National Instruments NI PXIe-5624 Manual

PXIe-5624

CALIBRATION PROCEDURE
NI PXIe-5624R
2 GS/s, 12-Bit IF Digitizer
This document contains the verification and adjustment procedures for the NI PXIe-5624R
(NI 5624R) IF digitizer. Refer to ni.com/calibration for more information about
calibration solutions.
NI LabVIEW Instrument Design Libraries for IF Digitizers includes example FPGA images to
use the NI 5624R in two modes of operation:
•Digitizer Mode—IF data is captured directly from the ADC without DSP and stored into
DRAM. This data is not equalized or calibrated. Use Interactive IF Acquisition
Without DSP (Host).vi from the Multirecord Acquisition sample project to acquire
data in digitizer mode.
•Digital Downconversion (DDC) Mode—Signal processing on the FPGA converts data
from the ADC into quadrature I/Q data. This DSP shifts the frequency of, decimates,
equalizes, and calibrates the data before storing it into DRAM. Use Interactive
Spectrum Acquisition (Host).vi from the Multirecord Acquisition sample
project or IQ Acquisition (Host).vi to acquire data in DDC mode.
Contents
Software.................................................................................................................................... 2
Documentation.......................................................................................................................... 2
Test Equipment......................................................................................................................... 2
Test Conditions......................................................................................................................... 5
Initial Setup............................................................................................................................... 5
Characterizing the Test System ................................................................................................ 5
Zeroing the Power Sensor................................................................................................. 6
Characterizing Power Splitter Balance............................................................................. 6
Self-Calibrating the NI 5624R.................................................................................................. 9
Self-Calibrating Using MAX............................................................................................ 9
Self-Calibrating Using LabVIEW .................................................................................... 9
As-Found and As-Left Limits................................................................................................... 9
Verification ............................................................................................................................... 10
Verifying Internal Frequency Reference .......................................................................... 10
Verifying Absolute Amplitude Accuracy......................................................................... 12
Updating Calibration Date and Time........................................................................................ 15
Adjustment................................................................................................................................ 16
Adjusting Internal Frequency Reference .......................................................................... 16
Adjusting Absolute Amplitude Accuracy......................................................................... 17
Reverification ........................................................................................................................... 20
Worldwide Support and Services ............................................................................................. 20

2|ni.com |NI PXIe-5624R Calibration Procedure
Software
Calibrating the NI 5624R requires you to install the following software on the calibration
system:
• NI LabVIEW 2014 Full/Pro or later
• A version of the NI LabVIEW Instrument Design Libraries for IF Digitizers that is
compatible with your LabVIEW version
You can download all required software from ni.com/downloads.
Documentation
You might find the following documentation helpful as you perform the calibration procedure:
• NI PXIe-5624R Getting Started Guide
• NI IF Digitizers Help
• NI PXIe-5624R Specifications
The latest versions of these documents can be found on ni.com/manuals.
Test Equipment
Table 1 lists the equipment NI recommends for the performance verification and adjustment
procedures.
If the recommended equipment is not available, select a substitute using the minimum
requirements listed in the following table.

NI PXIe-5624R Calibration Procedure |© National Instruments |3
Table 1. NI 5624R Required Equipment Specifications for NI 5624R Calibration
Equipment Recommended Model Measured Specification Minimum Requirements
Power sensor Rohde & Schwarz (R&S)
NRP-Z91
Test system characterization
Verifying absolute amplitude accuracy
Adjusting absolute amplitude accuracy
Range: -15 dBm to +10 dBm
Frequency range: 4 MHz to 2.005 GHz
Power linearity: <0.1 dB
VSWR: <1.11 at 2.005 GHz
Signal generator Rohde & Schwarz SMA100A Test system characterization
Verifying internal frequency reference
(B22 option needed for this procedure)
Verifying absolute amplitude accuracy
Adjusting internal frequency reference
(B22 option needed for this procedure)
Adjusting absolute amplitude accuracy
Frequency range: 4 MHz to 2.005 GHz
Amplitude range: -10 dBm to 10 dBm
Frequency accuracy: ±3.5 × 10-8
Power splitter Aeroflex/Weinschel 1593 Test system characterization
Verifying absolute amplitude accuracy
Adjusting absolute amplitude accuracy
VSWR: <1.25 at 4 MHz to 2 GHz
Amplitude tracking: <0.25 dB
Maximum Input Power: >10 dBm CW
6 dB attenuator Anritsu 41KB-6 or
Mini-Circuits BW-S6W2
Test system characterization
Verifying absolute amplitude accuracy
Adjusting absolute amplitude accuracy
Frequency range: DC to 2 GHz
VSWR: <1.2
50 ΩSMA
terminator (m)
—Test system characterization Frequency range: DC to 2 GHz
VSWR: 1.1

