rfid技術(shù)外文文獻翻譯

1、<p><b>　　外文文獻</b></p><p>　　Current RFID Technology</p><p>　　This section describes out of which parts RFID tags consist of, how they work in principle, and what types of tags do

2、 exist. It focuses on how tags are powered and what frequency ranges is used. The section concludes by covering a few important standards.</p><p>　　RFID transponders (tags) consist in general of: Micro chip,

3、 Antenna, Case, Battery (for active tags only)</p><p>　　The size of the chip depends mostly on the Antenna. Its size and form is dependent on the frequency the tag is using. The size of a tag also depends on

4、 its area of use. It can range from less than a millimeter for implants to the size of a book in container logistic. In addition to the micro chip, some tags also have rewritable memory attached where the tag can store u

5、pdates between reading cycles or new data like serial numbers.</p><p>　　A RFID tag is shown in figure 1. The antenna is clearly visible. As said before the antenna has the largest impact of the size of the t

6、ag. The microchip is visible in the center of the tag, and since this is a passive tag it does not have an internal power source </p><p>　　In principle an RFID tag works as follows: the reading unit generate

7、s an electro-magnetic field which induces a current into the tag's antenna. The current is used to power the chip. In passive tags the current also charges a condenser which assures uninterrupted power for the chip.

8、In active tags a battery replaces the condenser. The difference between active and passive tags is explained shortly. Once activated the tag receives commands from the reading unit and replies by sending its serial n<

9、/p><p>　　During a reading cycle, the reader has to continuously power the tag. The created field is called continuous wave, and because the strength of the field decreases with the square of the distance the re

10、aders have to use a rather large power. That field overpowers any response a tag could give, so therefore tags reply on side-channels which are located directly below and above the frequency of the continuous wave.</p

11、><p>　　1. Energy Sources</p><p>　　We distinguish 3 types of RFID tags in relation to power or energy: Passive, Semi-passive, Active Passive tags do not have an internal power source, and they t

12、herefore rely on the power induced by the reader. This means that the reader has to keep up its field until the transaction is completed. Because of the lack of a battery, these tags are the smallest and cheapest tags av

13、ailable; however it also restricts its reading range to a range between 2mm and a few meters. As an added benefit tho</p><p>　　The second type of tags is semi-passive tags. Those tags have an internal power

14、source that keeps the micro chip powered at all times. There are many advantages: Because the chip is always powered it can respond faster tore quests, therefore increasing the number of tags that can be queried per seco

15、nd which is important to some applications. Furthermore, since the antenna is not required for collecting power it can be optimized for back scattering and therefore increasing the reading range. And </p><p>

16、;　　The third type of tags is active tags. Like semi-active tags they contain an internal power source but they use the energy supplied for both, to power the micro chip and to generate a signal on the antenna. Active tag

17、s that send signals without being queried are called beacons. An active tag's range can be tens of meters, making it ideal for locating objects or serving as landmark points. The lifetime is up to 5 years.</p>

18、<p>　　2. Frequency Bands</p><p>　　RFID tags fall into three regions in respect to frequency: Low frequency (LF, 30- 500kHz), High frequency (HF.10-15MHz), Ultra high frequency (UHF, 850- 950MHz, 2.4-2.

19、5GHz, 5.8GHz)</p><p>　　Low frequency tags are cheaper than any of the higher frequency tags. They are fast enough for most applications, however for larger amounts of data the time a tag has to stay in a rea

20、ders range will increase. Another advantage is that low frequency tags are least affected by the presence of fluids or metal. The disadvantage of such tags is their short reading range. The most common frequencies used f

21、or low frequency tags are 125-134.2 kHz and 140-148.5 kHz.</p><p>　　High frequency tags have higher transmission rates and ranges but also cost more than LF tags. Smart tags are the most common member of thi

22、s group and they work at 13.56MHz. UHF tags have the highest range of all tags. It ranges from 3-6 meters for passive tags and 30+ meters for active tags. In addition the transmission rate is also very high, which allows

23、 to read a single tag in a very short time. This feature is important where tagged entities are moving with a high speed and remain only for </p><p>　　3. Standards</p><p>　　The wide range of pos

24、sible applications requires many different types of tags, often with conflicting goals (e.g. low cost vs. security). That is reflected in the number of standards. A short list of RFID standards follows: ISO11784, ISO1178

25、5, ISO14223, ISO10536, ISO14443, ISO15693, ISO18000. Note that this list is not exhaustive. Since the RFID technology is not directly Internet related it is not surprising that there are no RFCs available. There cent hyp

