外文翻譯---短波通信的現(xiàn)狀及發(fā)展趨勢

1、<p>　　Current Status and Developing Tendency for High</p><p>　　Frequency Communications</p><p>　　Abstract: </p><p>　　High frequency (HF) communications play an important role i

2、n the field of their communications because of their skywave propagation characteristics. In this paper, two advanced HF radios are selected to introduce the current status for HF communications. After analyzing the dema

3、nd for future HF communications,the developing tendency for HF communications techniques is also presented.</p><p>　　Key words: high frequency (HF) communications；adaptive；high speed modem；anti-jam；network&l

4、t;/p><p>　　1 Introduction</p><p>　　The shortwave communication said that the high frequency (HF) correspondence, the frequency of use scope is 3~30MHz, mainly uses the sky wave after the ionospheri

5、c reflection, does not need to establish relay station then to realize the remote communication. Simultaneously because the ionized layer cannot destroy the characteristic, the shortwave communication is one of throughou

6、t military command important means that but must obtain a more widespread application, the shortwave communication als</p><p>　　Correspondence reliability. Shortwave communication sky wave dissemination beca

7、use of ionized layer change and multipath propagation influence, but is extremely unstable, signaling multi-diameter phenomenon is serious, retards in a big way, the Doppler shift is big, declines seriously. Simultaneous

8、ly the shortwave channel is the band width the channel which limits, the radio-frequency spectrum is been crowded, between the channel does to harass seriously, obtains the reliable correspondence qual</p><p&g

9、t;　　Data transfer rate. The tradition shortwave communication rises with difficulty a substantial clause is data transfer rate is very low (does not surpass 600bit/s). In informationized war the military correspondence t

10、ransmission's information, has developed from the simple direction order to such as the radar sounding data, the computed result, the high speed image facsimile and so on some requests the data to pass on the speed h

11、igh information.</p><p>　　Antijamming ability. Because the shortwave communication is under the war condition director the only reliable way, rate shortwave disturbance equipment develops along with the dist

12、urbance technology's development as well as some new great merit the successfully, shortwave communication's antijamming way must diversify, the intellectualization, has in different electromagnetic environment s

13、urvivability.</p><p>　　Network. Along with the correspondence more and more to the network development, future shortwave communication should also more consider the network use and the network management. Us

14、es net to wind the type correspondence, may cause the shortwave communication the information content and the information processing speed enhances greatly, but may also select the best link in the net, increases the inf

15、ormation link survivable the nature and saves the nature obstinately.</p><p>　　2 shortwave communication development present situation</p><p>　　Because since the shortwave communication in the m

16、ilitary correspondence the interchangeability, the shortwave communication has not started to receive in the 1980s takes seriously. Because many kinds of new technique the technique's application, like the channel au

17、to-adapted technology, the difference frequency-hopping spread spectrum, the wide band direct sequence spread spectrum technology, the channel coding technology, the channel balanced technology, short wave group the net

18、technology, sh</p><p>　　HF-90H Subminiature frequency-hopping shortwave broadcasting station</p><p>　　HF-90H promotes by Australian Q-MAC Corporation, the most prominent characteristic was picks

19、 to use the intelligent sideband frequency-hopping spread spectrum.At present the world various broadcasting stations plant provides is the digital voice. The digital voice frequency-hopping's shortcoming is jumps th

20、e frequency frequency spectrum insufficient hiding, is distinguished easily, breaks the code and tracks, as shown in Figure 1 . But HF-90H picks the intelligent sideband frequency-hopping patt</p><p>　　Fig.1

21、 Instantaneous and accumulated over time spectrum view of HF digital voice ho p per</p><p>　　Fig.2 Instantaneous and accumulated over time spectrum view of HF SSB voice hopper</p><p>　　The short

22、wave channel is often doping the intense noise and the unwanted signal, for example by the Broadcasting station either Fixed station's strong signal blocking or the clutter crosstalk, in addition fades to fall with t

23、he multi-diameter effect creates is unstable, causes the shortwave environment very severe. HF-90H uses the intelligence frequency-hopping spread spectrum to be possible to overcome these difficulties, the intelligence f

24、requency-hopping is one kind has the greatly strengthen</p><p>　　CHESS system</p><p>　　The CHESS system Corporation promotes by American Lockheed Sanders, system structure as shown in Figure 3.

