Abstract: Certain embodiments make use of an array of passive primary concentrators positioned on the ground that provide primary concentrated solar radiation from below to an array of tracking secondary concentrators. The secondary concentrators further concentrate the solar radiation to one or more centralized receivers. The solar concentrator system may include apparatus for collection of solar radiation, concentration, and the absorbance of the concentrated solar energy. Some embodiments of the solar concentrator system include a large field of passive horizontal primary concentrators, overhead tracking secondary concentrators, and one or more receivers, which convert solar radiation into usable products or energy, such as electricity.

Abstract: A geographic tracking system with minimal power and size required at the mobile terminal collects observation data at the mobile terminal, forwards the data to a processor, which calculates the position. The mobile terminal needs only to gather a few milliseconds of observation data, and to relay this observation data to the processor. The range from the satellite (or other airborne transponder) to the terminal is determined using the known positions of an interrogating transmitter and a satellite, and a known terminal delay between the received signal and the transmission of the return signal, and the round trip time. An arc of locations is determined by computing an intersection of a sphere centered at the satellite having a radius given by the calculated range with a model of the Earth's surface. Only that portion of the arc within the region bounded by the satellite beam pattern is retained. Next, the time when the mobile terminal collected the GPS signal is determined.