US Patent 10371845 Acoustic ranging apparatus and methods

A ranging system comprises a plurality of streamers, each with a plurality of receivers. A plurality of transmitters is also disposed along one or more of the streamers, each configured to generate acoustic or ranging signals over one or more channels. A processor is configured to define a subset of the transmitters within a predefined limited range or listening distance of each receiver. In the subset, the transmitters are configured to generate the acoustic signals over different channels.