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I am working on a sun-synchronous satellite Simulink model wich determines its attitude from a Sun sensor and a star sensor whom measure the sun and star direction in the satellite body reference frame. I have to introduce measure errors on both sensors using a "white noise" Simulink block, but I prefer to generate the noise through a Matlab function block using the function "rand".

My issue is that I have to filter the noises on the measurements before sending them to a block who compute the attitude quaternion error to feed it to a PID controller blockset which commands a Reaction Wheels Assembly. Without noise the satellite flies smoothly.

I have tried some solution such as lowpass filter, Butterworth filter, mean on peaks and downs, but nothing seems to work properly.

I cannot figure out, for example, which should be the cut off frequency to set up on a lowpass filter ( I cannot figure out if the lowpass filter is the correct choice for such a problem, too).

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    $\begingroup$ Somewhat off topic for space SE given this is a maths or signal processing question, but first suggestion is - is your white noise exceeding your signal level? If so no filtering can recover it. Graphing your signal before and after noise addition and filtering will turn this into a classical signal conditioning problem that may be more tractable. $\endgroup$
    – GremlinWranger
    Commented Oct 29, 2019 at 11:03
  • $\begingroup$ Great question for Signal Processing SE instead of this site. It's possible that what you are looking for can be called "pink noise" instead; the word "pink" shows up 108 times there, mostly for 1/f noise though, and what you need may be something different. $\endgroup$
    – uhoh
    Commented Oct 29, 2019 at 11:23
  • $\begingroup$ Thank you both! I forwad my topic on the Signal Processing SE site. $\endgroup$
    – Emperor
    Commented Oct 29, 2019 at 12:10
  • $\begingroup$ Kind regards,Em $\endgroup$
    – Emperor
    Commented Oct 29, 2019 at 12:10
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    $\begingroup$ I see a very similar question here though it's by a different user name. It's generally discouraged to run parallel Stack Exchange accounts as it becomes tempting to start voting for your own questions which is strongly discouraged, detected, and reversed. If you have posted this question on another SE site then the standard procedure is for you to delete your question here. cross-posting the same question in multiple SE sites concurrently is also strongly discouraged. $\endgroup$
    – uhoh
    Commented Oct 30, 2019 at 1:05

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