26、e around RFID technology has resulted i</p><p>　　4. RFID Systems</p><p>　　A RFID reader and a few tags are in general of little use. The retrieval of a serial number does not provide much inform

27、ation to the user nor does it help to keep track of items in a production chain. The real power of RFID comes in combination with a backend that stores additional information such as descriptions for products and where a

28、nd when a certain tag was scanned. In general a RFID system has a structure as depicted in figure 2. RFID readers scan tags, and then forward the information to</p><p>　　This section describes how RFID tags

29、work in general, what types of tags exist and how they differ. The three frequency ranges that RFID tags typically use are LF, HF, and UHF. Also the difference between passive, semi-passive, and active tags was explained

30、 and their advantages and disadvantages were compared. The section concluded by looking at different standards and showed the great interest of the industry by counting the number of issued and backlogged patents [US Pat

31、ent Office].</p><p><b>　　翻譯：</b></p><p><b>　　當(dāng)前的RFID技術(shù)</b></p><p>　　該節(jié)描述的是RFID標簽由哪些部分組成、工作原理和確實存在的標簽類型，關(guān)注標簽的供電方式和使用頻率范圍。這部分也總結(jié)了一些重要的標準。</p><p>　

32、　RFID應(yīng)答器的一般組成:微芯片、天線、線圈和電池(僅適用于有源標簽)。</p><p>　　芯片的大小主要取決于天線，它的規(guī)模和形式的取決于標簽的使用頻率，也取決于它的使用面積。它的大小范圍可從不到一毫米的植入體大到一本關(guān)于集裝箱物流的書。除了微型芯片,有些標簽也附有可重寫內(nèi)存，這樣標簽就可儲存更新閱讀周期之間的或新的數(shù)據(jù)，如序號。</p><p>　　如圖1所示的RFID標簽。天線清

33、晰可見。正如前面所說的，天線對標簽大小的影響最大。在標簽的中心可看見的是芯片。因為這是一個無源標簽所以無內(nèi)部的能源。</p><p>　　RFID標簽工作原理是如下:閱讀單元產(chǎn)生電磁場引導(dǎo)電流流進標簽的天線。該電流用以給芯片提供能源。在無源標簽中該電流還為冷凝器充電，以保證芯片的不間斷供電。在有源標簽中電池取代了冷凝器。有源和無源標簽的區(qū)別是短期內(nèi)的信息闡釋。一旦被激活的標簽收到閱讀的命令它就可以發(fā)送序列號或所要

34、求的信息。總的來說,標簽沒有足夠的能量來創(chuàng)造自己的電磁場, 相反它可以采用反向散射調(diào)制（反映/吸收）來產(chǎn)生由閱讀單元發(fā)射的電磁場。由于大多數(shù)流體吸收電磁場和大多數(shù)金屬反射這些場，故可使用的標簽閱讀材料是復(fù)雜的</p><p>　　在一次循環(huán)解讀中, 閱讀器不得不持續(xù)給標簽供電。它所建立的場將產(chǎn)生連續(xù)波,因為磁場的強度隨距離的平方而減少，故閱讀器必須有一個相當(dāng)大的能源。該場迅速響應(yīng)標簽給的任何指示, 因此標簽位于正

35、下方的側(cè)渠道可以響應(yīng)上述連續(xù)波的頻率。</p><p><b>　　1.能源</b></p><p>　　我們辨別三種不同的RFID電子標簽的能量或能源：被動、半被動和主動。</p><p>　　被動式標簽沒有內(nèi)部電源,因此它們的能量來源于閱讀器。這意味著閱讀器必須保持磁場直到轉(zhuǎn)換完成。由于沒有電池,故這些都是可用的最小和最便宜的標簽。但它的閱

36、讀范圍可從2毫米和幾米。這些標簽的另一個好處是適用于印刷生產(chǎn)。此外，因為它不依賴于內(nèi)部電源，所以它們的壽命是無限的。</p><p>　　第二種類型是半被動式標簽。這些標簽都有內(nèi)部電源可在任何時候都給微芯片供電。它有許多優(yōu)點:由于芯片在持續(xù)帶電的情況下反應(yīng)迅速,因此可以增加每秒查詢的標簽數(shù)量，這是非常重要的應(yīng)用。此外,由于天線不需要收集能量，故可以優(yōu)化用以反向散射和回歸來增加閱讀范圍。最后但并非不重要，因為標簽不

