Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
sampling frequency would not be for a wave, only samples
To be honest wouldn't you know what the sampling frequency is, since the system over which the digital signal is running is designed by you.
A rough and really rough idea would be to take DFT-FFT (you might have to use a digital spectrum analyzer) and find out the maximum frequency component and assume that Fs would be greater than twice that component