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| Why do oscilloscopes have bandwidth limits? |
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| pdenisowski:
Here's my answer :) |
| pdenisowski:
--- Quote from: Anding on November 02, 2022, 06:36:08 am ---From experience how far can you use an oscilloscope beyond it's bandwidth limit? --- End quote --- It depends on the input waveform. If you're looking at a pure sinusoid, you can often use a scope well past it's 3dB bandwidth without the waveform being distorted, although the amplitude of the displayed sinusoid will be reduced. On the other hand, if you're looking at a signal with high frequency components (e.g. a square wave), then these higher frequency components will be attenuated more than the lower frequency components and waveform distortion will result. This is why a square wave (fundamental and odd harmonics) ends up looking line a sine wave when you have insufficient bandwidth: the higher frequency components have all been significantly attenuated. (ataradov mentioned this above as well :)) |
| joeqsmith:
I attempted to make a virtual oscilloscope to demonstrate LeCroy's Digital Bandwidth Interleaving. The basic idea was to combine two channels to double the bandwidth rather than the time resolution. Rodger Delbue chimed in with some additional comments on the subject: A few of us were attempting to build a simple oscillator on a breadboard for the fun of it. Far from a scope or anything useful, but it my give you some insight to the problems. https://www.eevblog.com/forum/projects/challenge-thread-the-fastest-breadboard-oscillator-on-the-mudball/msg3081669/#msg3081669 In this video I tried to measure some pulses that I sent down different media, from copper to optics. |
| RoGeorge:
Why there has to be a limit? For oscilloscope it's easy to say, you have a given budget (price, power, thermal, etc.) than there is the sampling theorem, and for your 8GSa/s ADC the most you can reconstruct (for an unknown non-repetitive signal is 4GHz). The question is much deeper, as in "why there is no observable infinite in the physical world"? Nobody knows, but so far infinite only exists as a concept, i.e. in math. In the physical world (as far as we can observe) nothing is infinite. :-// |
| Fungus:
--- Quote from: Anding on November 02, 2022, 10:05:13 am ---Can you put the equivalent physics for a 'scope in two sentences? --- End quote --- I can do it in two words: "Inductance" and "Capacitance" |
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