25、The CHESS system take advanced digital signal processing the technology and high speed DSP (Data Signal Processor) the chip as the foundation, the frequency-hopping band width is 2.56MHz, the frequency-hopping speed reac

26、hes as high as 5000Hops/s, data transmission rate highest may reach the 19.2kbit/s, CHESS system most prominent characteristic to use the difference frequency-hopping (Diffe</p><p>　　Fig.3 CHESS system arc

27、hitecture</p><p>　　3 shortwave communication technology trend of development</p><p>　　The shortwave communication technology developed in recent years is rapid, has made a series of breakthrough

28、s and the progress, in the future must further study in the following several aspects</p><p>　　3.1 shortwave auto-adapted digital communication technology</p><p>　　The shortwave channel multi-fa

29、ctor and so on diameter latency, amplitude fading, weather change influences is been unpredictable, must guarantee that the correspondence the reliability, needs the system according to short the wave channel's chang

30、e auto-adapted change system structure and the parameter. Present's shortwave adaptive communication technology , mainly refers to the frequency auto-adapted technology, but future the shortwave adaptive communicatio

31、n technology should be omni-directiona</p><p>　　Chooses the frequency and the channel establishment technology auto-adapted. The present chooses the frequency and the channel establishment technology is auto

32、-adapted with the correspondence unifies in together, will choose frequency quality to be lower than the frequency quality which like the special-purpose real-time frequency-selective system will provide. From now on the

33、 development direction should be unifies the special-purpose frequency-selective system and the adaptive communication sy</p><p>　　Transmission speed auto-adapted technology . Shortwave communication after d

34、esignation operating frequency, must in obtain the biggest data volume of goods handled along with on the time variation channel, must use the transmission speed auto-adapted technology. Usually should choose as far as p

35、ossible the high data transfer rate under the permission error rate condition, this need system uses the code and the modulator approach and the channel condition incident cross-correlation, when the chan</p><

36、p>　　Auto-adapted channel balanced technology. When shortwave time-variable channel transmission signal, to eliminate the multi-diameter effect, the Doppler shift and so on serious code which brings to disturb, must us

37、e the auto-adapted channel balanced technology. The decision feedback equalizer (Decision Feedback Equalizers, DFE) is the present shortwave communication is one kind of balanced technology which the series uses generall

38、y. In recent years proposed one kind of new balanced technical - Tu</p><p>　　Auto-adapted antenna technology . The auto-adapted antenna technology's principle is the signal which receives through docking

39、 carries on the real-time processing, the control and the adjustment antenna array element phase changes the antenna pattern characteristic, completes the auto-adapted beam forming, enables the antenna beam the zero posi

40、tion alignment disturbance direction, the signal direction gain to achieve most to be big, thus enhances the system anti-multi-diameter decline and antija</p><p>　　3.2 high speed modulation demodulation tech

41、nology</p><p>　　At present is widespread the application the narrow band shortwave broadcasting station's modem to have serial and the parallel two systems, the serial system uses the single carrier to m

42、odulate the transmitter data, before item of , the maximum speed is 9.6kb/s, is very high to the balanced request; The parallel system is the data parallel allocation which transmits to many sub-carriers in transmits, th

43、e tradition and in the good system each sub-carrier does not overlap mutually in the frequenc</p><p>　　Anti-frequency selectivity decline. The OFDM system and transforms the high speed data stream through th

44、e string, causes in each sub-carrier the data mark to continue length to increase, thus may reduce ISI which effectively wireless channel's time dissemination brings (InterSymbol Interference), like this reduced has

45、received the within the aircraft balanced order of complexity, sometimes even might not use the balancer, only through used the insertion prefix the method to eliminate ISI the adv</p><p>　　The frequency spe

46、ctrum use factor is high. Because the OFDM system between each sub-carrier has the orthogonality, allows the sub-channel's frequency spectrum to overlap mutually, therefore compares with the conventional frequency di

47、vision multiplying system, the OFDM system may maximum limit use the frequency spectrum resources.</p><p>　　Realizes simply. Uses IDFT (Inverse Discrete Fourier Transform) /DFT (Discrete Fourier Transform) t

48、o realize OFDM. Namely causes regarding sub-carrier integer many systems, is very easy to realize along with the large scale integrated circuit technology and the DSP technology's development.</p><p>　　3

