第一篇：證明資料中英文翻譯

證明Certificate 茲有××社區××組居民××在社區表現良好，無違法犯罪記錄，也未參加任何邪教組織。It is to hereby certify that ×× ××, as a resident of Group ×× in ×× Community, behaves well and is found of no criminal record.He has never joined any evil organization.情況屬實The information given above is true and correct.××派出所 ×××Police Station

2××年××月××日 April ××, 2××× ××市公安局××區分局××派出所（章）

×× Police Station of ×× District Branch of ××Public Security Bureau(Seal)

××社區×× Community

20××年××月××日April ××, 2××× ××街道辦事處××社區居民委員會（章）

×× Community Neighborhood Committee of ××Sub-district Office of ×××District(Seal)

證明資料中英文翻譯模板 伊萊特翻譯提供

電聯我們：▲〇二八■八五〇九五八〇九◆

特此證明

第二篇：12位-AD574A轉換器中英文翻譯資料 - 副本

英文原文

12-Bit A/D Converter

CIRCUIT OPERATION The AD574A is a complete 12-bit A/D converter which requires no external components to provide the complete successive approximation analog-to-digital conversion function.A block diagram of the AD574A is shown in Figure 1.Figure 1.Block Diagram of AD574A 12-Bit A-to-D Converter

When the control section is commanded to initiate a conversion(as described later), it enables the clock and resets the successiveapproximation register(SAR)to all zeros.Once a conversion cycle has begun, it cannot be stopped or restarted and data is not available from the output buffers.The SAR, timed by the clock, will sequence through the conversion cycle and return an end-of-convert flag to the control section.The control section will then disable the clock, bring the output status flag low, and enable control functions to allow data read functions by external command.During the conversion cycle, the internal 12-bit current output DAC is sequenced by the SAR from the most significant bit(MSB)to least significant bit(LSB)to provide an output current which accurately balances the input signal current through the 5kΩ(or10kΩ)input resistor.The comparator determines whether the addition of each successively-weighted bit current causes the DAC current sum to be greater or less than the input current;if the sum is less, the bit is left on;if more, the bit is turned off.After testing all the bits, the SAR contains a 12-bit binary code which accurately represents the input signal to within 1/2 LSB.The temperature-compensated buried Zener reference provides the primary voltage reference to the DAC and guarantees excellent stability with both time and temperature.The reference is trimmed to 10.00 volts ?0.2%;it can supply up to 1.5 mA to an external load in addition to the requirements of the reference input resistor(0.5 mA)and bipolar offset resistor(1 mA)when the AD574A is powered from ?15 V supplies.If the AD574A is used with ?12 V supplies, or if external current must be supplied over the full temperature range, an external buffer amplifier is recommended.Any external load on the AD574A reference must remain constant during conversion.The thin-film application resistors are trimmed to match the full-scale output current of the DAC.There are two 5 k?input scaling resistors to allow either a 10 volt or 20 volt span.The 10 k?bipolar offset resistor is grounded for unipolar operation and connected to the 10 volt reference for bipolar operation.DRIVING THE AD574 ANALOG INPUT

Figure 2.Op Amp – AD574A Interface

The output impedance of an op amp has an open-loop value which, in a closed loop, is divided by the loop gain available at the frequency of interest.The amplifier should have acceptable loop gain at 500 kHz for use with the AD574A.To check whether the output properties of a signal source are suitable, monitor the AD574’s input with an oscilloscope while a conversion is in progress.Each of the 12 disturbances should subside in sorless.For applications involving the use of a sample-and-hold amplifier, the AD585 is recommended.The AD711 or AD544 op amps are recommended for dc applications.SAMPLE-AND-HOLD AMPLIFIERS Although the conversion time of the AD574A is a maximum of 35 ?s, to achieve accurate 12-bit conversions of frequencies greater than a few Hz requires the use of a sample-and-hold amplifier(SHA).If the voltage of the analog input signal driving the AD574A changes by more than 1/2 LSB over the time interval needed to make a conversion, then the input requires a SHA.The AD585 is a high linearity SHA capable of directly driving the analog input of the AD574A.The AD585’s fast acquisition time, low aperture and low aperture jitter are ideally suited for high-speed data acquisition systems.Consider the AD574A converter with a 35 ?s conversion time and an input signal of 10 V p-p: the maximum frequency which may be applied to achieve rated accuracy is 1.5 Hz.However, with the addition of an AD585, as shown in Figure 3, the maximum frequency increases to 26 kHz.The AD585’s low output impedance, fast-loop response, and low droop maintain 12-bits of accuracy under the changing load conditions that occur during a conversion, making it suitable for use in high accuracy conversion systems.Many other SHAs cannot achieve 12-bits of accuracy and can thus compromise a system.The AD585 is recommended for AD574A applications requiring a sample and hold.Figure 3.AD574A with AD585 Sample and Hold

SUPPLY DECOUPLING AND LAYOUT CONSIDERATIONS It is critically important that the AD574A power supplies be filtered, well regulated, and free from high frequency noise.Use of noisy supplies will cause unstable output codes.Switching power supplies are not recommended for circuits attempting to achieve 12-bit accuracy unless great care is used in filtering any switching spikes present in the output.Remember that a few millivolts of noise represents several counts of error in a 12-bit ADC.Circuit layout should attempt to locate the AD574A, associated analog input circuitry, and interconnections as far as possible from logic circuitry.For this reason, the use of wire-wrap circuit construction is not recommended.Careful printed circuit construction is preferred.UNIPOLAR RANGE CONNECTIONS FOR THE AD574A The AD574A contains all the active components required to perform a complete 12-bit A/D conversion.Thus, for most situations, all that is necessary is connection of the power supplies(+5 V, +12 V/+15 V and –12 V/–15 V), the analog input, and the conversion initiation command, as discussed on the next page.Analog input connections and calibration are easily accomplished;the unipolar operating mode is shown in Figure 4.Figure 4.Unipolar Input Connections

