&lt;title&gt;Optical networks for earth-space communications and their performance&lt;/title&gt;

Shaik, Kamran S.; Wonica, Dennis; Wilhelm, Michael D.

doi:10.1117/12.184644

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…Direct sun can be avoided by where c 1c2 }/ z02]112 is angular beam wander rathus . Eq (8). agrees well with measured loss in coverage.…”

supporting

confidence: 84%

“…For deep space, however, operation at 532 nm results in the highest possible telemetry rates. Calculations show that nighttime telemetry rates of about 1 .7 Mb/s are possible at this wavelength for a strenuous Pluto mission [8]. From the mission point of view, if the optical navigation technology matures for longer wavelengths, there may be an advantage in using 1064 or 2000 nm wavelength [9].…”

Section: Introductionmentioning

confidence: 99%

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Wavelength selection criteria for laser communications

Shaik¹,

Hemmati

1995

SPIE Proceedings

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Laser communication systems can be based on a wide range of wavelengths in the optical and infrared regimes. This article provides a rationale for the selection of wavelengths particularly suited for free space laser communication systems. The choice of wavelengths is based on an analysis of propagation issues, especially through the atmosphere, optical background noise, and the necessary technologies that include lasers, detectors, and spectral filters. The maturity of technology is assessed and given due consideration to identify suitable wavelengths for today's laser communication systems. Figures of merit are also developed where useful to provide a comparative estimate of expected system performance as afunction of wavelength.

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“…Direct sun can be avoided by where c 1c2 }/ z02]112 is angular beam wander rathus . Eq (8). agrees well with measured loss in coverage.…”

supporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Wavelength selection criteria for laser communications

Shaik¹,

Hemmati

1995

SPIE Proceedings

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“…Over the years, many researchers have addressed pertinent aspects of the above phenomenology as they relate to optical communication [3][4][5][6][7] . In this section, we limit ourselves to identifying the relevant issues to provide a context to discuss the merits of the SPARCL concept.…”

Section: Atmospheric Effects On Optical Signalsmentioning

confidence: 99%

SPARCL: a high-altitude tethered balloon-based optical space-to-ground communication system

Badesha

2002

SPIE Proceedings

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The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has conducted a feasibility study to determine if a high altitude (20 km) tethered balloon-based space-to-ground optical communication system is a feasible concept. To support this effort, a detailed concept definition was developed and associated issues were identified and analyzed systematically. Of all the adverse atmospheric phenomena, cloud coverage was identified as the most prohibitive obstacle for a space-to-ground optical communication link. However, by placing a receiver on a balloon at a 20 km altitude, the proposed high altitude system avoids virtually all atmospheric effects. A practical notional scenario was developed (i.e. surveillance and/or reconnaissance of a regional conflict) involving end-to-end optical communication architecture to identify system elements, system level requirements, and to quantify realistic data rate requirements. Analysis of the proposed space-to-ground communication elements indicates that while significant development is required, the system is technically feasible and is a very cost effective 24/7solution. INTRODUCTIONThe DoD and NASA have a need for a very high data rate secure and reliable information transfer system between spacecraft and ground stations. Presently, space-to-ground communications are conducted via S band (2.3 GHz), X band (8 GHz), or Ka band (30 GHz). These RF bandwidths are deemed increasingly inadequate for current and future high speed communication transfer needs. According to Aviation Week and Space Technology, "Top Pentagon and defense industry officials contend that nearly all the intelligence and targeting information they need is already being collected. The problem is that the data usually stays with the platform that collects it, and is often purged if not of immediate use. Meanwhile, other organizations of fighting units are desperate for the discarded information. The preeminence of communications networking over sensors and platforms has been discussed for years, but only recently has the (optical) technology matured to the point that it is feasible in the near future." 1 Optical (laser) communications offer the benefit of obtaining a higher bandwidth, and therefore effectively higher data rates, than radio communications. Laser links are ideal for high data rate applications, however optical communication links are attenuated by clouds. In fact, opaque clouds can totally occlude optical signals. Investigators have considered the use of multiple ground stations to increase the probability that at any given time at least one space-to-ground link would be cloud free and active. As an alternative to this, we propose elevating the ground-based receiving sensor to an altitude higher than the clouds. This can be done by mounting the transceiver on a high altitude tethered balloon (HATB) that communicates with the ground through a fiber optic link in the tether. We refer to this concept as SPARCL (SPAce Relay Communications Link).Other atmospheric phenomena such as scintillatio...

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“…Ground Receiver Network ll.la Subnet Concepts: Four alternate concepts were examined in this study; a seven-station optical subnet (LDOS), a three-station optical subnet in the Continental US (CONIJS), and double-and single-station concepts. This work is based upon previously reported developments [1] and as such only new developments in areas of optical station design am described in this article.…”

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confidence: 99%

Comparative study of optical and rf communication systems for a Mars mission

et al. 1996

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We have performed a study on telecommunication systems for a hypothetical mission to Mars. The objective cf the study was to evaluate and compare the benefits that microwave (X-band and Ks-band) and Optical communications technologies afford to future missions. The telecommunication systems were required to ietum data after launch and in-orbit at 2.7 AU with daily data volumes ofO.1, 1, or 10 Gbits. Space-borne terminals capable of delivering each of the three data rates were proposed and characterized in terms of mass, power consumption, size, and cost. The estimated paimeters for Xband, Ka-band, and Optical frequencies are compared and presented here. For data volumes ofO.1 and 1 Giga-bit per day, the X-band downlink system has a mass 1.5 times that ofKa-band, and 2.5 times that of Optical system. Ka-band offeied about 20% power saving at 10 Gbit/day over X-band. For all data volumes, the optical communication terminals were lower in mass than the RF terminals. For data volumes of 1 and 10 Gb/day, the space-borne optical terminal also had a lower required DC power. In all three cases, optical communications had a slightly higher development cost for the space terminal.

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<title>Optical networks for earth-space communications and their performance</title>

Cited by 3 publications

References 2 publications

Wavelength selection criteria for laser communications

Wavelength selection criteria for laser communications

SPARCL: a high-altitude tethered balloon-based optical space-to-ground communication system

Comparative study of optical and rf communication systems for a Mars mission

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