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filtering sinusoidal digital signal in arduino

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adezie

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greetings, i have designed my own ZMPT101B to detect AC voltage, but I got some problem with reading the signal, here's the waveform using arduino plotter aa.JPG
does any one of you know how to only detect VPP of the signal ?bb.JPG
 

Hi,

Read a lot of samples.
* check for min value
* check for max value

Klaus
 

Use an analogue peak detector and you can sample at low speed.

Something likes this:
peak.jpg
 
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    adezie

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By evaluating the min and max value as Klaus suggested should usually do the job. Unfortunatly your signal can be interpreted as two sinewaves ("two channels") with an offset.

I'm more curious why your signal doesn't looks as it should, namely a sinewave. What's the signal frequency? I think the maximum arduino (uno) ADC sample frequency is 125 kHz. Do you acquire a whole array (set of samples) at once befor they are sent to the PC?

greets

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Ok, by using analogRead() the arduino ADC sample rate is even lower:

On ATmega based boards (UNO, Nano, Mini, Mega), it takes about 100 microseconds (0.0001 s) to read an analog input, so the maximum reading rate is about 10,000 times a second.
 
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    adezie

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Your bit time appears to be ~ 100 uS, but the sig riding on top of sine is ~ 22x faster, maybe 200 Khz ?

You can either sample faster, at least 2x the 5 uS, or average. Latter causes latency to detection.

There are processors out here with SARs on them that can handle 1 Msps easily, just a thought.


Regards, Dana.
 

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