All of the thin-film application resistors of the AD574A are trimmed for absolute calibration.Therefore, in many applications, no calibration trimming will be required.The absolute accuracy for each grade is given in the specification tables.For example, if no trims are used, the AD574AK guarantees ?1 LSB max zero offset error and ?0.25%(10 LSB)max full-scale error.(Typical full-scale error is ?2 LSB.)If the offset trim is not required, Pin 12 can be connected directly to Pin 9;the two resistors and trimmer for Pin 12 are then not needed.If the full-scale trim is not needed, a 50 ??1% metal film resistor should be connected between Pin 8 and Pin 10.The analog input is connected between Pin 13 and Pin 9 for a 0 V to +10 V input range, between 14 and Pin 9 for a 0 V to +20 V input range.The AD574A easily accommodates an input signal beyond the supplies.For the 10 volt span input, the LSB has a nominal value of 2.44 mV;for the 20 volt span, 4.88 mV.If a 10.24 V range is desired(nominal 2.5 mV/bit), the gain trimmer(R2)should be replaced by a 50Ωesistor, and a 200Ωtrimmer inserted in series with the analog input to Pin 13 for a full-scale range of 20.48 V(5 mV/bit), use a 500 ?trimmer into Pin 14.The gain trim described below is now done with these trimmers.The nominal input impedance into Pin 13 is 5kΩ, and 10kΩinto Pin 14.UNIPOLAR CALIBRATION The AD574A is intended to have a nominal 1/2 LSB offset so that the exact analog input for a given code will be in the middle of that code(halfway between the transitions to the codes above and below it).Thus, the first transition(from 0000 0000 0000 to 0000 0000 0001)will occur for an input level of +1/2 LSB(1.22 mV for 10 V range).If Pin 12 is connected to Pin 9, the unit will behave in this manner, within specifications.If the offset trim(R1)is used, it should be trimmed as above, although a different offset can be set for a particular system requirement.This circuit will give approximately ?15 mV of offset trim range.The full-scale trim is done by applying a signal 1/2 LSB below the nominal full scale(9.9963 for a 10 V range).Trim R2 to give the last transition(1111 1111 1110 to 1111 1111 1111).BIPOLAR OPERATION The connections for bipolar ranges are shown in Figure 5.Again, as for the unipolar ranges, if the offset and gain specifications are sufficient, one or both of the trimmers shown can be replaced by a 50 ??1% fixed resistor.Bipolar calibration is similar to unipolar calibration.Figure 5.Bipolar Input Connections

CONTROL LOGIC The AD574A contains on-chip logic to provide conversion initiation and data read operations from signals commonly available in microprocessor systems.Figure 6 shows the internal logic circuitry of the AD574A.The control signals CE, CS, and R/C control the operation of the converter.The state of R/C when CE and CS are both asserted determines whether a data read(R/C = 1)or a convert(R/C = 0)is in progress.The register control inputs AO and 12/8 control conversion length and data format.The AO line is usually tied to the least significant bit of the address bus.If a conversion is started with AO low, a full 12-bit conversion cycleis initiated.If AO is high during a convert start, a shorter 8-bit conversion cycle results.During data read operations, AO determines whether the three-state buffers containing the 8 MSBs of the conversion result(AO = 0)or the 4 LSBs(AO = 1)are enabled.The 12/8 pin determines whether the output data is to be organized as two 8-bit words(12/8 tied to DIGITAL COMMON)or a single 12-bit word(12/8 tied to VLOGIC).The 12/8 pin is not TTL-compatible and must be hard-wired to either VLOGIC or DIGITAL COMMON.In the 8-bit mode, the byte addressed when AO is high contains the 4 LSBs from the conversion followed by four trailing zeroes.This organization allows the data lines to be overlapped for direct interface to 8-bit buses without the need for external three-state buffers.It is not recommended that AO change state during a data read operation.Asymmetrical enable and disable times of the three-state buffers could cause internal bus contention resulting in potential damage to the AD574A.Figure 6.AD574A Control Logic An output signal, STS, indicates the status of the converter.STS goes high at the beginning of a conversion and returns low when the conversion cycle is complete.TIMING The AD574A is easily interfaced to a wide variety of microprocessors and other digital systems.The following discussion of the timing requirements of the AD574A control signals should provide the system designer with useful insight into the operation of the device.Figure 7 shows a complete timing diagram for the AD574A convert start operation.R/C should be low before both CE and CS are asserted;if R/C is high, a read operation will momentarily occur, possibly resulting in system bus contention.Either CE or CS may be used to initiate a conversion;however, use of CE is recommended since it includes one less propagation delay than CS and is the faster input.In Figure 7, CE is used to initiate the conversion.Figure 7

Once a conversion is started and the STS line goes high, convert start commands will be ignored until the conversion cycle is complete.The output data buffers cannot be enabled during conversion.Figure 8 shows the timing for data read operations.During data read operations, access time is measured from the point where CE and R/C both are high(assuming CS is already low).If CS is used to enable the device, access time is extended by 100 ns.Figure 8.Read Cycle Timing

In the 8-bit bus interface mode(12/8 input wired to DIGITAL COMMON), the address bit, AO, must be stable at least 150 ns prior to CE going high and must remain stable during the entire read cycle.If AO is allowed to change, damage to the AD574A output buffers may result.“STAND-ALONE” OPERATION

The AD574A can be used in a ―stand-alone‖ mode, which is useful in systems with dedicated input ports available and thus not requiring full bus interface capability.In this mode, CE and 12/8 are wired high, CS and AO are wired low, and conversion is controlled by R/C.The three-state buffers are enabled when R/C is high and a conversion starts when R/C goes low.This allows two possible control signals—a high pulse or a low pulse.Operation with a low pulse is shown in Figure 11.In this case, the outputs are forced into the high impedance state in response to the falling edge of R/C and return to valid logic levels after the conversion cycle is completed.The STS line goes high 600 ns after R/C goes low and returns low 300 ns after data is valid.Figure 11.Low Pulse for R/C—Outputs Enabled After Conversion

