Aerospace Patents 2011

G. Lui and K. Tsai, “Noncoherent Symbol Clock Recovery Subsystem,” U.S. Patent No. 7,864,887, Jan. 2011.

Digital communication systems transmit data by various carrier modulation techniques that typically involve synchronization of a transmitter clock and a receiver clock. This invention allows a receiver to recover the symbol epoch timing of a randomly modulated digital signal that may be noncoherently received through a noisy channel. A tap-delay line implementing a clock bank is used to sample the received signal at different times to generate time-staggered samples of the received signal, which are then fed through mean-magnitude generators to provide mean magnitudes that are insensitive to the phase offset of the carrier-signal. As the tap of the delay line that produces the largest mean magnitude is expected to be the closest to peak signal sampling timing than the other taps, its position in the delay line can be taken as an estimate of the timing offset between the transmitter and receiver clocks. This subsystem effectively provides rapid acquisition of the data symbol epoch of a signal received with arbitrary carrier phase. An advantage of the symbol clock recovery subsystem is its easy implementation and rapid acquisition performance even in noisy channels.

R. Douglas, “GPS M-Code Receiver Tracking System,” U.S. Patent No. 7,899,109, March 2011.

The GPS M-code autocorrelation function has seven modes or peaks, all indistinguishable with respect to conventional correlator tap arrangements. A problem with tracking the M-code signal is that it is not always clear which peak is being tracked. This results in either accurate but ambiguous tracking, or unambiguous but inaccurate tracking. This invention describes an M-code tracking system for use in a weak-lock, ultratight, or coherent navigation system. It determines multimodal code-phase errors by means of a coherent envelope, with the current mode aligned to a current code phase of a multimodal signal. The coherent envelope can encompass the multimodal correction function or a coherently received signal—for example, the autocorrelation function of a coherently received C/A-code signal. The system unambiguously and precisely determines the code-phase error of a multimodal spread-spectrum signal. By detecting a coherent envelope and unambiguously determining the mode, precise multimodal code-phase errors can be determined for improved tracking.

M. L. Polak, C. D. Nealy, J. P. Stafsudd, et al., “Infrared Gas Detection and Spectral Analysis Method,” U.S. Patent No. 7,956,761, June 2011.

Infrared spectroscopy is a rapid, sensitive, and chemically specific technique for chemical identification and quantification. When infrared spectroscopy is used continuously, threat and interferent chemicals could contaminate the infrared sensor. This invention is a data processing method for detection of threat chemicals contained in a user-specified list. The background model, which is key to this invention, is based on recent data history. Unless a threat chemical is detected in a given spectrum, that spectrum is used as part of the background model even if it contains signatures from interferent chemicals. As a result, detection of interferent chemicals is suppressed, but sensitivity towards the targeted threat chemicals is enhanced. When a threat chemical is detected, its concentration and detection confidence level is reported. The confidence level can then be used in an alarm decision process. The method can be operated continuously without human intervention, does not require independent calibration, and provides for sensitive detection with reduced false alarms. Its primary application is in infrared point detectors, which continuously protect a site.

B. B. Brady, “Noncircular Transient Fluid Fuel Injector Control Channels in Propellant Injector Combustion Systems,” U.S. Patent No. 7,958,719, June 2011.

Pulsed bipropellant thrusters are commonly used on spacecraft for in-space propulsion. Current propellant injector systems use conventional dribble channels and injectors producing mismatches in fuel and oxidizer delivery, contamination, and spikes in the combustion performance. Incomplete combustion could be one of the factors contributing to the low efficiency and high variability of pulsed thrusters. This invention provides for a fuel injector design that solves or reduces these disadvantages. It includes noncircular fuel and oxidizer injectors at the end of respective dribble channels to control the mixture of the propellants passing into a combustion chamber, thereby maintaining a desired mixture ratio and achieving a synchronized flow response. Synchronization of the propellant response times will prevent shifts in the mixture ratio, and lead to damping of pressure fluctuations and more stable combustion.

J. V. Osborn et al., “Surface Plasmon Polariton Actuated Transistors,” U.S. Patent No. 7,960,753, June 2011.

Conventional semiconductor interconnects suffer from increased dark current, limited frequency response, and relatively low bandwidths as compared to the optical regime. Semiconductor devices also suffer from polarization dependence limiting the plasmon waveguide. The invention is directed to a new class of semiconductors called plasmon polariton semiconductors, which receive and react to input excitation. These devices have a terminal that is electronically controlled by a surface plasmon waveguide, and a tip referred to as surface plasmon wire. The surface plasmon device solves the problem of slow interconnection by utilizing surface plasmon polariton wire structures as interconnects to the transistors comprising an integrated circuit. These devices can be applied to systems generally for large-scale chip interconnects. The small photo absorption volume of these devices reduces the dark current. Therefore, these devices can be used to make high-sensitivity infrared detectors.

A. D. Stapleton et al., “Electrically Tunable Plasmon Light Tunneling Junction,” U.S. Patent No. 7,961,995, June 2011.

The growth in demand for optical communication capabilities has created a renewed interest in nanoscale optical sources. This light source invention aims to fill the need for a compact high-speed optical emitter that can be modulated at speeds greater than 100 GHz. This emitter offers significant size, weight, and power advantages over the current field of semiconductor solid-state light emitters. Light emission is produced through the inelastic tunneling of electrons through a thin insulator that is sandwiched between two metal electrodes. As electrons tunnel through a thin insulator, they emit light through a scattering process. Light is coupled out of the small area tunnel junction through a gradual tapered contact. This tapered transition between the several-nanometer-thick tunnel junction and micron-scale output waveguide makes this invention more efficient than previous incarnations. Without the taper, light emitted in the tunnel junction would be absorbed in a few tens of nanometers by the surrounding metal electrode structure. The entire structure can be constructed with materials that are compatible with standard CMOS fabrication processes. Therefore, this device can be integrated within silicon microelectronic devices without requiring the complex and costly hybrid integration of other semiconductor materials. Applications include chip-to-chip and board-to-board level data communication at data rates that would otherwise be impossible with conventional electrical interconnects.

K. Siri, “Converter Channelized Uniform Power Distribution System,” U.S. Patent No. 7,964,991, June 2011.

Multiple dc-dc converters can be connected to form a serial-input connected parallel-output (SIPO) converter power channel. Many SIPO converter power channels can be parallel-connected across the power system output that shares a common load, allowing for an expanding number of converters within the same power system. This provides sufficient power to the load. Without proper control for equal sharing among the output currents of paralleled power channels, this channelized series-connected converter architecture alone introduces conflicts in output voltage regulation control. This leads to nonuniform power flows among channels and possible unequal utilization, consequently degrading system reliability. The invention is characterized by a channelized power system having a plurality of channels. Each channel contains power converters and respective channel controllers for controlling the power provided by the channels. The controllers are interconnected by a shared bus voltage signal and a shared bus current signal, so that the paralleled channels and converters within each channel are respectively controlled to have equal power sharing. The two shared-bus signals stabilize interactions among interconnected channels and converters within each channel, significantly reducing imbalances in power flow. Conflicts in the system output voltage regulation are also eliminated while achieving very stiff output voltage. Fault tolerance is also included among series-connected converters that actively sustain equal input voltages among remaining no-fault converters, even if one or more converters is down. The channelized power system can be used in satellite power systems having different voltage requirements and expansive battery charges.