Other topics about Advanced Calibration
The E5071C has a calibration feature for power level output that uses the power meter (power calibration).
The power calibration function outputs a stimulus signal with a more accurate power level (closer to the set value) by measuring calibration data (power level) in advance with the power meter and sensor. Then this function performs error correction of the power level by using the calibration data.
Power calibration data are acquired for each channel/test port, and you can turn ON/OFF the power level error correction independently for any channel or test port.
The status of the power level error correction of each channel is indicated by one of the symbols shown in table below in the channel status bar in the lower part of the window.
|
Symbol |
Status of power level error correction |
|
PC (displayed in blue) |
Error correction is performed for all stimulus ports |
|
PC (displayed in gray) |
Error correction is performed for some stimulus ports |
|
PC? (displayed in blue) |
Error correction is performed for all stimulus ports; interpolated calibration data is used. If you turn on the error correction function when the stimulus setting is different from that when the power calibration data were acquired, power level error correction is performed with interpolated calibration data only when calibration data can be interpolated (extrapolation is not performed for calibration data). |
|
PC? (displayed in gray) |
Error correction is performed for some stimulus ports; interpolated calibration data is used. If you turn on the error correction function when the stimulus setting is different from that when the power calibration data were acquired, power level error correction is performed with interpolated calibration data only when calibration data can be interpolated (extrapolation is not performed for calibration data). |
|
--- (displayed in gray) |
Error correction is not performed |
|
None |
Error correction is not performed |
Power level error correction is automatically turned on when you execute the measurement of calibration data. You can turn it on or off as necessary by using the following procedure.
Press Cal key.
Click Power Calibration.
Select a port.
Click Correction. Each press toggles this selection between ON/OFF.
To execute power calibration, you need to prepare the power meter and power sensor used to acquire power calibration data.
Power calibration may not be executed when the specified frequency and level is out of range of the power sensor specification.
Power meter is controlled via USB/GPIB connector or USB (for USB enabled Power Meters)
The table below shows available power meters and recommended power sensors for power calibration.
|
Product Description |
Model Number |
Supported ENA Firmware Revision |
|
Power meters |
Keysight 437B, 438A, E4418A/B, E4419A/B, N1911A/N1912A |
All |
|
HP EPM-441A/442A, EPM-P E4416A/E4417A (w/ USB/GPIB interface) |
||
|
Keysight N1911A/N1912A (USB to USB direct connection) |
A.09.2x and above |
|
|
Keysight N1913A/N1914A EPM Series |
A.11.0x and above |
|
|
Power sensors |
Keysight 8482A, E4412A, N1921A |
All |
|
HP ECP-E18A |
||
|
Keysight N1922A, E4413A, E9300A, E9301A, E9304A, E9304A-H18/H20, E9300H, E9300H-H19, E9301H, E9300B, E9301B |
A.09.1x and above |
|
|
Keysight U2000A/B/H, U2001A/B/H, U2002A/H, U2004A |
A.09.2x and above |
When acquiring power calibration data, the power meter is controlled via GPIB or USB (for USB enabled Power Meters) from the E5071C.
To control the power meter through GPIB from the E5071C, connect the USB port of the E5071C and the GPIB/USB connector of the power meter through the USB/GPIB interface and set the GPIB address of the connected power meter with the E5071C.
The USB/GPIB interface and USB enabled power sensor must be ready to use. When you connect them for the first time, new hardware wizard runs. For the procedure, refer to Setting system controller (USB/GPIB interface). The hardware wizard procedure for USB enabled power sensor is same. At the last step in the procedure, Assign USB device alias dialog box will be displayed. Select "When a new USB device is plugged in" or "Never show this dialog" instead of "Each time a USB devices is plugged in", or ENA sometimes fail to recognize the USB power sensor.
For detailed information, refer to "Hardware Installation and Configuration", page 15 to 19 of USB Power sensor operation manual, U2000-90405 November 14, 2008 3rd edition.
Check whether the USB power sensor is properly installed by referring to "Hardware Installation and Configuration" of USB Power sensor operation manual, U2000-90405. If you face trouble while connecting the USB power sensor for the first time, or just after reconnecting, try to restart the ENA firmware and re-connect the USB power sensor again.
Use the following procedure to select the type of GPIB or USB enabled power meter:
Press System key.
Click Misc Setup > Power Meter Setup > Select type > GPIB|USB
From Firmware revision 9.2, E5071C supports USB enabled power sensors.
Use the following procedure to set the GPIB address of the power meter:
Press System key.
Click Misc Setup > GPIB Setup > Power Meter Address.
Enter the GPIB address of the power meter you are using.
You can also set the GPIB address of power meter by pressing System > Misc Setup > Power Meter Setup > GPIB Address
Before using the power sensor calibration factor table of the E5071C, set the calibration factor to 100% and then calibrate the power sensor.
When you use the 437B or 438A as the power meter, you need to set the power sensor calibration factor table with the E5071C.
