Updating Cal Coefficients for Keysight Power Sensors (Pmeter77GHz)

This document describes how to modify the Pmeter77GHz instrument's calibration data that contains Sensor calibration coefficients (ri.sys.ObjCalss = RiInstrumentCal). This procedure can also create a new calibration object by starting with an existing one. The procedure to modify or create new is the same until the last "save" steps.

Background:
Keysight power sensor cal factors might be provided in one of two ways, as a label on the power sensor, or as coefficients inside the sensor. When using a power meter, the Cassini application must know these coefficients.

The Cassini application treats Keysight power meters/sensors differently than the Spanawave (Gigatronics) sensors. When using a Spanawave power meter, we simply tell the power meter the frequency and it automatically loads the correct coefficient, the software does not need to know the coefficients. When using Keysight sensors, where the coefficient is just a label, that's obviously impossible. Or when using Keysight sensors where the coefficient is stored in the sensor, the power meter is too slow when responding to the frequency change, so we treat those sensors the same way, storing the coefficients in the instrument calibration data.

To Modify or Create Calibration Coefficients:

Launch the latest "Dev" Cassini ShortCut to use the latest released calibration software and hardware drivers.
Open the Configuration window by choosing System > Tester buttons from the Cassini application.
Activate the Pmeter77GHz instrument as follows:

If using a tester with a power meter attached via GPIB Instrument Pod:

Make sure that the power meter is ON and connected through a GPIB Instrument Pod to the tester. If not, connect it, then choose System > Check from the Cassini application window.
If the power meter doesn't automatically appear active in the Configuration window, add it manually by choosing System > Tester to open the Configuration window, then choose Instrument > Add GPIB Inst... Select HP437B with a left mouse click and choose the Select button. Enter "Pmeter77GHz" (case sensitive) as the Instrument Name value and enter "20" as the GPIB Address value.
Note: RI defaults to always using GPIB address 20 for Keysight power meters. If your meter is set to a different GPIB address, enter the address for your meter, ensuring that it doesn't conflict with any other instruments on the GPIB bus.
Choose System > Check from the Cassini application and confirm that Pmeter77GHz appears in the Configuration window with "no sensor" label appearing to the right of the instrument name.

If using a Cassini Virtual Workstation ("simulator"):

From the configuration window, choose Instrument > Add GPIB Inst... Select HP437B with a left mouse click and choose the Select button. Enter "Pmeter77GHz" (case sensitive) as the Instrument Name value and enter "20" as the GPIB Address value.
Note: a valid GPIB address is not strictly necessary on a simulator, but this keeps things consistent, and avoids issues with other GPIB instruments when compiling.

Load Sensor Calibration, that includes its unique calibration coefficients, by left clicking on the Pmeter77GHz instrument and choose Instrument > Calibration > Import menu from the right mouse button menu. Choose Yes for the confirmation prompt and then select the sensor that you want to modify by left clicking on the list and choose Select; If you're creating cal data for a new sensor, find one that is the same type. (See Figure 1)
The configuration panel should now show the HP437B including a sensor definition. (See Figure 2)
Until now, what we have done is simply load a power meter/sensor, necessary even if we only wanted to just use the power meter. Now we will begin to change the cal coefficients.
Make sure the Pmeter77GHz instrument is highlighted and choose Instrument > Calibration > Inspect. (see Figure 3)
This loads an Inspecting Cal Table window. The cal factor shown is the sensor. It's possible to have coefficients for multiple sensors in one Guru object, but typically there will be only one. (See Figure 4)
Double-click on this to open the coefficients list.
Highlight the first entry and note that the right side of the panel shows a frequency and a power. To change frequency or power, click on the appropriate number. It will open a panel that allows you to enter a new value. If you've chosen the same type of sensor definition as your sensor, then the frequencies will be the same, and you only will have to change the powers. (See Figure 5)

Note that:

The frequencies are always entered in MHz. You might have to convert the provided values to MHz.
The power is always entered as a linear power. It's possible to accidentally change that to log, so make sure the middle button says 'lin' as shown.
The first entry is usually 50 MHz, regardless of the sensor's frequency range. This is for the power meter's zero/cal function.
Use the RiData menu to add or delete entries, as needed.
Repeat this with all the entries.

Once you've entered all of the factors, close all the 'Inspecting' windows and select Pmeter77GHz instrument and choose Instrument > Calibration > Save. (See Figure 6)
This will prompt asking for the name of the Power meter cal set that you want to save as. If you are updating an existing Cal Sensor data, use the same name. If you are creating a new Cal Sensor data, use a different name.
Use a name that clearly identifies the coefficients to the sensor. Underscores (_) and dashes (-) are acceptable. Avoid all other punctuation symbols.
(Naming convention is to match the physical labels on the device with the last valid cal date in YYYY-MM-DD notation)
Follow the steps below to update the internal cal factor name in the RiInstrumentCal object, if creating a new Sensor cal data. Skip these steps if updating the coefficients of an existing Power Sensor.

Choose System > Test Objects to open the Test Objects browser, or if using "RoosInst" login, open Cassini application Guru Browser window by choosing Program > Browse Guru menu. (See Figure 8)
From the Test Objects browser, choose Object Types from the right mouse button menu in the top left column or from the Cassini Guru Browser window, select Keys > Key1=Class.
Scroll down and select RiInstrumentCal in the left column.
Identify the Sensor Cal in the top right column and choose Edit Latest from the right mouse button menu. (See Figure 9)
If the Guru object is not in the list, then put the cursor over the right panel and choose Show All from the right mouse button menu to display all filtered objects.
You are now editing a Guru object directly. Every character has a meaning, including commas, etc.
IMPORTANT: Be very careful not to change anything other than precisely instructed below. If you accidentally change something, close without saving and re-open.
Note that the name of the cal factor is still the old name. Change it to the new name. Don't change anything else. (See Figures 10 and 11)
Choose Save-Find > Save menu action.
Close the editor window and close the Cassini Guru browser window.

Confirm data has been saved by choosing the Pmeter77GHz instrument from the Configuration window and, as before, select Instrument > Calibration > Import, confirm with Yes and then find the sensor modified above and choose Select. With the Pmeter77GHz instrument highlighted, choose Instrument > Calibration > Inspect and confirm that the cal factor is named correctly. Double-click on the cal factor, select a couple of values and confirm that the factors match your sensor.