School of Physics Lecture Demonstration Manual

Wf-2 The Fourier Synthesiser

Published: Wednesday 15 March 2006 - Updated: Thursday 31 March 2011

Aim

To demonstrate the basic properties of Fourier synthesis; i.e that any complex repetitive waveform may be synthesised by the addition of pure sinusoidal waves of the appropriate amplitude and phase.

Apparatus

Diagrams

Click on pictures to enlarge.

The Fourier Synthesiser

Fourier Synth Diagram

Videos

The Fourier Synthesiser

Description

The Pasco Fourier synthesiser enables the construction of complex waveforms by the addition of harmonics of the proper amplitude and phase. The device consists of two fundamental frequencies of 1100 Hz and seven harmonics. Amplitude and phase are controllable.

A reasonable square wave may be constructed using the following settings.

 

Harmonic

Amplitude

Phase

1

1

+C

3

0.33

-C

5

0.20

+C

7

0.14

-C

9

0.11

+C

 

where C = Cosine , ± = phase

Other experiments which may be performed are listed below

  1.  Addition of sine waves (same frequency):variable phase
  2.  Addition of sine waves (different frequencies)
  3.  Beats
  4.  Gibb's phenomenon
  5.  Musical instruments (synthesis)
  6.  Lissajous figures

For detailed information regarding these demonstrations consult the Pasco Manual or contact Steve or Nick.

Safety notes

Electrical safety 

Maintenance 

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