how to remove unwanted signal

4 次查看（过去 30 天）
rafael gonzalez
rafael gonzalez 2013-6-7
I have a signal that is roughly in the shape of a sine wave rectifier. At random intervals there are square wave pulses inserted in the signal. I wish to automatically remove the square wave signal whenever it occurs.
I could clean up the signal by interpolating in between the gap where the square pulse exists. I am struggling to do this automatically could you please give me suggestions on how to detect the pulse edge of the signal so that i can determine the points to interpolate.

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回答（4 个）

Youssef Khmou
Youssef Khmou 2013-6-7
hi,
One you know the mathematical formula of the square pulse you subtract it from your signal, or transform you signal into frequency domain and truncate the frequency of the square pulse,
Can you post an example of your data?
rafael gonzalez
rafael gonzalez 2013-6-7
Here is a copy of the signal for 60 seconds.
15716 16058 15830 15950 15850 16102 15942 15920 16244 16205 16193 15888 15933 16387 16274 16246 16116 16491 16392 16388 16238 16273 16549 16169 16376 16307 16478 16417 16297 16487 16582 16431 16817 16408 16862 16506 16437 16477 16739 16699 16644 16802 16907 16783 16965 16848 16817 16862 16787 17026 16678 16882 16901 16960 17057 17095 17125 17261 17214 17197 16915 16981 17150 17217 17378 17189 17243 17373 17149 17160 17379 17400 17559 17237 17193 17179 17191 17428 17243 17660 17444 17560 17594 17698 17637 17318 17754 17661 17670 17356 17533 17692 17612 17758 17609 17879 17789 17589 17829 18015 18015 18026 17689 17995 18006 17845 18075 18106 18129 17668 17866 18181 17882 18159 17876 17955 17969 18230 18024 18139 18198 18068 18142 17815 18113 18079 18093 18004 18242 18040 18335 18237 18055 18390 18160 18027 18314 18147 18403 18361 18226 18101 18121 18054 18179 18077 18219 18148 18477 18477 18438 18375 18149 18508 18101 18343 18166 18197 18371 18299 18182 18162 18373 18192 18377 18560 18407 18677 18580 18398 18472 18637 18532 18701 18628 18549 18695 18332 18700 18604 18220 18348 18687 18305 18277 18528 18425 18336 18575 18329 18366 18527 18371 18311 18483 18384 18569 18291 18717 18636 18668 18558 18475 18425 18577 18375 18617 18444 18528 18616 18260 18454 18345 18611 18620 18474 18588 18196 18484 18236 18627 18650 18162 18548 18307 18548 18590 18632 18245 18333 18500 18238 18212 18291 18504 18087 18433 18574 18504 18158 18093 18327 18321 18208 18482 18448 18243 18484 18345 18320 18061 18320 18152 18273 17995 18310 18289 18123 18000 18076 18080 17850 17841 17905 18165 17998 18033 17816 18202 18130 17834 18204 18091 18117 18138 17698 17772 18039 17718 18034 17610 17864 17870 17668 18037 17816 17746 17856 17873 17538 17465 17753 17745 17518 17497 17639 17700 17788 17468 17640 17497 17388 17336 17638 17446 17307 17382 17618 17446 17525 17362 17427 17248 17561 17490 17256 17135 17348 17447 17318 17413 17002 17121 16984 16936 16943 17346 17014 17309 16954 17110 16903 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Thanks for taking the time to look at the problem.
Image Analyst
Image Analyst 2013-6-8
Do you have the Signal Processing Toolbox? You could use diff() to identify drops greater than a certain amount and then use a Savitzky-Golay filter to smooth the signal by fitting it to a local polynomial. Or you could try to do an fft on the signal and do a really low pass filter on the signal by zeroing out any frequencies greater than the frequency of the sine wave.
rafael gonzalez
rafael gonzalez 2013-6-8
I managed to solve my problem by just recreating a signal with the similar shape and after filtering the original signal i applied a scale and offset to the new signal i created.
max(original_signal) - min(original_signal) + min(original_signal);
  2 个评论
Image Analyst
Image Analyst 2013-6-8
max(original_signal) - min(original_signal) + min(original_signal);
does not look right because the last two terms cancel out. You didn't tell us that we were able to synthesize a "perfect" signal - I thought all we had to work with was the original signal.
rafael gonzalez
rafael gonzalez 2013-6-9
sorry the correct term is
average = (max(original) + min(original))/2;
%amplitude of 1 * scale and offset
half_of_sinewave * (average) + min(original);
it's still not ideal because it only works if the timing is perfect. i need something to sync the two signals together if they are out of sync.

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