If conversion is initiated by a high pulse as shown in Figure 12, the data lines are enabled during the time when R/C is high.The falling edge of R/C starts the next conversion, and the data lines return to three-state(and remain three-state)until the next high pulse of R/C.Figure 12.High Pulse for R/C—Outputs Enabled While R/C High, Otherwise High-Z

Usually the low pulse for R/C stand-alone mode will be used.Figure 13 illustrates a typical stand-alone configuration for 8086 type processors.The addition of the 74F/S374 latches improves bus access/release times and helps minimize digital feedthrough to the analog portion of the converter.INTERFACING THE AD574A TO MICROPROCESSORS The control logic of the AD574A makes direct connection to most microprocessor system buses possible.While it is impossible to describe the details of the interface connections for every microprocessor type, several representative examples will be described here.GENERAL A/D CONVERTER INTERFACE CONSIDERATIONS A typical A/D converter interface routine involves several operations.First, a write to the ADC address initiates a conversion.The processor must then wait for the conversion cycle to complete, since most ADCs take longer than one instruction cycle to complete a conversion.Valid data can, of course, only be read after the conversion is complete.The AD574A provides an output signal(STS)which indicates when a conversion is in progress.This signal can be polled by the processor by reading it through an external three-state buffer(or other input port).The STS signal can also be used to generate an interrupt upon completion of conversion, if the system timing requirements are critical(bear in mind that the maximum conversion time of the AD574A is only 35 microseconds)and the processor has other tasks to perform during the ADC conversion cycle.Another possible time-out method is to assume that the ADC will take 35 microseconds to convert, and insert a sufficient number of ―do-nothing‖ instructions to ensure that 35 microseconds of processor time is consumed

Once it is established that the conversion is finished, the data can be read.In the case of an ADC of 8-bit resolution(or less), a single data read operation is sufficient.In the case of converters with more data bits than are available on the bus, a choice of data formats is required, and multiple read operations are needed.The AD574A includes internal logic to permit direct interface to 8-bit or 16-bit data buses, selected by connection of the 12/8 input.In 16-bit bus applications(12/8 high)the data lines(DB11 through DB0)may be connected to either the 12 most significant or 12 least significant bits of the data bus.The remaining four bits should be masked in software.The interface to an 8-bit data bus(12/8 low)is done in a left-justified format.The even address(A0 low)contains the 8 MSBs(DB11 through DB4).The odd address(A0 high)contains the 4 LSBs(DB3 through DB0)in the upper half of the byte, followed by four trailing zeroes, thus eliminating bit masking instructions.SPECIFIC PROCESSOR INTERFACE EXAMPLES Z-80 System Interface The AD574A may be interfaced to the Z-80 processor in an I/O or memory mapped configuration.Figure 15 illustrates an I/O or mapped configuration.The Z-80 uses address lines A0–A7 to decode the I/O port address.An interesting feature of the Z-80 is that during I/O operations a single wait state is automatically inserted, allowing the AD574A to be used with Z-80 processors having clock speeds up to 4 MHz.For applications faster than 4 MHz use the wait state generator in Figure 16.In a memory mapped configuration the AD574A may be interfaced to Z-80 processors with clock speeds of up to 2.5 MHz.附錄E 中文翻譯

12位-AD574A轉換器

電路工作原理

AD574A是一個完善的12位A/D轉換器，不需要外部組件提供完全的逐步逼近模擬數字轉換功能。圖1所示為AD574A的方塊結構圖。

圖1 AD574A的方塊結構圖

當控制部分收到初始化轉換命令（后邊會敘述）時，會開啟時鐘并把連續逼近寄存器（SAR）全部置零。一旦轉換周期開始，它就不能終止或重新開始，也不能從輸出緩沖中讀數。時鐘控制SAR寄存器的時序，SAR會安排好轉換周期的順序并向控制部分返回一個“轉換結束”（end-of-convert）標志。接著，控制部分停止時鐘，把輸出狀態標志位置低，并允許控制函數，以便外部命令可以執行數據讀取功能。

在轉換周期期間, 內部12 位當前的產品DAC 由SAR 程序化從最高位(MSB)對最低有效位(LSB)通過5 k(或10k)輸入電阻器提供準確地平衡輸入信號。比較器確定位電流的連續增大是否造成了DAC當前總電流比輸入電流增大或者減小;如果總電流較小，此位被留下;如果總電流較大，位被關閉。在測試完所有位以后，SAR包含了準確表示輸入信號在+1/2 LSB之內的12位二進制編碼。溫度補償是外部提供給DAC基準電壓并保證準確的轉換的時間和溫度的穩定性。基準在10.00?0.2%伏之間平衡，當AD574A使用15伏電源時，除了按要求向參考輸入電阻提供0.5mA，向雙極偏移電阻提供1mA電流外，它可以給外部負載提供提供高至1.5mA的電流。如果AD574A使用12伏電源，或者外部電流必須在全部溫度范圍內提供，那么我們推薦使用一個外部的緩沖放大器。任何在AD574A參考手冊上的外部負載都必須在轉換過程中保持穩定。要調整薄膜應用電容以匹配DAC（數模轉換器）的實比例輸出電流。有兩個5千歐的輸入測量電阻允許10伏或20伏的區間。10千歐的雙極偏移電容接地用于單極操作，或連接到10伏參考電壓上用于雙極性操作。

AD574模擬輸入電壓

圖2 OP放大器與AD574連接

OP放大器的輸出阻抗有一個開環值，在一個封閉回路中，這個值被回路增益（由增加的頻率產生）等分。放大器應該至少擁有500kHz的回路增益才能和AD574A一起使用。要檢查信號源的輸出特性是否合適，就要在轉換進行中使用示波鏡監控AD574的輸入端。每12個干擾應該在1秒以內衰減。

