General Engineering Polytechnic University Laboratory #8 Vibrations, Waves & Spectra General Engineering Polytechnic University 9/23/2018

Overview Wave Equations Frequency Response Graph Objectives Procedure Report Questions Original Data Graph Requirements Closing 9/23/2018

Wave Equations A = amplitude = max displacement from avg P = power = avg rate energy moves  A2 T = period = time for one oscillation = 1 f f = frequency = # of oscillations / sec = 1 T  = wavelength = length until wave repeats  = speed of wave = f  9/23/2018

Frequency Response Graph Filter graphs: frequency vs. gain Gain (db) = 20*log(Vout/Vin) X-axis: logarithmic scale 3 dB point: output power (Pout) = 1/2 input power (Pin) Non-ideal behavior 3 filters High-pass filter Low-pass filter Band-pass filter 9/23/2018

Objectives Learn about vibrations, waves, spectra, and frequency filters Learn how to store and retrieve wave forms digitally Record and analyze wave forms of tuning fork, notes and voices for frequency, period harmonics, and power spectrum Identify filter 0, filter 1 and filter 2 as high-pass, low-pass or band-pass 9/23/2018

Procedure Capture and analyze wave generated by tuning fork Repeat with two different notes from keyboard Calculate amplitude, period and frequency for tuning fork and keyboard notes Record/playback song with different voices Fill out chart for filters 0-2 to determine which type of filter each corresponds to 9/23/2018

Report Questions Major difference between waveforms Each member’s songs similar or not Verify relationship between frequency and period Compare frequencies obtained from FFT spectrum and calculations Other applications using frequency filtering Plot frequency response of each filter Chart of tuning fork tone and keyboard note: amplitude, period, frequency 9/23/2018

Original Data 4 LabVIEW graphs Timefreq.vi graph of tuning fork Timefreq.vi graphs of 2 keyboard notes Record.vi or playback.vi graphs of different voices EXCEL chart with 4 columns keyboard notes / tuning fork tone amplitude period frequencies (voltage/time graph = FFT spectrum) 3 EXCEL charts (1 per filter) 3 EXCEL graphs (1 per filter) 9/23/2018

Graph Requirements Semi-log scale Frequency response for each filter 3dB point X-axis labeled Frequency (Hz) Y-axis labeled Gain (dB) Logarithmic scaling for x-axis Label filter number and its correct filter type XY scatter with line connecting points 9/23/2018

Closing Independent written report Don’t forget to make a copy of all original data 9/23/2018