Telesonar Testbed Instrument Provides a Flexible Platform for Acoustic Propagation and Communication Research in the 8 – 50 kHz Band

The underwater channel remains a difficult medium for transmitting communication signals. Frequent field tests are required for validating models, testing new waveforms and coding schemes, developing link protocols, designing an adaptive multi‐mode modem, testing third‐party prototype modems, testing a new directional transducer, and developing new DSP‐efficient algorithms. A modular, flexible, autonomous instrument was designed to easily and inexpensively conduct such field tests. This instrument, called the Telesonar Testbed, was originally designed five years ago to specifically support the Telesonar Program at the Space and Naval Warfare Systems Center, San Diego. It has since taken on a wider role supporting the High‐Frequency Initiative, the SignalEx project, and a new project testing Multiple Input/Multiple Output (MIMO) systems. Over the last five years several major design changes have been made, making it smaller, lighter weight, more reliable, and acoustically commandable. This paper will describe the design and features of this instrument which has been the centerpiece of 10 experiments to date. This paper will also apply six carrier estimation and six symbol timing estimators to data received by the Telesonar Testbeds in the KauaiEx and ElbaEx Experiments.