49、.3 antijamming technologies</p><p>　　The shortwave communication is under the war condition director the only reliable way, along with the disturbance method to the wide frequency range, the multi-styles, th

50、e multi-level directions develops, antijamming the measure should also tend the integration, the intellectualization as well as multi-system coexisting, concrete sends the exhibition direction is:</p><p>　　S

51、ignal processing . If auto-adapted frequency-hopping , its principle like chart 10 shows. The auto-adapted frequency-hopping system has added on link in the convention frequency-hopping communications' foundation the

52、 quality analysis, through the reliable information link quality analysis (Link Quality Analysis, LQA), determined that frequency spot which disturbs, gives may use jumps to lead the collection repeatedly, and transmits

53、this frequency collection through the feedback channel for the </p><p>　　Spatial processing. If uses the auto-adapted antenna zero alignment technology, when receiving end receives the disturbance, causes it

54、s antenna pattern zero automatic direction disturbance direction, enhances communications receiver's SIR.</p><p>　　Time processing. If burst transmission technology and advanced error correction coding t

55、echnique. So-called burst transmission technology, first information storage, then when some flash by normalcy 10~100 time or higher speed burst. On the one hand may use the big pulse power to resist the intentional jamm

56、ing, because on the other hand launches the time randomness and the temporary causes the intercept communications probability to reduce greatly; Uses close the shannon limit the Turbo code uni</p><p>　　4 con

57、clusions</p><p>　　Because the shortwave communication holds in the military correspondence domain particularity, even if is the mobile communication and Internet so developed today, the world developed count

58、ry the stop to the shortwave communication technology's research, still unceasingly had not made throughout the significant technological breakthrough in the shortwave communication domain, is promoting the shortwave

59、 communication technology development. Now, the shortwave communication already followed us to </p><p>　　短波通信的現(xiàn)狀及發(fā)展趨勢</p><p><b>　　摘 要：</b></p><p>　　短波通信由于其天波傳播特性，在通信領(lǐng)域具有

60、其它通信手段無法替代的地位。本文選擇了兩種先進(jìn)的短波電臺對短波通信的現(xiàn)狀進(jìn)行了介紹，分析了未來短波通信的需求以及短波通信技術(shù)的發(fā)展趨勢。</p><p>　　關(guān)鍵詞：短波通信；自適應(yīng)；高速調(diào)制解調(diào)；抗干擾；組網(wǎng)</p><p><b>　　1 引言</b></p><p>　　短波通信又稱高頻(HF)通信，使用頻率范圍為3～30MHz，主要利用

61、天波經(jīng)電離層反射后，無需建立中繼站即可實現(xiàn)遠(yuǎn)距離通信。同時由于電離層的不可摧毀特性，短波通信始終是軍事指揮的重要手段之一，但是要得到更廣泛的應(yīng)用，短波通信在以下幾個方面還有待提高：</p><p>　　1) 通信的可靠性。短波通信的天波傳播因受電離層變化和多徑傳播的影響而極不穩(wěn)定，信號傳輸多徑現(xiàn)象嚴(yán)重，延遲大，多普勒頻移大，衰落嚴(yán)重。同時短波信道是帶寬受限的信道，射頻頻譜非常擁擠，信道間相互干擾嚴(yán)重，獲得可靠的通

62、信質(zhì)量一直是短波通信追求的目標(biāo)。</p><p>　　2) 數(shù)據(jù)傳輸率。傳統(tǒng)短波通信難以崛起的一個重要原因就是數(shù)據(jù)傳輸率很低(不超過600bit/s)。信息化戰(zhàn)爭中軍事通信傳遞的信息，已從簡單的指揮命令發(fā)展到諸如雷達(dá)探測的數(shù)據(jù)、計算結(jié)果、高速圖像傳真等一些要求數(shù)據(jù)傳速率較高的信息。</p><p>　　3) 抗干擾能力。由于短波通信是戰(zhàn)事狀態(tài)下指揮唯一可靠的途徑，隨著干擾技術(shù)的發(fā)展以及一些

