Let me try clarify some more. I'm sending the serial data to a transceiver that sends the information over a powerline. The receiving transceiver pumps out whatever bits it receives on the power line (the transceivers use a special phase modulation to send/receive bits over the power line). However, the power line is noisy, so the sender sends a 0 start bit but the receiver detects that a 1 was sent. The problem is that if that error occurs on a start/stop bit then I can't use ordinary UART to detect it because that will just produce frame errors and/or produce the wrong byte and I will lose out on detecting which bits caused the error.
I just need some way of sampling the serial output of the receiver fast enough to be able to record the full bit stream of what the receiver is detecting.
The serial has to be sent in one long stream and I can't have 'breaks' inbetween because the point is to characterise the powerline as a communication channel in terms of bit errors, and having breaks will not give a good representation.