Gabriel Francisco has been working on low frequency spectrum analyzer. It was meant to analyze accelerometer data gathered from automotive suspension system to measure comfort of the ride. But this analyzer can be used for any low frequency signals. Basically this measuring system consists of Graphical User Interface (GUI), data acquisition hardware based on LM4F120 TI’s ARM Cortex-M4 and data source – accelerometer.
Logic analyzer support 8 channels with 512Hz sampling frequency. Data is passed through software FIR low pass filter with 75Hz cuttoff frequency. Then it calculates 256 points FFT, Power Density Spectrum. Graphical interface has several handy controls and signal ploting. Gabriel have made additional custom board for better connectivity and also designed whole custom PCB which seems hasn’t been built yet.