Andrew Harms

Learn More
—This paper presents a significant modification to the Random Demodulator (RD) of Tropp et al. for sub-Nyquist sampling of frequency-sparse signals. The modification, termed constrained random demodulator, involves replacing the random waveform, essential to the operation of the RD, with a constrained random waveform that has limits on its switching rate(More)
Technological constraints severely limit the rate at which analog-to-digital converters can reliably sample signals. Recently, Tropp et al. proposed an architecture, termed the random demodulator (RD), that attempts to overcome this obstacle for sparse bandlimited signals. One integral component of the RD architecture is a white noise-like, bipolar(More)
Linear, time-varying (LTV) systems are operators composed of time shifts, frequency shifts, and complex amplitude scalings that act on continuous finite-energy waveforms. This paper presents a novel, resource-efficient method for identifying the parametric description of such systems, i.e., the time shifts, frequency shifts, and scalings, from the sampled(More)
—In this paper, motivated by the setting of white-space detection [1], we present theoretical and empirical results for detection of the zero-support E of x ∈ C p (xi = 0 for i ∈ E) with reduced-dimension linear measurements. We propose two low-complexity algorithms based on one-step thresholding [2] for this purpose. The second algorithm is a variant of(More)
—This paper presents a novel, resource-efficient method of identifying the parametric description of linear, time-varying (LTV) systems, consisting of time shifts, frequency shifts, and complex amplitude scalings. Linear Frequency Modulation (LFM) waveforms are used to probe the system, and the returns are used to identify the parametric description. The(More)
—The sampling rate of analog-to-digital converters is severely limited by underlying technological constraints. Recently, Tropp et al. proposed a new architecture, called a random demodulator (RD), that attempts to circumvent this limitation by sampling sparse, bandlimited signals at a rate much lower than the Nyquist rate. An integral part of this(More)
—Efficient spectrum sensing is an important problem given the large and increasing demand for wireless spectrum and the need to protect incumbent users. We can more efficiently use large swaths of underutilized spectrum by designing spectrum sensors that can quickly, and power-efficiently, find and opportunistically communicate over unused (or(More)
—Linear, time-varying (LTV) systems are operators composed of time shifts, frequency shifts, and complex amplitude scalings that act on continuous finite-energy waveforms. This paper builds upon a novel, resource-efficient method previously proposed by the authors for identifying the parametric description of such systems from the sampled response to linear(More)