providing the necessary current to drive the primary p of the rod position indicator 120 a sixty hertz sinusoidal generator 190 and a twenty hertz sinusoidal generator 200 are both electrically connected to the driver 180 for providing the desired frequency to the driver 180 the driver 180 may be switched between the generators 190 and 200 for changing the frequency of the current of which the driver 180 is supplying the secondary s of the rod position indicator 120 is also connected to another portion of the signal conditioning module 170 for receiving the output signal from the rod position indicator 120 this portion includes a differential receiver circuit 210 for eliminating any extraneous noise contained within the signal which is received from the secondary s a sixty hertz receiver circuit 220 and twenty hertz receiver circuit 230 both function to receive the processed signal from the differential receiver circuit 210 the sixty hertz receiver circuit 220 functions as a bandpass filter for signals having a frequency of approximately sixty hertz similarly the twenty hertz receiver circuit 230 functions as a bandpass filter for signals having a frequency of approximately twenty hertz as will be obvious to those skilled in the art although both the sixty and twenty hertz receiver circuits 220 and 230 receive the signal from the differential receiver circuit 210 only one of the two will at any given time process the signal from the differential receiver circuit 210 and produce an output if the received.