ku波段衛(wèi)星通信雨衰計算及分析外文翻譯

1、<p>　　Ku波段衛(wèi)星通信雨衰計算及分析</p><p>　　徐慨、向順祥、黃林書</p><p>　　電子工程系 海軍工程大學</p><p><b>　　中國武漢</b></p><p>　　摘要：使用雨量計、頻譜分析儀和其他設備，根據(jù)模擬結果，測量和分析了武漢市降雨率及雨衰對Ku波段衛(wèi)星通信信號的影響。

2、分析了降雨率和雨衰的關系，并將結果與國際電信聯(lián)盟無線電通信部門（ ITU-R） 估計值進行了比較，分析了實際測量值與預測值之間的不同之處。利用測得的數(shù)據(jù)，對不準確的預測模型，提出了一個改進算法，證明 ITU-R提出的預測模型是正確的。實驗結果表明，有必要通過長時間的測量，獲得足夠的數(shù)據(jù)，來確定不同站點雨衰與降雨率之間關系。</p><p>　　關鍵詞：頻譜分析儀、衛(wèi)星通信、雨衰、預測模型</p>&

3、lt;p><b>　　I 引言</b></p><p>　　在衛(wèi)星通信鏈路設計，必須計算鏈路的效率和冗余。因為信號可能會被吸收和過濾，所以必須提供冗余或一些對抗措施，如自適應功率控制，通過分集接收來提高鏈路效率。然后有兩個問題：應該提供多少冗余來滿足鏈路的有效性要求；應采取什么措施來對抗雨衰。</p><p>　　雖然國內外已經(jīng)做了許多理論的實驗研究，但是對于

4、不同的地域鏈路的設計要求，實驗結果不是很符合。</p><p>　　在論文中，通過一段時間測量武漢的降雨以及Ku波段衛(wèi)星信號衰減，繪制了降雨和信號衰減之間的關系圖。在比較獲得的關系圖和ITU-R給出的模型曲線后，證明ITU-R預測模型在不同地區(qū)之間存在一些錯誤，因此有必要進行一些測試，對ITU-R預測模型做一些修改。</p><p>　　II 測量系統(tǒng)的原理</p><

5、;p>　　圖一顯示了測量系統(tǒng)的原理。該圖的左側的是降雨衰耗估算 。下行鏈路信號由天線接收，并且其頻率被轉增下來的低噪聲B轉換，并且隨后轉到頻譜。最后，通過RS-232接口，信號電壓被保存到計算機。菱形天線 :0.6m，LNB振蕩器頻率 11300MHz ；輸入頻率：12.25GHZ~12.75GHZ；輸出頻率：950MHZ~1450MHZ；因為它是垂直極化測量信號,電源電路是采用12.5 V直流 ；光譜頻率范圍:3KHZ~ 3GH

6、Z,10個值是每分鐘收集。 </p><p>　　右側是降雨量的測量。這個雨量計的測量精度:0.1毫米~ 7毫米/小時,運行電壓:9 ~ 24 v直流電源提供的收集器.雨量計得到了降雨的每分鐘(毫米),并發(fā)送數(shù)據(jù)在計算機中的數(shù)據(jù)收集器。當數(shù)據(jù)乘以60,那么降雨的小時是有(毫米/小時)。</p><p>　　測試地點：武漢，緯度:30.52°；經(jīng)度：114.31°；高度：

7、23.3米測試頻率：12.333GHz;仰角的天線：48.45°。</p><p>　　Fig.1 實驗系統(tǒng)結構圖</p><p>　　III 測試結果及建模分析</p><p>　　A. ITU-R降雨衰減模型</p><p>　　A =g×L （dB） （1）</p><p>　　g

8、 = a×Rb （dB/km） （2）</p><p>　　其中，L是降雨的有效路徑，</p><p><b>　　g是降雨衰減比，</b></p><p><b>　　R是雨量比，</b></p><p>　　a，b是相關系數(shù)，其值隨頻率不同變化。</p><p>

