The US Navy operates an air combat maneuvering instrumented range, the Charleston Tactical Air Crew Training System (TACTS), off the Georgia coast. During training exercises, aircraft telemetry is relayed from tactical aircraft to a series of offshore platforms. A multi-hop digital microwave communications network relays the data between the platforms and the system operations center at the Marine Corps Air Station at Beaufort, South Carolina.
The microwave network was failing to meet reliability and availability requirements, making the range unusable for pilot training. The Howland Company was asked to evaluate the system and propose corrective measures.
System operators reported that propagation issues over the 47-mile microwave hop from the central offshore platform to the 1200-foot onshore tower were the source of frequent full-blown system crashes. We evaluated the microwave path, inspected the equipment configuration and measured transmit and receive signal levels over the RY1-R2 hop and identified several issues that limited the effectiveness of the network. We proposed replacing non-standard radios with commercially available models, repositioning preselector filters, and a new dual frequency space diversity configuration at both sites. After the Navy implemented these changes, the system performed at the required 99.995% reliability.