4|ni.com |NI PXIe-5624R Calibration Procedure
SMA (m)-to-SMA (m)
cable
—All procedures Frequency range: DC to 2 GHz
Impedance: 50 
Maximum length: 1 meter
SMA (f)-to-N (m)
adapter
Fairview Microwave
SM4226
All procedures Frequency range: DC to 2 GHz
Impedance: 50 
Return loss: 23 dB
SMA (m)-to-N (f)
adapter
Huber+Suhner
33_SMA_N-50-1/1-_UE or
Fairview Microwave
SM4241
Test system characterization
Verifying absolute amplitude accuracy
Adjusting absolute amplitude accuracy
Frequency range: DC to 2 GHz
Impedance: 50 
Return loss: 23 dB
SMA (f)-to-N (f)
adapter
Huber+Suhner
31_3-SMA-50-1/1-_UE or
Fairview Microwave
SM4236
Test system characterization Frequency range: DC to 2 GHz
Impedance: 50 
Return loss: ≥23 dB
3.5 mm
(m)-to-3.5 mm (m)
adapter
Huber+Suhner
32_PC35-50-0-2/199_NE or
Fairview Microwave
SM4960
Test system characterization
Verifying absolute amplitude accuracy
Adjusting absolute amplitude accuracy
Frequency range: DC to 2 GHz
Impedance: 50 
Return loss: 30 dB
3.5 mm (f)-to-
3.5 mm (f) adapter
Huber+Suhner
31_PC35-50-0-1/199_UE
Test system characterization Frequency range: DC to 2 GHz
Impedance: 50 
Return loss: 28 dB
Table 1. NI 5624R Required Equipment Specifications for NI 5624R Calibration (Continued)
Equipment Recommended Model Measured Specification Minimum Requirements

NI PXIe-5624R Calibration Procedure |© National Instruments |5
Test Conditions
The following setup and environmental conditions are required to ensure the NI 5624R meets
published specifications:
• Keep cabling as short as possible. Long cables act as antennas, picking up extra noise that
can affect measurements.
• Verify that all connections, including front panel connections and screws, are secure.
• Maintain an ambient temperature of 23 °C ±5 °C.
• Keep relative humidity between 10% and 90%, noncondensing.
• Allow a warm-up time of at least 20 minutes after the chassis is powered on, the
NI LabVIEW Instrument Design Libraries for IF Digitizers software is loaded by the host,
and the host recognizes the NI 5624R. The warm-up time ensures that the NI 5624R and
test instrumentation are at a stable operating temperature.
• Perform self-calibration on the NI 5624R.
• Plug the PXI Express chassis and the test equipment into the same power strip to avoid
ground loops.
• Use a torque wrench appropriate for the type of RF connector that you are using.
• In each verification procedure, insert a delay between configuring all devices and acquiring
the measurement. Adjust this delay depending on the instruments used but make sure it is
at least 5,000 ms for the first iteration and 10 ms for each other iteration.
• Ensure that the PXI Express chassis fan speed is set to HIGH, that the fan filters, if present,
are clean, and that the empty slots contain filler panels. For more information about cooling,
refer to the Maintain Forced-Air Cooling Note to Users document available at ni.com/
manuals.
Initial Setup
Refer to the NI PXIe-5624R Getting Started Guide for information about how to install the
software and hardware and how to configure the device in Measurement & Automation Explorer
(MAX).
Connect the SMA (f)-to-N (m) adapter to the RF OUT port of the signal generator.
Characterizing the Test System
You use the measured response of the test system during verification tests.
The power splitter and attenuation response is measured at the RF input frequencies used in the
verification and adjustment tests.
Caution The connectors on the device under test (DUT) and test equipment are
fragile. Perform the steps in these procedures with great care to prevent damaging any
DUTs or test equipment.