9、;　　B.陽光下計算放的信號的參考電平</p><p>　　吸光度的衰減在雨天、云和大氣的變化是緩慢的。大氣吸收有氧氣和水蒸氣組成。其中水的蒸氣在不同的天氣變化最大。相比較而言，吸收衰減在慢衰減中是最主要的因素。</p><p>　　為了去除噪聲和閃爍的影響，分析了在下雨之前三天和下雨之后三天的晴朗天氣所有的信號電平，得到了晴朗天氣的信號參考電平As。</p><p&g

10、t;<b>　　C.計算雨衰</b></p><p>　　取在1分鐘內獲得的10個信號得平均值,就得到了雨中每分鐘的信號電平。然后每分鐘雨衰如下：</p><p>　　A ??As ??Ar （dB）</p><p>　　其中，A是指雨衰，As是晴朗天氣的信號參考電平，Ar是雨中的每分鐘信號電平。</p><p><

11、;b>　　D.測量結果分析</b></p><p>　　圖2表示的是武漢地區(qū)2008-05-03 的降雨情況。水平軸是時間,垂直是雨衰減率。信號隨時間衰減如圖3所示。比較兩個圖，</p><p><b>　　可以得出以下結論：</b></p><p>　?。?）降雨越大，雨衰也越大。最大的降雨發(fā)生在5月3號的21:00，恰好信

12、號衰減發(fā)生在那個時候</p><p>　　（2）信號衰減是不僅發(fā)生在下雨的時候，下雨后也有，因為在某些方面天空中的云也使信號發(fā)生衰減。例如，5月3日在17:00-18:00，雖然不下雨，但很明顯，仍然有信號衰減。</p><p>　　雨衰減率期間的降雨量是相對持久。在相同的降雨，信號由降雨引起的為20的衰減分鐘顯然是大于一個或兩分鐘。</p><p>　　Fig2.

13、 武漢降雨環(huán)境</p><p>　　Fig 3 信號衰減</p><p><b>　　E.誤差分析</b></p><p>　　雨衰減和信號衰減之間的關系如圖4所示。水平軸是降雨,垂直軸的是雨衰減率?！?”曲線是降雨試驗測得,“ð”曲線是在ITU-R提供的公式模型的基礎上繪制?！啊鳌鼻€是草擬的測量值處理的最小二乘方法算法。如圖所示,

14、由ITU-R提供雨衰模型與武漢地區(qū)實際情況有很大不同，并且隨著降雨量的增加誤差也增大。</p><p>　　圖4：雨衰之間的關系</p><p>　　Fig 5. 誤差曲線</p><p>　　IV 改進后的算法模型</p><p>　　修改后的ITU-R雨衰模型：</p><p>　　Ap=Aitu-r—Perro

15、r</p><p>　　其中,Ap是修正后的雨衰減，Aitu-r是ITU-R雨衰模型預測的雨衰，Perror是修正因子。</p><p>　　圖5是誤差曲線?！?”是圖4所提供的誤差值曲線，曲線是由最小二乘法得到的。表達式為：</p><p>　　Perror=-0.0006*R*R+0.1308*R-0.1847 (dB)</p><p>

16、;　　其中，R是降雨量。則修改后的預測模型是:</p><p>　　Ap=Aitu-r—(-0.0006*R*R+0.1308*R-0.1847 ) (dB)</p><p><b>　　V. 結論</b></p><p>　　在本文中，利用相關設備測量了降雨量和Ku波段衛(wèi)星通信信號衰減的值。通過比較測量值和ITU-R提供的雨衰模型，發(fā)現(xiàn)

17、了測量值和預測值之間的一些不同。通過分析測量數(shù)據(jù)，提出了一個修改算法來修正ITU-R提供的雨衰模型。結果表明，隨著測得的數(shù)據(jù)的數(shù)量的增加這個修改后的數(shù)據(jù)會與實際值更吻合。</p><p>　　信號衰減與降雨持續(xù)時間有關。同樣的降雨比,持續(xù)20分鐘降雨引起的信號衰減比續(xù)1分鐘或2分鐘降雨大得多。與此同時,真正的</p><p>　　情況是非常復雜的、多方面的，特別是決定雨衰減一些因素,如雨滴

