Dominique Dallet

Accuracy of Sine Wave Frequency Estimation by Multipoint Interpolated DFT Approach

This paper focuses on the frequency-domain estimation of the normalized frequency of a sine wave corrupted by a stationary white noise. The weighted multipoint interpolated discrete Fourier transform method is considered, and its effect on both the spectral interference due to the image component and the additive wideband noise is taken into account. In particular, the expression of the combined standard uncertainty of the estimator is derived in the case when the H-term maximum sidelobe decay window (H ≥ 2) is used, and the number of interpolation points is 2J + 1 (J ≥ 1). Based on this expression, the number of interpolation points that minimize the estimator-combined uncertainty can be determined. The derived results are validated by means of computer simulations and applied to experimental data.

Detection and location of defects in electronic devices by means of scanning ultrasonic microscopy and the wavelet transform

In a highly competitive market, reliable techniques for manufacturing quality control of electronic devices are more and more demanded. In particular, scanning ultrasonic microscopy is nowadays showing itself a suitable, non-destructive tool for detecting and locating defects in a die-attach assembly of a wide range of components. Due to multiple reflections and scattering of the ultrasonic beam in multilayer die-attach assemblies, ultrasonic images can often appear very confused to be correctly interpreted, and the nature of defects very difficult to be pointed out. In the paper, the use of a digital signal-processing method, based on the Continuous Wavelet Transform, is suggested for automatically detecting and measuring the time-of-flight between ultrasonic echoes thus improving ultrasonic image understanding of complex structures. Methods performance is verified by means of numerical tests on several ultrasonic signals simulating different operating conditions; its reliability and efficacy come out from experiments on the die-attach assembly of actual electronic devices.

A Disruptive Receiver Architecture Dedicated to Software-Defined Radio

The next generation of mobile terminals is faced with the emergence of the software-defined radio (SDR) concept. The communication devices tend to provide various wireless services through a multi-functional, multi-mode and multi-standard terminal. The SDR concept aims at designing a re-configurable radio architecture accepting all cellular or noncellular standards working in the 0-5-GHz frequency range. Some technical challenges have to be solved in order to address this concept. Working in the digital domain may be a solution but the analog-to-digital conversion cannot be done at Radio Frequencies, at an acceptable resolution and at an acceptable level of power consumption. The idea proposed here was to interface an analog pre-processing circuit between the antenna and a digital signal processor to pre-condition the RF signal. It uses the principle of a fast Fourier transform to carry out basic functions with high accuracy in a low-cost technology like CMOS. This paper presents the design and the behavioral simulations of this analog discrete-time device which gives the hardware flexibility required for a cognitive radio component.

The Experimental Demonstration of a SASP-Based Full Software Radio Receiver

Many technological bottlenecks prevent from realizing a software radio (SR) mobile terminal. The old way of building radio architectures is now over because a single handled terminal has to address various communication standards. This paper exposes a SR receiver: a sampled analog signal processor (SASP) is designed to perform downconversion and channel presorting. The idea is to process analog voltage samples in order to recover in baseband any RF signal emitted from 0 to 5 GHz. An analog fast Fourier transform achieves both frequency shifting and filtering. An experimental demonstrator of the SASP using 65 nm CMOS technology from STMicroelectronics is here presented and measured. It validates the concept of a new SR receiver with the design of a demonstrator which runs at 1.2 GHz consuming 389 mW.

Accurate Amplitude Estimation of Harmonic Components of Incoherently Sampled Signals in the Frequency Domain

This paper focuses on estimating the amplitude of harmonic components of a harmonically distorted sine wave by the interpolated discrete Fourier transform (IpDFT) method with maximum sidelobe decay windows. The expression of the maximum of the interference error caused by the fundamental sine-wave component on the amplitude estimation of harmonic components is derived. In addition, for a signal corrupted by stationary white noise, the statistical efficiency of the IpDFT method is investigated with respect to the single-tone unbiased Crame¿r-Rao lower bound (CRLB). Based on the derived expressions, a constraint is derived ensuring that interference from the fundamental component could practically be neglected. Finally, the performance of the IpDFT method is compared with that of the energy-based method on the basis of theoretical, simulation, and experimental results and with that of a state-of-the-art method according to simulation and experimental results.

