60 research outputs found
Design Of An Induction Probe For Simultaneous Measurements Of Permittivity And Resistivity
In this paper, we propose a discussion of the theoretical design and move
towards the development and engineering of an induction probe for electrical
spectroscopy which performs simultaneous and non invasive measurements on the
electrical RESistivity \rho and dielectric PERmittivity \epsilon r of
non-saturated terrestrial ground and concretes (RESPER probe). In order to
design a RESPER which measures \rho and \epsilon r with inaccuracies below a
prefixed limit (10%) in a band of low frequencies (LF) (B=100kHz), the probe
should be connected to an appropriate analogical digital converter (ADC), which
samples in uniform or in phase and quadrature (IQ) mode, otherwise to a lock-in
amplifier. The paper develops only a suitable number of numerical simulations,
using Mathcad, which provide the working frequencies, the electrode-electrode
distance and the optimization of the height above ground minimizing the
inaccuracies of the RESPER, in galvanic or capacitive contact with terrestrial
soils or concretes, of low or high resistivity. As findings of simulations, we
underline that the performances of a lock-in amplifier are preferable even when
compared to an IQ sampling ADC with high resolution, under the same operating
conditions. As consequences in the practical applications: if the probe is
connected to a data acquisition system (DAS) as an uniform or an IQ sampler,
then it could be commercialized for companies of building and road paving,
being employable for analyzing "in situ" only concretes; otherwise, if the DAS
is a lock-in amplifier, the marketing would be for companies of geophysical
prospecting, involved to analyze "in situ" even terrestrial soils.Comment: 37 pages, 7 figures, 3 table
La ionosonda AIS-2: evoluzione nel progetto del sistema e primi collaudi.
Il presente lavoro descrive lo stato di avanzamento del progetto della ionosonda AIS-2, giĂ descritto
nel Rapporto Tecnico [Sciacca, Baskaradas, 2012]. Rispetto alla versione ivi riportata sono stati compiuti
vari interventi migliorativi, specialmente nella direzione di una semplificazione ed unione delle funzioni di
alcune delle schede previste inizialmente.
Parallelamente allâadeguamento del progetto sono state costruite e collaudate alcune delle schede
componenti ed il presente rapporto tecnico descrive in dettaglio il loro progetto e collaudo, che ha avuto un
sostanziale esito positivo
La ionosonda AIS-2: valutazioni utili ai fini del progetto a livello di sistema
Lâacquisizione di specifiche competenze nel Laboratorio di Geofisica Ambientale ha consentito allâinizio degli anni 2000 lo sviluppo della nuova ionosonda digitale AIS (Advanced Ionospheric Sounder). Il successo di quel progetto, unitamente al desiderio di migliorarne alcune limitazioni, hanno spinto verso la progettazione di una nuova ionosonda: AIS-2. Lâintento Ăš anche in questo caso quello di sviluppare lo strumento in ambito INGV, limitando al massimo lâacquisto di parti allâesterno. Rispetto alla prima ionosonda, nella nuova le prestazioni che si desidera migliorare sono: semplificazione del maggior numero possibile di funzioni, usando soluzioni circuitali piĂč semplici, compatte e versatili, estensione delle prestazioni hardware, miglioramento delle prestazioni del software e del DSP, predisposizione funzioni completamente nuove. Questo rapporto tecnico descrive il progetto della nuova ionosonda a livello di sistema; per questo motivo non si entra in dettagli tecnici sulla progettazione delle singole sezioni componenti; ad ogni modo, dato che molte di esse si trovano ad un avanzato stato di realizzazione, sono anche descritti alcuni schemi a blocchi di alcune sezioni componenti
Optimal Requirements of a Data Acquisition System for a Quadrupolar Probe Employed in Electrical Spectroscopy
This paper discusses the development and engineering of electrical
spectroscopy for simultaneous and non invasive measurement of electrical
resistivity and dielectric permittivity. A suitable quadrupolar probe is able
to perform measurements on a subsurface with inaccuracies below a fixed limit
(10%) in a bandwidth of low (LF) frequency (100kHz). The quadrupole probe
should be connected to an appropriate analogical digital converter (ADC) which
samples in phase and quadrature (IQ) or in uniform mode. If the quadrupole is
characterized by a galvanic contact with the surface, the inaccuracies in the
measurement of resistivity and permittivity, due to the IQ or uniform sampling
ADC, are analytically expressed. A large number of numerical simulations proves
that the performances of the probe depend on the selected sampler and that the
IQ is better compared to the uniform mode under the same operating conditions,
i.e. bit resolution and medium.Comment: 57 pages, 14 figures, 4 tables; Ann. Geophys. (2010
Optimal Requirements of a Data Acquisition System for a Quadrupolar PROBE employed in Electrical Spectroscopy
This paper discusses the development and engineering of electrical spectroscopy for simultaneous and non invasive measurement of electrical resistivity and dielectric permittivity. A quadrupolar probe is able to perform measurements on a subsurface with inaccuracies below a fixed limit in a band of low frequencies. The probe should be connected to an appropriate analogical digital converter (ADC) which samples in uniform or in phase and quadrature (IQ) mode. If the probe is characterized by a galvanic contact with the surface, the inaccuracies in the measurement of resistivity and permittivity, due to the uniform or IQ sampling ADC, are analytically expressed. A large number of numerical simulations prove that the performance of the probe depends on the selected sampler and that the IQ is better compared to the uniform mode under the same operating conditions, i.e. bit resolution and medium
Inaccuracy Assessment for Simultaneous Measurements of Resistivity and Permittivity applying Sensitivity and Transfer Function Approaches
This paper proposes a theoretical modelling of the simultaneous and non
invasive measurement of electrical resistivity and dielectric permittivity,