63、新型大功率短波干擾裝備的研制成功，短波通信的抗干擾方式必須多樣化，智能化，具有在不同電磁環(huán)境中的生存能力。</p><p>　　4) 網(wǎng)絡(luò)化。隨著通信越來越向網(wǎng)絡(luò)化發(fā)展，未來的短波通信也應(yīng)更多地考慮組網(wǎng)使用和網(wǎng)絡(luò)管理。采用網(wǎng)絡(luò)式通信，可以使短波通信的信息量和信息處理速度大大提高，還可在網(wǎng)內(nèi)選用最佳鏈路，增加通信鏈路的抗毀性及頑存性。</p><p>　　2 短波通信的發(fā)展現(xiàn)狀</p&

64、gt;<p>　　由于短波通信在軍事通信上的不可替代性，20 世紀(jì)80 年代以來，短波通信又開始受到重視。由于多種新技術(shù)的應(yīng)用，如信道自適應(yīng)技術(shù)、差分跳頻技術(shù)、寬帶直接序列擴(kuò)頻技術(shù)、信道編碼技術(shù)、信道均衡技術(shù)、短波組網(wǎng)技術(shù)，短波通信方式存在的許多問題得到解決；并且隨著微型計算機(jī)、移動通信和微電子技術(shù)的迅猛發(fā)展，人們利用微處理器、數(shù)字信號處理，不斷提高短波通信的質(zhì)量和數(shù)據(jù)傳輸速率，短波通信和裝備得到了很大發(fā)展，許多公司陸續(xù)推

65、出了一些性能優(yōu)良的設(shè)備和系統(tǒng)，比較著名的有：美國的短波通信電臺現(xiàn)代化、澳大利亞的HF-90H、瑞典的KV90、美國的CHESS、美國HARRIS 公司的RF-5800 系統(tǒng)、柯林斯公司的SELSCAN系統(tǒng)等。</p><p>　　1) HF-90H 超小型跳頻短波電臺</p><p>　　HF-90H 由澳大利亞Q-MAC 公司推出，最突出的特點是采用了智能邊帶跳頻技術(shù)。目前世界各電臺生產(chǎn)

66、廠提供的都是數(shù)字話音。數(shù)字話音跳頻的缺點是跳頻頻譜不夠隱蔽，容易被識別、破譯和跟蹤，如圖1 所示。而HF-90H 所采用的智能邊帶跳頻模式是利用SSB(Single Sideband Signal)調(diào)制方式傳送話音信號，瞬時頻譜很象噪聲，跳頻頻譜中由于跳頻碼隱含在話音的起伏中，無法確定跳頻頻率的設(shè)置，如圖2所示。</p><p>　　Fig.1Instantaneous and accumulated over

67、time spectrum view of HF digital voice ho p per</p><p>　　Fig.2 Instantaneous and accumulated over time spectrum view of HF SSB voice hopper</p><p>　　短波信道常摻雜著強烈的噪聲和干擾信號，例如被廣播電臺或固定電臺的強信號阻塞或雜波串?dāng)_，再加

68、上衰落和多徑效應(yīng)造成的不穩(wěn)定，使短波環(huán)境非常惡劣。HF-90H 采用智能跳頻技術(shù)可以克服這些困難，能跳頻則是一種具有極強的頻帶適應(yīng)性的技術(shù)，能夠周期性地自動測評跳頻段內(nèi)每個信道的信號強度，并指令網(wǎng)內(nèi)成員自動棄用嘈雜信道，通過不斷地“過濾”頻率，使通信背景明顯凈化，提高通信質(zhì)量。</p><p>　　2) CHESS 系統(tǒng)</p><p>　　CHESS 系統(tǒng)由美國Lockheed Sand

69、ers 公司推出,系統(tǒng)結(jié)構(gòu)如圖3所示。CHESS 系統(tǒng)以先進(jìn)的數(shù)字信號處理技術(shù)和高速DSP(Data Signal Processor)芯片為基礎(chǔ)，跳頻帶寬為2.56MHz，跳頻速率高達(dá)5000Hops/s，數(shù)據(jù)傳輸率最高19.2kbit/s，CHESS 系統(tǒng)最突出的特點為采用了差分跳頻（Differential Frequency Hopping，DFH）技術(shù)。差分跳頻實質(zhì)上是一種將頻率調(diào)制和編碼相結(jié)合的技術(shù)，通過對頻率編碼，增加頻率

70、域的冗余度，使得跳頻頻率間具有了特定的相關(guān)性，接收端利用了這種相關(guān)性來進(jìn)行頻率序列譯碼，糾正一定比例頻率誤判，起到了以頻帶換取信噪比或信干比的作用，以提高系統(tǒng)的性能。</p><p>　　Fig.3 CHESS system architecture</p><p>　　3 短波通信技術(shù)的發(fā)展趨勢</p><p>　　短波通信技術(shù)近年來發(fā)展非常迅速，已取得了一系