關于取樣—保持器的應用，我們推薦AD585型號。我們推薦讓AD711型號和AD544型號取樣—保持器應在直流電下工作。

雖然AD574A的轉換時間最高為35秒，但為了能夠實現幾個赫茲的頻率的精確12位轉換還是需要使用采樣－保持放大器（SHA）的。如果一個驅動AD574A的模擬輸入信號電壓在轉換所需的計時周期中變化超過LSB的一半，那么輸入端就需要一個SHA。

AD585是一種高線性的采樣－保持放大器（SHA），它能夠直接驅動AD574A的模擬輸入端。AD585的快速采集時間、低孔徑和低孔徑抖動都很好地使用于高速數據采集系統。考慮到AD574A的轉換時間為35秒，并且擁有10Vp-p的輸入信號，這是能夠實現1.5Hz精確轉換時所能用的最高頻率。如圖3所示，加上AD585后，最高頻率增加到了26kHz。

AD585的低輸出阻抗、快速連環反應和低損耗能夠在變化的周期性負荷工況下維持12位準確性，使它適當用于高精確度轉換。許多其他SHAs達不到12位轉換的準確性，并且可能因而減弱系統。AD585被推薦應用于AD574A的采樣與保持。

圖3 帶采樣保持器AD585的AD574A

AD574A 電源的濾波、良好地校準和遠離高頻噪聲是異常重要的.。噪聲補償的使用會造成不穩定的輸出信號。除非特別要求濾掉輸出端的電火花，交換式電源電路建議達到12比特的精確度。注意： 一點點毫伏的噪聲就代表著12比特ADC（電源）的巨大誤差。

電路布局應該嘗試定位AD574A,與之相連的相似物輸入電路,并使其從邏輯電路上盡可能連接起來.因為這個原因,不推薦使用線路電路結構.應該選擇好的印刷的電路體系.AD574A處理單極性信號

AD574A包括了所有進行完全12位AD轉換所需的活動組件。這樣，在大多數情況下，所需的只是電源連接（+5 V, +12 V/+15 V 和 –12 V/–15 V）、模擬輸入以及轉換初始化命令，下頁會討論到。模擬輸入連接和校準都很容易完成。單極操作模式如圖4所示。

圖4

AD574A所有的薄膜應用程序電阻是通過絕對刻度來衡量的。因此在許多應用程序中，并不需要刻度平衡。規格表給出了每個等級的絕對精度。例如，如果沒有應用區標，AD574AK保證1LSB最大零偏移誤差和0.25%(10LSB)最大滿額誤差。（通常滿額誤差是2 LSB）。如果不允許使用這個彎管平衡的話，pin 12 可以直接同pin 9連接；pin 12 的這兩個電阻器和這個微調電容器就不需要了。如果不允許使用完整的平衡，應該在pin 8和pin 10之間連接一個xxxx金屬薄膜微調電容器。

此器件在輸入電壓0到10伏連接時須接腳9和腳13,當輸入電壓在0到20伏之間時,應從腳14和腳9引入。AD574A提供輸入信號補償，輸入電壓在10伏以內時理論值是2.44mV,在輸入電壓在20伏以內時理論值是2.44mV

如果電壓達到10.24(也就是2.5mv/bit), 增益可調電阻就必須調整為50?.一個200Ω可變電阻串連到模擬輸入引腳13其滿刻度值為20.48V(5 mV/bit),用500Ω的可變電阻串連到模擬輸入引腳14.下述增益的調整用這些可變電阻完成.引腳13的名義輸入阻抗為5 kΩ, 而插腳14的名義輸入阻抗為10kΩ。

? 單極性輸入

AD574A擁有一個名義上是LSB一半的偏移量，以便對一個給定編碼的準確模擬輸入可以正好處于這個編碼的中央（在其前后各有一半的編碼轉換）。這樣，第一個轉換（從0000 0000 0000到0000 0000 0001）會在輸入電平為+1/2LSB（對于10V的范圍來說是1.22mV）時發生。

如果第12腳連在第9腳上，那么單元將在規格之內按此方式工作。如果使用了偏移調整（R1），雖然可以針對特定的系統要求設置不同的偏移量，但也應該按上述方法調整。這個電路會給出大約15mV的偏移調整范圍。

滿量程調整適用于一個信號在滿量程下產生1/2 LSB線性誤差，也就是對于10V范圍來說是9.9963。調整R2來實現最后一個轉換（1111 1111 1110到1111 1111 1111）

雙極性輸入

雙極的聯系范圍如圖5。還有，就單極的范圍，如果輸出量與增加量的數據充足的話，一個電容器或者兩個都可以拿一個50±1%的固定電阻來代替。單極標準與雙極標準是相似的。

圖5 邏輯控制

AD574A包含了芯片上邏輯，可以通過微處理器中通常存在的信號中提供開始轉換和讀取轉換結果操作‖ 如圖6是AD574A的內部邏輯電路。

控制信號CE、CS, 和R/C 控制交換器的操作。R/C 的狀態由CE 和CS 兩個信號的加入來確定進行數據讀取(R/C = 1)或數據轉換(R/C = 0)。記數器控制輸入AO ,12/8 控制轉換長度和數據格式。AO 線通常被連結到地址總線的最低有效位。如果AO置低(電位)開始, 按12 位A/D進行轉換。當12/8=1時，12位數據線一次讀出，主要用于16位微機系統；12/8=0時，可與8位機接口。此引腳輸入為高電平時，12位數據并行輸出；當此引腳為低電平時，與引腳A0配合，把12位數據分兩次輸出。12/8的引腳接DIGITAL COMMON輸出8位數據12/8引腳接VLOGIC輸出12位數據。12/8的引腳不與TTL兼容的，必須和vlogic或者digital連接，在8位模式下，當Ao置高的時候，低4位加上尾隨4個0有效。在不需要內部3態緩沖器的情況下，該結構允許直接接口的8位數據流重疊。在讀取轉換數據操作時不建議ao改變。三態緩沖器不對稱的允許與阻止時間可能造成內部總線沖突,對AD574A造成潛在危害.圖6

