2024 Update: The latest versions of InstrumentView support Touchstone .s1p format, so you can skip step 4 below.

Introduction

When working with the FPC1500 in Vector Network Analyzer (VNA) mode, it can be handy to transfer the captured data into math programs and other PC software.

Fortunately, that's very easy to do; there is an in-built file system and data can be transferred across easily. I find using the supplied PC software, InstrumentView, to be very handy for this.

This very short blog post describes how the data can be converted into a Touchstone format file, which is very popular for working with all sorts of RF software applications.

There's not much to it, it merely requires a couple of dozen lines of code to re-format content. The code is available on GitHub

1. Save the Data

Once the VNA shows what you wish to capture, press the Save/Recall button on the keypad on the instrument, then hit the Save soft-key that will appear, and then scroll to the Public\Datasets folder and then click the Save soft-key again.

The file will be saved with a name such as Dataset001.set and this can be viewed using the free InstrumentView software as shown below.

2. Transfer the Data to the PC

Start up InstrumentView and select Instrument->File Transfer. Transfer across the Dataset00x.set file as shown in the screenshot.

Then, with the dataset selected on the right portion of the display, click on the 'eye' icon labeled View (see screenshot).

3. Export the Data in CSV Format

After clicking on the View icon in the previous step, you should now see the data displayed graphically.

Click on Save on the left side, as shown above. Save the file in CSV format, to any suitable location.

4. Convert to .s1p Touchstone Format

Copy or rename the file to input.csv and then run Python code as shown here:

python ./csv2sparam.py

It will show some output like this:

Start of dataset found
Completed 201 entries (2000000 - 3000000000 MHz)
output.s1p generated.
Bye.

The transformation is complete, and now the output file can be used with any suitable RF software.

Example: Viewing using Python scikit-rf

The output.s1p Touchstone file was generated in the last step.

To view it, install matplotlib and scikit-rf Python packages to your PC, and then you can type the following within the Python command line, or in a .py program:

import matplotlib.pyplot as plt
import skrf as rf
n=rf.Network('output.s1p')
n.plot_s_smith()
plt.show()

If all goes well, the following should be displayed:

Summary

With little effort, data captured from the FPC1500 VNA mode can be exported and transformed into a format compatible with a lot of software.

Example files are attached if anyone wishes to examine them, or play with them without access to a VNA.

I confirmed the file can be opened successfully with the following software:

• Python scikit-rf library
• Iowa Hills Smith Chart
• SPARGraph

It did not open in RFOffice, but I have sent them an e-mail to find out why.