If you were a mind supervening on the behavior of some massive time/space scale computer, how would you know? How could you tell the difference between running on a human making marks with pen and paper and running on a modern CPU? Your experience updates based on information transformations, not based on how fast the fundamental substrate is changing. When your conscious experience changes, that means your current state is substantially different from your prior state and you can recognize this difference. Our human-scale chauvinism gets in the way of properly imagining this. A mind running on a CPU or a large collection of human computers is equally plausible.
A common question people like to ask is "where is the consciousness" in such a system. This is an important question if only because it highlights the futility of such questions. Where is Microsoft Word when it is running on my computer? How can you draw a boundary around a computation when there are a multitude of essential and non-essential parts of the system that work together to construct the relevant causal dynamic. It's just not a well-defined question. There is no one place where Microsoft Word occurs nor is there any one place where consciousness occurs in a system. Is state being properly recorded and correctly leveraged to compute the next state? The consciousness is in this process.
Another issue is that the brain is overly complex for consciousness to just be received from elsewhere. Typically a radio is much less complex than the signal being received, or at least less complex than the potential space of signals it is possible to receive. We don't see that with consciousness. In fact, consciousness seems to be far less complex than the brain that supports it. The issue of the specificity of brain damage and the corresponding specificity in conscious deficits also points away from the receiver idea.