R. Schiano Lo Moriello

A New Measurement Method Based on Music Algorithm for Through-the-Wall Detection of Life Signs

A new measurement method for through-the-wall detection of life signs is proposed hereinafter. The method analyzes the phase modulation that a sinusoidal signal, generated by means of a proper continuous-wave microwave transceiver, undergoes when reflected by the chest periodic displacement associated with breathing. It takes advantage of a suitable spatial smoothing decorrelation strategy applied to the traditional algorithm for MUltiple SIgnal Classification (MUSIC), mandated to single out the spectral components of the received phase signal. With respect to other measurement solutions, already available in the literature and exploiting either the traditional discrete-time Fourier transform, or matched filters, or standard singular value decomposition, the proposed method assures competitive performance in detecting the respiratory activity from the received microwave signal and effective noise/clutter rejection. The results of several tests both in simulated and actual scenarios, i.e., people behind walls in a furnished room, prove the efficacy and reliability of the method also in the presence of critical measurement conditions such as low signal-to-noise ratios and chest displacement associated with shallow breathing.

On the use of the warblet transform for instantaneous frequency estimation

A new digital signal processing method for instantaneous frequency estimation is proposed here. The attention is mainly paid to signals whose instantaneous frequency trajectories exhibit a periodic evolution versus time. Thanks to an optimized use of the warblet transform, the method assures superior accuracy and resolving capability with respect to other solutions already available in the literature, thus showing itself very attractive in the presence of multicomponent signals characterized by instantaneous frequency trajectories extremely similar and very close to one another. Theoretical notes regarding the warblet transform and its optimized use in the framework of the proposed method are first given. Then, the fundamental steps of the method are described in detail with references to a clarifying example. The results of a number of experiments on emulated and actual signals, aimed at assessing the performance of the method, are finally presented.

Ultrasonic time-of-flight estimation through unscented Kalman filter

This paper deals with distance or level measurements based on ultrasonic time-of-fight estimation. Moving from a past experience concerning the proposal of a method based on discrete extended Kalman filter (DEKF) to overcome some limitations of already available ultrasonic-based techniques, a new digital signal processing method capable of granting further improvements is presented. The method is based on the unscented Kalman filter (UKF), which is a new extension of the Kalman filter theory mandated to face some DEKF problems, mainly due to its inherent linearization approach. To this aim, UKF is applied to the acquired ultrasonic signal in order to estimate the returned echo envelope as well as to locate its onset more accurately. After describing key features and implementation issues of the new method, the results obtained in a number of tests on simulated and actual ultrasonic signals, which assess its reliability and effectiveness as well as advantages with respect to the previous one, are given.

Estimating ultrasonic time-of-flight through quadrature demodulation

A new digital signal-processing (DSP) method for ultrasonic time-of-flight (TOF) estimation is presented hereinafter. The method applies a traditional quadrature-demodulation scheme to the acquired ultrasonic signal in order to suitably extract the envelope of the main echo and locate its onset (i.e., the starting time of the echo). It is also possible to assure reduced bias and uncertainty in critical TOF measurements, such as those involving low signal-to-noise ratio (SNR) as well as severe distortion of echo shape. A number of numerical tests are conducted on simulated signals with the aim of highlighting the good performance of the method when operating in critical conditions; to reduce the computational burden without losing significance in the analysis, a statistical experimental design-based technique is enlisted. Results attained in TOF-based distance measurements finally assess the methods reliability and efficacy even in the presence of actual ultrasonic signals.

New proposal for uncertainty evaluation in indirect measurements

This paper deals with the uncertainty evaluation in indirect measurements. The attention is mainly paid to measurement models whose input quantities are modeled as correlated random variates. Moving from a past proposal related to the use of the unscented transform to overcome key limitations of current guide to the expression of uncertainty in measurement recommendations in the presence of the input quantities modeled as uncorrelated random variates, the authors are going to present a new proposal capable of extending the advantages of the cited transform when correlated input random variates are also concerned. The new proposal is, in particular, addressed to nonlinear and/or nonanalytical measurement models. After describing the key features and implementation issues of the proposal, the results obtained in a number of tests on simulated and actual measurement data are given, which assess its reliability and effectiveness.

