support, via email, at [e-mail]
if you encounter any issues.
After startup, the LEDs indicate the following status messages:
Status LED RF Out LED 10 MHz Ref LED
Off = No USB Connection Off = No RF Output Off: Internal Reference Used
Green = On, Ready, Stable
Green Blink = Busy
Green = RF Out On Green = External Ref locked successfully
Amber Blink = Temperature
Unstable (during warm-up period) - -
Red = USB Power Failure
Red Blink = Processor Error
Red Blink = USB Power Failure Red Blink = External Ref unlocked
Blue Blink = Self Identification - -

8 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal Software – Configuration
RCal Software – Configuration
The RCal controls can be accessed in the X-Series application by selecting Input/Output,
Calibration, Configuration. If this tab is missing, then the instrument is most likely using an older
software revision, missing a license, or is unsupported. (See “Available RCal Models and Options”
on page 4).
This section provides an overview of how to perform the RCal configuration, calibration, and
application.
RCal calibrations are created and applied within the calibration configuration window.

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 9
RCal Software – Configuration
Left-Panel Controls
Cal Group: Stores and groups combinations of user-created calibration states. This is useful for
test setups involving multiple external paths that multiplex into a single output; each path may
need its own individual calibration. The desired Cal Group can be specified here.
Cal Input: Specifies the desired input for instruments that have more than one input. Each Cal
Group can only support one Cal Input at the same time. If multiple inputs are desired, create a
Cal Group for each input.
Calibrate Checked Rows: Starts the RCal calibrations for each selected row according to all
user-specified parameters. (See “Configuration Table Overview” on page 10 for information on
how to set calibration parameters).
Copy From Cal Group: Allows you to import Cal Group settings into the current Cal Group. This
is useful for calibrating text fixtures that use the same parameters across multiple signal paths.
Apply Cal Group: Applies all active calibration states for the selected Cal Group.
Select Calibrator: Selects the RCal module for use. A single signal analyzer can have multiple
RCal modules connected to different ports, but only one module can be used and controlled at a
time. The RCal Model and Serial numbers will appear below this tab.
RCal Reference: Selects whether RCal is using its internal 100 MHz clock or is locked to an
external 10 MHz reference. The default (and strongly recommended) setting is to use an external
reference in order to synchronize the RCal module with the signal analyzer for complex
calibrations.
Identify RCal Module: Identifies the active RCal module. If multiple RCal modules are
connected to the signal analyzer, touching this key will cause LEDs on the active unit to flash.

10 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal Software – Configuration
RCal Status: Opens the RCal status and error message dialogue. See “Errors, Warnings, and
Status” on page 17 for more details.
Configuration Table Overview
The RCal configuration table is where you define the measurement parameters for your RCal
correction. The table is initially empty. Click on Insert Row below, or Use Current Meas1(located at
the top of the configuration window), to start populating the table.
The simplest and fastest configuration option is to define one, single state (row). If you anticipate
the need to make measurements that involve changing the analyzer’s state, you can provide ranges
within a row or define additional rows within the same Cal Group. Calibrating for multiple states will
require a longer calibration time, but allows for the RCal to match a wider range of states.
Rows
A row contains a collection of settings or ranges for RCal operation. A row is linked to the analyzer’s
settings or “state” which can be viewed as an internal path through the analyzer. The row with a
blue border is active for editing. To change the active editing row, use the Go to Row button or
touch/click within the desired row. The Insert, Duplicate, and Delete buttons operate on the active
row.
Columns
The columns contain the state settings or ranges that RCal needs for calibration. Some column
groups allow you to define a range of settings; e.g. Frequency and Attenuation have
Start/Stop/Step parameters. Other columns contain On/Off settings or provide a drop-down table
of options, such as for IF Path or μW Path Ctrl. If you want to calibrate more than one of these
choices, add another row and select each alternative in separate rows.
1. Use Current Meas automatically populates the Cal Row using parameters from the current X-Series Signal
Analyzer application. This feature is supported by the Signal Analyzer mode and many others, but it is not
supported by every X-Series Signal Analyzer application.
Not all columns fit on the display screen. Use a finger or mouse to grab
the scroll bar (just below the bottom of the active row) and scroll to the
left, or right to see all columns.