STS這個輸出信號表明了轉換器的狀況。STS值在轉換開始時升高，在轉換過程完成后降低回原樣。

AD574A 容易聯接于多種微處理器和其他數字化系統。下列AD574A控制信號的計時要求的討論應該為系統設計者提供有用的對設備的操作了解。

圖7

圖7顯示的是完整的AD574A運作時間矢量圖表.坐標軸R/C在CE和CS被捕獲之前都應較低;如果R/C顯示較高,操作提示會立即發生,并可能引發系統爭用.無論CE還是CS都能被用來轉換.但是,我們推薦使用CE,因為它比CS有更少的系統延遲,并且能被較快地 輸入.在圖表7,CE被用來轉換.一旦轉換開始STS置成高位，直到轉換循環完成,轉換開始命令將被忽略。直到轉換周期是完全的。在轉換期間，輸出數據緩沖無效。

圖8給出了數據讀取操作時間狀況,在數據讀取過程中, 當CE和R/C都處于高電平(假定CS已經處于低電平)的時候,開始測量訪問時間.如果這時CS能夠使得設備工作, 訪問時間可延長100納秒.圖8 在8位的總線接線模式中（和數字公用區連線的12/8 輸出），地址位AO，必須在CE升高的150毫秒之前和整個讀取循環中保持穩定。如果允許AO變化，將會導致對AD574A輸出緩存區的損壞。

AD5474A單機操作

AD5474A可以“獨立”模式使用，它是系統里很好用的、可用的和專用的端口，以這種方式不需要用總線連接。按這方式，CE和12/8置成高位，CS和AO置成低位，而轉化由RC控制。當RC置成高位時，三態緩沖器啟動，當RC置成低位時開始轉換。其允許兩種控制信號一種高電位脈沖，低高電位脈沖。由如圖11所示的低脈沖操作。在這種情況下R/C下降沿的輸出響應被強制為高阻狀態，在一個轉換周期結束后置回有效邏輯。STS線在R/C變為低電平600ns后變為高電平，當數據有效300ns后恢復低電平。

圖9

如果轉換是由如圖12所示的高電平脈沖所初始化的，那么在R/C為高電平時，數據鏈是被允許的。R/C的下降沿啟動下一個轉換，并且數據鏈返回到三態（并一直保持三態），知道下一個R/C高電平脈沖出現。

圖10

通常應用R/C單機模式下的低脈沖。圖13闡明了典型的8086型處理機的單機構造。額外的74F/S374 插銷提高了總線的訪問/放行次數并協助簡化轉爐數-模部分的連接線。

圖11

AD574與單片機接口

AD574A的控制邏輯使得絕大多數情況下和微處理器系統總線直接連線變成可能。然而它不可能描述出每一種微處理器類型的接口連接的所有細節，下面將舉幾個具有代表性的例子。

典型的數模轉換器接口程序序列涉及以下幾步：首先, 在初始化會話的時候，地址被寫進數模轉換。處理器必須等待會話周期的結束，因為多數數模轉換器需要一個以上的指令周期來完成會話操作。當然，有效數據只有在會話結束后才能被讀取。AD574A 提供信號端輸出(STS)，它能指示會話過程。這個信號可以由處理器通過讀取外部三態緩沖（或其它輸入端口）獲得。如果系統的計時要求非常嚴格（請記住AD574A的最大轉換時間只有35毫秒）并且處理器在ADC轉換周期中有其它任務要做的話，這個STS信號同樣可以用于產生一個中斷信號傳遞給轉換過程。另一種可行的延時方法是，先假設模數轉換器會消耗35微秒來進行轉換，然后插入足夠多的空指令來保證處理器消耗掉35微秒的時間。

一旦建立,即完成轉換,可以讀取數據.在8位(或數位更少)ADC的情況下,單次讀數運行即已足夠.在轉換器數位多于總線可使用數位的情況下,須選擇數據格式,需進行多重讀數運行.AD574A含有內部邏輯(器),允許通過選擇連接12/8輸入而直接到8位或多或16位數據總線界面上。在采用16位數據總線時,(12/8 高)數據總線(DB11 通過 DB0)既可以連接到數據總線的12位有效位或12位無效位。剩余4位應用軟件將其掩蔽.到8位數據總線的界面是采用左優格式來實現的。在數位的上半部偶數地址(A0 低)包含 8 MSBs(DB11 通過 DB4).。奇數地址(A0 高)包含 4 LSBs(DB3 through DB0),后面跟有4個零,從而消除數位掩蔽指令.AD574A可以在輸入/輸出或者儲存映像結構中被接線到Z-80 處理機上。圖15闡明了一個輸入/輸出或者映像結構。Z-80使用A0–A7 地址線來解碼輸入/輸出端口地址。

Z-80的一個有趣的特性就是當進行I/O操作時會自動插入一個等待狀態，允許AD574A和時鐘頻率高達4MHz的Z-80處理器一起使用。對于高于4MHz的實際應用，可以使用圖16所展示的等待狀態發生器。在配置內存內部，AD574A可以和時鐘頻率高達2.5MHz的Z-80處理器通過接口相連接。

第三篇：常用臨床申報資料翻譯中英文對照

FDA（FOOD AND DRUG ADMINISTRATION）：（美國）食品藥品管理局

IND（INVESTIGATIONAL NEW DRUG）：臨床研究申請（指申報階段,相對于NDA而 言）；研究中的新藥（指新藥開發階段，相對于新藥而言，即臨床前研究結束）NDA（NEW DRUG APPLICATION）：新藥申請 ANDA（ABBREVIATED NEW DRUG APPLICATION）：簡化新藥申請 EP訴（EXPORT APPLICATION）：出口藥申請（申請出口不被批準在美國銷售的藥品）TREATMENT IND：研究中的新藥用于治療 ABBREVIATED（NEW）DRUG：簡化申請的新藥 DMF（DRUG MASTER FILE）：藥物主文件（持有者為謹慎起見而準備的保密資料，可以 包括一個或多個人用藥物在制備、加工、包裝和貯存過程中所涉及的設備、生產過程或物 品。只有在DMF持有者或授權代表以授權書的形式授權給FDA，FDA在審查IND、NDA、ANDA時才能參考其內容）HOLDER：DMF持有者 CFR（CODE OF FEDERAL REGULATION）：（美國）聯邦法規 PANEL：專家小組 BATCH PRODUCTION：批量生產；分批生產 BATCH PRODUCTION RECORDS：生產批號記錄 POST-OR PRE-MARKET SURVEILLANCE：銷售前或銷售后監督 INformED CONSENT：知情同意（患者對治療或受試者對醫療試驗了解后表示同意接 受治療或試驗）

