通信工程外文翻譯---一點多址擴頻通信系統(tǒng)的應(yīng)用

1、<p><b>　　【附錄】</b></p><p><b>　　英文文獻</b></p><p>　　The Application of one point Multiple Access Spread Spectrum Communication System</p><p>　　Liu Jiangang,

2、 Nanyang City, Henan Province Electric Power Industry Bureau</p><p>　　【ABSTRACT】Spread Spectrum Digital Microwave communication as a communication, because their excellent performance have been widely used.

3、The article in Nanyang City Power Industry Bureau one point Multiple Access Spread Spectrum Communication System as an example. briefed the spread spectrum communications, the basic concept and characteristics of the pow

4、er system communication applications</p><p>　　.KEYWORDS ：one point multiple access; Spread-spectrum communication; Attenuation </p><p>　　Nanyang City in the outskirts of Central cloth 35 to 11 k

5、v substation farm terminals, their operation management rights belong to the Council East, Rural Power Company west (the eastern suburb of agricultural management companies -- four, the western suburbs of Rural Power Com

6、pany Management 7), Scheduling of the various stations of the means of communication to the original M-150 radio and telephone posts. 2002 With the transformation of rural network, the remote station equipment into opera

7、tio</p><p>　　Given the status and power grid substation level, nature, taking into account the carrier and optical-fiber communications to conduct multiple forwarding, increasing the instability factor, cons

8、idering the cost and conditions of the urban construction, Finally decided to adopt wireless spread-spectrum technology to establish that 11 farm terminal substation communication system. This paper describes the spread

9、spectrum technology and the current system of the building.</p><p>　　The basic concept of spread-spectrum communication.</p><p>　　Spread Spectrum Communication's basic characteristics, is us

10、ed to transmit information to the signal bandwidth (W) is far greater than the practical information required minimum (effective) bandwidth (△ F) , as the ratio of processing gain GP .</p><p>　　GP = W/△F <

11、;/p><p>　　As we all know, the ordinary AM, FM, or pulse code modulation communications, GP values in the area more than 10 times, collectively, the "narrow-band communication", and spread-spectrum com

12、munications GP values as high as hundreds or even thousands of times, can be called "broadband communications." </p><p>　　Due to the spread-spectrum signal, it is very low power transmitters, trans

13、mission space mostly drowned in the noise, it is difficult to intercepted by the other receiver, only spreading codes with the same (or random PN code) receiver, Gain can be dealt with, and despreading resume the origina

14、l signal. </p><p>　　The technology superiority of spread-spectrum communication .</p><p>　　Strong anti-interference, bit error rate is low.As noted above, the spread spectrum communication syste

15、m due to the expansion of the transmitter signal spectrum, the receiver despreading reduction signal produced spreading gain, thereby greatly enhancing its interference tolerance . Under the spreading gain, or even negat

16、ive in the signal-to-noise ratio conditions, can also signal from the noise drowned out Extraction, in the current business communications systems, spread spectrum communication</p><p>　　Anti-multi-path inte

17、rference capability, increase the reliability of the system. Spread-spectrum systems as used in the PN has a good correlation, correlation is very weak. different paths to the transmission signal can easily be separated

18、and may in time and re-alignment phase, formation of several superimposed signal power, thereby improving the system's performance to receive increased reliability of the system. </p><p>　　Easy to use th

19、e same frequency, improving the wireless spectrum utilization.Wireless spectrum is very valuable, although long-wave microwave have to be exploited, and still can not meet the needs of the community. To this end, countri

20、es around the world are designed spectrum management, users can only use the frequency applications, rely on the channel to prevent the division between the channel interference. </p><p>　　Due to the use of

21、spread-spectrum communication related receive this high-tech, low signal output power ( "a W, as a general-100 mW), and will work in the channel noise and thermal noise in the background, easy to duplicate in the sa

22、me area using the same frequency, can now all share the same narrow-band frequency communications resources.</p><p>　　Spread spectrum communication is digital communications, particularly for digital voice