using a quadrupole probe on a subjacent medium. A mathematical-physical model
is applied on propagation of errors in the measurement of resistivity and
permittivity based on the sensitivity functions tool. The findings are also
compared to the results of the classical method of analysis in the frequency
domain, which is useful for determining the behaviour of zero and pole
frequencies in the linear time invariant (LTI) circuit of the quadrupole. The
paper underlines that average values of electrical resistivity and dielectric
permittivity may be used to estimate the complex impedance over various
terrains and concretes, especially when they are characterized by low levels of
water saturation (content) and analyzed within a bandwidth ranging only from
low (LF) to middle (MF) frequencies. In order to meet the design specifications
which ensure satisfactory performances of the probe (inaccuracy no more than
10%), the forecasts provided by the sensitivity functions approach are less
stringent than those foreseen by the transfer functions method (in terms of
both a larger band of frequency f and a wider measurable range of resistivity
or permittivity).Comment: 50 pages, 11 figures, 3 tables; Earth-prints,
http://hdl.handle.net/2122/5180 (2009
Inaccuracy assessment for simultaneous measurement of resistivity and permittivity applying sensitivity and transfer function approaches
The present study proposes a theoretical modeling of simultaneous and noninvasive measurements of electrical resistivity and dielectric permittivity using a quadrupole probe on a subjacent medium. A mathematical-physical model is applied to the propagation of errors in the measurement of resistivity and permittivity based on a sensitivity functions tool. The findings are also compared with results of the classical method of analysis in the frequency domain, which is useful for determining the behavior of zero and pole frequencies in the linear time invariant circuit of the quadrupole. This study underlines that average values of electrical resistivity and dielectric
permittivity can be used to estimate complex impedance over various terrains and concretes, especially when they are characterized by low levels of water
saturation (content), and are analyzed within a bandwidth ranging only from low to middle frequencies. To meet the design specifications, that ensure satisfactory performances of the probe (inaccuracies of no more than 10%), the forecasts provided by the sensitivity functions approach are discussed in comparison with those foreseen by the transfer functions method (in terms of
both the band of frequency f and the measurable range of resistivity rho, or
permittivity epsilon)
Design of an induction probe for simultaneous measurements of permittivity and resistivity
In this paper, we propose a discussion of the theoretical design and move towards the development and engineering of an induction probe for electrical spectroscopy which performs simultaneous and non invasive measurements on the electrical RESistivity Ï and dielectric PERmittivity Δr of non-saturated terrestrial ground and concretes (RESPER probe). In order to design a RESPER which measures Ï and Δr with inaccuracies below a prefixed limit (10%) in a band of low frequencies (LF) (B=100kHz), the probe should be connected to an appropriate analogical digital converter (ADC), which samples in uniform or in phase and quadrature (IQ) mode, otherwise to a lock-in amplifier. The paper develops only a suitable number of numerical simulations, using Mathcad, which provide the working frequencies, the electrode-electrode distance and the optimization of the height above ground minimizing the inaccuracies of the RESPER, in galvanic or capacitive contact with terrestrial soils or concretes, of low or high resistivity. As findings of simulations, we underline that the performances of a lock-in amplifier are preferable even when compared to an IQ sampling ADC with high resolution, under the same operating conditions. As consequences in the practical applications: if the probe is connected to a data acquisition system (DAS) as an uniform or an IQ sampler, then it could be commercialized for companies of building and road paving, being employable for analyzing âin situâ only concretes; otherwise, if the DAS is a lock-in amplifier, the marketing would be for companies of geophysical prospecting, involved to analyze âin situâ even terrestrial soils
Rilevamento delle sorgenti doppler della ionosfera tramite radar-HF
Il presente lavoro contiene un insieme di concetti di base utili per comprendere la cosiddetta tecnica della âinterferometria dopplerâ, usata, nellâambito degli studi sulla ionosfera, per ricavare informazioni sulla conformazione e velocitĂ degli strati riflettenti (operazione chiamata anche sky mapping). Ă utile ricordare, infatti, che il sondaggio ionosferico tradizionale consente solo la determinazione dellâaltezza virtuale di ogni strato, pensato come un unico oggetto riflettente piano. Tale determinazione Ăš giunta nel tempo ad avere una risoluzione molto spinta, dellâordine di qualche chilometro, tuttavia una ionosonda tradizionale non possiede la capacitĂ di individuare la struttura degli strati riflettenti
THE NEW INGV DIGITAL IONOSONDE: DESIGN REPORT
The ionosonde is a system which exploits the radar technique: it applies electromagnetic waves with variable frequency in the HF band to measure the ionospheric layers electron density, height and other parameters. This paper is a technical report on the new digital ionosonde (AIS-INGV), which was designed both for research purposes and for the routine service of the HF radiowave propagation forecast. It has been developed almost completely within the Laboratorio di Geofisica Ambientale (LGA) at the Istituto Nazionale di Geofisica e Vulcanologia (INGV). It exploits advanced techniques for the signal analysis, recent technological devices and PC resources. The report is divided into two parts; the first is a general description of the design development, the second is a more detailed description of the blocks and circuits actually built and tested, directed to a specialist reader
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