Decoding position information in space-based systems

A method, comprising:

• receiving, from each of a plurality of satellite-based receivers, a pair of messages received by each of the plurality of satellite-based receivers, the pair of messages comprising encoded position information of a transmitter of the pair of messages;
• decoding the encoded position information;
• determining a pool of a plurality of candidate locations for the transmitter based on the decoded position information;
• and
• for each of the plurality of satellite-based receivers:
• determining whether each candidate location in the pool is within a coverage area for the satellite-based receiver;
• and
• if any candidate location in the pool is not within the coverage area for the satellite-based receiver, removing that candidate location from the pool.

A terrestrial processing center that tracks aircraft positioning using a multi-satellite, satellite constellation, the terrestrial control center comprising:

• one or more processing elements;
• and
• a non-transitory, computer-readable storage medium storing computer-readable instructions that, when executed by the one or more processing elements, cause the terrestrial control center to:
• process pairs of compact position reporting (“CPR”) encoded, automatic dependent surveillance-broadcast (“ADS-B”) surface position messages received from each of one or more space-based receivers, the pairs of messages comprising encoded surface position information of a transmitter of the pair of messages and having been received by each of the one or more space-based receivers;
• determine a latitude component of a location of the transmitter based on the encoded surface position information;
• determine a pool of a plurality of candidate longitude values for the location of the transmitter based on the encoded surface position information;
• select a longitude component of the location of the transmitter of the message from the pool, wherein the selecting comprises:
• eliminating each candidate longitude value from the pool that is not within a coverage area of each of the one or more space-based receivers;
• eliminating each candidate longitude value from the pool that is not within a predetermined distance of at least one previous candidate longitude location from a previous pool of candidate longitude values;
• determining that a remaining candidate longitude value is within the coverage area of each of the one or more space-based receivers;
• determining that the remaining candidate longitude value is within the predetermined distance of at least one previous candidate longitude location from the previous pool of candidate longitude values;
• and
• selecting the remaining candidate longitude value based on determining that the remaining candidate longitude value is within the coverage area of each of the one or more space-based receivers and within the predetermined distance of the at least one previous candidate longitude location;
• determine the location of the transmitter based on the determined latitude component and selected longitude component;
• and
• transmit the determined location of the transmitter to an external system.