No, mud pulse telemetry doesn't provide much bandwidth - it transmits at around 10 bits/sec. Interesting tidbit: I was told that the flow rate is manually contr

No, mud pulse telemetry doesn't provide much bandwidth - it transmits at around 10 bits/sec. Interesting tidbit: I was told that the flow rate is manually controlled at the surface, as in when a command needs to be sent downhole, a guy goes to the control valve and adjusts it manually. As for using the drill string itself, since there is no separate return path, no current can flow through it. Further, there is no way I can see them setting up a common ground to get a voltage across the drill string. For this reason, they need to run a cable down the drill string to do this.