文摘
We design a sublinear Fourier sampling algorithm for a case of sparse off-grid frequency recovery. These are signals with the form \(f(t) = \sum _{j=1}^k a_j \mathrm{e}^{i\omega _j t} + \int \nu (\omega )\mathrm{e}^{i\omega t}d\mu (\omega )\); i.e., exponential polynomials with a noise term. The frequencies \(\{\omega _j\}\) satisfy \(\omega _j\in [\eta ,2\pi -\eta ]\) and \(\min _{i\ne j} |\omega _i-\omega _j|\ge \eta \) for some \(\eta > 0\). We design a sublinear time randomized algorithm which, for any \(\epsilon \in (0,\eta /k]\), which takes \(O(k\log k\log (1/\epsilon )(\log k+\log (\Vert a\Vert _1/\Vert \nu \Vert _1))\) samples of \(f(t)\) and runs in time proportional to number of samples, recovering \(\omega _j'\approx \omega _j\) and \(a_j'\approx a_j\) such that, with probability \(\varOmega (1)\), the approximation error satisfies \(|\omega _j'-\omega _j|\le \epsilon \) and \(|a_j-a_j'|\le \Vert \nu \Vert _1/k\) for all \(j\) with \(|a_j|\ge \Vert \nu \Vert _1/k\). We apply our model and algorithm to bearing estimation or source localization and discuss their implications for receiver array processing. Keywords Sparse signal recovery Fourier sampling Sublinear algorithms