General Electric Company

Lockheed Martin Corporation

Aircell LLC

Stephen Michael Hladik

Nick Andrew Van Stralen

John Erik Hershey

John Anderson Fergus Ross

Abdallah Mahmoud Itani

Gary Jude Saulnier

Robert Gideon Wodnicki

Glen William Brooksby

Ralph Thomas Hoctor

Daniel David Harrison

Richard Charles Gaus, Jr

John B Anderson

Amer A Hassan

Sandeep Chennakeshu

Harold Woodruff Tomlinson, Jr

Charles McDonald Puckette, Iv

John Anderson Ross

Irfan Ali

Anantha Krishnan Pradeep

Kenneth Brakeley Welles

Scott Charles Evans

David Michael Davenport

David Allen Langan

Kenneth B Welles, Ii

Raymond L Toy

Jimmy C Ray

Richard August Korkosz

Ravinder David Koilpillai

Michael Paul Weir

Harold W Tomlinson

Robert L George

John Bailey Anderson

Brian J Glinsman

Robert F Fleming, Iii

Howard L Lester

Richard L Frey

Sandeep Channakeshu

William Alan Check

Wayne Curtis Taft

Anatha Krishnan Pradeep

Ravinder D Koilpllai

Michael P Weir

Location of an object to be tracked is determined by measuring, at a receiver situated at the object, the propagation time differences between the signals from a plurality of GPS satellites, each of which is received by the receiver situated at the object. The measured propagation time difference values are transmitted to a central station where the location of the object to be tracked is calculated based upon the propagation time differences of the signals transmitted from the satellites and data derived from a receiver apart from the object but also receiving signals from the satellites.

Reduced-power GPS-based system for tracking multiple objects from a central location

A time-division-multiplexed radio communication system and method uses transmitted-reference, delay-hopped (TR/DH) ultra-wideband (UWB) broadcast signal to provide a pilot signal to all mobile devices in a coverage area from which time synchronization is derived. Using this TR/DH UWB pulse pilot signal and low-complexity demodulation in the mobile devices, the mobile devices utilize a simple signal detection algorithm to acquire synchronization with the pilot signal. As a result, all devices in a local area network become synchronized to the system's bit clock. This greatly reduces the search space required for signal acquisition, receiver signal processing complexity, and length of message preambles required to synchronize the base station receiver to a transmission from any of the mobile devices.

Method and apparatus for synchronizing a radio telemetry system by way of transmitted-reference, delay-hopped ultra-wideband pilot signal

A turbo decoder control comprises an address generator for addressing systematic data, parity data, and systematic likelihood ratios according to a pre-determined memory mapping. The systematic data samples are accessed in the order required by the MAP decoding algorithm such that interleaving and de-interleaving functions in the MAP decoding algorithm are performed in real-time, i.e., without delay. Such memory-mapping in combination with data handling functions (e.g., multiplexing and combinatorial logic) minimizes memory requirements for the turbo decoder and allows for use of programmable interleavers, variable block lengths, and multiple code rates.

Turbo decoder control for use with a programmable interleaver, variable block length, and multiple code rates

A method and apparatus of initial synchronization, or acquisition, of time modulated ultra-wideband (UWB) communications uses a transmitted-reference preamble. The method and apparatus require that the transmitter first send a time-reference, delay-hopped (TR/DH) burst; such a burst is easily detected and can be processed to provide a time mark accurate to within a few nanoseconds. Following the transmission of the TR/DH burst, the transmitter waits a fixed period of time, the duration of which is known to the receiver, and then the transmitter sends a burst of pulse position modulation, time hopped (PPM/TH) or other time modulated UWB. After the reception of the first burst, the receiver can estimate the time of reception of the second burst to the accuracy of the time mark.

Synchronization of ultra-wideband communications using a transmitted-reference preamble

A turbo decoder system utilizing a MAP decoding algorithm has a predetermined number of turbo decoder modules for decoding segments of a turbo code component code word in parallel, thereby expanding the block-length and data rate capability of the turbo decoder. Upon completion of any half iteration of the MAP decoding algorithm, the a posteriori bit probability estimates are provided to an interleave/de-interleave-and-convert-data function block wherein they are re-ordered, segmented, used to modify the original received data samples, and provided back to the respective turbo decoder modules as input data samples for the systematic bits. Decoding continues in this manner until a predetermined number of half iterations is performed, and data decisions are made on the final a posteriori estimates.