23、and data transmission while, spread spectrum communication with their own encryption, only in the same PN code communication between users, is good for hiding and confidential in nature, facilitating communications busin

24、ess . Easy to use spread-spectrum CDMA communications, voice compression and many other new technologies, more applicable to computer networks and digitization of voice, image information tra</p><p>　　Commun

25、ication is the most digital circuits, equipment, highly integrated, easy installation, easy maintenance, but also very compact and reliable. The average failure rate no time was very long. </p><p>　　We have

26、decided to adopt the spread-spectrum communication technology construction of 11 farm terminal substation communications system, Due to the spread-spectrum communication by the line-of-sight transmission distance restric

27、tions, has become unstoppable system design premise. </p><p>　　If the PUC scheduling Building and 11 substations have stopped, and the problem becomes more complicated, use spread spectrum system on the feas

28、ibility greatly reduced. Therefore, we look at the city Aerial topographical map, initially identified has not stopped to consider systems design, and requests the companies used this equipment Spread Spectrum 11 points

29、transmission routing of the measured and the results have been satisfactory.</p><p>　　Then spread spectrum wireless equipment market supply of cash, Initially, we selected a series of Spread Spectrum Comlink

30、 third generation products. Because most of the point-to-point mode, Merit function of the spread-spectrum equipment in a point-to-multipoint application environments encountered many problems : First is the issue of fre

31、quency resources. Even a minimum of 64 kbit / s data rate radio, space also occupied bandwidth 5 MHz, Because 32 of the PN code isolation is only about 15 dBm,</p><p>　　Second antenna erection problems, poin

32、t-to-point equipment for the main radio station, the main station need to set up a number of terminal antennas, the vast majority of domestic engineering companies used by the U.S. Conifer 24 dBi parabolic semi-cast magn

33、esium grid directional antenna. vertical polarization - 1 m wide, it is difficult to top the layout and avoid flap flap and the mutual interference, Although the project can be set up to take stratified, or through coope

34、ration and on the road</p><p>　　In addition, the RF cable laying, The application of network management software such factors we have also decided to adopt the final 1:00 Comlink Multiple Access Spread Spect

35、rum products. Its system configuration, as shown in Figure 2:</p><p>　　Routing Analysis</p><p>　　Combining visual distance access and use the radio and antenna gain, cable attenuation and enviro

36、nmental factors, and testing the design is reasonable, determine the attenuation affluent channel capacity. Spread spectrum microwave link attenuation depends on the reliability margin.</p><p>　　Attenuation

37、margin calculation formula : FG= GSG + GANT - LGL - LPL</p><p>　　FG——Attenuation margin ； </p><p>　　GSG——System Gain (dB）； </p><p>　　GANT——Antenna Gain (dBi）； </p><p>

38、　　LGL——Connectors and cables attenuation (dB)； </p><p>　　LpL—— Channel attenuation (dB）。 </p><p>　　Gain spread spectrum radio system : GSG = +27 - (-97) = 124 (dBm)； </p><p>　　Ante

39、nna Gain : master-use 2.4 GHz, 12 dBi Omni-Directional Antenna, stop-use 2.4 GHz, 24 dBi parabolic directional antennas; </p><p>　　Connector and cable attenuation : cable attenuation of about 3 dB, as a join

40、t dB attenuation, LGL = 3 + 1 = 4 (dB); </p><p>　　Channel attenuation to the farthest distance from the building scheduling substation (27 km) as an example : LPL = 92.4 + + 20lg27 20lg2.4 = 128 (dB); </p

41、><p>　　Therefore attenuation cushion : FG = 124 + 12 + 24-2 × 4-128 = 24 (dB). </p><p>　　Calculated from the amount of affluent link can be seen, the program has larger reserves and thus the r

42、ational design of the program, According to the measured and the results showed the channel can ensure quality and reliability. </p><p>　　Operation of the system.</p><p>　　System since May 2003