6|ni.com |NI PXIe-5624R Calibration Procedure
Zeroing the Power Sensor
1. Ensure that the power sensor is not connected to any signals.
2. Zero the power sensor using the built-in function, according to the power sensor
documentation.
Characterizing Power Splitter Balance
Zero the power sensor as described in the Zeroing the Power Sensor section prior to starting this
procedure.
This procedure characterizes the balance between the two output terminals of the splitter, where
the second terminal is connected to an attenuator. The power splitter balance is required for the
following procedures:
• Verifying Absolute Amplitude Accuracy
• Adjusting Absolute Amplitude Accuracy
The verification and adjustment procedures use test points from 5 MHz to 2.005 GHz in 5 MHz
steps for the splitter balance characterization. Frequencies in which harmonics alias on the
fundamental frequency are excluded from the adjustment procedure. Be careful when applying
splitter balance correction to measurements in the adjustment procedure. Ensure that you are
applying the splitter balance for the correct frequency.
1. Connect the RF OUT connector of the signal generator to the input port of the power splitter
using an SMA (m)-to-SMA (m) cable.
2. Connect the 50 (m) terminator to one of the power splitter output ports. Refer to this port
as splitter output 1.
3. Connect the other power splitter output to the SMA (f) connector of the 6 dB attenuator
using a 3.5 mm (m)-to-3.5 mm (m) adapter. Refer to the combined power splitter output and
6 dB attenuator as splitter output 2.

NI PXIe-5624R Calibration Procedure |© National Instruments |7
4. Connect the power sensor to splitter output 2 using the SMA (f)-to-N (f) adapter.
The following figure illustrates the hardware setup.
Figure 1. Connection Diagram for Measuring at Splitter Output 2
5. Configure the signal generator using the following settings:
• Frequency: 5 MHz
• Power level: 4 dBm
6. Configure the power sensor to correct for frequency using the power sensor frequency
correction function.
7. Use the power sensor to measure the power at the frequency from step 6.
8. Repeat steps 5 through 7, by updating the signal generator frequency from 5 MHz to
2.005 GHz in 5 MHz steps.
Record the resulting measurements as splitter output 2 power. Each frequency should have
a corresponding value.
9. Disconnect the power sensor and 50 terminator from the power splitter.
10. Connect the power sensor to splitter output 1 using an SMA (m)-to-N (f) adapter.
1 Signal Generator
2 SMA (m)-to-SMA (m) Cable
3 Power Sensor
4 SMA (f)-to-N (m) Adapter
5 6 dB Attenuator
6 3.5 mm (m) to 3.5 mm (m) Adapter
7 Power Splitter
850Terminator
1
2
87
6
5
4
3

8|ni.com |NI PXIe-5624R Calibration Procedure
11. Connect the 50 terminator to splitter output 2 using the 3.5 mm (f)-to-3.5 mm (f) adapter.
The following figure illustrates the hardware setup.
Figure 2. Connection Diagram for Measuring at Splitter Output 1
12. Configure the signal generator using the following settings:
• Frequency: 5 MHz
• Power level: 4 dBm
13. Configure the power sensor to correct for frequency using the power sensor frequency
correction function.
14. Use the power sensor to measure the power.
15. Repeat steps 12 through 14 by updating the signal generator frequency from 5 MHz to
2.005 GHz in 5 MHz steps.
Record the resulting measurements as splitter output 1 power. Each frequency should have
a corresponding value.
16. Calculate the splitter balance for each frequency point using the following equation:
splitter balance = splitter output 2 power - splitter output 1 power
17. Disconnect the 50 terminator and 3.5 mm (f)-to-3.5 mm (f) adapter from splitter
output 2. The resulting fixture is used in Verifying Absolute Amplitude Accuracy and
Adjusting Absolute Amplitude Accuracy.
1 Signal Generator
2 SMA (m)-to-SMA (m) Cable
3 50 Terminator
4 3.5 mm (f)-to-3.5 mm (f) Adapter
5 6 dB Attenuator
6 3.5 mm (m)-to-3.5 mm (m) Adapter
7 Power Splitter
8 SMA (f)-to-N (m) Adapter
9 Power Sensor
1
7893456
2

