Breaking Communications 'Stovepipes' -- An All-digital Receiver

The Office of Naval Research has moved the Navy--and all the services--a big step closer to needing only one radio to talk to the many already in service with the development of an all-digital radio receiver. The inherent accuracy and very high processing speed enable these receivers to handle multiple simultaneous signals spread over considerably wider communications bandwidths.

HYPRES Inc., a small New York State company, is building the new digital receivers. Deborah Van Vechten, program officer in ONR's Electronics division, says that this company will deliver a demonstration receiver that simultaneously "digitizes" all the signals in the most critical over-the-horizon military communications bands (HF and VHF) and uses a technique called software-controlled digital filtering to select the signals to output.

Such software control is the fundamental innovation required to realize the Department of Defense's vision for the joint tactical radio system (JTRS) program, now underway, which seeks to develop a generic radio for all the services. This program addresses the lack of interoperability among the "stovepipe-type" tactical radios, in use aboard ships, aircraft, and carried by ground units. Each handle only a single proprietary waveform. Such radios require expensive hardware changes to communicate with other radios. Software control allows the user to select the waveform he wishes to receive and transmit in real time.

During Operation Iraqi Freedom, Marines were overwhelmed with the high number of varied communications equipment they were expected to use, a situation that was exacerbated in some vehicles where every "shelf" was taken up by a radio and seat spaces and floor space was taken up with open computers for communications devices. Marines recounted numerous instances where units would call via one radio to verify that a message was received, while the receiving unit had just put that radio aside to monitor another since a previous unit had called asking about the receipt of a digital photo. In Field Reports during the war, consolidation of communications assets / capabilities was cited as a priority. Software-controlled radios can be customized for multiple missions, integrated with older fielded systems, and be upgraded by the easy and cheap insertion of software modules instead of new hardware.

The services plan to purchase thousands of new JTRS tactical radios per year. The new units should drastically simplify joint operations and logistics support. Only minimal changes will be required for one radio to cover the entire JTRS range (2 Megahertz to 2 Gigahertz), or even the newly announced 2 Megahertz to 55 Gigahertz range.

The new JTRS radios also will replace older analog communications components with digital technology, a change that will reduce the complexity and cost of the radios. HYPRES already is teamed with Boeing, winner of the JTRS "Cluster 1" contract for the Army. The company now is hoping to get selected for Cluster 3, the maritime JTRS, which is managed by the Space and Naval Warfare Systems Command.

Van Vechten says that the HYPRES receiver will be able to listen to signals of varying data rates that have been "layered" on top of each other, improving data transmission rates. She adds that the HYPRES technology also provides a simultaneous "stare and scan" capability that may meet the some of needs of one of ONR's flagship efforts, the advanced multi-function radio frequency system concept, now called AMRF-C. The AMRF-C initiative, set for a major demonstration next year, aims at developing a highly reconfigurable set of antenna apertures to handle all shipboard radio communications, radar, and electronic warfare systems.