# A signal noise analysis method question for a transducer

Let's say a transducer's desired signal is p(t), and the transducer's frequency of interest is 100Hz. And let's assume we dont know the total signal x(t) which is the desired signal plus the noise and interference.

Sample the signal with a proper anti aliasing filter and call it x(t). So we only have x(t) as sampled data at first. Here is what I think:

Now to set the transducer voltage p(t) to a DC value, fix the transducer physically as for an offset measurement.

Now sample the the signal and see the FFT of x(t). If there is 50Hz in the spectrum call it m(t). And for the random/white noise call it n(t).

So we can define the total signal as:

x(t) = p(t) + m(t) + n(t)

*So now I take the average of the x(t) and call it p(t), because m(t) and n(t) averages are zero(?).

Now from the FFT find the power of m(t) call it Pm. Similarly power for x(t), p(t) and n(t) are Px, Pp and Pn.

So for SNR can we write?:

SNR = 10*log10[Pp/(Pm+Pn)]

1-) Do we need to do any windowing here to calculate Pm?

2-) How can Pm be calculated form the FFT of x(t)?