FDA（FOOD AND DRUG ADMINISTRATION）：（美國）食品藥品管理局 IND（INVESTIGATIONAL NEW DRUG）：臨床研究申請（指申報階段,相對于NDA而 言）；研究中的新藥（指新藥開發階段，相對于新藥而言，即臨床前研究結束）NDA（NEW DRUG APPLICATION）：新藥申請 ANDA（ABBREVIATED NEW DRUG APPLICATION）：簡化新藥申請 EP訴（EXPORT APPLICATION）：出口藥申請（申請出口不被批準在美國銷售的藥品）TREATMENT IND：研究中的新藥用于治療 ABBREVIATED（NEW）DRUG：簡化申請的新藥 DMF（DRUG MASTER FILE）：藥物主文件（持有者為謹慎起見而準備的保密資料，可以 包括一個或多個人用藥物在制備、加工、包裝和貯存過程中所涉及的設備、生產過程或物 品。只有在DMF持有者或授權代表以授權書的形式授權給FDA，FDA在審查IND、NDA、ANDA時才能參考其內容）HOLDER：DMF持有者 CFR（CODE OF FEDERAL REGULATION）：（美國）聯邦法規 PANEL：專家小組 BATCH PRODUCTION：批量生產；分批生產 BATCH PRODUCTION RECORDS：生產批號記錄 POST-OR PRE-MARKET SURVEILLANCE：銷售前或銷售后監督 INformED CONSENT：知情同意（患者對治療或受試者對醫療試驗了解后表示同意接 受治療或試驗）

PREscriptION DRUG：處方藥 OTC DRUG（OVER—THE—COUNTER DRUG）：非處方藥 U．S．PUBLIC HEALTH SERVICE：美國衛生福利部 NIH（NATIONAL INSTITUTE OF HEALTH）：（美國）全國衛生研究所 CLINICAL TRIAL：臨床試驗 ANIMAL TRIAL：動物試驗 ACCELERATED APPROVAL：加速批準 STANDARD DRUG：標準藥物 INVESTIGATOR：研究人員；調研人員

PREPARING AND SUBMITTING：起草和申報 SUBMISSION：申報；遞交 BENIFIT（S）：受益 RISK（S）：受害 DRUG PRODUCT：藥物產品 DRUG SUBSTANCE：原料藥 ESTABLISHED NAME：確定的名稱 GENERIC NAME：非專利名稱 PROPRIETARY NAME：專有名稱； INN（INTERNATIONAL NONPROPRIETARY NAME）：國際非專有名稱 NARRATIVE SUMMARY記敘體概要 ADVERSE EFFECT：副作用 ADVERSE REACTION：不良反應 PROTOCOL：方案 ARCHIVAL COPY：存檔用副本 REVIEW COPY：審查用副本 OFFICIAL COMPENDIUM：法定藥典（主要指USP、NF）． USP（THE UNITED STATES PHARMACOPEIA）：美國藥典（現已和NF合并一起出 版）NF（NATIONAL formULARY）：（美國）國家藥品集 OFFICIAL＝PHARMACOPEIAL= COMPENDIAL：藥典的；法定的；官方的 AGENCY：審理部門（指FDA）SPONSOR：主辦者（指負責并著手臨床研究者）IDENTITY：真偽；鑒別；特性 STRENGTH：規格；

規格含量（每一劑量單位所含有效成分的量）LABELED AMOUNT：標示量 REGULATORY SPECIFICATION：質量管理規格標準（NDA提供）REGULATORY METHODOLOGY：質量管理方法（FDA用于考核原料藥或藥物產品是 否符合批準了的質量管理規格標準的整套步驟）REGULATORY METHODS VALIDATION：管理用分析方法的驗證（FDA對NDA提 供的方法進行驗證）Dietary supplement：食用補充品 PREscriptION DRUG：處方藥 OTC DRUG（OVER—THE—COUNTER DRUG）：非處方藥 U．S．PUBLIC HEALTH SERVICE：美國衛生福利部 NIH（NATIONAL INSTITUTE OF HEALTH）：（美國）全國衛生研究所 CLINICAL TRIAL：臨床試驗 ANIMAL TRIAL：動物試驗 ACCELERATED APPROVAL：加速批準 STANDARD DRUG：標準藥物 INVESTIGATOR：研究人員；調研人員 PREPARING AND SUBMITTING：起草和申報 SUBMISSION：申報；遞交 BENIFIT（S）：受益 RISK（S）：受害 DRUG PRODUCT：藥物產品 DRUG SUBSTANCE：原料藥 ESTABLISHED NAME：確定的名稱 GENERIC NAME：非專利名稱 PROPRIETARY NAME：專有名稱； INN（INTERNATIONAL NONPROPRIETARY NAME）：國際非專有名稱 NARRATIVE SUMMARY記敘體概要 ADVERSE EFFECT：副作用 ADVERSE REACTION：不良反應 PROTOCOL：方案 ARCHIVAL COPY：存檔用副本 REVIEW COPY：審查用副本 OFFICIAL COMPENDIUM：法定藥典（主要指USP、NF）． USP（THE UNITED STATES PHARMACOPEIA）：美國藥典（現已和NF合并一起出 版）NF（NATIONAL formULARY）：（美國）國家藥品集 OFFICIAL＝PHARMACOPEIAL= COMPENDIAL：藥典的；法定的；官方的 AGENCY：審理部門（指FDA）SPONSOR：主辦者（指負責并著手臨床研究者）IDENTITY：真偽；鑒別；特性 STRENGTH：規格；規格含量（每一劑量單位所含有效成分的量）LABELED AMOUNT：標示量 REGULATORY SPECIFICATION：質量管理規格標準（NDA提供）REGULATORY METHODOLOGY：質量管理方法（FDA用于考核原料藥或藥物產品是 否符合批準了的質量管理規格標準的整套步驟）REGULATORY METHODS VALIDATION：管理用分析方法的驗證（FDA對NDA提 供的方法進行驗證）Dietary supplement：食用補充品