A Disruptive Software-Defined Radio Receiver Architecture Based on Sampled Analog Signal Processing

Software defined radio (SDR) aims at bringing digital treatment chip closer to the antenna in a mobile terminal architecture. The main goal is to create a re-configurable radio architecture accepting all the cellular or non-cellular standards working in the 0-5 GHz frequency range. But, in this environment, the analog to digital conversion and the digital operations face issues like power supply and processing speed. The idea is to interface a preprocessing circuit between the antenna and a digital signal processor (DSP) to pre-condition the RF signal. This paper presents the design of an analog discrete-time device located between antenna and a DSP in standard radio architecture. It uses the principle of the discrete Fourier transform (DFT) to reduce the frequency of the DSP-input-signal treatment to fulfil the SDR purpose. It has been validated through system level simulation.

A High-Performance Procedure for Effective Number of Bits Estimation in Analog-to-Digital Converters

This paper deals with a procedure for high-accuracy fast estimation of the effective number of bits ( ENOB) of an analog-to-digital converter (ADC). According to this procedure the ADC output sine-wave parameters are determined through the interpolated discrete Fourier transform (IpDFT) method. One criterion for the selection of the window that will be used in the IpDFT method is provided. In addition, mathematical expressions for the accuracy of both the sine-fitting procedure based on the IpDFT method and the proposed ENOB estimation method are derived, and a lower bound on the number of acquired samples that ensures accurate ENOB estimates with a high confidence level is proposed. In particular, it is proved that the uncertainty of the proposed ENOB estimation procedure is almost the same as the theoretical lower bound for the variance of any unbiased ENOB estimator. Finally, the accuracy of the proposed procedure and the algorithms suggested in the existing standards for ADCs testing are compared through both computer simulations and experimental results. In addition, the processing times required by each considered method are compared, therefore proving the advantage of the proposed procedure in terms of the required computational burden.

Frequency estimation of a sinusoidal signal via a three-point interpolated DFT method with high image component interference rejection capability

This paper proposes a three-point Interpolated Discrete Fourier Transform (IpDFT) method for frequency estimation of a discrete-time sinusoidal signal. It is based on the maximum sidelobe decay (MSD) windows and is highly effective in rejecting the detrimental effect on the estimation accuracy due to the image component of the signal spectrum. This remarkable feature is achieved by using an analytical expression based on a suitable weighting of the three largest DFT spectrum samples. The proposed method provides good results when the effect of the spectral interference due to the image component dominates other estimation error sources. The accuracy of the proposed method and of other state-of-the-art methods such as the multi-point IpDFT methods and the four-parameter sine-fitting (4PSF) algorithm are compared through both computer simulations and experimental results in the case of ideal, noisy, and harmonically distorted sinusoids. A small number of acquired cycles is assumed in order to analyze situations in which the contribution from the image component interference is significant. The performed comparison shows that the proposed method outperforms the considered multi-point IpDFT methods when the Signal-to-Noise Ratio (SNR) is higher than 30 dB and the number of acquired cycles is enough small. The proposed method outperforms also the 4PSF algorithm when the frequency estimation error is dominated by harmonics rather than wideband noise.

Amplitude Estimation by a Multipoint Interpolated DFT Approach

This paper focuses on the amplitude estimation by a multipoint interpolated discrete Fourier transform (DFT) method. Accurate results are obtained using the weighted multipoint interpolated DFT (WMIpDFT) method with maximum sidelobe decay windows. In addition, using the WMIpDFT method with maximum sidelobe decay windows, it is mathematically proven that the systematic errors affecting the amplitude estimation decrease as the number of interpolation points and/or the window order increases. Computer simulations confirm the accuracy of the derived expressions. Moreover, the influence of white Gaussian noise on the amplitude estimations has been analyzed by means of computer simulations.

Non coherent spectral analysis of ADC using filter bank

The spectral analysis of ADC digital data has traditionally been done with discrete Fourier transform. This method imposes restrictions to optimize the results: one of these is coherent sampling. Recently, some filter structures have been used for the spectral analysis of sinusoidal signal corrupted by harmonics and noise. In this paper, we present a filter bank structure used for decomposition of a signal into his main spectral components. The main application examined is ADC spectral parameters extraction (SINAD, SNR, THD) with non coherent sampling. Computer simulations are used to demonstrate the performance of the proposed filter structure.