General Question

bhec10's avatar

How does an oscilloscope measure frequency and voltage?

Asked by bhec10 (6457points) February 13th, 2010

I’d like to have a brief description of how an oscilloscope can measure voltage and frequency.

How would you describe this in a language that shows that you understand a bit more than just the basics?

I mean, not in an “Albert Einstein” way of explaining it, but also not in a 5th grade way.

I hope I made myself clear enough. If not, please say so.

Thanks in advance!

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10 Answers

grumpyfish's avatar

Maybe not the most helpful, but here’s a schematic of a digital oscilloscope:

http://www.sparkfun.com/datasheets/Kits/DIY-Oscope-schematic.pdf

engineeristerminatorisWOLV's avatar

Okay, then why not to do that in an interactive way?
http://www.wisc-online.com/objects/ViewObject.aspx?ID=ACE3503

The link would guide you step by step on how to measure frequency using oscilloscopes.It’s just like using an oscilloscope in real world.Just be patient and do as it’s mentioned step wise.It would lead you from starting an oscilloscope till getting a final answer.

Regarding the measurement of voltage,it’s a pretty easy one.There are volts/div adjustments ind an oscilliscope.So you have to count the number of divisions from peak to peak and multiply it with the volt/div setting you have chosen and finally divide it by 2.The more screen area your graph covers the better accuracy you’ll get in voltage measurements.

Let me know if you need any further explanation on any of the above.

gasman's avatar

@engineeristerminatorisWOLV Hey, that online simulation looks just like my old Tektronix in the basement ! One of the last of a line of analog scopes.

FireMadeFlesh's avatar

Since a cathode ray tube relies on the voltage of electrodes to determine the position of the electron beam, an input that varies these voltages will affect the pattern formed by the movement of the electron beam. If you apply an input of a certain frequency and voltage, the output pattern of the oscilloscope will reflect this pattern.

gasman's avatar

To answer the question:
Oscilloscopes are calibrated to precisely reproduce voltages and time intervals at standard settings. Once you adjust the knobs to get a good looking waveform you just read off the voltages and times from a grid, then calculate frequency in Hertz as 1/T, where T is period in seconds.

engineeristerminatorisWOLV's avatar

@gasman,:Yes everything started as analog and with the passage of time, they became digtized making us more lazy and dumbing down our analytical skills.I like playing around experimenting with some of the old electrical analog devices in lab and learned much more than what books could have taught me.

gasman's avatar

@engineeristerminatorisWOLV I gotta admit, digital TV looks better than analog! But not so sure audio CDs sound better than good vinyl. Analog VOMs (multimeters) are also better than their digital counterparts—you can see the needle swing, etc.

engineeristerminatorisWOLV's avatar

@gasman :Indeed.When we talk about communication,digital transmission rules way above the analog ones.Analog equipments are good for research and learning, but not for commercial use.Techies like you and me could deal with analog stuffs, but that’s not eveybody else’s ball game.What people want, is a user friendly UI and things to be done at ease without breaking a sweat on anything.
.
Taking more on digital trasmission,NTSC had plans to digitize all TVs in US by the end of 2009, but due to the economic slowdown the plan implementation is postponed till the end of 2010.Ip Tv is a luxury available to only some privileged ones.The idea of digitizing entire US television network is a good one.That would eliminated the poor quality of analog transmission and the interband shuffle, but the questions is, is everyone willing for a change paying a bit higher than what they are used to?
Well we have to wait and see how things go.

gasman's avatar

@engineeristerminatorisWOLV I’m still using a rabbit-ears with digital converter box—don’t yet have the infrastructure in place for dish & home theater. But I get a nice picture—when I can receive the station at all. With analog you could see & hear the snow of weak stations but still get some kind of picture.

engineeristerminatorisWOLV's avatar

@gasman,:Yes that’s true.In case of analog mode of transmission of signals, even the weak signals could be tapped, but in case of digital, it’s either 1(means crystal clear picture and sound without interference) or 0( no signal at all).There’s no mid way in between.
.
Infrastructure plays a big role in digitizing the networks and even for personal viewing.IMO,people should be given a choise to opt for what they want and what is convenient and economical for them to use.

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