19 resultados para ALMATracker tracking antenna satellite orbita LabVIEW


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Data registration refers to a series of techniques for matching or bringing similar objects or datasets together into alignment. These techniques enjoy widespread use in a diverse variety of applications, such as video coding, tracking, object and face detection and recognition, surveillance and satellite imaging, medical image analysis and structure from motion. Registration methods are as numerous as their manifold uses, from pixel level and block or feature based methods to Fourier domain methods.

This book is focused on providing algorithms and image and video techniques for registration and quality performance metrics. The authors provide various assessment metrics for measuring registration quality alongside analyses of registration techniques, introducing and explaining both familiar and state-of-the-art registration methodologies used in a variety of targeted applications.

Key features:
- Provides a state-of-the-art review of image and video registration techniques, allowing readers to develop an understanding of how well the techniques perform by using specific quality assessment criteria
- Addresses a range of applications from familiar image and video processing domains to satellite and medical imaging among others, enabling readers to discover novel methodologies with utility in their own research
- Discusses quality evaluation metrics for each application domain with an interdisciplinary approach from different research perspectives

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This letter presents a simple tracking phased locked loop (PLL) that can be used to track phase-modulated signals and provide a phase-conjugated signal for retrodirective retransmission. The configuration allows the retrodirective antenna to directly track phase-modulated signals with no requirement for a separate continuous wave (CW) pilot tone. The ability to directly track phase-modulated signals is carried out using a 4× multiplier on the tracking PLL reference signal. Practical phase conjugation results are presented for a five-element retrodirective array simultaneously sending and receiving phase-modulated (QPSK) signals. Signals with levels as low as -122 dBm can be phase-conjugated and retransmitted with 30 dBm EIRP.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

We present an in depth look at the challenges involved in using analogue retrodirective arrays for satellite communications. The main technical issues surrounding the development of a retrodirective (self-steering) Satellite Communications (SATCOM) system are given and techniques for mitigating these issues provided. Detailed results are given for a prototype high performance circularly polarized retrodirective array architecture suitable for mounting on an un-stabilized mobile platform. The paper concludes with practical retrodirective L-band array results with the array used to acquire actual broadband satellite data signals from a commercial L-band satellite system. Received satellite signals as low as -130dBm at the antenna elements are tracked. Accurate self-tracking occurs over the azimuth range of up to +/- 40 degrees.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The spread of nonindigenous species into new habitats is having a drastic effect on natural ecosystems and represents an increasing threat to global biodiversity. In the marine environment, where data on the movement of invasive species is scarce, the spread of alien seaweeds represents a particular problem. We have employed a combination of plastid microsatellite markers and DNA sequence data from three regions of the plastid genome to trace the invasive history of the green alga Codium fragile ssp. tomentosoides. Extremely low levels of genetic variation were detected, with only four haplotypes present in the species’ native range in Japan and only two of these found in introduced populations. These invasive populations displayed a high level of geographical structuring of haplotypes, with one haplotype localized in the Mediterranean and the other found in Northwest Atlantic, northern European and South Pacific populations. Consequently, we postulate that there have been at least two separate introductions of C. fragile ssp. tomentosoides from its native range in the North Pacific.