Abstract: In one example, a long endurance airship system includes a first combined airship with a payload airship and a first logistics airship. The first combined airship is configured for stationkeeping at a predetermined station during meteorological conditions with wind speeds below a predetermined threshold. The airship system also includes a second combined airship which is a reconfiguration of the first combined airship and includes the payload airship and a second logistics airship. The second combined airship is configured for stationkeeping at the predetermined station in all meteorological conditions, including meteorological conditions with wind speeds above the predetermined threshold.

Abstract: A method for launch of an airship includes connecting a cargo airship to a deflated second airship, launching the cargo airship, inflating the second airship with lifting gas carried by the cargo airship while aloft; and releasing the second airship from the cargo airship. A high-altitude airship launch system is also provided.

Abstract: A system for lifting gas replenishment in a tethered airship system includes an upper airship with a first end of a tether attached to the upper airship. A balloon is configured to travel up the tether toward the upper airship carrying a payload of lifting gas. A method for gas replenishment of an airship is also provided.

Abstract: An illustrative airship system for long endurance stratospheric operations includes an upper airship and a first end of a tether attached to the upper airship. A lower airship is attached to a second end of the tether and a payload airship is reversibly mated to the lower airship. The airship system is free flying and configured to maintain long duration station keeping. Illustrative methods for long endurance stratospheric operations are also provided.

Abstract: In one example, a tethered airship system for high altitude long endurance missions includes a first airship configured to be equiliberally buoyant in a first altitude range and a second airship configured to be equiliberally buoyant in a second altitude range, such that the first airship is at least five kilometers above the second airship. The first airship and second airship are connected by a tether.

Abstract: A system for lifting gas replenishment in a tethered airship system includes an upper airship with a first end of a tether attached to the upper airship. A balloon is configured to travel up the tether toward the upper airship carrying a payload of lifting gas. A method for gas replenishment of an airship is also provided.

Abstract: A method for launch of an airship includes connecting a cargo airship to a deflated second airship, launching the cargo airship, inflating the second airship with lifting gas carried by the cargo airship while aloft; and releasing the second airship from the cargo airship. A high-altitude airship launch system is also provided.

Abstract: An illustrative airship system for long endurance stratospheric operations includes an upper airship and a first end of a tether attached to the upper airship. A lower airship is attached to a second end of the tether and a payload airship is reversibly mated to the lower airship. The airship system is free flying and configured to maintain long duration station keeping. Illustrative methods for long endurance stratospheric operations are also provided.

Abstract: In one example, a long endurance airship system includes a first combined airship with a payload airship and a first logistics airship. The first combined airship is configured for stationkeeping at a predetermined station during meteorological conditions with wind speeds below a predetermined threshold. The airship system also includes a second combined airship which is a reconfiguration of the first combined airship and includes the payload airship and a second logistics airship. The second combined airship is configured for stationkeeping at the predetermined station in all meteorological conditions, including meteorological conditions with wind speeds above the predetermined threshold.

Abstract: A system and method to transmit and receive forward error corrected data in a diversity communications system is provided. Using diversity techniques, multiple copies of the transmitted data are received with varying degrees of corruption due to channel impairments. In addition to the multiple copies of forward error corrected data, an additional data set of implicit parity bits is used in the data decoding process, wherein the reliability of these parity bits is assumed to be very high. The implicit parity bits are not transmitted or received by the system, but are introduced in the receivers' decoding process. These implicit parity bits add an extra highly reliable dimension of forward error correction codes. Therefore the present system and methods provide an improved data decoding process with high coding gain and channel efficiency, while minimizing system resources.

Abstract: The present invention is directed to the determination of a relative position between moving platforms, using satellite-based navigation techniques and equipment installed on said platforms. It combines the concepts of observation-space and navigation-space differential systems, and operates a DGNSS base station in a time-varying mode, in order to rely on the built-in differential positioning and navigation capabilities of particular GNSS receivers while minimizing datalink loading and computational load in auxiliary processors. The invention achieves accurate relative positioning and navigation with respect to a moving base station, using DGNSS equipment that assumes it is stationary when operated in a reference station mode.

Abstract: The present invention is directed to the determination of a relative position between moving platforms, using satellite-based navigation techniques and equipment installed on said platforms. It combines the concepts of observation-space and navigation-space differential systems, and operates a DGNSS base station in a time-varying mode, in order to rely on the built-in differential positioning and navigation capabilities of particular GNSS receivers while minimizing datalink loading and computational load in auxiliary processors. The invention achieves accurate relative positioning and navigation with respect to a moving base station, using DGNSS equipment that assumes it is stationary when operated in a reference station mode.

Abstract: A system and method to transmit and receive forward error corrected data in a diversity communications system is provided. Using diversity techniques, multiple copies of the transmitted data are received with varying degrees of corruption due to channel impairments. In addition to the multiple copies of forward error corrected data, an additional data set of implicit parity bits is used in the data decoding process, wherein the reliability of these parity bits is assumed to be very high. The implicit parity bits are not transmitted or received by the system, but are introduced in the receivers' decoding process. These implicit parity bits add an extra highly reliable dimension of forward error correction codes. Therefore the present system and methods provide an improved data decoding process with high coding gain and channel efficiency, while minimizing system resources.

Abstract: The present invention applies a two dimensional turbo product code to data packets handled by a data transmitting communications equipment before the data is processed by data communications equipment. The data packets are sequentially numbered and sized appropriately for transmission. The turbo product coding of the data packets allows the receiving equipment to compensate for packets that have been lost in transmission or discarded due to errors. The coding/decoding strategy may be optimized to allow for varying latency based on the severity of the errors encountered on a channel and according to the message flow rates of the transmitting equipment.

Abstract: An improved GPS or GNSS receiver can operate at low signal levels and in the presence of RF interference including multipath. Three separate technologies known in the prior art are integrated: a) vector tracking of multiple parameters in a multi-dimensional state space; b) fast correlation processing (107) of GPS or GNSS signals; and c) multiple signal characterization based on eigenvalue/eigenvector analysis of correlation matrices.

Abstract: The present invention uses a VDL Mode 4 RF network as the primary transmission path for data transmitted from aircraft to ground stations, and one or more separate non-VDL Mode 4 RF network(s) as the primary transmission path for data transmitted from ground stations to aircraft. The unique characteristics of each network provide for a cost-effective solution to the two-way aeronautical networking problem.