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 11
RCal Software – Configuration
Shown below are all parameters (columns) for an RCal calibration state (row):
RCal Configuration Table – Parameters
The following table details the parameters for each column in every calibration row.
Column Title Description Additional Information
Calibrate
(checkbox)
Rows that are selected will be included when
Calibrate Checked Rows is used to start a
calibration.
Apply
(checkbox)
Rows that are successfully calibrated will be
applied to measurements when selected.
Name User defined row name.
Last Calibrated (Read only) Date and time that last calibration
was successfully executed.
Applied (Read only)
“Yes” if successfully applied, “---“ if not yet
calibrated, and “No” if not applied.
Ext Mixer (Read only)
Applies only if Input = Ext Mixer
Type Magnitude: Select for correcting magnitude
only (no phase corrections). Use for swept
measurements.
Complex: Select for correcting magnitude and
phase. Use for correcting IF responses for IQ
demodulation measurements.
Complex is only available if RCal Option
CPX is installed.

12 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal Software – Configuration
Frequency:
Start Freq
Stop Freq
Freq Step
Freq Points
Defines frequency range for calibration. Step
and Points are coupled parameters; use either
one to modify the “density” of the points over the
selected frequency range.
For Complex calibrations, refers to the
center of the IQ analysis span.
Mechanical
Attenuation:
Mech Atten
Mech Atten Start
Mech Atten Stop
Mech Atten Step
Defines the range of main mechanical attenuator
to calibrate.
Mech Atten Step uses start, stop, and step
range.
Calibrating over large attenuation ranges
can take a long time, and calibration may
not be possible at the highest attenuation
levels.
Step size is typically 2 dB.
Electronic
Attenuation:
Elec Atten
Elec Atten Start
Elec Atten Stop
Elec Atten Step
Defines the range of the electronic attenuator to
calibrate.
All calibrates the entire range of electronic
attenuation
Elec Atten Step uses the start, stop, and step
range.
Bypass disables electronic attenuation.
Operates only at frequencies < 3.6 GHz.
IF Gain Auto (default)
High Gain
Low Gain
All
Recommended to use Auto and set Match
State = False. High Gain sets the IF gain
to 10 dB for better noise levels, while Low
Gain sets the IF gain to 0 dB for large
signals. Auto will set the IF gain to 10 dB if
the input attenuator is set to 0 dB. All will
calibrate for both High Gain and Low Gain.
IF Path Selects the IF and digitizer path to be calibrated.
Swept is only used for Magnitude calibrations.
Other paths for IQ demodulation include:
—40MHz
— 160 MHz
— 255 MHz
— 520 MHz
—1GHz
Only IF Paths that are available in an
instrument’s HW configuration will appear.
Calibration is valid for the maximum
bandwidth of the IF path.
Column Title Description Additional Information

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 13
RCal Software – Configuration
Preamp Off
Low Band: Use for frequencies less than
3.6 GHz
Full Range: Use for frequencies up to 50 GHz
Low Band path is not compatible with
Options LNP (Low Noise) or FBP (Full
Bypass).
Coupling AC or DC Not all instruments support both AC and
DC.
Phase Noise
Opt = PNO
Selects PNO mode used by LO synthesizer
system. Options include:
—BestClose-In
— Balance Noise and Spurs
— Best Spurs
— Best Wide-Offset
— Fast Tuning
—All
Best Close-In: better phase noise
performance at the cost of higher spurs for
offset < 600 kHz*
Balance Noise and Spurs: balanced spur
and phase noise for offset < 600 kHz*
Best Spurs: spurs held to -90 dB at the cost
of phase noise for offset < 600 kHz*
Best Wide-Offset: optimized phase noise for
offset > 800 kHz*
Fast Tuning: provides faster tuning speed
All: calibrates for all PNO modes
*Phase Noise Optimization offset
frequencies vary based on the Synthesizer
option (EP0, EP1, EP2)
μW Path Options:
— Low Noise (LNP)
—μW Presel Bypass (MPB)
— Full Bypass (FBP)
μW path reverts to STD if any points are <
3.6 GHz. In STD mode, the μW Preselector
is in the circuit and the Low Noise Path is
disabled.
LNP: bypasses low-band switch to lower
noise floor (only for signals > 3.6 GHz)
MPB: bypasses preselector to lower noise
floor (only for signals > 3.6 GHz)
FBP: bypasses both the low-band switch
and preselector for the best dynamic range
(only for signals > 3.6 GHz)
Mixing Mode Refers to ‘high-side’ or ‘low-side’ mixing (LO>RF
or LO<RF).
Normal is default for a given band (can be either
LO > RF or LO < RF).
Alternate if using alternate-side mixing for
digital demodulation to flip the side of image
products, then you would want to calibrate the
alternate mixing side.
All does both.
Normal is sufficient for most use cases.
Column Title Description Additional Information

