Is it possible to subtract two waveforms without a common reference or ground?

[juming]

Morning :)
I am trying to sample two different waveforms, and subtract the one from the other. Basically, I have A, B, and want C=A-B.
The device calculating the C=A-B is remote, connected to the two sampling A and B via a wireless link.
A and B do not have any common reference or ground, and the devices sampling them are battery operated.
Can I simply take the potential difference between A and a battery's negative terminal... and B and the next battery's negative terminal... and assume that the negative terminals are equal, such that I now have two waves that I can subtract from each other to get a proper difference between the two?

 

[berkeman]

It sounds like each floating wireless sensor is sending the amplitude of A and the amplitude of B. As such, they are stand-alone quantities, without any reference anymore. So yes, just do a simple arithmetic subtraction at the receiving end of the wireless link.

 

[ravenprp]

Morning! It is possible to subtract two waveforms without a common reference or ground, but it may not be accurate or reliable. When subtracting two waveforms, it is important to have a common reference or ground to ensure accurate measurements. Without a common reference or ground, there could be errors introduced into the subtraction calculation, resulting in an incorrect or unreliable waveform.

In your situation, taking the potential difference between A and a battery's negative terminal and B and the next battery's negative terminal may provide a rough estimate of the difference between the two waveforms, but it may not be precise. This is because the negative terminals of the batteries may not be exactly equal, and there could be variations due to battery life or other factors.

Therefore, it is recommended to have a common reference or ground when subtracting two waveforms to ensure accuracy and reliability in the measurement. This can be achieved by using a common ground wire or by connecting the devices to a common power source. I hope this helps clarify your question. Have a great day!