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How to measure AC amplitude

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Mohamed Slama

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Hello All

how can i measure the amplitude of Frequency signal by PIC 16f877A ?
 
Last edited:

If you don't give any information about your signal is impossible to answer.
 

First use a TRMS to DC converter that is able to measure 500 kHz. It must be able to have enough bandwidth to measure the frequency, but also think about waveshape (sinewave, pulse etc) DC offset and crest factor. For a sinewave it is most simple but 500 kHz pulses with a 10% dutycycle and DC offset is an other thing. Im just building a TRMS converter and It must be measured by a Launchpad. I now have it working over 500 kHz for squarewaves but it is not stable enough yet, one opamp starts oscillating now and then. Not enough phase marging.
 

You need to say, at least, also the min and the max value of your signal. Before to analyze it, if fact, you have to "translate" your signal voltage range into that of the ADC. Once the signal is properly digitized you can analyze it using the method that better fit your application.
The external circuitry can also provide filtering, in order to clean the signal from unwanted spurious (if needed).
Also the information about the waveform you want to analyze is useful. You are speaking about a 200-500 kHz signal frequency: if it is a waveform other than a sinewave you have to consider a certain number of harmonics that have to pass in order not to have lack of precision due to attenuation.
 

albbg said:
You need to say, at least, also the min and the max value of your signal. Before to analyze it, if fact, you have to "translate" your signal voltage range into that of the ADC. Once the signal is properly digitized you can analyze it using the method that better fit your application.
The external circuitry can also provide filtering, in order to clean the signal from unwanted spurious (if needed).
Also the information about the waveform you want to analyze is useful. You are speaking about a 200-500 kHz signal frequency: if it is a waveform other than a sinewave you have to consider a certain number of harmonics that have to pass in order not to have lack of precision due to attenuation.
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So , what is required exactly to measure amplitude ?

if u can , code and circuit >
 

What is required exactly is you giving answers on those questions instead of quoting them.
The fastest and easiest way is buying a scope.
Google on TRMS and arduino If you do not want to program yourself.
 

PA4TIM said:
What is required exactly is you giving answers on those questions instead of quoting them.
The fastest and easiest way is buying a scope.
Google on TRMS and arduino If you do not want to program yourself.
Click to expand...

Dear PA4TIM measuring amplitude is apart from large project in ( image processing project ) .

my major knowledge in Image processing and development a c# program .
 

Hi Mohamed, that is no problem, if you knew you would not ask. Butas long as you do not give the information asked we can not tell you what you need. Measuring AC can be very difficult. This because the high frequency, many expensive 6,5 digit TRMS meter are even not able to measure at 500 kHz. And then I´m talking about a true pure sinewave. If you are talking about pulses, with DC offset and changing duty cycles it becomes even more difficult. I´m not good in digitaL or math But I read on a web blog about measuring TRMS with an Arduino and baseds on sampling and FFT. I was the first hit in google when I searched for Arduino and TRMS
 

If you are doing research on image processing .... 200k~500k sounds like the pixel rate , and thus the PIC chosen would be unsuitable for high speed ADC and image processing. No doubt.

I suggest you add more detail and clarity to your next question.
 

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