NASA's Langley Research Center has developed a novel fine interpolation technique that is useful in signal processing for applications in lidar, sonar, radar, and similar modalities. The interpolation technique uses repeating waveforms, Fourier transform reordering, and Richardson-Lucy deconvolution to obtain faster and more accurate results. The prime target application is range finding, but the technique is equally suitable for differential absorption studies, such as determining CO 2 concentrations in the atmosphere.
Compared to standard methods such as fitting, which tend to be slow, this technology uses a simple technique of the reordering of an array used in the Fourier transform to obtain results much more rapidly and with greater accuracy. By applying certain nonlinear deconvolution techniques to single or multiple pulses, the pulses can be sharpened, allowing measurement of objects that are actually smaller than the resolution of the lidar. This is then enhanced further using Richardson-Lucy deconvolution. The resulting resolution and pulse width can be enhanced by about two orders of magnitude using these techniques, thus breaking the fundamental resolution limit for BPSK modulation of a particular bandwidth and bit rate.
This technique can be applied broadly with any repeating waveform, and not confined to PN code and PSK modulation. In addition, it allows use of continuous wave (CW) lasers rather than the costlier, bulky pulsed lasers. Potential applications include range finding, differential absorption studies, and cloud and tree canopy thicknesses determination.