So, basically I am trying to get the difference in time received between 2 rf pulses from the same source. All I need is a timestamp from each in nanoseconds to be passed to the arduino. The arduino will do the math for the 2 timestamps to get the difference, that part is fine if it is slower. I did the math and as long as the receiver is more than 0.26 meters from the transmitter it won't be quicker than a nanosecond, so I don't need to worry about picoseconds.
What sort of external hardware do you mean?