NI PXIe-5624R Calibration Procedure |© National Instruments |9
Self-Calibrating the NI 5624R
Allow a 20 minute warm-up time before you begin self-calibration.
Note The warm-up time begins after the PXI Express chassis is powered on and the
operating system completely loads.
The NI 5624R includes precise internal circuits and references used during self-calibration to
adjust for any errors caused by short-term fluctuations in the environment. It is important that
you perform a self-calibration function to validate the specifications listed in the next section.
You can perform the self-calibration through Measurement & Automation Explorer (MAX) or
programmatically using LabVIEW.
Self-Calibrating Using MAX
To initiate self-calibration in MAX, complete the following steps:
1. Disconnect or disable any AC inputs to the digitizer.
2. Launch MAX.
3. Expand My System»Devices and Interfaces»PXI System.
4. Select the device that you want to calibrate.
5. Initiate self-calibration using one of the following methods:
•ClickSelf-Calibrate in the upper right corner of MAX.
• Right-click the name of the device in the MAX configuration tree and select Self
Calibrate from the drop-down menu.
Self-calibration takes approximately 1 minute to complete.
Self-Calibrating Using LabVIEW
To initiate self-calibration using LabVIEW, complete the following steps:
1. Disconnect or disable any AC inputs to the digitizer.
2. Use the Self-Calibrate VI located at FPGA Interface»Software Designed Instruments»
IF Digitizer»Calibration to initiate self-calibration.
Self calibration takes approximately 1 minute to complete.
As-Found and As-Left Limits
The as-found limits are the published specifications for the NI 5624R. NI uses these limits to
determine whether the NI 5624R meets the device specifications when it is received for
calibration.
The as-left limits are equal to the published NI specifications for the NI 5624R, less guard bands
for the measurement uncertainty, temperature drift, and drift over time. NI uses these limits to
ensure that the NI 5624R meets the published specifications over its calibration interval.

10 |ni.com |NI PXIe-5624R Calibration Procedure
Verification
The performance verification procedures assume that adequate traceable uncertainties are
available for the calibration references.
Verifying Internal Frequency Reference
This procedure verifies the frequency accuracy of the NI 5624R onboard frequency reference
using a signal generator. Use digitizer mode of the NI 5624R. Use Interactive IF
Acquisition Without DSP (Host).vi in the Multirecord Acquisition sample project as
a starting point.
1. Connect the signal generator RF OUT front panel connector to the NI 5624R IF IN front
panel connector using an SMA (m)-to-SMA (m) cable.
The following figure illustrates the hardware setup.
Figure 3. Internal Frequency Reference Verification Cabling Diagram
1 NI 5624R 2 Signal Generator 3 SMA (m)-to-SMA (m) Cable
ACCESS ACTIVE
2
13

NI PXIe-5624R Calibration Procedure |© National Instruments |11
2. Configure the signal generator using the following settings:
• Frequency: 11 MHz
• Power level: 0 dBm
3. Configure the NI 5624R to acquire and measure the signal generated in step 2, using the
following settings:
• Digitizer mode
• Dither: Off
• Samples: 1 × 106
• Reference Clock source: Onboard
4. Measure the frequency of the peak acquired tone using Extract Single Tone
Information.vi.
5. Calculate the deviation using the following equation:
6. Compare the value determined in step 5 to the verification test limits in the following table.
where
initial accuracy = ±200 × 10–9
aging = × number of years since last adjustment
temperature stability = ±2 × 10–6
Note You can find number of years since last adjustment programmatically using
NI LabVIEW Instrument Design Libraries for IF Digitizers.
Table 2. Internal Frequency Reference Verification Limits
As-Found Limit initial accuracy + aging + temperature stability
As-Left Limit initial accuracy
f∆fmeasured 11MHz–
11MHz
-----------------------------------------------
=
0.5±x10 6–
year
-------------------------

12 |ni.com |NI PXIe-5624R Calibration Procedure
Verifying Absolute Amplitude Accuracy
This procedure verifies the absolute amplitude accuracy of the NI 5624R input channel.
Accuracy is specified using the calibration IP on the default 400 MHz acquisition FPGA image
provided in the Multirecord Acquisition sample project. The Interactive Spectrum
Acquisition (Host).vi provides a starting point for this procedure. The calibration IP
equalizes the frequency response and corrects for losses. Because a digital downconverter
(DDC) is used, multiple center frequencies are chosen in order to cover the entire specified
bandwidth. The response across 400 MHz of bandwidth for each center frequency is measured.
This procedure requires the test setup and data collected in the Characterizing Power Splitter
Balance section. Characterize the power splitter balance before running this procedure.
Zero the power sensor as described in the Zeroing the Power Sensor section prior to starting this
procedure.
1. Connect the signal generator RF OUT front panel connector to the input terminal of the
power splitter using an SMA (m)-to-SMA (m) cable.
2. Connect splitter output 1 directly to the power sensor input connector using the
SMA (m)-to-N(f) adapter.
3. Connect splitter output 2 to the SMA (f) end of the 6 dB attenuator using a
3.5 mm (m)-to-3.5 mm (m) adapter.
Note The power splitter configuration must match the configuration used in the
Characterizing Power Splitter Balance procedure.

