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人工智能木蟲 (著名寫手)
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[求助]
英譯漢潤色（航天通信相關(guān)）
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英文原文： NASA’s Evolution to Ka-Band Space Communications for Near-Earth Spacecraft Over the next several years, NASA plans to launch multiple earth‐science missions which will send data from low-Earth orbits to ground stations at 1‐3 Gbps, to achieve data throughputs of 5‐40 terabits per day. These transmission rates exceed the capabilities of S-band and X‐band frequency allocations used for science probe downlinks in the past. Accordingly, NASA is exploring enhancements to its space communication capabilities to provide the Agency’s first Ka‐band architecture solution for next generation missions in the near‐earth regime. This paper describes the proposed Ka-band solution’s drivers and concept, constraints and analyses which shaped that concept, and expansibility for future needs. For over five decades, NASA has launched and operated spacecraft for studying Earth and space phenomena. As both scientific knowledge and instrument technology have advanced during this period, the observation capabilities of these spacecraft have grown as well. The transmission rates and daily volumes of data collected by science probes orbiting the earth have correspondingly increased by several orders of magnitude. As the science data downlink rates have increased, so, too, have the signal bandwidths required to support these transmissions. NASA, like all users of the radio spectrum, must respect frequency allocations established by the International Telecommunications Union (ITU). In ITU parlance, science data downlinks are designated as space-to-earth communications for the Earth Exploration Satellite Service or for the Space Research Service. The ITU has allocated about 5 MHz for such purposes at S-band (approximately 2-4 GHz), 10 MHz for Space Science links and 375 MHz for Earth Science links at X-band (about 7-12 GHz), and 1.5 GHz for direct downlinks and 2.25 GHz space-to-space links at Ka-band (about 19-36 GHz). With growing bandwidths needed to support increasing data rates, downlink designs have evolved over the decades from S-band to X-band, and near-term future needs compel advancing further to Ka-band. In advance of anticipated needs for Ka-band downlinks in the near-Earth region, NASA has developed a design for its networks operating in that region to support corresponding capabilities. This approach leverages three missions, presently under development, as references for understanding relevant needs and constraints for a solution enabling Ka-band near-Earth missions of the future. 我初步翻譯的中文： 美國宇航局近地航天器的Ka波段空間通信的演變 在未來的幾年中，美國宇航局計(jì)劃發(fā)射多個(gè)地球科學(xué)航天任務(wù)，將以1-3 Gbps的速率從近地軌道發(fā)送數(shù)據(jù)到地面站，以達(dá)到每天5-40Tb的數(shù)據(jù)吞吐量。該傳輸速率超過了過去的科學(xué)探測器所使用S波段和X波段的下行能力。因此，美國宇航局正在探索增強(qiáng)其空間通信能力，以提供下一代近地任務(wù)的Ka波段通信架構(gòu)的解決方案。本文介紹了提出的Ka波段解決方案的緣由和概念、約束，并分析概念的形成，以及對(duì)未來需求的可擴(kuò)展性。 在過去的五十年中，美國宇航局已經(jīng)發(fā)射和運(yùn)轉(zhuǎn)用于研究地球和空間現(xiàn)象的飛船。在此期間，科技和儀器工藝都有所進(jìn)步，這些航天器的觀測能力也得以增強(qiáng)。繞地科學(xué)探測器的傳輸速率和每日收集到的數(shù)據(jù)量也相應(yīng)增加了幾個(gè)數(shù)量級(jí)。隨著科學(xué)數(shù)據(jù)下行速率的增加，需要一定的信號(hào)帶寬，以支持這些數(shù)據(jù)的傳輸。 與所有其他無線電頻譜的用戶一樣，美國宇航局必須遵循國際電信聯(lián)盟（ITU）劃分的頻譜分配方案。國際電信聯(lián)盟規(guī)定，科學(xué)數(shù)據(jù)下行被指定為用于地球探測衛(wèi)星服務(wù)或空間研究服務(wù)的空-地通信。國際電信聯(lián)盟（ITU）在S波段（約2-4 GHz）分配了約5 MHz用于空-地通信；在X波段（約7-12 GHz），分配了約10 MHz用于空間科學(xué)鏈接，約375 MHz用于地球科學(xué)鏈接；在Ka波段（約19-36 GHz），分配了約1.5 GHz用于直接下行，約2.25 GHz用于空-空鏈接。為支持更高的數(shù)據(jù)傳輸速率，通信帶寬需求日益增長，近幾十年，下行設(shè)計(jì)已從S波段發(fā)展到了X波段，在不久的將來，將迫使其進(jìn)一步發(fā)展到Ka波段。 超過近地區(qū)域Ka波段下行的預(yù)期需求，美國宇航局已經(jīng)制定了其在該區(qū)域的網(wǎng)絡(luò)運(yùn)作方案，以支持相應(yīng)的功能。這種方法利用了三個(gè)任務(wù)，目前正在開發(fā)中，作為理解相關(guān)需求的參考，以及未來Ka波段近地任務(wù)解決方案的限制條件。 要求潤色，謝謝！ [ 來自科研家族 人工智能 ] |
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金蟲 (小有名氣)
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愛與雨下: 金幣-1, 規(guī)則！ 2012-06-06 18:50:42
愛與雨下: 金幣-1, 規(guī)則！ 2012-06-06 18:50:42
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