Turbo decoder with modified input for increased code word length and data rate

A turbo decoder system utilizing a MAP decoding algorithm has a predetermined number of turbo decoder modules for decoding segments of a turbo code component code word in parallel, thereby expanding the block-length and data-rate capability of the turbo decoder system. Input data samples are provided to an interleaver/de-interleaver module wherein they are divided into segments of predetermined size, each segment being provided to a respective turbo decoder module. The outputs of each turbo decoder module are a posteriori probabilities which are re-ordered in the interleaver/de-interleaver module, segmented, and provided back to the turbo decoders as a priori information-bit probabilities. For the case of a turbo code comprising two component codes, the a posteriori information-bit probabilities are re-ordered according to the interleaver definition at the end of odd-numbered half iterations, while at the end of even-numbered half iterations, they are re-ordered according to the de-interleaver definition. Decoding continues until the desired number of iterations have been performed. Data decisions are made on the final a posteriori bit probability estimates.

Modular turbo decoder for expanded code word length

An apparatus for inspecting an operational condition of a rail track from a railcar includes an antenna positioned on the railcar that directs radar signals toward the rail track and collects radar signals returned from the rail track. A radar transceiver is connected to the antenna and supplying the radar signals to the antenna. The radar transceiver receives radar returned signals from an interaction of the radar signal with the rail track. A controller is connected to the radar transceiver for controlling transmission of the radar signals from the radar transceiver and receipt of the radar returned signals. A signal processing unit is connected to the controller and a sensor unit that supplies input data to the signal processing unit. The signal processing unit processes at least the input data and the radar returned signal to produce processor output data and to determine the operational condition of the rail track.

Apparatus and method for rail track inspection

The signaling overhead required for pilot symbol aided modulation is significantly reduced by recognizing that the residual uncertainty in the carrier frequency decreases after an initial carrier frequency estimate is made during an initial signal interval. This allows a commensurate reduction in channel process sampling rate during the remainder of the message; i.e., the frequency uncertainty of the pilot symbols can be decreased. This technique may be particularly effective when the rate of change of the received carrier frequency and phase is low as in fixed satellite terminal equipment. The resultant increase in spectral efficiency makes reduced-overhead pilot symbol aided modulation attractive for applications in low-cost/low-complexity terminal equipment.

Variable-interval pilot symbol aided modulation and demodulation

An integrated tracking, telemetry and local area networking system is provided. A communications system comprises a broadband subsystem comprising at least one UWB node including a first UWB transceiver and at least one application node linked to the UWB node by a broadband link. The system further comprises a wireless subsystem comprising at least one remote communicator, the remote communicator including a second UWB transceiver. The first and second UWB transceivers are configured to communicate with each other via an UWB communications link.

Integrated wireless broadband communications network

A high-speed turbo decoder utilizes a MAP decoding algorithm and includes a streamlined construction of functional units, or blocks, amenable to ASIC implementation. A gamma block provides symbol-by-symbol a posteriori state transition probability estimates. Two gamma probability function values are provided via selection switches to the alpha and beta blocks for calculating the alpha and beta probability function values, i.e., performing the alpha and beta recursions, respectively, in parallel, thus significantly increasing decoding speed. A scaling circuit monitors the values of the alpha and beta probability functions and prescribes a scale factor such that all such values at a trellis level remain within the precision limits of the system. A sigma block determines the a posteriori state transition probabilities (sigma values) and uses the sigma values to provide soft-decision outputs of the turbo decoder.

High-speed turbo decoder

A feedback control for a turbo decoder controls the feedback between component decoders of the turbo decoder by substituting either a neutral value or a weighted value for the channel transition probabilities utilized by each component decoder during the iterative decoding process. A control switch selects either estimated channel transition probabilities, modifications of these values, or neutral values as the channel transition probabilities utilized by the next component decoder in the subsequent decoding iteration.

Turbo code decoder with modified systematic symbol transition probabilities

A feedback control for a turbo decoder controls the feedback between component decoders by modifying updated a priori probabilities calculated by one component decoder and used as inputs to another component decoder during the decoding process, resulting in a significant performance advantage. A feedback control switch selects either previously estimated a posteriori probabilities, modifications of these values, or neutral values as a priori probabilities utilized by the next component decoder.

Turbo code decoder with controlled probability estimate feedback

In a communications system, a trellis code word is segmented by both the encoder and a segmented MAP decoder. The segmented MAP decoder operates on code word segments as if they were individual code words and takes advantage of knowing the state of the encoder at specified times to reduce decoding latency and required memory. In a turbo coding system, for example, coding gain is maintained by interleaving the information bits across the segments of a component code word.

High data rate maximum a posteriori decoder for segmented trellis code words

Forward and backward recursive calculations in a maximum a posteriori decoding process are performed in parallel processes, rather than sequentially, allowing the a posteriori transition probabilities to be calculated in the same time interval as the recursions, thereby reducing decoding latency and required memory.

Maximum A posterior estimator with fast sigma calculator

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Albany, NY, United States of America

Stephen Michael Hladik