Physics307L F08:People/Rivera/Notebook/070827

Basic waveform measurement
Remember to record everything in your wiki lab notebook!  Everything hooked up fine ''Got sine wave Came up with no extra work.'' ''Peak to peak voltage 150mV'' ''Peak to Peak 84mV-(-66mV)= 150mV'' ''Peak to peak voltage 152mV'' For lowest amplitude on wave generator: Read 62.0mV peak to peak voltage using measure function Using grid 60mV Cursor reading 60mV'' ''For highest amplitude on wave generator: Read 2.2V Peak to peak voltage using measure function Using grid ~2.2V Cursor reading 2.16V''
 * 1) Hook up the output of the function generator to the oscilloscope
 * 2) * Set the function generator to output a sine wave. Say 200 Hz maybe, or pick your frequency.
 * 3) * Use BNC cables (why are they called BNC cables?)
 * 4) * Should you use a T connector and a terminator?
 * 1) Fiddle with the oscilloscope settings so you can see the sine wave on the screen.
 * 1) Measure characteristics of a sine wave
 * 2) * Measure peak to peak voltage (thus amplitude) and measure the period (thus frequency)
 * 3) *# First, use the grid on the oscilloscope screen ("divisions" are the dotted lines)
 * 1) *# Next, use the cursors
 * 1) *# Finally, use the "measure" functions.
 * 1) * Repeat this for a few different waves: Very large amplitude; very low amplitude; large DC offset
 * 1) ** Are there waveforms that the oscilloscope cannot measure properly?

As the frequency approaches zero the scope seems to have a problem displaying the wave.''

Triggering
'' The rising edge is the point on the wave where the slope is positive. Therefore it starts you on the upswing of the curve. Edge gives a stable sine wave with 2 periods displayed an averaged view of the wave form. Video shows the wave oscillating and moving across the screen as the wave is detected. Pulse gives a view of the wave at a rate of 1 ms.''
 * 1) Re-read Wikipedia section about triggering
 * 2) Common way to trigger is on a rising edge (what does this mean?).  What happens to the signal when you use different triggers?  Be able to explain this orally.

AC Coupling
This is a tricky concept at first! '' Edge triggering is better for viewing the "ripple" because it is a static image therefore easier to take measurments on.'' ''276mV 10% value = 13.1mV Fall time ~53ms''  57.48ms  This implies the RC time constant.
 * 1) This Wikipedia article on capacitive coupling isn't too helpful
 * 2) Apply a large DC voltage to the oscilloscope input (we'll have to figure out how to do this).  Compare DC coupling with AC coupling.    You may need to adjust the triggering.  Which mode is better for viewing any "ripple" on the DC voltage?
 * 1) [[Image:Oscilloscope_fall_time.jpg|right|thumb|Using rising part of square wave to measure fall time]]Measure the fall time of the AC coupling
 * 2) * Function generator: Square wave; zero DC offset; amplitude about 8.6 V
 * 3) * Use cursors to measure fall time (peak to 10% value)
 * 1) * Use "measure" function to measure fall time
 * 1) What RC constant does this imply? (See Wikipedia article on rise time
 * 1) How does this compare with the expected value for the oscilloscope? (Can you find the answer on Google?)

Found this article Tektronix see question 13 Says "Counter Range: AC coupled, 10 Hz minimum to rated bandwidth" should be in the .1ms range.''

FFT
 My sine wave is at a frequency of 80.9Hz according to the FFT math tool.  There is a lot of noise in the harmonics  The applet is much cleaner and seems to portray the same basic image I get on the oscilloscope.  Would be useful for finding the frequency of noise that may be embedded in your signal.
 * 1) Find the frequency of a sine wave using FFT "Math" function
 * 1) Look at the harmonics in triangle and square wave
 * 1) Compare with what you see on this applet: Fourier series applet
 * 1) Be able to explain what is going on with an FFT and when it may be useful

Other

 * 1) Play with XY mode to make some fun patterns
 * 2) Build your own low or high pass filter using resistors, capacitors and breadboard.
 * 3) Measure something else you find in the lab