AN/TPS-71 ROTHR (Relocatable Over-the-Horizon Radar) Transmitter Site

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Description
The AN/TPS-71 Relocatable Over-The-Horizon Radar (ROTHR) is a tactical land-based, bistatic ionospheric backscatter radar system originally designed to provide wide-area surveillance as part of US national defences during the Cold War, but now principally used to track aircraft movements in support of the US national Counter Drug (CD) mission. It enables the detection of aircraft at all altitudes and ships more than 100 ft long at ranges of up to 2,000 nautical miles (2300 miles) offshore and 300 miles inland in an arc of 100°. Each radar provides more than 2.5 million square miles of coverage. At the operator's option the system can be used for overall surveillance and tracking within the coverage area, spotlighting specific regions to handle targets of interest, or the assessment of the size of a target complex.Raytheon quotes the system as detecting and tracking upwards of 8,000 targets per day, nearly three million per year.The ROTHR system was designed to be relocatable to previously prepared sites in support of its original mission of tactical surveillance. As a CD asset, however, it is a permanent installation and the data is remoted to the main Operations Control Centre (OCC) in Chesapeake, Virginia, from each sensor via a high-quality telephone line.The system depends on the ionosphere to see over the horizon. The changing conditions of the ionosphere must be monitored frequently to ensure accurate tracking performance. This monitoring function is usually performed by remote downrange sounding radars. However, the ROTHR provides this function from the sensor location

Status
The Raytheon/TRW team received a contract in 1984 to develop the ROTHR prototype system. It was tested in 1988 in Virginia and later redeployed to Amchitka, Alaska, where it was further tested and became operational. Based on the results of these tests, Raytheon was awarded a contract in 1989 to build three systems. These systems have been completed. The first system was made operational at the site of the prototype in Chesapeake, Virginia, in March of 1993; the second radar is installed near Corpus Christi, Texas, and became operational in June 1995; the third system was installed in Puerto Rico and became operational in 1999. The command and control is networked with the Joint Interagency Task Force (JIATF) South.The system is being continuously upgraded with new hardware and software under contracts to Raytheon and others. In 2003 Raytheon was awarded a USD24.8 million contract for operation and maintenance services. Work was expected to be completed by September 2004. In January 2005 a further five year (one plus an optional four) contract worth a potential USD93.9 million was awarded for operation and maintenance, engineering and training services.In October 2005 Raytheon was awarded a five year indefinite delivery, indefinite quantity USD52 million contract to provide further engineering services. The work will support plans for the ROTHR's role to be expanded to include a surveillance capability for homeland defence.In August 2007 Raytheon was awarded a further contract modification worth an estimated USD72.7 million for the provision of 'additional projected requirements.
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