In many underwater applications it is impractical, unsafe, or inconvenient to penetrate a housing, hull, or pressure vessel with wire penetrators for data and power transmission. However, neither acoustic methods nor traditional RF wireless data communications technologies will work in most of these applications due to the materials involved. Modern pressure hull materials include aluminum, steel, and titanium depending on the specific application. The highly conductive nature of these hull materials result in the hull acting as an RF blocking Faraday cage thus preventing RF wireless communications. The degree to which RF is blocked depends on the electrical conductivity of the material.

Acoustic through-hull communications methods can be extremely data rate limited through materials which experience multipath and multimodal acoustic effects in thin barriers. Additionally, acoustic methods require a good acoustic interface to each side of a hull or barrier. Finally, neither acoustic nor RF techniques are able to pass usable amounts of power along with data through hull materials.

An alternative to wireless RF communications or through-hull acoustics is the Hull Penetrator Replacement System (HPRS) developed by Hydro Technologies. This system is designed to eliminate the need for hull penetrations while still allowing for high speed, low power, and secure data and power transmission between systems inside and outside of a pressure hull or other material. To accomplish this, HPRS uses a technique referred to as multi-frequency local magnetic field modulation to produce magnetic fields capable of carrying data and power through almost any material. US and International Patents for this technology have been applied for.

The HPRS platform has application anywhere data and/or power needs to be communicated from one side of a hull, pressure vessel, pipe, or other barrier to the other within a range of about 1 meter. Along with permanent installations such as placing sensors in sealed containers, HPRS is also appropriate where data and power is required through a barrier without permanent modification.

Some of the many applications of HPRS include:

􀂄 Inter-pressure vessel communication on UUVs and ROVs

􀂄 Supporting testing for new sensors on manned submersibles and submarines without alterations to the hull

􀂄 Temporary installation of multibeam or acoustic positioning equipment on vessels of opportunity

􀂄 Simplification of moored ocean floor sensor connectors

􀂄 Transmission of sensor data and power through the wall of sealed containers such as nuclear waste storage containers

􀂄 Data communication through pipe walls

􀂄 High speed (1 Mb/s) data transfer and power transmission through materials such as aluminum, stainless steel, titanium, fiberglass, glass, seawater, and air

􀂄 Moderate speed data (10-50 kb/s) and low power transmission though magnetic materials such as HY-80.

􀂄 High temperature applications (transducers have been tested to 200° C)

Availability

The core of the HPRS platform has been field tested and is in use in active US Navy submarine applications. The HPRS system is currently being made available to select partners with full availability expected by the fourth quarter of 2009.

Why use HPRS?

Eliminate Connectors:        HPRS technology eliminates the need for drilling pass through holes in pressure hulls for communications and power transmission

High data rates: Since HPRS is a direct through the-hull communications technique, data rates of >1Mb/s can be achieved depending on materials

Power Transmission: Along with data, HPRS supports transferring power through hulls or barriers utilizing low frequency magnetic field generation for inductive power coupling

Low signature:  Since HPRS is a non acoustic technique, there is no acoustic signature. The magnetic fields are extremely localized and result in no detectable field except in the immediate vicinity of the transducers

Secure communication: HPRS is compatible with digital encryption to prevent outside sources from unauthorized access. HPRS supports the 256-bit AES encryption standard which has been cleared for Top-Secret transmissions by the NSA as of June 2003.