Implementing Real-time FFT in FTI Hardware to Help Optimize PCM Bandwidth
Flight test engineers can lower the time required to complete a flight test campaign if they have the data available to maximize the number of flight test points completed per flight. However, the limited bandwidth available for pulse code modulation (PCM) data transmission means choices must be made between what data can be transmitted and what must wait until post-test analysis using data from onboard storage.
One strategy that could help is to perform some data analysis in real-time on the platform and transmit the results rather than the more bandwidth-intensive raw data. This can be especially beneficial for high sample rate accelerometer data, where a tenfold reduction in bandwidth is achievable by sending only the desired results. Thus, the PCM bandwidth usage can be optimized, allowing more data to be telemetered, ultimately saving time and reducing the overall cost of a flight test campaign.
This white paper discusses an approach where data acquisition units (DAU) conduct the fast Fourier transform (FFT) analysis in real-time, some of the challenges of doing this, and highlights the potential benefits with a worked example.