18、的大小,降水在整個衰減路徑的分布、風速和溫度，他們都對雨衰有影響。所以我們應該建立一個長期的觀察機制，來獲得降雨衰減和降雨的足夠數(shù)據(jù)。這些數(shù)據(jù)將是未來研究ka波段衛(wèi)星通信重要的基礎。</p><p><b>　　參考文獻</b></p><p>　　[ 1 ] Zulfajri B H，Kiyotaka F, Kenichi I, and Mitsuo T。日本九州島

19、Ku波段雨衰測量，[ J ]。IEEE天線與無線傳播快報，2002（1）：116-119.。</p><p>　　[2] J.Kang，H.Echigo K.Ohnuma，S.Nishida，R.Sato，“VSAT系統(tǒng)三年測量和在Ku波段雨衰衛(wèi)星通道CCIR估計”，IEICE Trans.Commun，vol.E79-B，pp.1546-1558，1997年10月。</p><p>　　

20、[3]Amaya C, Rogers D V亞太海事展氣候變化Ka波段衛(wèi)星地球鏈接降雨衰減特性[J]。IEEE Trans. On Microwave Theory and</p><p>　　Techniques, 2002, 50(1): 41-45</p><p>　　[4] Dissanayake A, Allnuh J.雨衰減和其他傳播障礙以及地球衛(wèi)星路徑的預測模型[J].IEE

21、E Trans. On Antennas andPropagation, 1997, 45(10): 1546-1557.</p><p>　　[5] Dong You Choi，使用1小時降雨率無1分鐘降雨率轉換的雨衰預測模型[J]。IJCSN計算機科學國際期刊和網(wǎng)絡安全報,2006(6):130-133</p><p>　　[6] Rec.ITU-R PN.618-8，地球電信系統(tǒng)空間

22、設計方法需要傳播數(shù)據(jù)和預測方法[S].ITU,Geneva,2003.</p><p>　　作者：許凱（M'90）出生于1965年，江蘇，中國。他在2001年成為聯(lián)營公司教授。他的興趣包括波的傳播，散射和衛(wèi)星通信系統(tǒng)。</p><p><b>　　外文原文：</b></p><p>　　Measuring and Analyzer of

23、 Rain Attenuation for Satellite</p><p>　　Communication in Ku band </p><p>　　XU kai, Xiang shunxiang, Huang Linshu</p><p>　　Electronics Engineering Department,</p><p>　　

24、Naval Univ. of Engineering ,</p><p>　　Wu han,China</p><p>　　Abstract—Using a rain gauge, spectrum analyzer and other equipments,rain rate and rain attenuation for the satellite communication sig

25、nals in Ku band(14/12GHz) in Wuhan city are measured and analyzed simultaneously according to simulations. The relation between rain</p><p>　　attenuation and rain rate are analyzed, the result is compared wi

26、th the estimated International Telecommunication Union Radio Communication Sector (ITU-R) and the difference between the prediction and the measuration is analyzed. To the inaccuracy of the forecasting model, a modified

27、algorithm is presented and by using the data measured, the ITU-R forecasting model is corrected. The experiment results suggest it is necessary to measure for long time to get enough data of the relation</p><p

28、>　　between rain attenuation and rain rate at differentstations.</p><p>　　Keywords：spectrum analyzer; satellite communication; rain attenuation；forecasting model</p><p>　　I. INTRODUCTION</p

29、><p>　　In the satellite communication link designing,efficiency and redundancy of link must be computed.For the signal may be absorbed and glittering ,enough redundancy or some counter-measure must be provided,

30、 such as the adaptive power control, receiving by dividing to improve the efficiency of link[1]. Then there are two problems: how much does the link redundancy should be provided to meet the demand of the efficiency of t

31、he link; what kind of counter measure to rain attenuation should be taken. Al</p><p>　　In the paper, by measuring on the rainfall in Wuhan and the satellite signal attenuation of Ku band for a period, the re

32、lationship shown in graph between the rainfall and its attenuation are got. After the comparison between the result graph and the modeling curve given by the ITU-R, it is proved that inaccuracy exist in the ITU-R foreca

