I wanted to find out the stability of my system so for that i calculated standard deviation of power samples data which is in dB but I am not sure whether i have used correct formula or not.
As far as I know, I can not directly take standard deviation of the dB, so i converted dB the linear using formula as follow :
After that I take a mean of this linear samples then I calculated variance after that standard deviation and finally calculated standard error and then I converted back this result into dB using following formula:
After converting back to the db the result is very strange I don't know why.
Any guidance on this matter would be highly appreciated.