Question About My O'Scope Findings

Discussion in 'General Electronics Chat' started by Terp, Feb 11, 2009.

  1. Terp

    Thread Starter Active Member

    Jun 6, 2008
    32
    1
    Hi all:

    I was in the EE lab at my school last week working on my first lab assignment for the semester. I was playing around with the oscilloscope. I connected a probe to the o'scope, and stuck a piece of wire to the probe. I left the ground lead floating not connected to the scope. After obtaining the datapoints from the scope screen onto my computer, I ran an FFT on MATLAB. The frequency response shows rapid oscillations that begin around 100.7 Hz. What could be the reason for such oscillations? I believe the room acoustics (material, walls, etc.) and room surroundings (people talking, computers/electronics with their hmmmm sound etc.) play some part in causing these oscillations. What other factors might be involved?
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    It could be a beat frequency of two noise sources. It could be just about anything.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    I got a signal on my Oscope when I was calibrating test equipment many orbits ago. I finally noticed the modulation matched an AM radio playing in the back room. They were recieving the same radio station, audio and all.

    Oscopes are by definition high impedance. Good ones have good frequecy response. You can pick up 60 Hz with the touch of a finger, and radio stations too.
     
  4. PRS

    Well-Known Member

    Aug 24, 2008
    989
    35
    It's the noise of the many electronic machines in your lab, plus the noise of the circuit powering your o scope plus radio in your area, etc. It comes down to noise. I'll just point out here that if we are not alone in the universe, there should be alot of rf out there, but there is not. Makes you wonder, huh?
     
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