SBIR-STTR Award

Underwater Acoustic Modems (UW-A) have seen significant R&D and commercial product introductions in recent years. Standards including JANUS (NATO) and JSATS (USACE), have emerged. Yet, interoperability remains limited due to the generally proprietary nature of commercial products, the complexity and vulnerability of high bandwidth options, and high costs/size/power consumption limiting modem use in smaller and expandable platforms. The adaptive Simple Acoustic Modem (aSAM) builds on the design philosophy of our commercial SAM-1 modem, which has achieved success in cost sensitive yet demanding applications, in particular commercial fishing. As with SAM-1, aSAM will be small and inexpensive with minimal power consumption and low design complexity. A frequency agile software defined modem, aSAM will boost performance by supporting modulation methods such as very high-speed high-frequency PSK burst transmissions that capitalize on advantageous aspects of underwater sound propagation, yet can be implemented in a small, low power consumption, affordable modem. aSAM will boost interoperability through JANUS compatibility. A dual-band design, it can switch to faster modes after a JANUS link is established. The design will encourage collaboration and third party manufacturer adoption by publishing all coding schemes and supporting code, and providing users with a development environment to implement their own coding schemes.

During phase-1, we designed and then manufactured a batch of electronics modules (EM-60) for an underwater acoustic modem, named aSAM, the adaptive Simple Acoustic Modem. aSAM is optimized for use in smaller and expandable UUV where size, power consumption and cost are all important design factors. aSAM emphasizes relatively simple and adaptive methods to identify and utilize advantageous aspects of the acoustic path. For example, rather than compensating for acoustic reverberations using processing intensive methods, aSAM will identify and utilize the brief reverberation free period before indirect signals arrive to burst-transmit data at a very high speed. In phase-2, we will at first implement and in-water test a base set of acoustic communication protocols. The communication protocols will include the NATO standard JANUS (ANEP-87) to provide wide interoperability, and a new methods, environment adaptive PSK burst communications. aSAM is a software defined modem. While fast progress towards a useful and vehicle integration ready capability set will be the first priority, the project will also include additional advanced capabilities. UUV must operate in varied underwater environments and be responsive to many mission requirements. We consider the solution lies not in any one particular communication method, but in modem agility with a broad set of options and methods to meet the conditions and circumstances at hand. Advanced capabilities will include for example passive ranging and bearing determination for a communication partner. And based on that information, the use of directed rather than omnidirectional acoustic transmissions that may reduce reverberations and boost speed. Once within close range, a switch to off-band ‘buddy channel’ communications may be initiated. As an open platform, aSAM will be supported by a comprehensive developer environment. And in order to minimize both technical performance and time risk, in-water field testing will be woven through the project from the beginning.