Example Code

Spectral Measurements on IQ Recorded Signal.

Products and Environment

This section reflects the products and operating system used to create the example.

To download NI software, including the products shown below, visit ni.com/downloads.

    Software

  • LabVIEW

Code and Documents

Attachment

Overview

Coding that exemplifies how to obtain Spectral Measurements out from a previously recorded IQ data.

 

Description

This example must use a previously saved binary files that contains IQ measurements. We might also insert a new binary file, or use it as a start point to modify the code in order to acquire IQ data from an Signal Analyzer device using the NI RFSA driver. The IQ recording was generated by using the RFSA Stream Binary IQ Data to Disk.vi VI found in the shipping examples of the RFSA drivers.


The example is created in order to obtain spectral measurements out from the IQ data. At the end, we expect to obtain:
1. Center Frequency
2. Occupied Bandwidth
3. Average Power
4. Peak Power

 

Requirements
1. LabVIEW 2012 (or compatible)
2. NI Spectral Measurements Toolkit

 

Steps to Implement or Execute Code
1. Open the "Insert Data Into Array-LV2012 NIVerified.vi"
2. Select the Run button.
3. Choose any options fro the User Control
4. Observe the Output Array indicator being updated

 

Additional Information or References

Capture.PNG

Best Regards,
Jignesh Patel
Principal RF Software Engineer

Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.

Comments
Kevin.Shirey
Member Member
Member
on

I've tried this example and several others like it for OBW -20 down and 99%, but the spectrum doesn't match any SpecAn or data captured from NI RFSA Spectrum mode. There are some key differences on how Spectrum is captured by repeating the same IQ packet 25x on an OOK (On-Off Keying) modulated signal from Spectrum mode vs 1 capture of 1 packet on IQ. I've tried appending the same packet 25x, or sub dividing the same packet into 25-X batches, same look and feel that the FFT to Power Spectrum will not behave the same. I've also tried using the RFmx Analysis model for OBW and same response. How can someone 'play back' an IQ in software to recreate the analog smoothing and FFT models that Spectrum offers? 

Kevin Shirey | CLA | Champion | Senior Project Engineer II | DMC