43、has been put into operation more than two years, each station to transmit information, there are two phones, 600 or 1200 Porter remote information operations, clear voice station, Channel stability, without error, System

44、 not had any serious interruptions and failures, equipment operating normally. Thus, the spread spectrum link to the design and equipment selection has been very good to meet the voice and remote automated information tr

45、ansmission, Network for the safe and s</p><p>　　Concluding remarks .</p><p>　　Spread-spectrum technology in the initial stages of development, it has become a theory and a major technological br

46、eakthrough, Later in the development process is the improvement and hardware performance improved. Development to the present, spread-spectrum technology and the theory has been almost perfect, mainly from the point of v

47、iew of overall performance, and other new technology applications. Therefore, the application has been driven by the development of spread-spectrum technology is a </p><p>　　Although fiber technology in the

48、power system communication applications become increasingly common. But the county power communication network or higher cost-effective communications network, 1:00 Multiple Access microwave communications will continue

49、to play an important role in spread spectrum technology and will enjoy even broader application of space.</p><p><b>　　中文文獻</b></p><p>　　一點多址擴頻通信系統(tǒng)的應(yīng)用</p><p>　　劉建剛 河南省南陽市

50、電力工業(yè)局</p><p>　　【摘要】擴頻通信作為數(shù)字微波通信的一種，由于其本身具備的優(yōu)良性能而得到廣泛應(yīng)用。該文以南陽市電力工業(yè)局一點多址擴頻通信系統(tǒng)為例，簡要介紹了擴頻通信技術(shù)的基本概念、特點及其在電力系統(tǒng)通信中的應(yīng)用。</p><p>　　關(guān)鍵詞：一點多址；擴頻通信；衰耗 </p><p>　　在南陽市郊區(qū)環(huán)布著11座35 kv農(nóng)用終端變電站，其運行管理權(quán)分

51、屬市局東、西郊農(nóng)電公司（其中東郊農(nóng)電公司管理4座，西郊農(nóng)電公司管理7座），調(diào)度到各站的通信方式原為150 M無線電和郵電市話。2002年隨著農(nóng)網(wǎng)改造的進行，各站遠動設(shè)備投入運行，對通信通道提出了更高要求。由于市局調(diào)度通信大樓到東、西郊農(nóng)電公司之間分別有光纖相連，故如果這11座變電站建立了和調(diào)通大樓的聯(lián)系，則可將各站數(shù)據(jù)和話音分別送往兩個農(nóng)電公司調(diào)度室，從而為農(nóng)網(wǎng)調(diào)度自動化的實施創(chuàng)造必要的條件。 </p><p>

52、　　鑒于電網(wǎng)現(xiàn)狀和變電站的等級、性質(zhì)，考慮到載波和光纖通信要經(jīng)過多次轉(zhuǎn)接，增加了不穩(wěn)定因素，綜合考慮成本及市區(qū)施工條件，最后決定采用無線擴頻技術(shù)建立這11座農(nóng)用終端變電站的通信系統(tǒng)。本文簡要介紹了擴頻技術(shù)及在此次系統(tǒng)建設(shè)中的應(yīng)用。 </p><p>　　1 .擴頻通信技術(shù)的基本概念 </p><p>　　擴頻通信的基本特點，是其傳輸信息所用信號的帶寬（W）遠大于信息本身實際所需的最?。ㄓ行?/p>

53、）帶寬（△F），其比值稱為處理增益GP </p><p>　　GP = W/△F </p><p>　　眾所周知，在普通的調(diào)幅、調(diào)頻或脈沖編碼調(diào)制通信中，GP值一般都在十</p><p>　　多倍范圍內(nèi)，統(tǒng)稱“窄帶通信”，而擴頻通信的GP值高達幾百甚至幾千倍，可以稱為“寬帶通信”。 </p><p>　　由于擴頻后的信號，它的發(fā)射功率很低，傳