If you use a power meter other than the 437B or 438A, refer to the following table.
|
Power sensor |
Setting of calibration factor table |
|
8482A |
Set the calibration factor table with the E5071C only when you do not set the calibration factor table with the power meter. If you set the calibration factor table with both the power meter and the E5071C, calibration is executed by both of them and you cannot obtain correct measurement results. |
|
E4412A ECP-E18A |
You do not need to set the calibration factor table with the E5071C. Even if you set the calibration factor table with the E5071C, this setting would be ignored. |
If you use the E4418A, E4419A, EPM-441A, or EPM-442A with Firmware revision Ax.02.00 or earlier and you set the calibration factor table with the E5071C, calibration is executed by both the power meter and the E5071C due to this Firmware revision, and thus you cannot obtain correct measurement results. Therefore, never set the calibration factor table under this condition with the E5071C.
Use the following procedure to set the power sensor's calibration factor table:
Press Cal key.
Click Power Calibration.
Click Sensor A Settings (for power sensor connected to channel A) or Sensor B Settings (for power sensor connected to channel B).
Click Ref Cal Factor.
Enter the reference calibration factor (the calibration factor at 50 MHz).
According to the calibration factor data attached to the power sensor, set the frequency (Frequency) and the coefficient (Factor) of the calibration factor table by using the hardkeys and softkeys.
Pressing Preset > OK does not affect the current setting of the reference calibration factor and the calibration factor table.
For a frequency other than one set in the table, a value obtained by linear interpolation of the calibration factors at the 2 points adjacent to the frequency is used. If a frequency is lower than the lowest frequency in the table, the calibration factor at the lowest frequency is used; if larger than the highest frequency in the table, the calibration factor at the highest frequency is used.
When setting the table by using the front panel keys or the keyboard, you need to first set the focus on (select) the operation target (table or softkey). You can change the focus by pressing Focus key in the ENTRY block. When the focus is placed on the table, the window frame of the table is displayed as bright as the window frame of the active channel. When the focus is placed on the softkey menu, the softkey menu title area is displayed in blue.
You can save the power sensor calibration factor table as a CSV (Comma Separated Value) format file.
Press Cal key.
Click Power Calibration.
Click Sensor A Settings or Sensor B Settings.
Click Export to CSV File to open the Save As dialog box. At this time, CSV File (extension *.csv) is selected as the file type.
Enter a file name in the File Name box and press the Save button to save the power sensor calibration factor table.
By recalling a power sensor calibration factor table saved in the CSV format according to saving power sensor calibration factor table, you can set the power sensor calibration factor table.
Press Cal key.
Click Power Calibration.
Click Sensor A Settings or Sensor B Settings.
Click Import from CSV File to open the Open dialog box. At this time, CSV File (extension*.csv) is selected as the file type.
Select the CSV format file you want to import and press the Open button to recall the power sensor calibration factor table.
This operation is not guaranteed under the following two conditions:
1) you imported a CSV format file created/edited on a spreadsheet program, or
2) you imported a CSV format file that had been exported according to Saving power sensor calibration factor table but then modified.
Use the following procedure to select the USB power meter:
Press System key.
Click Misc Setup > Power Meter Setup > USB.
Select desired USB power sensor.
When USB enabled power sensor is plugged to ENA, it will take about 30 seconds to be ready. If you perform calibration or zeroing before the ENA is ready, an error will occur.
Zeroing a power sensor is performed in order to reduce zero measurement offset and noise impact to improve the accuracy of RF power measurement. The U2000 Series USB power sensors have two types of zeroing INTernal zeroing and EXTernal zeroing. For more information, refer to http://literature.cdn.keysight.com/litweb/pdf/U2000-90405.pdf.
Use the following procedure to perform zeroing/calibration:
Press Cal key.
Click Power Calibration > Sensor A/B Settings > Zero Type > INT|EXT to select from internal or external zeroing.
Click Power Calibration > Sensor A/B Settings > Zero/Calibrate Sensor
For U2000 Series USB power sensors, Sensor B setting is disabled.
The power level error correction is executed for each channel/test port. You can set the following items for each channel/test port:
ON/OFF of error correction
Setting of loss compensation
Selection of the power sensor
Number of power level measurements at one measurement point
Calibration data
Follow the steps below to select the test port for which you want to set/execute power level error correction.
Press Cal key.
Click Power Calibration.
Press Channel Next/Channel Prev keys to select the channel.
Click Select Port.
Click the softkey corresponding to the test port you want to select.
If you need to apply a signal with a more accurate power level to the DUT, you can use the loss compensation feature to obtain calibration data for correcting the difference in power loss due to the difference in connection method (cable, adapter, etc.) between the time when the power calibration data are measured and when the actual DUT is measured.
The loss compensation feature corrects the power measurement result based on the preset power loss data. More specifically, if you turn on the loss compensation, the measurement result of the power level obtained in the power calibration data measurement is a value obtained by adding the loss value set in the loss compensation table to the measured power value.
Follow the steps below to turn ON/OFF the loss compensation.
Press Cal key.
Click Power Calibration.
Select a port (refer to Selecting target port of error correction).
Click Loss Compen > Compensation. Each press toggles the selection between ON/OFF.
Follow the steps below to set the loss compensation table.
Press Cal key.
Click Power Calibration.
Select a port (refer to Selecting target port of error correction).
