Waveform digitizer based lock in amplifier using GPU digital signal processing

Alexandre Castonguay; Romain Deterre; Muneeb Khalid

doi:10.1117/12.2508012

1 March 2019 Waveform digitizer based lock in amplifier using GPU digital signal processing

Alexandre Castonguay, Romain Deterre, Muneeb Khalid

Proceedings Volume 10937, Optical Data Science II; 109370C (2019) https://doi.org/10.1117/12.2508012
Event: SPIE OPTO, 2019, San Francisco, California, United States

Abstract

Lock-in amplification is a technique used in many applications such as non-linear optics, spectroscopy and biomedical imaging. It is used to recover weak signals from noisy environments using a known carrier wave. Historically, this has been achieved using dedicated instruments, which suffer from slow connections to computer for further analysis. Here we present a technique that uses a PCIe waveform digitizer to stream data to a graphics processing unit, where digital lock-in amplification occurs. Briefly, the input signal is multiplied by an in-phase and quadrature reference before undergoing low-pass filtering with a sinc filter. The DC components of the in-phase and quadrature signals are then used to give the magnitude and phase of the signal. The bottleneck in this digital implementation is low-pass filtering due to the long filter length required to efficiently remove higher frequencies. To achieve the highest data throughput, convolution of the input signal with the low-pass filter was implemented in both time domain and frequency domain. Furthermore, decimation of the filtered data can further reduce processing time. Preliminary results show that the implemented digital lock-in amplification can sustain a continuous sampling rate of 3 billion samples per second. Using a 12 bit resolution analog to digital converter with an 800 mV input range, signals under 3 μV are reliably detectable. This GPU-based lock-in amplification implementation provides an ideal and low-cost solution for continuous and gapless signals acquisition.

Conference Presentation

Citation Download Citation

Alexandre Castonguay, Romain Deterre, and Muneeb Khalid "Waveform digitizer based lock in amplifier using GPU digital signal processing", Proc. SPIE 10937, Optical Data Science II, 109370C (1 March 2019); https://doi.org/10.1117/12.2508012

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