54、輸時大多淹沒在空間的噪聲中，因此很難被其它接收機截獲，只有具有相同擴頻碼（或稱PN隨機碼）的接收機，才能獲得處理增益，解擴并恢復(fù)出原發(fā)的信號。 </p><p>　　2. 擴頻通信技術(shù)的優(yōu)越性 </p><p>　　抗干擾性強，誤碼率低。如上所述，擴頻通信系統(tǒng)由于在發(fā)送端擴展信號頻譜，在接收端解擴還原信號，產(chǎn)生了擴頻增益，從而大大地提高了抗干擾容限。根據(jù)擴頻增益不同，甚至在負(fù)的信噪比條件下

55、，也可以將信號從噪聲的淹沒中提取出來，在目前商用的通信系統(tǒng)中，擴頻通信是惟一能夠工作于負(fù)信噪比條件下的通信方式。 </p><p>　　抗多徑干擾能力強，增加了系統(tǒng)的可靠性。由于擴頻系統(tǒng)中采用的PN碼具有很好的自相關(guān)性，互相關(guān)性很弱，不同路徑傳輸來的信號能容易地被分開，并可在時間和相位上重新對齊，形成幾路信號功率的疊加，從而改善了接收系統(tǒng)的性能增加了系統(tǒng)的可靠性。 </p><p>　　易

56、于同頻使用，提高了無線頻譜利用率。無線頻譜十分寶貴，雖然從長波到微波都已得到開發(fā)利用，仍然滿足不了社會的需求。為此，世界各地都設(shè)計了頻譜管理機構(gòu)， 用戶只能使用申請獲得的頻率，依靠頻道劃分來防止信道之間發(fā)生干擾。 </p><p>　　由于擴頻通信采用了相關(guān)接收這一高技術(shù)，信號發(fā)送功率極低（< 1 W，一般為1～100 mW），且可工作在信道噪聲和熱噪聲背景中，易于在同一地區(qū)重復(fù)使用同一頻率，也可以與現(xiàn)今各

57、種窄帶通信共享同一頻率資源。 </p><p>　　擴頻通信是數(shù)字通信，特別適合數(shù)字話音和數(shù)據(jù)同時傳輸，擴頻通信自身具有加密功能，只能在PN碼相同的用戶之間進行通信，隱蔽性好，保密性強，便于開展各種通信業(yè)務(wù)。擴頻通信容易采用碼分多址、語音壓縮等多項新技術(shù)，更加適用于計算機網(wǎng)絡(luò)以及數(shù)字化的話音、圖像信息傳輸。 </p><p>　　擴頻通信絕大部分是數(shù)字電路，設(shè)備高度集成，安裝簡便，易于維護

58、，也十分小巧可靠，平均無故障率時間也很長。 </p><p>　　在我們決定采用擴頻通信技術(shù)建設(shè)這11座農(nóng)用終端變電站的通信系統(tǒng)之后，由于擴頻通信的傳輸距離受到視距的限制，阻擋就成為系統(tǒng)的設(shè)計前提。若市局調(diào)度大樓和11座變電站之間有阻擋，則問題就變得較為復(fù)雜，選用擴頻系統(tǒng)的可行性就大打折扣。因此，我們查看了我市航測地形圖，初步確定沒有阻擋才考慮進行系統(tǒng)設(shè)計，并請有關(guān)公司用擴頻設(shè)備對這11個點的傳輸路由進行了實

59、測，結(jié)果令人滿意。 </p><p>　　根據(jù)當(dāng)時市面上無線擴頻設(shè)備現(xiàn)貨供應(yīng)情況，我們初步選定了Comlink擴頻系列第三代產(chǎn)品。因為大多數(shù)在點對點方式下，功能優(yōu)異的擴頻設(shè)備在一點對多點的應(yīng)用環(huán)境中遇到許多問題：首先是頻率資源問題，即使最低64 kbit/s數(shù)據(jù)速率的電臺，空間帶寬也要占用5 MHz，由于32位PN碼的碼間隔離度只有15 dBm左右，所以工程上不得不采用頻分多址，以獲得35 db左右的理論隔離度。

