An electroacoustic transducer has reduced loss due to acoustic waves emitted in the transverse direction. The method combines hybridization of two differently labelled probes A and B on either side of a restriction site, restriction endonuclease digestion, and detection of the labels in the resulting digest. A processor is operatively connected to each of the access point base stations and operative to process communication signals transmitted from a mobile device and determine which signals are first-to-arrive signals based on a common timing signal and conduct differentiation of the first-to-arrive signals to locate the mobile device.