The Joint Tactical Radio and the Navy RF distribution system challenge

Abstract

In an effort to increase communications capability while decreasing life-cycle costs, the US Navy has recently begun procurement of the Digital Modular Radio (DMR), one of the first communications systems to address the requirements under the Joint Tactical Radio System (JTRS). Radios procured in the future must conform to the requirements under the JTRS. These requirements include open architecture, software programmability, use of commercial-off-the-shelf technology, and the ability to transmit or receive at any frequency between 2 MHz and 2.5 GHz. Line of sight communications such as ship-to-ship, ship-to-plane, or ship-to-shore, usually occur in the 30 to 400 MHz frequency range. The wide scale deployment of a JTRS compliant radio is one factor in the need for an advanced RF distribution system. Reducing the number of antennas while increasing communications capabilities presents significant new challenges in the area of electromagnetic interference (EMI). The requirement to reduce EMI is probably the most significant factor in the need for an advanced RF distribution system. One approach to reducing the EMI is an interference mitigation system that taps off some of the transmitted signal, changes its phase by a known amount, and adds it to that at the receive antenna. An advanced RF distribution system is needed to accommodate JTRS compliant systems on US Navy ships. At a minimum the distribution system should accommodate the spectrum of line of sight communications for the JTRS. This is a significant challenge in the area of communications for the US Navy, in the twenty-first century.