I have seen several times boards which have "digital grounds" and "analog grounds". Different devices are connected to one or another depending of the type of signal they are manipulating.

Back at the power supply common, they are interconnected with an inductor.

At DC, they are essentially the same ground. But at higher frequencies, or the harmonics of those frequencies, they will be an open circuit. The idea is to prevent digital noise from corrupting sensitive analog circuitry.

This makes sense! I get the idea. I assume that hooking both GND types together would not be a dangerous thing like causing a short or something like that, right? As I understand it has more to do with having cleaner signals in terms of noise, etc at sensitive parts of the circuit as you pointed.

Thanks

 

Correct

 

For certain mains connections in hospitals and transmitters you might have two grounds. One is a reference and the other for faults.

You can buy orange 120V outlets which are designed for "isolated ground" applications. The outlet ground goes all the way back to the main panel without stopping. The protective ground goes to the outlet box case.