Control circuitry is configured to control a sampler, in a sampling phase determination process, to sample a signal at a sampling period of T\xb1Tn for outputting a sample set for each one of n phases of the sampled signal. The sensor system comprises a camera and an image processing system as well as, if necessary, a distance measuring system, which determines the distance between a predefined zero point and a measuring point on the surface of the piece. The signal processing circuit includes a plurality of signal processing paths with each path scaling the electrical echo signal to a different degree and including a respective analog to digital converter for converting the electrical echo signal to a digital electrical echo signal. The method is especially effective for controlling the presence of gypsy moth caterpillars on trees. The implant abuts a surface of the inferior vertebral bone but does not attach. The junction is adapted to exert sufficient pressure on a portion of a patient’s urethra to prevent unintentional voiding of the patient’s bladder.