33、sting to the rainfall in various district then it is necessary to take some testing and do</p><p>　　some modification.</p><p>　　II. PRINCIPLE OF MEASUREMENT SYSTEM</p><p>　　Princip

34、le of measurement system is shown in fig.1. The left of the figure are the rainfall attenuation measurement. The downlink signal is received by the antenna and its frequency are conversed down by the</p><p>

35、　　Low Noise B conversion and then goes to the spectrum. At last it saves the signal voltage to the computer through the RS-232 interface. Antenna diamond:0.6m; LNB oscillator frequency: 11300MHz ； input frequency：12.25GH

36、z～12.75GHz；output frequency：950MHz～1450MHz；since it is the vertical polarized signal measured ,the power supply circuit is adapted the 12.5V DC; the spectrum frequency range :3KHz～3GHz， 10 values are collected per minute

37、.</p><p>　　The right is the rainfall measurement. The pluviometer’s measure precision：0.1mm～7mm/h； denotation error ： one-off rainfall ¡Ü10mm ，error¡Ü±0.2mm，one-off rainfall >10mm

38、，error¡Ü±2%；</p><p>　　running voltage：9～24V DC are provided by the collector. The pluviometer gets the rainfall per minute（mm）and send the data to the computer by the data collector. When the

39、data are multiplied by 60, then the rainfall of that hour is got（mm/h）.</p><p>　　Testing place: Wuhan; latitude:30.52°；longitude114.31° ； altitude ： 23.3m ； testing frequency ：12.333GHz； elevation

40、of the antenna：48.45°。</p><p>　　Fig.1 Experimental system structure</p><p>　　III. TESTING RESULT AND MODELING ANALYSIS</p><p>　　ITU-R rainfall attenuation model[6]</p>

41、<p>　　A =g×L （dB） （1）</p><p>　　g = a×Rb （dB/km） （2）</p><p>　　Where, L is the rainfall effective path,</p><p>　　g is the ratio of rainfall attenuation , R is the rat

42、io of rainfall, a 、b are correlative coefficient. the value is varied with the different frequency.</p><p>　　B. Calculating of the signal referenced level in sunshine</p><p>　　The change of abso

43、rbance attenuation of rain, cloud and atmosphere is slow change. Atmosphere absorption are made of oxygen and water vapors, among them the water vapors are varied mostly with the different weather. Taking one with anothe

44、r, absorption attenuation are the most important factors among slow change attenuations.</p><p>　　To remove the influence of the noise and scintilla , the mean is got from all the signal levels in sunshine w

45、eather in the three days before and after the rain, the signal referenced level in sunshine weather s A is obtained then .</p><p>　　C. Calculating the rain attenuation</p><p>　　To take the avera

46、ge of the 10 signal levels which are adapted in one minute, the signal level per minute in rain is obtained .Then the rain attenuation of the minute is got as follows:</p><p>　　A = As - Ar （dB） （3）</p>

47、<p>　　Where, A is the rain attenuation，As is the signal referenced level in sunshine, r A is the signal level per minute in rain.</p><p>　　D. Measuring Result Analysis</p><p>　　It is sho

48、wn in figure.2 that the raining circumstance in Wuhan district on 2008-05-03.The horizontal axes is time, the vertical is the rain attenuation ratio. The signal attenuation corresponding with the time is shown in figure

49、.3. Compared the two graphs, these conclusion can be drawn: </p><p>　　The heavier is the rainfall, the greater is the corresponding rain attenuation ratio.When the maximum of rainfall happened at about 21:00

50、 hour on May 3rd, the signal attenuation happened just at that time then. </p><p>　　(2).The signal attenuation are not only happen during the rain time, but also after the rain, because the cloud in sky also

51、 causes the</p><p>　　attenuation in some respects. For instance, during 17:00 -18:00 on May 3rd, though there is not rain ,but it is obvious that there is still signal attenuation. </p><p>　?。?）

52、 The rain attenuation ratio is relative with the period which the rainfall is lasting. To the same rainfall, the signal</p><p>　　attenuation which is caused by the rainfall for 20 minutes is clearly greater

53、than that for one or two minutes.</p><p>　　Fig2. Raining circumstance inWuhan</p><p>　　Fig 3 Signal attenuation with the time</p><p>　　E. Error analysis</p><p>　　The re

