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Exam 1999 Question 4
"Explain what is meant by the frequency response of a system. Describe an experiment in which the frequency response of a simple resonator is measured. How is the bandwidth of a simple resonator related to the rate of energy lost from the resonator during vibration?"
20 things you should mention:
- Frequency Response
- tells us how the system deals with signals passed through it
- response is ratio of output amplitude to input amplitude
- can measure it for some frequencies using a sinusoid at that frequency
- frequency response graph is a graph of the response - axes
- - measured for different sinusoidal frequencies
- what system can do to a signal / examples / pictures
- natural resonant frequency
- Measurement
- e.g. an acoustic resonator/pendulum
- input: sinusoid generator
- fixed amplitude, variable frequency
- pass through system, e.g. loudspeaker, microphone
- output: millivoltmeter
- calculate response, express in dB
- plot graph, example picture
- measure bandwidth
- - from 3dB points
- Bandwidth/Time response
- wide bandwidth = wide range of frequencies giving moderate response
- rapid loss of energy from system, high damping
- narrow bandwidth = narrow range of frequencies giving large response
- energy retained in system, less damping
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