Automatic detection of train arrival through an accelerometer

The paper deals with the problem of train arrival detection in tracks maintenance sites. Worker safety has, in fact, to be guaranteed and injuries due to undetected train transits are, unfortunately, very common. Several solutions have already been presented based either on human sentinels or automatic detection systems. They, however, suffer from high operating costs and long assembly time, respectively. To overcome the aforementioned problems and provide workers and maintenance factory with a safety system suitable also for short time operations, the authors propose hereinafter a new method for train detection based on the use of an accelerometer mounted on the track. Thank to a suitable data acquisition system and a proper digital signal processing algorithm, the method is capable of sensing the train transit about 1 km apart from the accelerometer installation site. Several tests carried out on actual tracks highlight the reliability of the method, thus suggesting its implementation in an automatic track warning system.

A new method based on a multisensor system for through-the-wall detection of moving targets

The paper deals with the problem of through-the-wall detecting, localizing and tracking moving targets by means of radio-frequency imaging. In particular, the authors present hereinafter a new method capable of locating and tracking the position of hidden targets (e.g. human bodies in rescue missions) thanks to the use of multisensor system and a proper linear inversion scheme. Preliminary results obtained in numerical tests confirm the effectiveness of the proposed approach and measurement strategies.

A Digital Signal Processing Instrument for Real-Time Phase Noise Measurement

A digital-signal-processing-based instrument for phase noise measurement on sinusoidal signals is described. It incorporates a special hardware architecture, which is made up of a core digital signal processor that is connected to a data acquisition board, and takes advantage of a new measurement procedure based on a quadrature demodulation scheme, which has been proposed by the authors. Thanks to an optimized implementation of this procedure, the instrument exploits all its hardware resources to achieve high performance and real-time operation. For input frequencies of up to some hundreds of kilohertz, the instrument proves to be capable both of updating phase noise power spectrum while seamlessly capturing the analyzed signal into its memory and of granting frequency resolution as good as a few units of hertz.

A chloroform transducer based on sPS-/spl delta/-coated quartz-crystal microbalance for gaseous environment

A prototype of a quartz-crystal microbalance-based transducer is proposed for in-situ measurements of very low chloroform activity in a gaseous environment. The sensing element consists of an innovative semicrystalline form of syndiotactic polystyrene sprayed as a thin film on the piezoelectric quartz electrode of the microbalance. Chloroform sorption and desorption in the film give rise to a mass variation, implying a related shift in the resonance frequency of the quartz. Results of static and dynamic metrological characterization of the transducer prototype at varying chloroform concentration and temperature in a gaseous environment are reported. Satisfactory sensitivity, repeatability, and dynamic hysteresis are highlighted.

A method based on passive acoustic sensors for detection of vital signs in closed structures

The paper deals with the problem of non intrusive detection of concealed people by means of passive acoustic sensors To this aim, the authors present hereinafter a new method capable of detecting and recognizing vital signs, typical of human beings, thanks to the use of a suitable data acquisition system, based on a geophones network, and a proper digital signal processing algorithm. In particular, the passive sensors are mandated to (i) detect the reduced-amplitude vibrations on a solid structure generated by peoples heartbeat, breathing and associated (voluntary and involuntary) motions and (ii) convert them in a signal whose power spectrum proves to be significant in two different frequency bands, referred to as audio and infrasonic band. With regard to the processing algorithm, it is based on adaptive filter and estimates the so-called pseudo period of the received signal to single out the desired detection of vital signs. Preliminary results, carried out in a number of numerical and experimental tests, confirm the effectiveness of the proposed approach and measurement strategies.