A search and rescue system comprising: a plurality of reference beacons deployed across remote locations, each reference beacon having a known geographical location; and a ground-based station having one or more antennas for communicating with the plurality of reference beacons via a plurality of Earth-orbiting satellites; wherein the ground-based station is configured to receive via the plurality of Earth-orbiting satellites, reference signals from each of the reference beacons and calculate estimates of the locations of the reference beacons from the received reference signals, wherein the location estimates are based on frequency and time parameters obtained from signals transmitted along different paths between known positions of the plurality of reference beacons, the plurality of Earth-orbiting satellites, and the ground-based station; wherein the ground-based station is further configured to receive via a plurality of Earth-orbiting satellites, location information related to the known geographical locations of the reference beacons and calculate system calibration factors based on the calculated location estimates of at least one reference beacon and the received location information of the at least one reference beacon; wherein the reference beacons comprise a global navigation satellite system (GNSS) receiver configured to receive signals from a plurality of GNSS satellites, and wherein the reference beacons are configured to transmit the reference signals based at least in part on signals received from the plurality of GNSS satellites via the GNSS receiver; and wherein the ground-based station is further configured to receive distress signals from at least one distress beacon via at least one of the Earth-orbiting satellites and calculate an estimate of the location of the distress beacon from the received distress signals, wherein the calculated location estimate of the distress beacon is calibrated based on the calculated system calibration factors. a plurality of reference beacons deployed across remote locations, each reference beacon having a known geographical location; and a ground-based station having one or more antennas for communicating with the plurality of reference beacons via a plurality of Earth-orbiting satellites; wherein the ground-based station is configured to receive via the plurality of Earth-orbiting satellites, reference signals from each of the reference beacons and calculate estimates of the locations of the reference beacons from the received reference signals, wherein the location estimates are based on frequency and time parameters obtained from signals transmitted along different paths between known positions of the plurality of reference beacons, the plurality of Earth-orbiting satellites, and the ground-based station; wherein the ground-based station is further configured to receive via a plurality of Earth-orbiting satellites, location information related to the known geographical locations of the reference beacons and calculate system calibration factors based on the calculated location estimates of at least one reference beacon and the received location information of the at least one reference beacon; wherein the reference beacons comprise a global navigation satellite system (GNSS) receiver configured to receive signals from a plurality of GNSS satellites, and wherein the reference beacons are configured to transmit the reference signals based at least in part on signals received from the plurality of GNSS satellites via the GNSS receiver; and wherein the ground-based station is further configured to receive distress signals from at least one distress beacon via at least one of the Earth-orbiting satellites and calculate an estimate of the location of the distress beacon from the received distress signals, wherein the calculated location estimate of the distress beacon is calibrated based on the calculated system calibration factors.