Radyne Corp. in Phoenix and General Dynamics C4 Systems in Scottsdale, Ariz., are introducing a troposcatter over-the-horizon modem called the TM-20 for long-distance data communications. Troposcatter communications is the ability to transmit radio waves over the curvature of the Earth by bouncing signals off small changes in humidity, temperature, and pressure in the troposphere approximately six miles above the Earth’s surface. The TM-20 will have the General Dynamics VertexRSI brand name. The TM-20 moves data at speeds as fast as 20 megabits per second. The modem also provides support for a variety of communications techniques to make the most of transmission range and data integrity. The U.S. military now employs AN/TRC-170 troposcatter systems using 1980s technology for tactical and strategic communications throughout the world; several terminals are deployed in the Middle East. For more information contact Radyne online at www.radyne.com, or General Dynamics C4 Systems at www.gdc4s.com.