Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

Identification and Restoration of a Class of Aliased Signals

Walia, Aasma (2004) Identification and Restoration of a Class of Aliased Signals. Master's Thesis, University of Pittsburgh. (Unpublished)

Primary Text

Download (1MB) | Preview


A fundamental theorem of Digital Signal Processing is Shannon's sampling theorem, whichdictates the minimum rate (called the Nyquist rate") at which a continuous-time signalmust be sampled in order to faithfully reproduce the signal from its samples. If a signalcan be reproduced from its samples, then clearly no information about the original signalhas been lost in the sampling process. However, when a signal is sampled at a rate lowerthan the Nyquist Rate, the true spectral content of the original signal is distorted due toaliasing," wherein frequencies in the original signal greater than the sampling frequencyappear as lower frequencies in the sampled signal. This distortion is generally held to beirrecoverable, i.e., whenever aliasing occurs, information is considered to be inevitably lost.This research challenges this notion and presents a technique for identifying aliasingand recovering an unaliased version of a signal from its aliased samples. The method isapplicable to frequency-modulated (FM) signals with a continuous instantaneous frequency(IF), and utilizes analysis of the IF of the aliased signal to 1) determine whether the signalhas potentially been aliased and, if so, 2) compensate for the aliasing by reconstructingan estimate of the true IF of the signal. Time-frequency methods are used to analyzethe potentially aliased signal and estimate the IF, together with modulation, re-samplingand interpolation stages to reconstruct an estimate of the unaliased signal. The proposedtechnique can yield excellent reconstruction of FM signals given ideal estimates of the IF.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Walia, Aasmaaaw4@pitt.eduAAW4
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairLoughlin, Patrickpat@engr.pitt.eduLOUGHLIN
Committee MemberEl-Jaroudi,
Committee MemberChaparro, Luis Fchaparro@ee.pitt.eduLFCH
Date: 9 June 2004
Date Type: Completion
Defense Date: 6 April 2004
Approval Date: 9 June 2004
Submission Date: 14 April 2004
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Electrical Engineering
Degree: MSEE - Master of Science in Electrical Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Aliasing; instantaneous frequency; time-frequency
Other ID:, etd-04142004-135143
Date Deposited: 10 Nov 2011 19:37
Last Modified: 15 Nov 2016 13:40


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item