Hand Held Products, Inc.

Ems Technologies, Inc.

Dspace Pty., Ltd.

Inmarsat Limited

Mark Rice

Michael Robert Peake

Timothy Clifton Giles

Wade Nicholas Farrell

Philip Spear

Sanjeev Naguleswaran

Andrey Tyagunov

Richard Renner

Simon Richard Swift

Search and rescue (SAR) systems utilizing Earth-orbiting satellites are provided. In one implementation, a SAR system comprises a plurality of reference beacons, each having a known geographical location, and a ground-based station. The ground-based station includes one or more antennas for communicating with the reference beacons via a plurality of Earth orbiting satellites. The ground-based station is configured to receive reference signals from each of the reference beacons and calculate estimates of the locations of the reference beacons from the received reference signals. Also, the ground-based station is configured to calculate system calibration factors based on the location estimates and known geographical locations of the reference beacons. The ground-based station is further configured to receive distress signals from at least one distress beacon via the Earth-orbiting satellites and calibrate the distress signals based on the system calibration factors.

Programmable reference beacons

The present disclosure is generally directed to systems and methods for utilizing an operating schedule to place a satellite communication device in a sleep state for reducing power consumption in the satellite communication device during periods of time when no satellite is available to communicate with the satellite communication device. The operating schedule, which can be a wake-up schedule and/or a sleep schedule, is dynamically updated by a scheduling server that receives two-line element (TLE) data from a TLE server on a recurring basis and uses the TLE data to determine timing information pertaining to line-of-sight visibility of one or more satellites to the satellite communication device. A push routine is then used by the scheduling server to periodically push the timing information to the satellite communication device for dynamically updating the operating schedule of the satellite communication device.

Systems and methods for reducing power consumption in a satellite communication device

The present invention relates to a communication method, system and signal, and in particular to a method and system for communicating information in a digital signal. It has particular application to satellite or terrestrial packet-based multi-user radio communication systems. A method for communicating information in a digital signal comprising data symbols is disclosed, wherein the information is encoded in a sequence characteristic of pilot symbols distributed amongst the data symbols, such that a receiver is able to determine the sequence characteristic and retrieve the transmitted information. The invention allows information to be encoded into a sequence characteristic of pilot symbols, rather than relying on modulating such information onto the pilot symbols themselves. This allows a significantly larger number of pieces of information to be transmitted than hitherto possible, and the technique is more resistant to large frequency errors than prior techniques.

Method and system for communicating information in a digital signal

The present invention relates to a communication method, system and signal, and in particular to a method and system for communicating information in a digital signal. It has particular application to satellite or terrestrial packet-based multi-user radio communication systems. A method for communicating information in a digital signal comprising data symbols is disclosed, wherein the information is encoded in a sequence characteristic of pilot symbols distributed amongst the data symbols, such that a receiver is able to determine the sequence characteristic and retrieve the transmitted information. The invention allows information to be encoded into a sequence characteristic of pilot, symbols, rather than relying on modulating such information onto the pilot symbols themselves. This allows a significantly larger number of pieces of information to be transmitted than hitherto possible, and the technique is more resistant to large frequency errors than prior techniques.

This invention relates to signal processing in telecommunications, particularly but not exclusively for use in wireless TDMA systems. In particular, the invention concerns methods for use in communication systems making use of pilot symbols. The invention provides a method of placing pilot symbols in a data stream for telecommunication systems, wherein the pilot symbols are spaced in time using a range of different intervals between symbols. The intervals between the pilot symbols are substantially fractal in nature, the distribution of pilot symbols involving repetitions of irregular groupings of pilot symbols in the data stream. Preferably, the irregular groupings of pilot symbols are irregularly spaced in the data stream. The invention also provides a method and means for acquiring the time and frequency offset of a packet of data by using pilot symbols distributed within the packet as defined above.

Pilot symbols in communication systems

The invention relates to the field of signal processing for telecommunications, and concerns a method and receiver for processing a multi-user signal. In the method of the invention, a multi-user signal is processed by a receiver using an iterative receiver process including the steps of (a) receiving a signal transmission including a plurality of user signals on a TDMA channel, (b) detecting one or more user signals and determining transmission channel estimates for each said user signal, (c) deriving a soft signal for a first user by subtracting, if available, weighted representations of other user signals from the detected user signal of said first user, (d) calculating a-posteriori probabilities for each symbol comprising the soft signal, (e) refining said probabilities utilizing the transmission channel estimate for the first user in an iterative decoding algorithm, wherein a probability is either partially or fully decoded depending on the application of decoder convergence criteria, and (f) returning to step (a), (b) or (c) with the refined probabilities forming part of the weighted representations to be subtracted from detected user signals of other users. This method allows for efficient detection and decoding of multiple user signals by controlling the behaviour of an iterative decoding algorithm operating within an iterative receiver process.

Method and receiver for processing a multi-user signal

A parallel concatenated coder ( ) outputs a sequence of data sets in which earlier data sets contain data bits (d) and non-interleaved parity bits (p) without interleaved parity bits (q), while later data sets include the interleaved parity bits (q). Each data set is modulated as one symbol. The output format partially overcomes the delay incurred by interleaving the parity bits (q), with a substantially even distribution of data and parity bits in the sequence of data sets. The delay may be reduced further by interleaving with an index constraint.

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Kensington Park, Australia

Mark Rice