Click Loss Compen
Set the frequency (Frequency) and the loss (Loss) of the loss compensation table by using the hardkeys and softkeys.
Pressing Preset > OK does not affect the current setting of the reference calibration factor and the calibration factor table.
For a frequency other than one set in the table, a value obtained by linear interpolation of the calibration factors at the 2 points adjacent to the frequency is used. If a frequency is lower than the lowest frequency in the table, the calibration factor at the lowest frequency is used; if larger than the highest frequency in the table, the calibration factor at the highest frequency is used.
When setting the table by using the front panel keys or the keyboard, you need to first set the focus on (select) the operation target (table or softkey). You can change the focus by pressing Focus key in the ENTRY block. When the focus is placed on the table, the window frame of the table is displayed as bright as the window frame of the active channel. When the focus is placed on the softkey menu, the softkey menu title area is displayed in blue.
You can save the loss compensation table as a CSV (Comma Separated Value) format file.
Press Cal key.
Click Power Calibration.
Select a port (refer to Selecting target port of error correction).
Click Loss Compen.
Click Export to CSV File to open the Save As dialog box. At this time, CSV File (extension*.csv) is selected as the file type.
Enter a file name in the File Name box and press the Save button to save the loss compensation table.
By recalling a loss compensation table saved in the CSV format according to the Saving loss compensation table, you can set this loss compensation table.
It is possible to recall a file from a different channel/port from where it was saved.
Press Cal key.
Click Power Calibration.
Select a port (refer to Selecting target port of error correction).
Click Loss Compen.
Click Import from CSV File to open the Open dialog box. At this time, CSV File (extension*.csv) is selected as the file type.
Select the CSV format file you want to import and press the Open button to recall the loss compensation table.
This operation is not guaranteed under the following two conditions: 1) you imported a CSV format file created/edited on a spreadsheet program, or 2) you imported a CSV format file that had been exported according to Saving loss compensation table but then modified.
The tolerance value sets the target power tolerance for the power calibration. Follow the steps below to set the tolerance for power calibration:
Press Cal key.
Click Power Calibration > Tolerance.
Enter the tolerance value for power calibration.
When you want to make a power calibration with higher accuracy, use the Iteration function. This function repeats the cycle of updating the power calibration coefficient and measuring the power level until the Max Iteration number at each stimulus point is reached.
On the other hand, Num of Readings just repeats the power measurement and averages the measurement results without updating the power calibration coefficient. This capability should be used only when the measurement of the power sensor is unstable due to some circumstances.
When the max iteration is set to 0, no iteration is performed. The output power level is measured and the power calibration coefficient is set by comparing the targeted power level and the actually measured power level at each stimulus point. If the measured power level is out of the tolerance, the power calibration process is aborted with an error message.
When the max iteration is 1 and above, the power measurement is re-performed after the initial power measurement and updating the power calibration coefficient. And if the measured power level is within the tolerance, the analyzer goes to the next stimulus point to be calibrated. If the measured power level is out of the tolerance, the analyzer repeats the cycle of updating the calibration coefficient and measuring the power level until the max iteration number. If the power measurement value is out of the tolerance even after the max iteration, the power calibration process is aborted with an error message.
Max Iteration is independent of measurement type. It corrects the E5071C source regardless of which receivers are being used in a measurement. Therefore, it can be used with both ratio or non-ratio measurements.
Applies only to those measurements on the selected channel that use the test port specified as the source for the calibration. For example, if you specify Channel 1 and Port 1 as the source to be calibrated, only those measurements on channel 1 that use port 1 as the source will be corrected.
Can be used in conjunction with other measurement calibrations, such as a full 2-port calibration. For highest accuracy, perform the measurement calibration after the source calibration.
Can be used with Power Sweep type. Source Power Cal corrects the power at all power levels across the power sweep.
Can also be used with Port Power Uncoupled.
To set the maximum iteration, follow the steps below:
Press Cal > Power Calibration > Maximum Iteration, then set the maximum iteration value.
Before measuring calibration data, you need to execute the zero adjustment and calibration of the power sensor. For information on how to execute these operations, see the manual of the power meter you are using.
When using the power sensor calibration factor table of the E5071C, set the calibration factor to 100% and execute the calibration of the power sensor.
Press Cal key.
Click Power Calibration.
Select a port (refer to Selecting target port of error correction).
Click Use Sensor. Each press toggles between channel A and channel B. If you use a power meter with one channel, channel A is always selected.
Click Tolerance and enter the tolerance value (for example, 0.1 dB).
Click Max Iteration and enter the max iteration number (for example, 5).
Connect the power sensor for the selected channel to the selected port.
Click Take Cal Sweep to start the measurement of calibration data.
You can abort the measurement by pressing Abort during measurement.
When the measurement is complete, the power level error correction is automatically turned on.
If the power meter GPIB address is not set correctly or if the power sensor is not connected to the specified channel, an error occurs and calibration data are not measured.
If appropriate calibration data cannot be obtained, an error may occur for each sweep after the measurement of calibration data is complete. In this event, turn off the power level error correction, check the connection and setting, and then measure the calibration data again.