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- Eriksson, Håkan, et al.
(författare)
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A robust correlation receiver for distance estimation
- 1994
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Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - New York : Institute of Electrical and Electronics Engineers (IEEE). - 0885-3010 .- 1525-8955. ; 41:5, s. 596-603
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Tidskriftsartikel (refereegranskat)abstract
- Many methods for distance estimation, such as the ultrasonic pulse-echo method, involve the estimation of a time-of-flight (TOF). In this paper, a signal model is developed that, apart from the TOF, accounts for an unknown, linear frequency dependent distortion as well as for additive noise. We derive a TOF estimator for this model based on the criteria of maximum likelihood. The resulting receiver can be seen as an extension or generalization of the well known cross-correlation, or "matched filter", estimator described, e.g., by Nilsson. The novel receiver is found to be more robust against unknown pulse shape distortion than the cross-correlation estimator, giving less biased TOF estimates. Also, bias versus noise sensitivity can be controlled by proper model order selection
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- Eriksson, Håkan B., et al.
(författare)
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Modelling of waveform deformation and time-of-flight estimation, with application to the ultrasonic pulse-echo method
- 1992
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Ingår i: International Symposium on Signal Processing and Its Applications. - Edgecliff, N.S.W. - 909394288 ; , s. 188-191
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Konferensbidrag (refereegranskat)abstract
- In this paper we address the problem of estimating the time-of-flight of ultrasonic pulse-echo signals. The shape of the received waveform is modelled by a linear combination of bass signals. A method for obtaining these base signals Is presented. The method presumes that the excitation signal is narrowbanded in the frequency domain
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| 9. |
- Sundström, N., et al.
(författare)
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Registration of surface structures using airborne focused ultrasound
- 1991
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 17:5, s. 513-518
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Tidskriftsartikel (refereegranskat)abstract
- A low-cost measuring system, based on a personal computer combined with standard equipment for complex measurements and signal processing, has been assembled. Such a system increases the possibilities for small hospitals and clinics to finance advanced measuring equipment. A description of equipment developed for airborne ultrasound together with a personal computer-based system for fast data acquisition and processing is given. Two air-adapted ultrasound transducers with high lateral resolution have been developed. Furthermore, a few results for fast and accurate estimation of signal arrival time are presented. The theoretical estimation models developed are applied to skin surface profile registrations
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