71、列的突破和進(jìn)展，未來在以下幾個方面仍需進(jìn)一步研究。</p><p>　　3.1 短波自適應(yīng)數(shù)字通信技術(shù)</p><p>　　短波信道受多徑時延、幅度衰落、天氣變化等因素的影響變化莫測，要保證通信的可靠性，需要系統(tǒng)根據(jù)短波信道的變化自適應(yīng)改變系統(tǒng)結(jié)構(gòu)和參數(shù)?，F(xiàn)在的短波自適應(yīng)通信技術(shù)，主要是指頻率自適應(yīng)技術(shù)，而未來的短波自適應(yīng)通信技術(shù)應(yīng)該是全方位的，包括：自適應(yīng)選頻與信道建立技術(shù)、傳輸速率自適

72、應(yīng)技術(shù)、自適應(yīng)信道均衡技術(shù)、自適應(yīng)天線技術(shù)等。</p><p>　　1) 自適應(yīng)選頻與信道建立技術(shù)?，F(xiàn)在的自適應(yīng)選頻與信道建立技術(shù)都是與通信結(jié)合在一起，這樣選頻質(zhì)量會低于專用實時選頻系統(tǒng)提供的頻率質(zhì)量。今后發(fā)展方向應(yīng)該是將專用選頻系統(tǒng)和自適應(yīng)通信系統(tǒng)結(jié)合起來，進(jìn)一步提高短波通信質(zhì)量。</p><p>　　2) 傳輸速率自適應(yīng)技術(shù)。短波通信在選定工作頻率后，要在隨時間變化的信道上得到最大數(shù)據(jù)

73、吞吐量，就必須采用傳輸速率自適應(yīng)技術(shù)。通常在允許的誤碼率條件下應(yīng)選擇盡可能高的數(shù)據(jù)傳輸率，這需要系統(tǒng)所采用的編碼和調(diào)制方法與信道條件相互關(guān)聯(lián)，當(dāng)信道傳播特性良好時用較高傳輸速率發(fā)送信息，而當(dāng)傳播特性變差時則降低傳輸速率，使誤碼率始終能滿足通信質(zhì)量的要求。</p><p>　　3) 自適應(yīng)信道均衡技術(shù)。在短波時變信道中傳輸信號時，為了消除多徑效應(yīng)、多普勒頻移等帶來的嚴(yán)重碼間干擾，必須采用自適應(yīng)信道均衡技術(shù)。判決反饋

74、均衡器(Decision Feedback Equalizers，DFE)是目前短波通信系統(tǒng)普遍采用的一種均衡技術(shù)。近幾年提出了一種新的均衡技術(shù)－Turbo 均衡技術(shù)，它結(jié)合信道編解碼技術(shù)，充分利用了信道信息，經(jīng)比較在短波通信系統(tǒng)中應(yīng)用Turbo 均衡技術(shù)較之DFE 又提高了2～3dB。</p><p>　　4) 自適應(yīng)天線技術(shù)。自適應(yīng)天線技術(shù)的原理是通過對接收到的信號進(jìn)行實時處理，控制和調(diào)節(jié)天線陣元的相位來改變

75、天線方向圖特性，完成自適應(yīng)波束形成，使天線波束的零位對準(zhǔn)干擾方向，信號方向的增益達(dá)到最大，從而有效地提高系統(tǒng)抗多徑衰落和抗干擾能力。</p><p>　　3.2 高速調(diào)制解調(diào)技術(shù)</p><p>　　目前廣泛應(yīng)用的窄帶短波電臺的調(diào)制解調(diào)器有串行和并行兩種體制，串行體制使用單載波調(diào)制發(fā)送信息，目前最高速率為9.6kb/s，對均衡的要求很高；并行體制是將發(fā)送的數(shù)據(jù)并行分配到多個子載波上傳輸，傳

