點多址擴頻通信系統(tǒng)的應用畢業(yè)論文外文翻譯

1、.英文文獻The Application of one point Multiple Access Spread Spectrum Communication SystemLiu Jiangang, Nanyang City, Henan Province Electric Power Industry Bureau【ABSTRACT】Spread Spectrum Digital Microwave communication as a communication, because their excellent performance have been widely used. The

2、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 power system communication applications.KEYWORDS ：one point multiple access; Spread-spe

3、ctrum communication; Attenuation Nanyang City in the outskirts of Central cloth 35 to 11 kv 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

4、Power Company 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 operation and communication channels to put a higher demand .As PUC Dispatch

5、 Communication Building to the east and west of farmers - the difference between a company linked to fiber, Therefore, if 11 substations and the establishment of a transfer Link Building links Point may be the data and voice were sent to two rural power companies dispatch room, Rural Network schedul

6、ing for the implementation of automation to create the necessary conditions.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, considering the cost and condition

7、s 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 spectrum technology and the current system of the building.1. The basic concept of spread-spectrum communicati

8、on.Spread Spectrum Communication's basic characteristics, is used 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 .GP = W/F As we all know, the ordinary AM, FM, or p

9、ulse code modulation communications, GP values in the area more than 10 times, collectively, the "narrow-band communication", and spread-spectrum communications GP values as high as hundreds or even thousands of times, can be called "broadband communications." Due to the spread-s

10、pectrum signal, it is very low power transmitters, transmission 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 original signal. 2. The technol

11、ogy superiority of spread-spectrum communication .Strong anti-interference, bit error rate is low.As noted above, the spread spectrum communication system due to the expansion of the transmitter signal spectrum, the receiver despreading reduction signal produced spreading gain, thereby greatly enhan

12、cing its interference tolerance . Under the spreading gain, or even negative 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 is only able to work in a negative signal-to-nois

13、e ratio under the conditions of communication. Anti-multi-path interference 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 and may in ti

14、me and re-alignment phase, formation of several superimposed signal power, thereby improving the system's performance to receive increased reliability of the system. Easy to use the same frequency, improving the wireless spectrum utilization.Wireless spectrum is very valuable, although long-wave

15、 microwave have to be exploited, and still can not meet the needs of the community. To this end, countries 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. Due to the use of

16、 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 same area using the same frequency, can now all share the same narrow-band freque

17、ncy communications resources.Spread spectrum communication is digital communications, particularly for digital voice 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 natu

18、re, facilitating communications business . 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 transmission. Communication is the most digital circuits, equipment, highly

19、 integrated, easy installation, easy maintenance, but also very compact and reliable. The average failure rate no time was very long. We have decided to adopt the spread-spectrum communication technology construction of 11 farm terminal substation communications system, Due to the spread-spectrum co

20、mmunication by the line-of-sight transmission distance restrictions, has become unstoppable system design premise. If the PUC scheduling Building and 11 substations have stopped, and the problem becomes more complicated, use spread spectrum system on the feasibility greatly reduced. Therefore, we lo

21、ok 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 transmission routing of the measured and the results have been satisfactory.Then spread spectrum wireless equipment marke

22、t supply of cash, Initially, we selected a series of Spread Spectrum Comlink 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 frequen

23、cy 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, the project had to use frequency division multiple access 35 db to get around the theoretical isolation. 11 stations will use 11 frequency, freq

24、uency greater waste of resources. Comlink and Spread Spectrum products in the same frequency to achieve a point-to-multipoint communications. Second antenna erection problems, point-to-point equipment for the main radio station, the main station need to set up a number of terminal antennas, the vast

25、 majority of domestic engineering companies used by the U.S. Conifer 24 dBi parabolic semi-cast magnesium 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 stratifi

26、ed, or through cooperation and on the road to one or more omnidirectional antenna launch, However, as construction of a road and the signal attenuation, transmission result is not satisfactory. In addition, the RF cable laying, The application of network management software such factors we have also

27、 decided to adopt the final 1:00 Comlink Multiple Access Spread Spectrum products. Its system configuration, as shown in Figure 2:3. Routing AnalysisCombining visual distance access and use the radio and antenna gain, cable attenuation and environmental factors, and testing the design is reasonable,

