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Sampling and reconstruction (S&R) are used in virtually all areas of science and technology. The classical sampling theorem is a theoretical foundation of S&R. However, for a long time, only sampling rates and ways of the sampled signals representation were derived from it. The fact that the design of S&R circuits (SCs and RCs) is based on a certain interpretation of the sampling theorem...
Short wave or high-frequency (HF) radios are currently used for international broadcasting, various types of communications, over-the-horizon radar, and some scientific experiments. In the future, they can also be employed for communications among unmanned and manned stations on other planets with ionospheres. The reception conditions in the HF range are determined mainly by the short wave propagation...
An effective approach to exploiting statistical differences between desired and jamming signals named adaptive robustness is proposed and analyzed in this paper. It combines conventional Bayesian, adaptive, and robust approaches that are complementary to each other. This combining strengthens the advantages and mitigates the drawbacks of the conventional approaches. Adaptive robustness is equally...
Digital image compression reduces the bandwidth, time, and energy needed for transmission of images and signals, as well as memory needed for their storage. However, it cannot solve the digitization problems. Recently proposed compressive sampling (or sensing) solves these problems by reducing the average number of projections required for representing images and signals through exploiting their sparsity...
In many applications, software defined receivers (SDRs) can be victims of intentional and/or unintentional jamming. Often, multiple jamming signals (JSs) at their antennas have significantly different power levels. In this paper, suppression of JSs is considered for the most challenging case when some of the JSs are strong enough to desensitize or even damage the input circuits of victim SDRs. Two-stage...
Novel energy-efficient modulation technique and circuits for transceivers operating in body sensor networks (BSNs) are described and investigated. They are obtained as a result of the development of differential binary phase shift keying (DBPSK) and named alternating quadratures DBPSK (AQ-DBPSK). While keeping the noise immunity and simplicity of synchronization and realization of DBPSK, AQ-DBPSK...
Switching among spaced antenna elements can be used for various purposes in software defined receivers (SDRs). Since this switching introduces delays between transmit and receive points, it produces locally-controlled virtual motion of the receiver and transmitter antennas relative to each other. This motion creates a direction- and velocity-dependent Doppler shift of the received signal relative...
Conventional sampling based on traditional interpretation of the sampling theorem has inherent problems. Most of them are related to the necessity to accumulate signal energy in the capacitors of track-and-hold amplifiers (THAs) during a small fraction of the sampling interval. This limits the dynamic range and attainable bandwidth of software defined receivers (SDRs) and makes digitization close...
Modern analog-to-digital converters (A/Ds) are composite structures that contain one or more internal A/Ds. The composite A/Ds carry out significant amount of mixed-signal processing in addition to the quantization performed by the internal A/Ds. Exploiting specific features of mixed-signal processing and/or specific properties of digitized signals enables improvement in performance of the composite...
Bandpass sampling, reconstruction, and antialiasing filtering in analog front ends potentially provide the best performance of software defined radios. However, conventional techniques used for these procedures limit reconfigurability and adaptivity of the radios, complicate integrated circuit implementation, and preclude achieving potential performance. Novel sampling and reconstruction techniques...
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