NI PXIe-5624R Calibration Procedure |© National Instruments |13
4. Connect the 6 dB attenuator SMA (m) connector directly to the NI 5624R IF IN front panel
connector.
The following figure illustrates the complete hardware setup.
Figure 4. Absolute Amplitude Accuracy Verification Cabling Diagram
1 Power Sensor
2 SMA (m)-to-N (f) Adapter
3 Power Splitter
4 3.5 mm (m)-to-3.5 mm (m) Adapter
5 6 dB Attenuator
6 NI 5624R
7 SMA (m)-to-SMA (m) Cable
8 Signal Generator
ACCESS ACTIVE
4
5
7
3
2
1
6
8

14 |ni.com |NI PXIe-5624R Calibration Procedure
5. Configure the NI 5624R with the following settings:
• DDC mode
• Center frequency: The first frequency listed in the NI 5624R Center Frequency (MHz)
column in Table 3.
• I/Q rate: 500 MHz
• Dither: On (High)
6. Configure the signal generator with the following settings:
• Frequency: The first frequency listed in the Generator Start Frequency (MHz) column
in Table 3
• Power level: 4 dBm
7. Configure the power sensor to correct for the current frequency of the signal generator
using the power sensor frequency correction function.
8. Use the power sensor to measure the power. Record the result as measured input power.
Note Power sensor readings are in dBm, not watts.
9. Calculate the corrected input power using the following equation:
corrected input power = measured input power + splitter balance
Tip Find the splitter balance by using the appropriate data points from the
Characterizing Power Splitter Balance section.
10. Perform an acquisition and measure the tone present at the frequency generated by the
signal generator.
11. Calculate the absolute amplitude accuracy using the following equation:
absolute amplitude accuracy = NI 5624R input power – corrected input power
Table 3. Configured Center Frequencies
NI 5624R Center
Frequency (MHz)
Generator Start
Frequency (MHz)
Generator Stop
Frequency (MHz) Step Size (MHz)
225 25 425 5
500 300 700 5
800 600 995 5
1200 1005 1400 5
1500 1300 1700 5
1800 1600 1975 5

NI PXIe-5624R Calibration Procedure |© National Instruments |15
12. Repeat steps 6 through 11, increasing the generator frequency by the value in the Step Size
column, until you reach the value in the Generator Stop Frequency (MHz) column.
13. Repeat steps 5 through 12 for the remaining frequencies in the NI 5624R Center
Frequency (MHz) column in Table 3.
14. Compare the absolute amplitude accuracy values measured to the verification test limits in
the following table.
Updating Calibration Date and Time
This procedure updates the date and time of the last NI 5624R calibration in the NI 5624R flash
memory.
Successfully complete all required verifications or successfully complete reverification
following adjustment prior to updating the calibration date and time on the NI 5624R.
Complete the following steps to update the NI 5624R calibration date and time.
1. Call niIFDig Group A ExternalCal v1 Host.lvclass:Initialize
External Calibration.vi. The default password is NI.
2. Call niIFDig ExternalCal v1 Host.lvclass:Write Ext Cal Date.vi. Wire
in the current date and time.
3. Call niIFDig External Cal v1 Host.lvclass:Close External
Calibration.vi. Set the write calibration to hardware? input to TRUE to store the
results.
Table 4. Absolute Amplitude Accuracy Verification Limits
Frequency As-Found Limit (dB) As-Left Limit (dB)
25 MHz to 1 GHz ±0.25 ±0.10
1 GHz to 1.975 GHz ±0.30 ±0.15

16 |ni.com |NI PXIe-5624R Calibration Procedure
Adjustment
This section describes the steps needed to adjust the NI 5624R to meet published specifications.
Adjusting Internal Frequency Reference
This procedure adjusts the internal frequency reference.
1. Connect the signal generator RF OUT front panel connector to the NI 5624R IF IN front
panel connector using an SMA (m)-to-SMA (m) cable.
The following figure illustrates the hardware setup.
Figure 5. Internal Frequency Reference Adjustment Cabling Diagram
2. Configure the signal generator using the following settings.
• Frequency: 11 MHz
• Power level: 5 dBm
3. Call niIFDig Group A ExternalCal v1 Host.lvclass:Initialize
External Calibration.vi. The default password is NI.
1 NI 5624R 2 Signal Generator 3 SMA (m)-to-SMA (m) Cable
ACCESS ACTIVE
2
13