37、使用任何磁場能量所以反向散射的信號越強，閱讀范圍更廣。由于最后兩個原因，半被動標簽通常比被動標簽應(yīng)用范圍更廣泛。</p><p>　　第三種類型是主動式標簽。類似于半主動標簽，它的內(nèi)部也有能源但它的能源用于兩個方面：給微芯片供電和使天線產(chǎn)生信號。主動式標簽發(fā)送信號而不被質(zhì)疑,這被稱為信標。主動標簽可查詢的范圍是幾十公尺,從而使其適宜于定位對象或理想標志點。壽命長達5年的。</p><p>

38、<b>　　2.頻帶</b></p><p>　　RFID電子標簽按照頻率分為三個部分:低頻(LF,30-500千赫)、高頻 (HF、10-15兆赫)、超高頻 (UHF),（850-950兆赫,2.4-2.5兆赫,5.8兆赫)。</p><p>　　低頻標簽比任何高頻率的標簽都便宜。對于大多數(shù)應(yīng)用程序來講,它們的響應(yīng)速度很快。 但是，留在閱讀器的大量標記數(shù)據(jù)的時間范圍

39、將增加。另一個優(yōu)點是低頻標簽由于流體的存在或金屬的存在而受到的影響最小。這類標簽的缺點是它們識別范圍很短。最常見的低頻標簽頻率是125-134.2千赫和140-148.5千赫。 </p><p>　　高頻標簽有更高的傳輸速率和更廣的范圍，成本也比低頻標簽高。該類標簽中最常見的是智能標簽，工作于13.56赫茲。</p><p>　　超高頻標簽是所有標簽中工作范圍最廣的，其范圍可從被動標簽的3

40、-6米到主動標簽的30米。此外傳送速率也很高,這使得可在很短時間識別單標簽。此功能在標記高速度運動實體的位置時是很重要的，但在識別范圍內(nèi)只保持很短的一段時間。超高頻標簽也比其他任何標簽都貴，受流體和金屬的影響也是最嚴重的。這些特性在超高頻自動收費系統(tǒng)中得到了極大應(yīng)用。它的典型頻率是868 MHz(歐洲),915兆赫(美國),950兆赫(日本)和2.45兆赫。</p><p>　　LF和HF標簽頻率無限制，全球通用

41、。但UHF標簽的頻率標準不同，各國分別都有認證標準。</p><p><b>　　3.標準</b></p><p>　　標簽的應(yīng)用范圍廣泛并且由于矛盾的目的(如低成本和安全)，這就可能需要很多不同種類的標簽。這體現(xiàn)在標準的數(shù)量上。一個短期的RFID標準名單如下:國際標準11784,年國際標準11785、國際標準14223,國際標準10536、國際標準14443,國際標

42、準15693、國際標準18000。 注意該列表并不是完全的。由于RFID技術(shù)不是直接與互聯(lián)網(wǎng)有關(guān)的，所以是否有可用的RFC這并不奇怪。最近圍繞RFID技術(shù)的炒作，導(dǎo)致了專利爆炸。目前，已經(jīng)發(fā)行的RFID相關(guān)專利超過了1800個（從1976年至2001年），積壓了超過5700個描述RFID系統(tǒng)或應(yīng)用程序的專利。</p><p><b>　　4 .RFID系統(tǒng)</b></p>&l

43、t;p>　　一個RFID閱讀器和一些標簽一般來說是沒用的。檢索序列號不向用戶提供大量的信息，也無助于保持生產(chǎn)鏈中的項目跟蹤。真正的動力來自于RFID的后端存儲額外的結(jié)合信息，如產(chǎn)品的描述和一定的標簽被掃描時。在一般的RFID系統(tǒng)結(jié)構(gòu)如圖2所示。射頻識別讀取機掃描標簽,提出后臺的信息。后臺一般包括一個數(shù)據(jù)庫和一個非常明確的應(yīng)用接口。當(dāng)后臺接收新信息時,根據(jù)是否需要執(zhí)行一些相關(guān)領(lǐng)域的計算來決定增加數(shù)據(jù)庫。應(yīng)用程序檢索后臺數(shù)據(jù)。在許多情

44、況下,閱讀器都配有應(yīng)用程序。例如超市的結(jié)帳點(注:給的例子是使用條碼代替RFID電子標簽,因為它們更常見,然而如果標簽被使用,這個系統(tǒng)也會產(chǎn)生同樣效果) 。當(dāng)閱讀器掃描條碼時，應(yīng)用程序使用派生標識符查找當(dāng)前價格。此外，后端也提供合格產(chǎn)品的折扣信息。如果數(shù)量低于一定的閾值，后端也減少了那種產(chǎn)品的數(shù)量，并通知經(jīng)理。</p><p>　　該節(jié)描述RFID標簽一般是如何工作的, 存在的類型和區(qū)別。RFID標簽通常使用的三