14 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal Software – Configuration
Match State False (default) allows instrument to interpolate
and approximate when correction data is “close”;
reduces frequency of Apply errors.
True requires strict match between correction
data and instrument settings.
See “How to Utilize Match State”
on page 18 for more details.
Column Title Description Additional Information

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 15
RCal Software – Calibration and Application
RCal Software – Calibration and Application
Running a Calibration
Once the desired measurement state(s) have been configured, select the states to calibrate by
clicking/tapping on each state’s Calibrate check box to select.
After selecting the states for calibration, select the Calibrate Checked Rows button on the left
panel. You should see the following message:
After ensuring that the RCal module is connected to the signal path, select OK to start the
calibration.
The following is a brief summary of what occurs during the calibration process:
— The RCal configuration software automatically prepares the signal analyzer to control the RCal
module for the calibration process.
— The signal analyzer reads relevant factory calibration data from the RCal module to prepare for
corrections.
— The signal analyzer makes measurements and calculates the difference between expected and
actual measurements.
— The differences are stored as corrections to be applied to a later measurement.
Calibrations involving multiple states take longer to execute.

16 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal Software – Calibration and Application
The following message will be displayed during the calibration process:
When calibration is complete, you should see the following message which will disappear
automatically:
To cancel a calibration in progress, press the Cancel button or use the Esc key.
After calibration, you should see a time stamp for all calibrated rows under the Last Calibrated
column.
Applying a Calibration
To apply the correction, select the Apply column in the row. The instrument will compare its current
state to all corrections in the active RCal correction pool and apply correction factors according to
the Match State rules. The Applied column should now show Yes, indicating that the selected
calibration is being applied.
When calibrations are active, the Corr CCorr (Complex Correction) option on the measurement
panel should show "RCal" in orange as shown below.
The Apply indicator is dynamic; as you change analyzer settings, RCal will re-evaluate to check if
any RCal corrections in the active correction pool are applicable.

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 17
RCal Software – Calibration and Application
Typically, only 1 single correction should be actively applied at a time. Multiple states can be
selected to apply, but these states should be configured in such a way that only 1 is active per given
instrument state. If 0, or more than 1 state matches, the system will display a warning.
To remove a row from the active calibration pool, clear the Apply box. This state can always be
added back to the pool by selecting Apply again.
Errors, Warnings, and Status
The RCal system displays status and error conditions in three ways:
—Meas Bar: The Corr CCorr option displays “RCal” in white if it is connected but inactive, and
displays “RCal” in orange if calibrations are active.
—Status Bar: Located at the bottom of screen; is used to report high-level errors or warnings from
any cause (not just from RCal). Only the most recent status changes are displayed. Select the
‘balloon’ with “…” to see the error queue history with details.
—RCal Status dialog: This table is fully devoted to RCal and provides the greatest detail. To open,
select Input/Output menu > Calibration > Configuration > RCal Status.
In this table, errors and warnings appear listed by both group and row number. Errors (red circle,
white X) indicate failure, meaning RCal calibration is not successful. Warnings (yellow triangle, with
“!”) indicates caution about a possible issue, but RCal can still calibrate successfully.
Correcting State Mismatches
Apply-time errors usually occur because an instrument state was changed and no longer matches
any correction. To fix this:
— Modify the current state to stay within ranges or paths that are already calibrated.
— Change settings from “Auto” to “Man” (manual), to prevent automatic or coupled changes to
parameters.
— Expand the range of RCal, and/or add RCal rows, to include the state or path that caused the
mismatch, and recalibrate.
In most applications, the state parameters of a given measurement can be found and set via:
— The “Meas Bar” summary (at top of screen)
—TheMeasSetupmenu
Best RCal Configuration Practices
The following recommendations should be considered when creating RCal calibration states:

