Wednesday, May 11, 2011

Lab 9 - Oscilloscope 101




This lab was an introduction to the oscilloscope which is a tool used to analyze time-varying signals.  The scope operates by deflecting an electron beam onto a special phosphor-coated screen which lights up when the beam hits it.  Controls allow you to vary the voltage and time scale so that the input signal can be displayed as desired.  In our case we used a function generator to generate the 4 different signals below which could then be analyzed.  The first 3 were known sinusoid and squarewave signals with/without DC offsetting and the final was an unknown mystery signal.  This mystery signal appeared as a modified squarewave with a slight decay at the peaks.

Ex 1:5 kHz 5V Sinusoid
Period200 microsec
Pk-Pk ampl10 V
Zero-Pk ampl5 V
RMS3.53 V
DMM readings:
VDC0 V
VAC3.3 V
Ex 2:5 kHz Sinusoid w 2.5 V DC Offset
DMM readings:
VDC2.51 V
VAC3.32 V
Ex 3:5 kHz Squarewave w 2.5 V DC Offset
DMM readings:
VDC2.51 V
VAC5.25 V

Calculated RMS3.34 V
Ex 4:Mystery signal
DC voltage2.5 V
Frequency100 Hz
Pk-Pk Amp.4 V