Abstract: A method for estimating and tracking locally oscillating signals. The method comprises the steps of taking measurements of an input signal that approximately preserve the inner products among signals in a class of signals of interest and computing an estimate of parameters of the input signal from its inner products with other signals. The step of taking measurements may be linear and approximately preserve inner products, or may be non-linear and approximately preserves inner products. Further, the step of taking measurements is nonadaptive and may comprise compressive sensing. In turn, the compressive sensing may comprise projection using one of a random matrix, a pseudorandom matrix, a sparse matrix and a code matrix. The step of tracking said signal of interest with a phase-locked loop may comprise, for example, operating on compressively sampled data or by operating on compressively sampled frequency modulated data, tracking phase and frequency.

Abstract: We have developed a new method and apparatus for tracking and estimating parameters of locally oscillating signals from measurements that approximately preserve the inner product among signals in a class of signals of interest. Random demodulation, random sampling, and coset sampling are three prime examples of these techniques. One example of this is a compressive phase locked loops (PLL), which has a wide variety of applications, including but not limited to communications, phase tracking, robust control, sensing, and frequency modulation (FM) demodulation. The design modifies classical PLL designs to operate with CS-based sampling systems. By introducing a compressive sampler at the output of the oscillator and by appropriately adjusting the phase difference estimator we enable the use of PLLs with modern CS sampling technology. Other modifications can be made to reduce concerns such as normalization of the measurements, for example using the QCS-PLL.