第四篇：中英文對照資料外文翻譯文獻

中英文對照資料外文翻譯文獻

平設計任何時期平面設計可以參照一些藝術和專業學科側重于視覺傳達和介紹。采用多種方式相結合，創造和符號，圖像和語句創建一個代表性的想法和信息。平面設計師可以使用印刷，視覺藝術和排版技術產生的最終結果。平面設計常常提到的進程，其中溝通是創造和產品設計。共同使用的平面設計包括雜志，廣告，產品包裝和網頁設計。例如，可能包括產品包裝的標志或其他藝術作品，舉辦文字和純粹的設計元素，如形狀和顏色統一件。組成的一個最重要的特點，尤其是平面設計在使用前現有材料或不同的元素。平面設計涵蓋了人類歷史上諸多領域，在此漫長的歷史和在相對最近爆炸視覺傳達中的第20和21世紀，人們有時是模糊的區別和重疊的廣告藝術，平面設計和美術。畢竟，他們有著許多相同的內容，理論，原則，做法和語言，有時同樣的客人或客戶。廣告藝術的最終目標是出售的商品和服務。在平面設計，“其實質是使以信息，形成以思想，言論和感覺的經驗”。在唐朝（618-906）之間的第4和第7世紀的木塊被切斷打印紡織品和后重現佛典。阿藏印在868是已知最早的印刷書籍。在19世紀后期歐洲，尤其是在英國，平面設計開始以獨立的運動從美術中分離出來。蒙德里安稱為父親的圖形設計。他是一個很好的藝術家，但是他在現代廣告中利用現代電網系統在廣告、印刷和網絡布局網格。于1849年，在大不列顛亨利科爾成為的主要力量之一在設計教育界，該國政府通告設計在雜志設計和制造的重要性。他組織了大型的展覽作為慶祝現代工業技術和維多利亞式的設計。從1892年至1896年威廉?莫里斯凱爾姆斯科特出版社出版的書籍的一些最重要的平面設計產品和工藝美術運動，并提出了一個非常賺錢的商機就是出版偉大文本論的圖書并以高價出售給富人。莫里斯證明了市場的存在使平面設計在他們自己擁有的權利，并幫助開拓者從生產和美術分離設計。這歷史相對論是，然而，重要的，因為它為第一次重大的反應對于十九世紀的陳舊的平面設計。莫里斯的工作，以及與其他私營新聞運動，直接影響新藝術風格和間接負責20世紀初非專業性平面設計的事態發展。誰創造了最初的“平面設計”似乎存在爭議。這被歸因于英國的設計師和大學教授Richard Guyatt，但另一消息來源于20世紀初美國圖書設計師William Addison Dwiggins。倫敦地鐵的標志設計是愛德華約翰斯頓于1916年設計的一個經典的現代而且使用了系統字體設計。在20世紀20年代，蘇聯的建構主義應用于“智能生產”在不同領域的生產。個性化的運動藝術在 2 俄羅斯大革命是沒有價值的，從而走向以創造物體的功利為目的。他們設計的建筑、劇院集、海報、面料、服裝、家具、徽標、菜單等。Jan Tschichold 在他的1928年書中編纂了新的現代印刷原則，他后來否認他在這本書的法西斯主義哲學主張，但它仍然是非常有影響力。Tschichold，包豪斯印刷專家如赫伯特拜耳和拉斯洛莫霍伊一納吉，和El Lissitzky 是平面設計之父都被我們今天所知。他們首創的生產技術和文體設備，主要用于整個二十世紀。隨后的幾年看到平面設計在現代風格獲得廣泛的接受和應用。第二次世界大戰結束后，美國經濟的建立更需要平面設計，主要是廣告和包裝等。移居國外的德國包豪斯設計學院于1937年到芝加哥帶來了“大規模生產”極簡到美國;引發野火的“現代”建筑和設計。值得注意的名稱世紀中葉現代設計包括阿德里安Frutiger，設計師和Frutiger字體大學;保蘭德，從20世紀30年代后期，直到他去世于1996年，采取的原則和適用包豪斯他們受歡迎的廣告和標志設計，幫助創造一個獨特的辦法，美國的歐洲簡約而成為一個主要的先驅。平面設計稱為企業形象;約瑟夫米勒，羅克曼，設計的海報嚴重尚未獲取1950年代和1960年代時代典型。從道路標志到技術圖表，從備忘錄到參考手冊，增強了平面設計的知識轉讓。可讀性增強了文字的視覺效果。設計還可以通過理念或有效的視覺傳播幫助銷售產品。將它應用到產品和公司識別系統的要素像標志、顏色和文字。連同這些被定義為品牌。品牌已日益成為重要的提供的服務范圍，許多平面設計師，企業形象和條件往往是同時交替使用。教科書的目的是本科目，如地理、科學和數學。這些出版物已布局理論設計說明和圖表。一個常見的例子，在使用圖形，教育是圖表人體解剖學。平面設計也適用于布局和格式的教育材料，使信息更容易和更容易理解的。平面設計是應用在娛樂行業的裝飾，景觀和視覺故事。其他的例子娛樂設計用途包括小說，漫畫，電影中的開幕和閉幕，在舞臺上節目的和道具的安排。這也包括藝術品在T恤衫的應用和其他物品的出售。從科學雜志報道，提出意見和事實往往是提高圖形和深思熟慮的組成視覺信息-被稱為信息的設計。報紙，雜志，博客，電視和電影紀錄片，可以使用平面設計通知及娛樂。隨著網絡，信息與經驗的交互設計的工具，Adobe和Flash正越來越多地被用來說明的背景新聞。一個平面設計項目可能涉及程式化和介紹現有的文字，或者事先存在的意向或圖像開發的平面設計師。例如，一家報紙的故事始于記者和攝影記者，然后成為平面設計師的工作安排到一個合理的頁面布局，并確定是否有任何其他圖形元素應當要求。在一本雜志的文章或廣告，往往是平面設計師或藝術總監將委員會攝影師或插圖創建原始文件只是被納入設計規劃。現代設計的做法已經擴展到了現代的計算機，例如在使用所見的用戶界面，通常被稱為交互式設計，或多媒體設計。任何圖形元素用于設計之前，圖形元素必須是源于通過視覺藝術技能。這些圖形通常（但并不總是）被設計師開發。視覺藝術的作品主要是視覺性的東西從使用傳統的傳播媒介、攝影或電腦產生的藝術。平面設計原則可以適用于每一個人的版畫藝術元素，并最終組成。3 印刷術是藝術，工藝和技術型，修改類型字形，并安排類型的設計。類型字形（字符）的創建和修改使用各種說明方法。這項安排的類型是選擇字體、大小、線長、主要的（行距）和文字的間距。刷術是由排字工機，排字，印刷工人，圖形藝術家，藝術總監，工作者和辦事員。直到數字時代，印刷成為一個專業的領域。數字化開辟了新的視覺設計師和用戶。排版設計師平面設計的一部分，是在網頁設計中是圖形設計，處理安排風格（內容）的要素。從早期的照明網頁手工復制書籍的中世紀和程序，以錯綜復雜的現代雜志和目錄布局，適當的網頁設計公司長期以來一直是考慮的印刷材料，與印刷媒體，內容通常包括類型（文字，圖片（照片）偶爾發生持有者圖形的內容，沒有印刷油墨，如模具/激光切割，燙金壓印或盲目壓花。平面設計師常常專心研究于界面設計，如網頁設計和軟件設計，最終用戶的交互性是一個設計考慮的布局或接口。視覺溝通技巧、互動溝通技巧與用戶互動得相結合和在線品牌推廣，平面設計師往往與軟件開發和網絡開發人員創建的外觀和風格的網站或軟件應用程序，來加強用戶或網絡網站的訪問者互動體驗。版畫是在紙上，其他有機材料或者表面上印刷藝術品的過程。每一張不會被復制，但時最初的因為它不是一個復制的另一藝術作品，并在技術上稱為留下深刻的印象。繪畫或素描，另一方面，創造了獨特的原始藝術品。版畫是由一個單一的原始表面創造的，在技術上已經作為基質而被已知。常見的矩陣包括：金屬板，通常是銅或鋅的雕刻或蝕刻石料，用于光刻;塊木刻的木材，油氈和織物板的絲網印刷。但也有許多其他種類，討論如下：作品從一個單一的印刷板創造一個版本，在現代通常每個簽署和編號，形成限量。打印也可編制成冊，作為藝術家的書籍。一個單一的打印可能是產品的一種或多種技術。色彩學領域是如何在打印機上和顯示器上用眼睛識別顏色和如何解釋和組織這些色彩。眼睛的視網膜被兩個被命名為視桿和視錐的感光體涵蓋。視桿對光很敏感但是對顏色不是很敏感。視錐卻與視桿恰恰相反。他們對光不太敏感，但是顏色可以被感知。隨著科技的發展，人們越來越認識到環境問題日益嚴重，大氣污染、森林破壞、水土流失、土地沙漠

