Systems and methods for improving data communication over less than perfect power lines or transmission lines are described. The systems and methods allow for pushing out electrically any null within a frequency range of interest and/or for lossless transmission by providing impedance matching between communication devices and the transmission line. This is achieved by implementing line equalizing modules within the transceivers, at the transmitter side and/or the receiver side, or by plugging, as a stand-alone module, into an electrical outlet within a building. The line equalizing module includes multiple inductor-capacitor cells coupled in cascade where multiple switches allow for selective and concurrent connection between the inductor-capacitor cells. In another embodiment, the line equalizing module includes variable inductor-capacitor cells. The line equalizing module provides a variable propagation delay that allows for stretching electrically the transmission line. Further improvement may achieve by adjusting the operational frequency using an up-conversion or down-conversion operation.

The present invention relates to inspection apparatus for use in wellbores in the oil and gas industries. In particular the invention relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method and apparatus for determining analog filter parameters for an analog front end comprising a plurality of filter stages receiving signals from a telemetry module, by repeating the steps of; receiving a signal of a known frequency and processing said signal by determining the magnitude of the frequency of the received signal until a plurality of signals have been received and processed; calculating an optimum set of filter parameters in dependence upon the measured frequency magnitudes and a predefined set of filter stage frequency responses.