How to capture the instantaneous waveform with an oscilloscope and automatically lock it?

QWE4562009

How to capture the instantaneous waveform with an oscilloscope and automatically lock it? [Copy link]

 

Two questions

: 1. The waveform of the electrochemical test paper reaction is often instantaneous, and it may disappear after a few hundred us. How to capture such instantaneous waveforms with an oscilloscope and automatically latch them?


2. Some ICs or MCUs can output sine waves! Sine waves are very meaningful for measuring bioimpedance? Why not use square waves, triangle waves, or sawtooth waves? What are the advantages of sine waves in these applications?

freebsder

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littleshrimp

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I think it is because the sine signal has a single frequency, which is convenient for calculation.

dcexpert

Sine waves have fewer harmonics, making signal processing easier

QWE4562009

littleshrimp posted on 2020-9-5 06:30 I think it is because the sine signal has a single frequency, which is convenient for calculation

Single frequency? Can't other waveforms also have single frequency? Are you talking about 50HZ?

QWE4562009

dcexpert posted on 2020-9-5 13:48 Sine waves have fewer harmonics, making signal processing easier

Why does a sine wave have fewer harmonics?

littleshrimp

QWE4562009 posted on 2020-9-7 18:43 Single frequency? Then can't other waveforms also achieve single frequency? Are you talking about 50HZ?

Square wave triangle wave you do FFT look at the spectrum will know

littleshrimp

QWE4562009 posted on 2020-9-7 18:44 Why does a sine wave have fewer harmonics? Moderator

I recommend you an article from NetEase. You can find it by searching Baidu <What is the magic of the sine function? Learn about the spectrum!>

QWE4562009

littleshrimp posted on 2020-9-7 18:58 You can tell the square wave and triangle wave by looking at the spectrum by doing FFT

How do I know about Fourier transformation?

littleshrimp

QWE4562009 posted on 2020-9-8 18:43 How do I know about Fourier transformation?

QWE4562009

littleshrimp posted on 2020-9-8 19:48 QWE4562009 posted on 2020-9-8 18:43 Fourier change How do I know this...

Did it change step by step?

littleshrimp

QWE4562009 posted on 2020-9-9 18:24 Did it change step by step?

I'm telling you about that article. If you read it carefully you should be able to understand it.

All square waves and triangle waves can be understood as a combination of sine waves of different frequencies.

For example, a 1KHz sine wave is a 1KHz sine wave.

The 1KHz square wave and triangle wave are formed by combining a 1KHz sine wave and multiple harmonics.

The three pictures above are the spectrum distribution of different waveforms.

So the sine wave is a single frequency with few harmonics.