The AN/SPN-43 is the Navy's marshalling air traffic control (ATC) radar system used on all aircraft carriers and amphibious assault ships for vectoring aircraft into final approach.
The AN/SPN-43C is a two-dimensional, air traffic control, air-surveillance radar system that provides for simultaneous control and identification of aircraft within ownship area of responsibility. The AN/SPN-43C has two sets of transmitters (modulators), receivers, and their associated power supplies; the second set provides an immediate on-line backup capability in case of either a transmitter or receiver equipment failure. The AN/SPN-43C is used in conjunction with the AATC DAIR system for the marshalling and tactical deployment of aircraft. The AN/SPN-43C is also used in conjunction with the carrier-controlled-approach radar for aircraft landing operations. In addition to the above, the AN/SPN-43C serves as a backup short-range, air-search radar system.
The AN/SPN-43 provides azimuth and range information from 50 miles to a minimum range of 250 yards at altitudes from radar horizon to 30,000 feet. Special indicators in the Carrier Air Traffic Control Center enable operators to direct aircraft along a predetermined azimuth to a point approximately one-quarter mile from touchdown. At this point the aircraft is "handed-off" to the final approach controller who uses the AN/SPN-42.
The AN/SPN-43C is a coherent on receive radar system with a pulsed magnetron transmitter. The MTI/MTD upgrade consists of an add-on unit developed from commercial-off-the-shelf (COTS) parts for the VME chassis as well as RF and signal interface boxes. The RF and signal interface boxes provide the necessary connections to the signal processor and the radar. The MTI/MTD upgrade incorporates three key features to improve performance:
- Digital Direct conversion to baseband for improved I/Q phase quadrature performance.
- Equalization of the return with respect to the magnetron transmit pulse.
- Multiple interval clutter cancellation using optimal Doppler filters.
The resulting signal processing features combine to provide better than 50 dB of clutter cancellation from a pulsed magnetron radar. The radar without any upgrade does not have any moving target indicator (MTI)/moving target detection (MTD) capability: this degrades performance in clutter (i.e. land, sea, weather, and birds). In many circumstances aircraft carriers and amphibious assault ships are now required to operate in a littoral environment which is generally high in clutter; MTI/MTD capability in these situations is critical to maintain operation of the Navy's aircraft. The MTI/MTD upgrade provides improved target visibility in clutter over the original radar making it possible to operate and provide the needed ATC for the Navy.
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