The disclosure is directed to method and apparatus for communication through a fluid. The method includes measuring signals in the fluid at at least two spaced apart positions; estimating a subset of a separation matrix; and using the estimated subset and the signals to estimate a signal sent by the message source. The apparatus may include a message source on a bottom hole assembly; sensors disposed at least two spaced apart locations; and at least one processor configured to: estimate a subset of a separation matrix based on the signals and use the subset to estimate a message signal set by the message source.