We present an analysis for evaluating the probability density function (pdf) of the noise at the output of the frequency demodulator. It is shown that the noise is non-Gaussian and that for low to medium signal-to-noise power ratios, its pdf differs very significantly from the Gaussian pdf commonly assumed in simplified analysis. These results are very important for analyzing the performance of...

This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requi...

Signal Processing systems for communications will have to operate in rapidly changing environments. To suitably adapt to the varying requirements, control strategies targeted at selecting and tuning the signal processing algorithms need to be developed. The work being reported in this thesis is part of the bigger initiative by DARPA to develop and exploit reconfigurable computing for evolving d...

The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM) consists of cantilever thermal noise, tip-surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density d(z) at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density d(Δ...

In this project, an efficient all-digital demodulator in digital communication receivers is proposed and implemented on a reconfigurable hardware platform in order to compensate timing and carrier phase offset. In the proposed design, a feedforward architecture which has better stability and performance than traditional feedback architectures is used in the timing synchronization loop. To mitig...

Two reinforcement learning neural network architectures which enhance the performance of a soft-decision Viterbi decoder used for forward error-correction in a digital communication system have been investigated and compared. Each reinforcement learning neural network is designed to work as a co-processor to a demodulator dynamically adapting the soft quantization thresholds toward optimal sett...

Code-division multiple-access (CDMA) with direct-sequence/spread-spectrum (DS/SS) modulated signals has emerged as a strong candidate for the air interface of the universal wireless personal communication network planned for the end of the century. In this paper, we take into consideration a recently proposed low-complexity blind adaptive interference-mitigating detector (BAID) scheme that mini...

Orthogonal time frequency space (OTFS) modulation is a two-dimensional signaling technique that has recently emerged in the literature to tackle the time-varying (TV) wireless channels. OTFS deploys the Doppler-delay plane to multiplex the transmit data where the time variations of the TV channel are integrated over time and hence the equivalent channel relating the input and output of the syst...

Simulation results of a 863-870-MHz frequency-hopped spread-spectrum transceiver with binary frequency shift keying (BFSK) modulation at 20 kb/s for wireless sensor applications is presented. The various blocks parameters of the transmit/receive RF front end like noise figure (NF), gain, 1 dB compression point (P-1dB), and IIP3 are simulated and optimized to meet transceiver specifications. The...

Sigma-delta (Σ-Δ) modulation techniques have moved into mainstream applications in signal processing and have found many practical uses in areas such as high-resolution A/D, D/A conversions, voice communication, and software radio. Σ-Δ modulators produce a single, or few bits output resulting in hardware saving and thus making them suitable for implementation in very large scale integration (VL...