Satellite Communication Systems

Richharia, M.

doi:10.1007/978-1-349-15131-8

Cited by 12 publications

(11 citation statements)

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“…An orbit where the satellite moves in opposite direction to the Earth rotation is called retrograde orbit. The inclination of a retrograde orbit always lies between 90º and 180º [3], [4].…”

Section: Nodal Regressionmentioning

confidence: 99%

“…But, the potential generated by the non-spherical Earth causes variations of the orbital elements. Most effected orbital elements are the right ascension and the argument of perigee, as presented in Figure.1 [3], [4]. The right ascension of the ascending node (Ω) defines the location of the ascending and descending orbital crossing nodes (these two nodes make a line of nodes) with respect to a fixed direction in space.…”

Section: Nodal Regressionmentioning

confidence: 99%

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The Apsidal Precession for Low Earth Sun Synchronized Orbits

Cakaj¹,

Kamo²,

Lala³

et al. 2015

ijacsa

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Abstract-By nodal regression and apsidal precession, the Earth flattering at satellite low Earth orbits (LEO) is manifested. Nodal regression refers to the shift of the orbit's line of nodes over time as Earth revolves around the Sun. Nodal regression is orbit feature utilized for circular orbits to be Sun synchronized. A sun-synchronized orbit lies in a plane that maintains a fixed angle with respect to the Earth-Sun direction. In the low Earth Sun synchronized circular orbits are suited the satellites that accomplish their photo imagery missions. Nodal regression depends on orbital altitude and orbital inclination angle. For the respective orbital altitudes the inclination window for the Sun synchronization to be attained is determined. The apsidal precession represents major axis shift, respectively the argument of perigee deviation. The apsidal precession simulation, for inclination window of sun synchronized orbital altitudes, is provided through this paper.

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Section: Nodal Regressionmentioning

confidence: 99%

Section: Nodal Regressionmentioning

confidence: 99%

The Apsidal Precession for Low Earth Sun Synchronized Orbits

Cakaj¹,

Kamo²,

Lala³

et al. 2015

ijacsa

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“…While GEO satellites continually view large areas of the Earth, and can provide immediate alerting and identification of 406 MHz beacons, there is no Doppler shift of the received beacon carrier since the geostationary satellites are by definition stationary with respect to the Earth, [9][10][11]. Another issue is that GEOs can not cover the Polar Regions adequately since the antenna footprint is limited to latitudes of about 75º-80º [12][13][14].…”

Section: Space Segmentmentioning

confidence: 99%

The Downlink Adjacent Interference for Low Earth Orbiting (LEO) Search and Rescue Satellites

Cakaj¹,

Fitzmaurice²,

Reich³

et al. 2010

IJCNS

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NOAA (National Oceanic and Atmospheric Administration) -LEO environmental satellites provide continuous coverage of Earth, supplying high-resolution global meteorological, oceanic and space observation data. In addition, these satellites are part of the international COSPAS -SARSAT program, which aides search and rescue teams worldwide. The USA segment, referred to as SARSAT (Search and Rescue Satellite Aided Tracking) system, is designed to provide distress alert and location data to assist on search and rescue operations. SARSAT locates distress beacons (406MHz) activated at distress locations. The system calculates a location of the distress event using Doppler processing techniques. Processed data is continuously retransmitted through the SARSAT downlink to Local User Terminals (LUT) when satellites are in view. The downlink adjacent interference is expected when two satellites operate in close proximity and share the same frequency. The downlinks of all SARSAT LEO satellites use the same 1544.5 MHz frequency. In cases where the satellites are within the main lobe of the local user terminal antenna, transmissions from adjacent satellites act as interference to one-another, effectively decreasing the signal-to-noise ratio of the desired downlink. This can result in missed distress beacon bursts or no stored solutions received at the LUT, consequently no data is provided about a distress location. Analysis on interference prediction, impacts on system operation and recommendations for mitigating interference periods where the duration may be significant, are presented in this paper.

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“…Impulsive noise occurs in communication systems like power line, digital subscriber line systems, mobile radio systems [3][4] and many types of satellite communication link [5].…”

Section: Introductionmentioning

confidence: 99%

Communication Equalizer Algorithms with Decision Feedback based on Error Probability

Kim

Hwang²

2011

Journal of the Korea Academia-Industrial cooperation Society

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For intersymbol interference (ISI) compensation from communication channels with multi-path fading and impulsive noise, a decision feedback equalizer algorithm that minimizes Euclidean distance of error probability is proposed. The Euclidean distance of error probability is defined as the quadratic distance between the probability error signal and Dirac-delta function. By minimizing the distance with respect to equalizer weight based on decision feedback structures, the proposed decision feedback algorithm has shown to have significant effect of residual ISI cancellation on severe multipath channels as well as robustness against impulsive noise.

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Satellite Communication Systems

Cited by 12 publications

References 0 publications

The Apsidal Precession for Low Earth Sun Synchronized Orbits

The Apsidal Precession for Low Earth Sun Synchronized Orbits

The Downlink Adjacent Interference for Low Earth Orbiting (LEO) Search and Rescue Satellites

Communication Equalizer Algorithms with Decision Feedback based on Error Probability

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