Com Dev Limited

Com Dev International, Inc.

Exactearth Ltd.

Robert C Peach

Gary Beauchamp

Bharat Tailor

Ken Lazaris-Brunner

Weiguo Chen

Ian A D'Souza

Mario Lisi

Philip R Cowles

Thai Vo

Charles Van Lingen

Nicholas Svensson

Val O'Donovan

Simon Lam

Xavier M H Albert-Lebrun

Kamal Ali

Nigel Miller

Phillip R Cowles

Methods and systems for validating positions reported in AIS message signals by fitting suitably chosen functions to signal characteristic data, such as timing and Doppler shift data, derived from a plurality of AIS message signals. Ships whose reported positions deviate from the fitted function may be flagged as suspect.

Methods and systems for consistency checking and anomaly detection in automatic identification system signal data

A method of extracting automatic identification system (AIS) message segments from AIS signals received by a satellite. The method includes: (a) receiving AIS signals from satellite antennas; (b) generating multiple versions of the AIS signals; (c) extracting message segments contained within each of the AIS signals using one or more AIS receivers; (d) sorting the message segments by time; and (e) deleting any duplicate message segments. Multiple versions of the AIS signals may be generated by one or more of the following methods: (i) processing the AIS signals multiple times, each time with different AIS receiver parameter settings; (ii) splitting each signal into multiple signals and filtering each of the multiple signals separately; (iii) receiving multiple AIS signals and combining them with different phases and amplitudes to produce a plurality of combined AIS signals; and (iv) removing extracted message segments from the received AIS signals and reprocessing the modified AIS signals.

Systems and methods for decoding automatic identification system signals

Various embodiments are described herein for a system and method of detecting Automatic Identification System (AIS) signals in space and decoding these signals. In one aspect, a system for performing this function is described which includes a receiver configured to receive the plurality of AIS signals and pre-process the plurality of AIS signals to produce digital input data, and a processing unit configured to process the digital input data to identify one or more candidate AIS message signals based on Doppler offsets associated with the digital input data, determine corresponding Doppler offset estimates and time estimates of the one or more candidate AIS message signals, decode the one or more candidate AIS message signals to obtain corresponding message segments and validate the decoded message segments for proper AIS formatting.

System and method for decoding automatic identification system signals

Embodiments describe methods of correcting S-parameter measurements for a DUT. The method includes coupling at least one tracking module associated with a set of electrical standards to a S-parameter measurement device to form a test system. An initial calibration for the test system is then determined. This may include measuring the S-parameters of the electrical standards, generating a calibration along a calibration plane, generating a calibration along a correction plane and determining at least one error adapter from the calibrations. The DUT is coupled to the test system and the S-parameters of the DUT are measured. Changes in the initial calibration are tracked using the tracking modules. Tracking may include measuring the S-parameters of the electrical standards, generating a correction plane calibration and generating a corrected calibration plane calibration from the correction plane calibration and the error adapter(s). The measured S-parameters are corrected using the tracked changes.

Method and system for tracking scattering parameter test system calibration

A system and method of calibrating an S parameter measurement instrument (such as a vector network analyzer) in which the number of calibrations required to fully characterize the error model of an n-port system is n/2 calibrations for an even number of ports and (n&plus;1)/2 calibrations for an odd number of ports. Each test port in the system is involved in at least one full calibration, thus n/2 test paths are fully calibrated. For each measured test path, the error terms of the applicable error model are calculated. These error terms are then decoupled from the associated test path into error parameters that are localized to the individual test ports of the test path. Having localized the error parameters, the error model for each test port can then be treated independently from the other test ports. The error terms for the test paths that are not calibrated are then constructed using the localized error parameters for the individual test ports.

Scattering parameter calibration system and method

An improved multi-beam bent-pipe communications satellite system and method includes a subchannel switching processor for extracting and switching subchannels of information to and from a plurality of uplink and downlink beams and an intersatellite link for routing certain of the extracted subchannels to another satellite in the system. The subchannel switching processor preferably employs a partial subchannelization processor that combines a coaxial switching network for switching some of the uplink channels at the channel level with an analog or digital transparent subchannel switching network connected to a portion of the uplink channels for extracting and switching at the subchannel level. The switched subchannels are combined to form channels, and then routed to either the downlink beams (where they are combined with other switched channels), or to the intersatellite link for transmission to another satellite. The system of the present invention could be a constellation of satellites, each satellite in the constellation connected to a plurality of other satellites using a plurality of intersatellite links.

Intersatellite communications systems

A repeater for a multibeam communications satellite combines the features of coaxial channel interbeam switching and subchannelization of some of the channels. In one embodiment described, the input radio-frequency signals from the input beams are fed through the input multiplexers to form channels. Some, but not all, channels are subsequently subchannelized for interbeam switching. In another embodiment of the invention, a portion of the incoming radio frequency signals bypasses the input demultiplexer and is filtered for noise-limiting reasons, converted down to an intermediate frequency and then subchannelized using SAW filters. The specification also teaches that digital techniques can be used to obtain the same results. Especially in the case of satellites with a large number of beams and a large number of channels, it is not necessary to have full interbeam switching of all the subchannels derived from one channel: instead, the specification proposes the use of parallel configurations of smaller, less complex switching networks.

Repeaters for multibeam satellites

An interdigital transducer for use in a surface acoustic wave filter has two busbars of an irregular shape to reduce the effect of internally reflected surface waves. The busbars will usually have an identical shape to one another and have stepped outer and inner edges. The distance between a portion of the outer edge and a corresponding portion of the inner edge can be constant for a particular busbar or that distance can vary. With previous busbars, the outer and inner edges are linear and each busbar has a rectangular shape.

Interdigital transducer for use in a surface acoustic wave filter

A filterbank using surface acoustic wave technology and having a plurality of filters. Each filter has an input transducer and an output transducer. The input transducers are connected in parallel to a single matching circuit. The output transducers each have a separate matching circuit. The transducers are formed by a thin film of aluminum pattern on a piezoelectric substrate. The input transducers all have the same structure and the output transducers all have the same structure, though that structure is different from the input transducers. The only difference between the transducers of each filter is the location of electrode breaks for each electrode. A weighting function of the transducers is scaled and biased to provide a constant impedance across the bandwidth of the filterbank and to equalize the output amplitudes and capacitances of the output transducers. This produces a continuous level response across the bandwidth of the filterbank. Previously, while a continuous level response was theoretically achievable, it cannot be achieved in practice.

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Cambridge, Canada

Robert C Peach