Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568597
Title: Modelling of pyroelectric detectors detection by digital signal processing algorithms
Author: Efthymiou, Spyros
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2013
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Abstract:
Pyroelectric Detector (PED) models are developed considering the classical heat balance equation to simulate the detector’s response under specified radiation conditions. Studies on the behaviour of a PED are presented under the conditions of step function and a pulsed load. Finite Element Methods (FEMs) have been used to obtain 3D models of the resulting temperature field in a Lithium Tantalate (LiTaO3) pyroelectric crystal, incorporated in a complete commercial detector, taking into account details of its geometry and thermal connectivity. The novelty is the achieved facility to predict the response to pulsed radiation, which is valuable for the engineering of pulsed-source sensor systems requiring detection at room temperature. In this thesis, we present a signal processing (SP) algorithm, which combines the principle of Quadrature Synchronous Demodulation (QSD) and Gated Integration (GI), to achieve an improved signal-to-noise ratio (SNR) in pulsed signal measurements. As a first step, the pulse is bracketed by a gating window and the samples outside the window are discarded. The gate duration is calculated to ensure that the periodic signal at the output has an 'apparent' duty factor close to 0.5. This signal is then fed continuously for QSD to extract the magnitude and phase of its fundamental component, referenced to a sinusoidal signal with period defined by the gate length. An improved SNR performance results not only from the increase of the average signal energy, but also from the noise suppression inherent to the QSD principle. We introduce this method as Gated Quadrature Synchronous Demodulation (GQSD), emphasizing the synergy between GΙ and QSD.
Supervisor: Ozanyan, Krikor Sponsor: EPSRC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.568597  DOI: Not available
Keywords: Pyroelectric Detectors ; Gated Quadrature Synchronous Demodulation
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