76、統(tǒng)的并行體制中各個子載波在頻譜上互相不重疊，在接收端用濾波器組來分離各個子信道，各個子信道之間要留有保護(hù)頻帶，頻帶利用率低，而且多個濾波器的實現(xiàn)也有難度，目前最高速率僅為2.4kb/s。正交頻分復(fù)用(Orthogonal Frequency Division Multiplexing，OFDM)調(diào)制方式以其傳輸速率快、頻帶利用率高和抗多徑能力強等優(yōu)點越來越受到人們的重視，也開始逐步被應(yīng)用于短波通信領(lǐng)域 。相對于單載波和非正交頻分復(fù)用方式

77、，OFDM 應(yīng)用于短波通信具有以下優(yōu)勢 ：</p><p>　　1) 抗頻率選擇性衰落。OFDM 系統(tǒng)把高速數(shù)據(jù)流通過串并轉(zhuǎn)換，使得每個子載波上的數(shù)據(jù)符號持續(xù)長度相對增加，從而可以有效地減小無線信道的時間彌散所帶來的ISI（InterSymbol Interference），這樣就減小了接收機(jī)內(nèi)均衡的復(fù)雜度，有時甚至可以不采用均衡器，僅通過采用插入前綴的方法消除ISI 的不利影響。</p><

78、p>　　2) 頻譜利用率高。OFDM 系統(tǒng)由于各個子載波之間存在正交性，允許子信道的頻譜相互重疊，因此與常規(guī)的頻分復(fù)用系統(tǒng)相比，OFDM 系統(tǒng)可以最大限度地利用頻譜資源。</p><p>　　3) 實現(xiàn)簡單。采用IDFT(Inverse Discrete Fourier Transform)/DFT(Discrete Fourier Transform)實現(xiàn)OFDM。即使對于子載波個數(shù)很多的系統(tǒng)，隨著大規(guī)模

79、集成電路技術(shù)與DSP 技術(shù)的發(fā)展都是很容易實現(xiàn)的。</p><p><b>　　3.3 抗干擾技術(shù)</b></p><p>　　短波通信是戰(zhàn)事狀態(tài)下指揮唯一可靠的途徑，隨著干擾手段向?qū)掝l域、多樣式、多層次的方向發(fā)展，抗干擾措施也應(yīng)趨于綜合化、智能化以及多體制并存，具體的發(fā)展方向為：</p><p>　　1) 信號處理。如自適應(yīng)跳頻。自適應(yīng)跳頻系

80、統(tǒng)在常規(guī)跳頻通信的基礎(chǔ)上加上了鏈路質(zhì)量分析， 通過可靠的通信鏈路質(zhì)量分(Link Quality Analysis，LQA)，確定被干擾的頻點，給出可以使用的跳頻頻率集，并把該頻率集通過反饋信道傳送給發(fā)射方，使雙方自動適應(yīng)信道變化情況，同時刪除被干擾的全部頻率，然后在無干擾或干擾很小的頻點進(jìn)行可靠通信。</p><p>　　2) 空間處理。如采用自適應(yīng)天線調(diào)零技術(shù)，當(dāng)接收端受到干擾時，使其天線方向圖零點自動指向干

81、擾方向，以提高通信接收機(jī)的信干比。</p><p>　　3) 時間處理。如猝發(fā)傳輸技術(shù)和先進(jìn)的糾錯編碼技術(shù)。所謂猝發(fā)傳輸技術(shù)，先將信息存儲起來，然后在某一瞬間以正常時10～100倍或更高速率猝發(fā)。一方面可使用較大的脈沖功率來抵御有意干擾，另一方面由于發(fā)射時間的隨機(jī)性和短暫性使偵收概率大大降低；采用接近香農(nóng)極限的Turbo碼結(jié)合交織技術(shù)、迭代技術(shù)以及抗干擾技術(shù)在一定程度上可提高系統(tǒng)的抗干擾性能。</p>

82、<p><b>　　4 結(jié)論</b></p><p>　　由于短波通信在軍事通信領(lǐng)域占有的特殊性，即便是移動通信和互聯(lián)網(wǎng)如此發(fā)達(dá)的今天，世界發(fā)達(dá)國家始終沒有停止對短波通信技術(shù)的研究，在短波通信領(lǐng)域仍不斷取得重大技術(shù)突破，推動著短波通信技術(shù)的發(fā)展。如今，短波通信已經(jīng)伴隨著我們進(jìn)入了信息時代，隨著技術(shù)的進(jìn)步和人們研究的深入，曾一度被認(rèn)為落后的短波通信必將以嶄新的面貌跨入國際先進(jìn)通信