A method and apparatus for reducing echo in a communication system are provided. A hydraulic control system leads pressurized hydraulic fluid into and out of a hydraulic fluid space such that the stress element causes a stress pulse in the tool. The content is presented in a presentation skin selected from a number of available presentation skins. The first and second voltage rails form a grid overlying the power switching circuit, the first and second voltage rails being formed in different planes relative to one another. An exact analytic inversion is then found for this idealized model. Thus, it is possible to make a circumference of a dielectric layer even although a dielectric material to be used is low in viscosity.