Applied Fft to my temperature sensor readings and don't understand the result

Question

Vasco Sampaio 2018-3-5

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/386352-applied-fft-to-my-temperature-sensor-readings-and-don-t-understand-the-result

回答： Rijal Al Kautsar 2019-4-17

Hi everybody,

I'm reading data from my temperature sensor with arduino at a sampling frequency of 100Hz. Arduino writes data to the serial port and Matlab gets it perfectly (no data is missing). When I do the fft to see at which frequency I'm getting this result.

Second image is the zoomed graph of the 1st.

I'm new to digital signal processing, so I'm a bit confused: shouldn't DC gain be negligible? Is there an explanation for this result, or is it wrong.

Time series is plotted here also

Thanks in advance

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Christoph F. 2018-3-5

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/386352-applied-fft-to-my-temperature-sensor-readings-and-don-t-understand-the-result#answer_308363

> Is there an explanation for this result, or is it wrong.

The result looks correct. The Fourier transform shows a large DC component, because the signal has a large DC component.

> I'm new to digital signal processing, so I'm a bit confused: shouldn't DC gain be negligible?

What do you mean by "DC gain"? From the graph, it looks like the average value (-> DC component) is about 32.75°C, and all other variations are in the +/- 2.5°C range. A large DC component in the frequency domain correctly represents the temperature data.