Ground Stations (LUTs)

Ground station (LUT) antennas provide the connection between the satellites and the MCCs

Local User Terminals

Cospas-Sarsat ground stations are called Local User Terminals (LUTs). These LUTS are specifically designed computer stations with designated antennas that are used to catch satellite downlink signals. The LUTs then process the signals received from the satellites and calculate the location of a 406 distress beacon alert. Once that signal is received and processed, the information is transmitted to the mission control center (MCC) that operates that particular LUT. The LUTs are fully automated and completely unmanned at all times.

Image courtesy of Cospas-Sarsat

The type of processing equipment typically found in a MEOLUT

There are two distinct LUT designs used with Cospas-Sarsat satellites. One design has a bowl-shaped parabolic antenna which receives individual signals from one satellite at a time. Depending on the type of satellite, the satellite dish either moves to track the orbits of a low-earth (LEO) and Medium-earth (MEO) satellite or is fixed in a specific direction to catch signals from a geostationary satellite. A second type of ground station or LUT uses an antenna setup called phased array. This type of ground station is configured with two antennas. Each antenna is made up of 64 digital ‘patches’ fixed to the surface of a small flat panel. These antennas are designed to detect multiple moving MEOSAR satellites at the same time.

Image courtesy of Cospas-Sarsat

Phased Array technology takes a different approach to communication with satellites

NOAA manages and operates three-types of LUTs. Low Earth Orbit LUTs (LEOLUTs), Medium Earth Orbiting LUTs (MEOLUTs) and Geostationary Earth Orbit LUTs (GEOLUTs) – All these LUTs are configured to track, receive, and process alerts from 406 distress beacons.

Image courtesy of Cospas-Sarsat

LEOLUT Satellite dishes are pre-programmed to move to pick up a LEOSAR satellite signal as the satellite passes overhead.

Low Earth Orbit LUTs (LEOLUTs)

Each LEOLUT usually consists of a tracking-enabled antenna, a processor, and communications equipment. LEOLUTs track, receive and process alerts from the LEOSAR satellites operated by NOAA as well as other countries. When not within view of a LEOLUT, LEO satellites store the beacon distress signal information onboard until it comes into visual contact with the next LEOLUT. Then it downloads the stored information.

In the U.S., dual LEOLUTs are located at:

Andersen Air Force Base (AFB), Guam
USCG Communications Station, Hawaii
NOAA Command and Data Acquisition Station, Alaska
USCG Communications Station, Florida

Dual LEOLUTs at each site allow NOAA to resolve satellite tracking conflicts and provides redundancy in case of failure.

Click here to see a map of the LEOLUT locations around the world.

Six MEOLUTs are considered the ideal combination to track MEOSAR satellites for fast signal detection, and location accuracy.

Image courtesy of Cospas-Sarsat

The six dome-shaped MEOLUTS in the image above this one are really just shells called radomes with regular satellite dishes inside. They are designed to protect the satellite dishes from bad weather and at the same time allow satellite signals to be received without blockage or distortion.

Medium Earth Orbit LUTs (MEOLUTs)

MEOLUTs track, receive and process alerts from the SAR payloads on U.S. GPS satellites as well as European Union Galileo satellites and Russian Federation GLONASS satellites. The ideal satellite dish configuration for MEOLUTs is six dishes.

In the U.S., six channel MEOLUTs are located at:

USCG Communications Station, Hawaii
USCG Communications Station, Florida

Geostationary, as the name implies, means the GEOLUT satellite dish remains fixed in place, creating a constant connection with the GEOSAR satellite that is locked in synchronous motion with the earth.

Geostationary Earth Orbit LUTs (GEOLUTs)

GEOLUTs track, receive and process alerts from the SAR payloads on the GOES East and GOES West satellites. In the U.S., two GEOLUTs are located in Suitland, Maryland. Both GEOLUTs perform error detection and correction on 406 MHz distress beacon messages and automatically generate alert messages to the USMCC. Although Geostationary satellites cannot determine beacon location unless the beacon is equipped with a GNSS component, these satellites can relay the HEX ID which provides valuable registration information to initiate a search.