It would be interesting to learn more about these systems in the context of today's systems (say, a cell-phone receiving GPS signals), in terms of power received, bandwidth, signal:noise ratio, and so forth.
This kind of comparison can be really enlightening, especially to younger folks. (I'm not one of those folks ... I find it simply amazing how the tiny antenna in my cellphone can receive GPS signals at enough power to be useful for decoding position.)
You may know that GPS is built around pseudo-random sequences. By correlating the known sequence with what you receive, you can extract the signal from a lot of noise. By determining the time offset in the correlation you get the distance from the satellite.
The interesting thing is that Apollo used a very similar system for determining the distance of the spacecraft. They sent a pseudorandom signal from the ground and the spacecraft returned it. By correlating the sent and received signals, they determined the distance of the spacecraft.
This kind of comparison can be really enlightening, especially to younger folks. (I'm not one of those folks ... I find it simply amazing how the tiny antenna in my cellphone can receive GPS signals at enough power to be useful for decoding position.)