60、11個站就要使用11個頻點，頻率資源浪費較大，而Comlink擴頻產(chǎn)品可在同一頻點實現(xiàn)一點對多點通信。其次是天線架設(shè)問題，點對點設(shè)備，對于主站的多個電臺，需要在主站端架設(shè)多個天線，國內(nèi)工程絕大多數(shù)采用美國Conifer公司24 dBi的半拋物面鑄鎂柵格定向天線，垂直極化面展寬1 m，很難在塔頂布置且避開側(cè)瓣和后瓣的相互干擾，雖然工程上可以采取分層架設(shè)，或是通過合路器并至一個或多個全向天線發(fā)射，但由于施工及合路器的信號衰減等原因，傳輸效果

61、并不理想。此外，射頻電纜的鋪設(shè)、網(wǎng)管軟件的應(yīng)用等因素也使我們最后決定采用Comlink一點多址擴頻產(chǎn)品。其系統(tǒng)配置，如圖2所示。 </p><p><b>　　3. 路由分析 </b></p><p>　　結(jié)合可視通道距離、選用的電臺、天線增益、電纜衰耗及環(huán)境因素，檢驗設(shè)計是否合理，確定通道的衰耗富裕量。擴頻微波鏈路的可靠性取決于衰減裕量。 </p>&

62、lt;p>　　衰減裕量計算公式FG= GSG + GANT - LGL - LPL </p><p>　　式中 FG——衰減裕量； </p><p>　　GSG——系統(tǒng)增益(dB）； </p><p>　　GANT——天線增益(dBi）； </p><p>　　LGL——接插件及電纜衰耗(dB)； </p><p&g

63、t;　　LpL——通道衰耗(dB）。 </p><p>　　擴頻電臺系統(tǒng)增益：GSG = +27 - (-97) = 124 (dBm)； </p><p>　　天線增益：主站端選用2.4 GHz，12 dBi的全向天線，分站端選用2.4 GHz，24 dBi的拋物面定向天線； </p><p>　　連接頭及電纜衰耗：電纜衰耗約為3 dB，接頭衰耗為1 dB，LGL

64、= 3 + 1 = 4 (dB)； </p><p>　　通道衰耗，以距離調(diào)度大樓最遠的變電站（27 km）為例：LPL = 92.4 + 20lg2.4 + 20lg27 = 128(dB)； </p><p>　　因此衰減余量為：FG= 124 + 12 + 24 - 2×4 - 128 = 24 (dB)。 </p><p>　　從計算出的鏈路富裕量

65、可以看出，該方案有較大儲備，因此本方案設(shè)計合理，并根據(jù)實測結(jié)果表明可保證通道的質(zhì)量和可靠性。 </p><p>　　4. 系統(tǒng)運行情況 </p><p>　　系統(tǒng)自2003年5月投入運行至今已有兩年多時間，每站傳輸信息有兩路電話、600或1200波特的遠動信息一路，各站話音清晰，通道穩(wěn)定，無誤碼，系統(tǒng)未出現(xiàn)過嚴(yán)重中斷和故障，設(shè)備運行正常。因此，該擴頻鏈路的設(shè)計及設(shè)備選型已很好地滿足了話音及

66、遠動自動化信息的傳輸要求，為電網(wǎng)的安全穩(wěn)定運行提供了可靠保證。 </p><p><b>　　5 結(jié)束語 </b></p><p>　　擴頻技術(shù)在發(fā)展的初始階段，就已經(jīng)實現(xiàn)了理論和技術(shù)上的重大突破，在此后的發(fā)展過程中主要是硬件的改善和性能的提高。發(fā)展到現(xiàn)在，擴頻技術(shù)理論和技術(shù)都已趨于完善，主要應(yīng)從系統(tǒng)的角度考慮總體性能，且與其它新技術(shù)結(jié)合應(yīng)用。因此，應(yīng)用的驅(qū)動一直是擴