18 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
RCal Software – Calibration and Application
— Plan for how the signal analyzer will be used after calibration, so that the corrections are valid
for later changes in measurement parameters.
— Start with a a simple configuration and gradually configure for higher complexity. For example,
start with a single row, a small number of frequency steps, and a small range of attenuation
steps before further increasing these values as needed.
— In general, leave Match State set to False. See “How to Utilize Match State” on page 18 for
more information.
— If you use the “Duplicate Row” feature, verify that the original row works correctly, and doesn’t
take an excessively long time, before copying to another row.
Multiple SA Input Ports and RCal Modules
Most signal analyzer systems employ a single input port. However, some analyzers (such as the
N9041B) have more than one input. If you need to calibrate both inputs, create a Cal Group for
each RF input port, since each Cal group may choose which module is associated with that group.
How to Utilize Match State
Acquisitions rarely match the exact hardware state at which the original RCal correction was
performed. The stored correction must be converted to the correction required for the exact
hardware acquisition state. This conversion is controlled by the Match State parameter within the
RCal configuration window.
If you want to only apply corrections to test setups that exactly match the state of their RCal
calibration(s), you should set the Match State to True. If you want to apply RCal corrections to
similar hardware states that may not exactly match the original hardware calibration state, you
should set the Match State to False. When the Match State is set to False, the following rules are
followed:
— Situations that are “close enough” will use the closest available correction.
— Situations that are too different will never be selected even when the Match State is set to
False.
— Situations that are in between will utilize interpolation to get the desired correction.
Multiple Rows, Overlap, and Dual Corrections
If you create multiple rows, calibrate them, and select Apply in more than one row, the RCal system
may raise apply-time warnings. As long as one row matches the current state, the calibration will
be applied successfully for that row despite the warning.
If two or more rows both match state, they are considered overlapping and yield a
double-correction. This overlap may be over a portion of the spectrum trace. This usually is
undesired, and should be avoided or fixed by:
— Selecting Apply in a single row, or fewer rows, until the warning goes away, or configuring RCal
to avoid overlap.

U9361C/F/G/M RCal Receiver Calibrator Measurement Guide 19
RCal Software – Calibration and Application
The following warning indicates that more than two rows match state:
When performing a calibration, no corrections will be made outside of the calibration bandwidth.
However, if performing a calibration on a signal with a wider bandwidth than the calibration
bandwidth, corrections will still be applied within the calibrated bandwidth.
Key Steps for Every RCal Calibration
The following procedure should be followed before every RCal calibration to guarantee the best
possible accuracy:
1. RCal calibrations are independent of measurement time and temperature, which are
parameters that are handled through routine spectrum analyzer alignments. For the best
possible accuracy, alignments should be run before every RCal calibration and after a 30
minute warm-up time. The RCal module does not replace spectrum analyzer calibrations and
alignments.
2. Make sure that the Ext 10 MHz reference is connected and that the selected USB connection
supplies ample current.
3. If source control is desired for the calibration, connect the necessary input and output triggers
between the analyzer and source.

20 U9361C/F/G/M RCal Receiver Calibrator Measurement Guide
Demonstrations
Demonstrations
Demo Setup
The following diagram shows the configuration for all front-panel demonstrations.
These demonstrations show how to correct for absolute power accuracy under the Swept SA
application.
— Some demos involve the use of fixed attenuators, which should be inserted into the RF path
such that the attenuator is present in both the signal generator to signal analyzer path as well as
the RCal to signal analyzer path.
— The switch in the diagram represents changing the physical connection to the signal analyzer to
use either the signal generator or RCal as the RF input.
— The Trig connections between the signal generator and signal analyzer are recommended for
demos involving source control. The software trigger can also be used without a physical
connection.
— The USB-C connection is located above the Ext Ref In and Trig Out ports, as shown below.