Some examples disclosed herein include a method. The method may include determining a relationship between a property of a position, navigation, and timing (PNT)-based timing signal and a property of a virtual time source. The method may also include determining a state of the PNT-based timing signal at least partially responsive to the determined relationship. The method may also include one or more of: providing the PNT-based timing signal at least partially responsive to determining that the state of the PNT-based timing signal corresponds to a first state, disregarding the PNT-based timing signal at least partially responsive to determining that the state of the timing signal corresponds to a second state, and providing an indication of the state of the PNT-based timing signal at least partially responsive to determining that the state of the timing signal corresponds to a second state. Related devices, systems and methods are also disclosed.