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The baseband and intermediate frequency (IF) frequency modulated continuous wave (FMCW) radar receiver topologies are compared on the bases of receiver nonlinearity, time domain interferometry, receiver noise and demodulator port isolation. It is shown that an IF receiver is capable of suppressing distortions, where the same nonlinearity would result in a baseband (or zero-IF) receiver detecting false...
This paper addresses several issues which are novel in respect of the rapidly-evolving state of the art of low-terahertz radars: firstly, the sensitivity available from currently-available radars, secondly the likely effects of source noise and thirdly the effects of the fact that even relatively small targets, like people, occupy more than one resolution cell, as a consequence of the high resolutions...
The paper deals with research of energy characteristics of multilevel modulation techniques for modern broadband radio systems. The problems of modeling and analysis of digital data transmission channel are considered
Work presented in this paper investigates the feasibility of Continuous-Phase Quaternary Frequency Shift Keying (CP-QFSK) with limiter-discriminator detection modem as a viable dual data rate system that can be employed in TDMA short range communications systems. It offers a great deal of spectral efficiency in multi-channel systems, hardware simplicity and robustness to adjacent Channel Interference...
Phasor measurement unit (PMU) performance depends on the performance of the PMU’s analog input section and the limitations of its DSP algorithms. For the different PMU performance requirements established in the standards, the relative importance of these two factors varies significantly. For steady-state frequency and rate-of-change-of-frequency (ROCOF) measurements, this paper shows that estimation...
We achieve absorption sensitivity of 6.4 × 10−11 cm−1 Hz−1/2 per spectral element with near-infrared Fourier-transform-based noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), which allows detection of CO2 at ppb concentration levels.
An octave-spanning frequency comb is generated using electro-optic modulation of a 1550 nm laser and nonlinear broadening. With this comb we demonstrate offset frequency detection, precise metrology, and ultrastable synthesis of 10 GHz microwaves.
A bandpass delta-sigma modulator with a widely tunable center frequency range for direct digitization of IF or RF signals can be a key building block for highly digitized radio receivers. The performance of the bandpass modulator is highly dependent on the accuracy of the noise transfer function zero locations in the presence of process spread. An automatic calibration method is proposed to calibrate...
This paper presents the theoretical analysis and experimental results of frequency modulation (FM) due to the electromagnetic interference (EMI) to the voltage-controlled oscillators (VCO). Physical models of the oscillator core and injected signals are implemented to precisely predict the EMI. A low frequency continuous wave is injected into a 900 MHz monolithic LC-VCO, which is implemented on a...
Condition Based Maintenance is a field where a lot of studies have been developed in order to improve performance when intended to assure quality of maintenance of an equipment. This is as much important as bigger is the impact of possible injuries for people, or concerning high economic losses, due to malfunctions, failures and/or faults. Predictive maintenance or condition-based maintenance focuses...
This article consists of a collection of slides from the author's conference presentation. Some of the specific areas/topics discussed include: Introduction and basic concepts; Parametric Processes; Historical Prospective; Key requirements; One mode phase sensitive operation; Low-noise amplification; Phase regeneration/Electric field decomposition; Two-mode phase sensitive operation; Phase regeneration/quantization;...
When periodic halftoned documents (e.g., books, newspapers, and magazines) are scanned for image reproduction, moiré patterns occur. In order to avoid these moiré artifacts, it is necessary to detect the periodic halftone. This paper provides a fast Fourier transform based method to classify periodic halftoned documents. Experimental results show that the overall accuracy of this method is 97% on...
In this paper, fractional spur suppression techniques for all-digital PLLs (ADPLLs) are summarized. The attention is paid to the recently proposed digital-to-time converter (DTC)-based ADPLL architecture. DTC's nonlinearity dominates the fractional spurs contribution. Its influence is modeled with a pseudo phase-domain ADPLL and its relationship with the spur level is quantitatively described. An...
This paper describes an effective way of relaxing the nonlinearity problem of the digitally-controlled oscillator (DCO) in the two-point modulator design. A separate coarse varactor array dedicated for the high-pass modulation significantly simplifies the nonlinearity calibration of the DCO with a few-bit control. In addition, a finite-impulse response (FIR) filter is designed for the multi-bit high-pass...
With the wide application of power converters, the electromagnetic interference (EMI) problem of power converters has drawn more and more attention. EMI is caused by high dv/dt and di/dt during the rapid turn-on and turn-off of switching devices, which is harmful to power grids as well as power converters themselves. In order to suppress high EMI peaks which discretely distribute in switching frequency...
This paper proposes a simple and effective criterion based on the switching rate of the output bit-stream of a delta-sigma modulator to estimate the performance and stability of the modulator. The switching rate and its relation to the NTF design are analyzed for both single and multi-bit delta-sigma modulators as well as lowpass and bandpass modulators. A calibration method is proposed using the...
This paper presents the design and development of a low-power interface circuit for piezoresistive transducers. This circuit combines the chopping technique with the correlated double sampling (CDS) technique in order to eliminate both the amplifier offset and the chopper ripple at the sampling frequency. In addition, programmable current sources compensate for the transducer offset and the low frequency...
This paper details the architecture for a minimal commensal radar system which makes use of commercial FM broadcast band transmitters for the detection of aircraft. The architecture, consisting of a RF front-end, digital acquisition and radar signal processing up to the detection stage (after CFAR on a Range-Doppler plot), is intended to be small, easily portable, low power, and yet able to operate...
In this paper, two approaches to mitigating the impact of DAC mismatch on the performance of continuous-time Delta-Sigma modulators are presented. The first approach equals an optimized analog calibration which provides better robustness to disturbances of the calibration signal. The second approach, a new dynamic element matching technique labeled clock frequency modulation, modulates mismatch dependent...
The localization of an acoustic source in the oceanic waveguide is a difficult task because the oceanic environment is often poorly known. Uncertainty in the environment results in uncertainty in the source position and poor localization results. Hence, localization methods dealing with environmental uncertainty are required. In this paper, a Bayesian approach to source localization is introduced...
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