28、 determine the attenuation affluent channel capacity. Spread spectrum microwave link attenuation depends on the reliability margin.Attenuation margin calculation formula : FG= GSG + GANT - LGL - LPL FGAttenuation margin ； GSGSystem Gain (dB）； GANTAntenna Gain (dBi）； LGLConnectors and cables attenuat

29、ion (dB)； LpL Channel attenuation (dB）。 Gain spread spectrum radio system : GSG = +27 - (-97) = 124 (dBm)； Antenna Gain : master-use 2.4 GHz, 12 dBi Omni-Directional Antenna, stop-use 2.4 GHz, 24 dBi parabolic directional antennas; Connector and cable attenuation : cable attenuation of about 3 dB, a

30、s a joint dB attenuation, LGL = 3 + 1 = 4 (dB); Channel attenuation to the farthest distance from the building scheduling substation (27 km) as an example : LPL = 92.4 + + 20lg27 20lg2.4 = 128 (dB); Therefore attenuation cushion : FG = 124 + 12 + 24-2 × 4-128 = 24 (dB). Calculated from the amou

31、nt of affluent link can be seen, the program has larger reserves and thus the rational design of the program, According to the measured and the results showed the channel can ensure quality and reliability. 4. Operation of the system.System since May 2003 has been put into operation more than two ye

32、ars, each station to transmit information, there are two phones, 600 or 1200 Porter remote information operations, clear voice station, Channel stability, without error, System not had any serious interruptions and failures, equipment operating normally. Thus, the spread spectrum link to the design

33、and equipment selection has been very good to meet the voice and remote automated information transmission, Network for the safe and stable operation to provide a reliable guarantee.5. Concluding remarks .Spread-spectrum technology in the initial stages of development, it has become a theory and a m

34、ajor technological breakthrough, 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 view of overall performance, and other new technology applic

35、ations. Therefore, the application has been driven by the development of spread-spectrum technology is a powerful driving force, the future wireless communication systems, such as mobile communications, Wireless LAN, global personal communications, spread spectrum technology will certainly play an i

36、mportant role. Although fiber technology in the 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 to play an important role in spr

37、ead spectrum technology and will enjoy even broader application of space.中文文獻一點多址擴頻通信系統(tǒng)的應用劉建剛 河南省南陽市電力工業(yè)局【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的基本概念、特點及其在電力系統(tǒng)通信中的應用。 關鍵詞：一點多址；擴頻通信；衰耗 在南陽市郊區(qū)環(huán)布著11座35 kv農(nóng)用終端變電站，其運行管理權分屬市局東、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

38、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。 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及在此次系統(tǒng)建設中的應用。 1 .擴頻通信技術的基本概念 擴頻通信的基本特點，是其傳輸信息所用信號

39、的帶寬（W）遠大于信息本身實際所需的最小（有效）帶寬（F），其比值稱為處理增益GP GP = W/F 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”。 由于擴頻后的信號，它的發(fā)射功率很低，傳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，解擴并恢復出原發(fā)的信號。 2. 擴頻通信技術的優(yōu)越性 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

40、容限。根據(jù)擴頻增益不同，甚至在負的信噪比條件下，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信噪比條件下的通信方式。 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性，互相關性很弱，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。 易于同頻使用，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，世界各地都設計了頻譜管理機構， 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

41、干擾。 由于擴頻通信采用了相關接收這一高技術，信號發(fā)送功率極低（< 1 W，一般為1100 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)重復使用同一頻率，也可以與現(xiàn)今各種窄帶通信共享同一頻率資源。 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。擴頻通信容易采用碼分多址、語音壓縮等多項新技術，更加適用于計算機網(wǎng)絡以及數(shù)字化的話音、圖像信息傳輸。 擴頻通信絕大部分是數(shù)字電路，設備高度集成，安裝簡便，易于維護，也十分小巧可靠，平均無故障率時間也很長。 在我們決定采用擴頻通信技術建設這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)設計，并請有關公司用擴頻設備對這11個點的傳輸路由進行了實測，結果令人滿意。 根據(jù)當時市面上無線擴頻設備現(xiàn)貨供應