Spectral leakage, Electrical Engineering

This assignment is intended to provide an easier analysis of how windows work. Begin by looking at individual spectrum bins as affected by off-bin-centred frequency components with different windows.

A sine wave component of the test signal is bin-centred if it has an integer number of periods in the data segment being analyzed. This almost never happens without planning.

When the signal is periodic and an integer number of periods fill the acquisition time interval, the FFT turns out such that the signal frequency matches one of the FFT frequency bins. When the number of periods in the acquisition is not an integer, the endpoints are discontinuous. The result is the high side lobes seen in the un-windowed spectrum plot. This phenomenon is called Spectral Leakage.

Consider the case of a sampling rate of 1024 Hz being used to look at a 16 Hz. Clearly 16 is a divisor of 1024, but how many samples are needed to uniquely identify the component.

a) using different sample lengths as shown, produce the corresponding FFT of the signal, explaining your results.

b) Repeat this exercise for frequencies 16.5 Hz, 17.0 Hz & 17.5 Hz

It is now necessary to consider the effects of windowing the data set with a view to minimizing leakage effects of a non bin-centered signal on the spectra computed.

c) repeat parts a) & b) by applying windowing to the data sets.

This has been illustrated graphically below using von Hann (Hanning) & Hamming windows, although clearly other could be used.. Graphs are shown for 16 Hz and again for 16.5 Hz.

Posted Date: 3/16/2013 2:54:50 AM | Location : United States

Related Discussions:- Spectral leakage, Assignment Help, Ask Question on Spectral leakage, Get Answer, Expert's Help, Spectral leakage Discussions

Write discussion on Spectral leakage
Your posts are moderated
Related Questions
Q. Explain the Importance of distributing frames? Basically four levels of cabling are used as displayed in Figure. At the subscriber end, drop wires are taken to a distributio

Normal 0 false false false EN-IN X-NONE X-NONE   Permanent   Magnet Stepper Motor The s

Explain pnp transistor circuit . pnp transistor: A transistor consist of  three terminals. In this pnp transistor there is two blocks of p- type semiconductors that are separa

list the key parameters to describe the ideal operational amplifier

derive transfer function of S= 2.25+j4.5

Q For a parallel-plate capacitor with plates of area A m 2 and separation d m in air, the capacitance in farads may be computed from the approximate relation Compute the a

Q. Explain Block diagram of the system? The block diagram is a pictorial representation of the equations of the system. Each block represents a mathematical operation, and the

Q Using a combination of Uni-selectors and two motion selectors, draw a diagram of thousand line exchange and illustrate its working. Ans: The diagram for such an exchange i

Active-mode PNP transistors in circuits: In the figure, the arrows showing current point in the direction of conventional current - the flow of electrons is in the opposite di

LDA  Load Accumulator Direct Instruction This instruction is used to copy  data from  memory whose  address is directly specified in the  instruction to th e accumulator. The i