- #1
tboh
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Hi all!
First off: I don't know which forum to post this. I'm no grad student or PHD so academic forum seemed wrong, and it's not really just math, since it was the result of a measurment and the signals can come from environment, etc.
Ok. I measured the magnetic field using a sensor (HMC2003 of Honeywell) that gives me an analog output voltage dependent on the magnetic field. I have used a Agilent 34411A Multimeter to save the data on the computer.
Most important: Sampling rate was 1 data per second! 86400 measurements were made. Of the result I got I used the FFT algorithm (traing also different Windows just in case) of Origin 8.6. The result I got is shown in picture below.
http://postimage.org/image/j8jra66kl/
So my problem is basically this distribution of discrete peaks under an envelope. What can produce such a signal in my measurment? Also the number of peaks is different for the two envelopes at 0.2Hz and 0.4Hz and the difference of frequency the same, so the second should be no harmonic wave of the first. I found no signals of that frequency around my measurment location.
So at all those experienced physicists out there: What can cause these signals? Physically? Or some mathematical property?...
First off: I don't know which forum to post this. I'm no grad student or PHD so academic forum seemed wrong, and it's not really just math, since it was the result of a measurment and the signals can come from environment, etc.
Ok. I measured the magnetic field using a sensor (HMC2003 of Honeywell) that gives me an analog output voltage dependent on the magnetic field. I have used a Agilent 34411A Multimeter to save the data on the computer.
Most important: Sampling rate was 1 data per second! 86400 measurements were made. Of the result I got I used the FFT algorithm (traing also different Windows just in case) of Origin 8.6. The result I got is shown in picture below.
http://postimage.org/image/j8jra66kl/
So my problem is basically this distribution of discrete peaks under an envelope. What can produce such a signal in my measurment? Also the number of peaks is different for the two envelopes at 0.2Hz and 0.4Hz and the difference of frequency the same, so the second should be no harmonic wave of the first. I found no signals of that frequency around my measurment location.
So at all those experienced physicists out there: What can cause these signals? Physically? Or some mathematical property?...
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