NI PXIe-5624R Calibration Procedure |© National Instruments |17
4. Call niIFDig ExternalCal v1 Host.lvclass:Clock FrequencyCal.vi. Wire
the frequency of the signal generator to the actual frequency (Hz) input.
5. Call niIFDig ExternalCal v1 Host.lvclass:Close External
Calibration.vi. Set the write calibration to hardware? input to TRUE to store the
results to the NI 5624R flash memory.
Adjusting Absolute Amplitude Accuracy
This procedure measures the response of the IF IN signal path of the NI 5624R.
This procedure requires the test setup and data collected in the Characterizing Power Splitter
Balance section. Characterize the power splitter balance before running this procedure.
Make sure to use the power splitter balance characterization data for the correct frequency, as
the following frequencies are excluded from the adjustment procedure due to harmonics aliasing
back on to the fundamental and disrupting the measurement:
• 200 MHz
• 250 MHz
• 400 MHz
• 500 MHz
• 600 MHz
• 750 MHz
• 800 MHz
• 1.2 GHz
• 1.5 GHz
• 1.6 GHz
Zero the power sensor as described in the Zeroing the Power Sensor section prior to starting this
procedure.
1. Connect the signal generator RF OUT front panel connector to the input terminal of the
power splitter using an SMA (m)-to-SMA (m) cable.
2. Connect splitter output 1 directly to the power sensor input connector using an
SMA (m)-to-N (f) adapter.
3. Connect the splitter output 2 to the SMA (f) end of the 6 dB attenuator using a
3.5 mm (m)-to-3.5 mm (m) adapter.
Note The power splitter configuration must match the configuration used in the
Characterizing Power Splitter Balance procedure.

18 |ni.com |NI PXIe-5624R Calibration Procedure
4. Connect the 6 dB attenuator SMA (m) connector directly to the NI 5624R IF IN front panel
connector.
The following figure illustrates the hardware setup.
Figure 6. Absolute Amplitude Accuracy Adjustment Cabling Diagram
5. Ensure that the NI 5624R and the signal generator share a common reference. The
following steps assume you have connected the signal generator reference frequency
REF OUT to the NI 5624R REF IN connector.
6. Call niIFDig Group A ExternalCal v1 Host.lvclass:Initialize
External Calibration.vi.
1 Power Sensor
2 SMA (m)-to-N (f) Adapter
3 Power Splitter
4 3.5 mm (m)-to-3.5 mm (m) Adapter
5 6 dB Attenuator
6 NI 5624R
7 SMA (m)-to-SMA (m) Cable
8 Signal Generator
ACCESS ACTIVE
4
5
7
3
2
1
6
8

NI PXIe-5624R Calibration Procedure |© National Instruments |19
7. Call niIFDig ExternalCal v1 Host.lvclass:Amplitude Cal
Initialize.vi. Wire External 10 MHz Reference Clock to the reference clock
source input.
8. Call niIFDig ExternalCal v1 Host.lvclass:Amplitude Cal
Configure.vi.
9. Configure the signal generator using the following settings:
• Frequency: value of the frequency to generate (Hz) output from niIFDig
External Cal v1 Host.lvclass:Amplitude Cal Configure.vi
• Power level: value of the power to generate (dBm) output from niIFDig
External Cal v1 Host.lvclass:Amplitude Cal Configure.vi plus
12 dB
• Reference Clock source: Internal
10. Configure the power sensor to correct for the frequency to generate (Hz) output from
niIFDig External Cal v1 Host.lvclass:Amplitude Cal Configure.vi
using the power sensor frequency correction function.
11. Measure the power of the signal present at splitter output 1 of the power splitter using the
power sensor. Record this value as the measured input power.
12. Calculate the corrected input power using the following equation:
corrected input power = measured input power + splitter balance
Tip Find the splitter balance by choosing the correct data point from the
Characterizing Power Splitter Balance section. Remember that certain frequencies
are not measured due to harmonics aliasing back on the fundamental.
13. Call niIFDig ExternalCal v1 Host.lvclass Amplitude Cal Adjust.vi.
Wire the corrected input power calculated in step 12 to the actual power (dBm) input.
Wire the frequency output from niIFDig External Cal v1 Host.lvclass:
Amplitude Cal Configure.vi to the actual frequency (Hz) input.
14. Repeat steps 8 through 13 until the amplitude calibration complete output of niIFDig
ExternalCal v1 Host.lvclass:Amplitude Cal Adjust.vi returns a value of
TRUE.
15. Call niIFDig ExternalCal v1 Host.lvclass:Close External
Calibration.vi. Set the write calibration to hardware? input to TRUE to store the
results to the NI 5624R flash memory.