54、lationship between the rain attenuation and the signal rain attenuation is shown in fig.4. The horizontal axes is rainfall, the vertical is the rain attenuation ratio. “*”-curve is the rainfall measured in experiment,“&#

55、161;ð”-curve is drawn based on the formula provided by the ITU-R model. “△”-curve is drawn up of measured value processed by the method of Least Squares Algorithm. As shown, the rain attenuation model provided by IT

56、U-R is greatly varied from the</p><p>　　real situation in Wuhan district and the error increases with the rainfall’s increasing</p><p>　　IV. MODIFIED ALGORITHM TO THE MODEL</p><p>

57、　　To modify the rain attenuation model from ITU-R , it is defined as:</p><p>　　Ap=Aitu-r—Perror （4）</p><p>　　Where, P A is the rain attenuation after compensating, ITU R A - is the fo

58、recasted attenuation from the ITU-R model, error P is</p><p>　　the compensating factor. Fig.5 is the error curve. “*”is the error value</p><p>　　provided by the result of fig.4 and curve is dr

59、awn up by the method of Least Squares Algorithm, the expression is:</p><p>　　Perror=-0.0006*R*R+0.1308*R-0.1847 (dB)</p><p>　　Where , R is the rainfall. Then the modified rainfall forecasting m

60、odel is:</p><p>　　Ap=Aitu-r—(-0.0006*R*R+0.1308*R-0.1847 )</p><p>　　Fig 4 Relationship between the rain attenuation</p><p>　　Fig 5. The error curve.</p><p>　　V. CONCLUS

61、ION </p><p>　　In this paper, the rainfall and Ku-band satellite signal attenuation are measured by using the equipments. And then the measured value is compared with the rainfall model provided by the ITU-R

62、and some differences are found between the measured and forecasted. We propose a modified algorithm to modify the model provided by ITU-R by analyzing the measured data. The result shows that after modifying data will be

63、 more consistent with the real value with the</p><p>　　increasing of the measured data number. Signal attenuation is related with the rainfall lasting period. For the same rainfall ratio, the signal attenuat

64、ion caused by rainfall lasting for 20 minutes is greater then the one for one or two minutes. Meanwhile ,the real situation is very complex and various, especially some factors decided the rain attenuation ,such as the d

65、imension of raindrop, the rainfall distributing on the whole attenuation path, wind velocity and temperature ,they are all even.</p><p>　　REFERENCES</p><p>　　[1]Zulfajri B H, Kiyotaka F, Kenichi

66、 I, and Mitsuo T.Measurement of Ku-Band Rain Attenuation Using Several VSATs in Kyushu Island,Japan[J]. IEEE Antennas and Wireless Propagation Letters, 2002(1): 116-119.</p><p>　　[2]J.Kang,H.Echigo,K.Ohnuma,

67、S.Nishida,and R.Sato,”Three-year measurement by VSAT system and CCIR estimation for rain attenuation in Ku-band satellite channel, ”IEICE Trans.Commun.,vol.E79-B,pp.1546-1558, Oct.1997.</p><p>　　[3]Amaya C,

68、Rogers D V. Characteristics of Rain Fading on Ka-Band Satellite–Earth Links in a Pacific Maritime Climate[J]. IEEE Trans. On Microwave Theory and Techniques, 2002, 50(1): 41-45.</p><p>　　[4] Dissanayake A, A

69、llnuh J. A Prediction Model that RainAttenuation and other Propagation Impairments alongEarth-Satellite Path[J]. IEEE Trans. On Antennas andPropagation, 1997, 45(10): 1546-1557.</p><p>　　[5] Dong You Choi,Ra

70、in attenuation prediction model by using the 1-hour rain rate without 1-minute rain rate conversion[J].IJCSNS International Journal of Computer Science and Network Security,2006(6):130-133.</p><p>　　[6] Rec.

71、ITU-R PN.618-8,"Propagation data and prediction methods required for the design of earth-space telecommunications systems"[S].ITU,Geneva,2003. </p><p>　　Author: Xu Kai(M’90-) was born in 1965,in Ji