author = "Pamboukian, Sergio and Kaufmann, Pierre and Moraes, Rodolpho 
                         Vilhena de and Kaufmann, Pedro L.",
          affiliation = "{Universidade Presbiteriana Mackenzie} and {Universidade 
                         Presbiteriana Mackenzie} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Universidade Federal do Estado de S{\~a}o 
                         Paulo (UNIFESP)}",
                title = "GNSS-FREE geo-referecing system using multiple LEO CUBESAT 
                 year = "2016",
         organization = "Latin American IAA CubeSat Workshop, 2.",
             abstract = "CubeSats are ideal transponder carriers to integrate a new 
                         GNSS-free geo-referencing system. The system concept might be 
                         viewed as an in-verted GPS configuration, utilizing four 
                         groundbased reference sta-tions and a number of repeaters in 
                         space. A time signal transmitted by one of the reference bases is 
                         retransmitted by transponders in space, re-ceived back at the 
                         bases, producing four ranging measurements for each satellite. The 
                         measurements are corrected for time delays in every time coded 
                         retransmission caused by three main sources: the transit time at 
                         the transponders, the path delays, and delays at the ground-based 
                         trans-mitter and receivers antennas, cables and electronics. An 
                         algorithm compares the repeaters positions for at least two groups 
                         of three refer-ence bases, minimizing unknown signal delays, 
                         providing the accurate position for each repeater. Once the 
                         repeaters coordinates are known, the other determinations and 
                         applications become straightforward. It is demonstrated by 
                         simulations, based on the system performance algo-rithms, that 
                         with a formation of at least four repeaters, the position of a 
                         remote target is determined for a single coded time signal 
                         transmission. A formation of multiple CubeSats in low earth orbits 
                         (LEO) is particular-ly suitable to accomplish the new 
                         georeferencing system. Simulations are presented, exhibiting 
                         accuracies which may become comparable to other space-based 
                         systems. This system has various strategic and eco-nomic 
                         applications in remote clock synchronism, navigation and target 
                         geo-positioning. It may be used as a backup to GNSS location 
                         systems in critical applications, or when such systems are not 
  conference-location = "Florian{\'o}polis, SC",
      conference-year = "28 Feb. - 02 Mar.",
           targetfile = "pamboukian.pdf",
        urlaccessdate = "04 dez. 2020"