A variable gain amplifier that has a high linearity gain stage coupled with a low noise gain stage, and a steering circuit that steers the input signal between these two stages depending on the gain requirement. The apparatus includes means for generating a magnetic flux along a portion of a pipeline wall, means for detecting the magnetic field, and at least one proximity sensor. With the techniques described herein, the touchsurface is constrained to remain in a level orientation while a user presses the touchsurface like a button or key. A polar amplifier amplifies and amplitude modulates the filtered up-converted signal based on the modulating signal to generate a transmit signal. The material may be included in a fixed binder matrix. The active air suspension and adaptive damping system can operate independently of each other, or can work in conjunction with each other to provide the desired output.