Patent ID: 7940192

Claim:
A method of communicating a signal through a fluid in a borehole between a downhole source location and a surface location, the method comprising: generating a message signal at the source location and receiving a first signal at the surface location responsive to the message signal; and estimating the message signal by applying a channel equalization filter to the first signal; wherein the channel equalization filter is derived at least in part from a measured signal at the surface location responsive to a reference signal at the downhole location and minimizing an error function of the form: ε 2 =( s ref −{circumflex over (r)} ref *h inv ) 2 where ε 2 is a function being minimized, s ref is the reference signal, h inv is the equalization filter, and {circumflex over (r)} ref is a signal received at the surface location responsive to the reference signal.