The US Global Positioning System (GPS) and the USSR (and later Russian) system Glonass have existed for decades. Europe is developing Galileo and China launched Beidou which was the first Regional Navigation Satellite System (RNSS) and then announced Compass, a Global Navigation Satellite System (GNSS). Japan is planning its own regional augmentation to GPS and Galileo known as the Quasi-Zenith...

On bi-static or multi-static space-borne radar the appropriate digital beam-former (DBF) algorithms can obtain multi-angular synthetic aperture radar (SAR) data and enhance signal-tonoise ratio. Some applications ask for short revisit time that need to ensure seamless coverage to obtain a wide swath SAR image data with a single satellite using digital beam-forming on receive scheme [1]. The tra...

A novel and highly efficient design of a Software defined radiation tolerant baseband module for a LEO satellite telecommand receiver using FPGA is presented. FPGAs in space are subject to Single Event Upsets (SEUs) due to high radiation environment. Traditionally, Triple Modular Redundancy (TMR) is used for mitigating Single Event Upsets (SEUs). The drawback of using TMR is that it consumes a ...

In the next few years, surveyors using high productivity, real-time kinematic (RTK) positioning and indeed all other precision positioning users will be faced with a barrage of new global navigation satellite system (GNSS) signals from GPS, GLONASS, GALILEO and possibly COMPASS/Beidou2 as well as Satellite Based Augmentation Systems (SBAS) signals and Regional Navigation Satellite Systems (RNSS...

To achieve reliable GPS positioning results a realistic stochastic model for GPS carrier phase observations has to be specified for data processing. In order to develop such a stochastic model, the quality characteristics of GPS carrier phase measurements made by a receiver must be well understood. Recently investigators have used two types of data, Signal-to-Noise Ratio (SNR) and satellite ele...

Localization is one of the most important issues associated with underwater acoustic sensor networks, especially when sensor nodes are randomly deployed. Given that it is difficult to deploy beacon nodes at predetermined locations, localization schemes with a mobile beacon on the sea surface or along the planned path are inherently convenient, accurate, and energy-efficient. In this paper, we p...

Paper presents a Neural Network Modelling approach to microwave LNA design. To acknowledge the specifications of the amplifier, Mobile Satellite Systems are analyzed. Scattering parameters of the LNA in the frequency range 0.5 to 18 GHz are calculated using a Multilayer Perceptron Artificial Neural Network model and corresponding smith charts and polar charts are plotted as output to the model....

With over 600 receiver cartridges, ALMA will have several thousand SMA connectors, many of which will be subjected to periodic cryogenic cooling. At present, ALMA has no specifications on the proper torquing of SMA connectors nor on whether any type of staking should be used. This note summarizes the experience of a number of engineers involved with receiver construction for radio astronomy and...

An experiment has been devised which will validate, in space, a miniature, high-performance receiver. The receiver blends three complementary technologies: high temperature superconductivity (HTS), pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuits (MMIC), and a miniature pulse tube cryogenic cooler. Specifically, an HTS band pass filter, InP MMIC l...

In the autumn of the year 2000, four radio receivers capable of tracking various beacon satellites were set up along the southwestern coast of Greenland. They are used to reconstruct images of the ionospheric plasma density distribution via the tomographic method. In order to test and validate tomographic imaging under the highly variable conditions often prevailing in the high-latitude ionosph...