化、水資源污染、大量物種滅絕、石油、天然氣、煤等資源枯竭。作為工業設計師，應該有強烈的環境 保護意識，使得自己的設計建立在不破壞環境及節約自然資源的基礎上。

其中，溫室效應、臭氧層破壞和酸雨是當今全球性的三大環境問題。

溫室效應就是大氣變暖的效應其形成原因是太陽短波輻射可以透過大氣射入地面，而地面增暖后放

出的長波輻射卻被大氣中的二氧化碳就像一層厚厚的玻璃，把地球變成了一個大暖房。甲烷、臭氧、氯、氟烴以及水汽等也對溫室效應有所貢獻。隨著人口的急劇增加和工業的迅速發展，越來越多的二氧化碳 排入大氣中；

又由于森林被大量砍伐，大氣中原本應被森林吸收的二氧化碳沒有被吸收，致使二氧化碳 逐漸增加，溫室效應也不斷增強。溫室效應的后果十分嚴重，自然生態將隨之發生重大變化，荒漠將擴

大，土地侵蝕加重，森林退向極地，旱澇災害嚴重，雨量增加；溫帶冬天更濕、夏天更旱；熱帶也將變 得更濕，干熱的亞熱帶變得更干旱，迫使原有水利工程重新調整。沿海將受到嚴重威脅。由于氣溫升高，兩極冰塊將融化，使海平面上升，將會淹沒許多城市和港口。

臭氧層破壞現象引起科學界及整個國際社會的震動。美國的兩位科學家 Monila 和 Rowland 指出，正是人為的活動造成了今天的臭氧洞。元兇就是現在所熟知的氟利昂和哈龍。

酸雨目前已成為一種范圍廣泛、跨越國界的大氣污染現象。酸雨破壞土壤，使湖泊酸化，危害動植

物生長；刺激人的皮膚，誘發皮膚病，引起肺水腫、肺硬化；會腐蝕金屬制品、油漆、皮革、紡織品和 含碳酸鹽的建筑。

總而言之，人類生活的環境已經日益惡化。

而惡化的原因大部分屬于人類本身的不良生活方式和不 尊重客觀規律，急功近利，對于地球資源的使用沒有科學的計劃性，而且在設計、制造產品以及日常生

活中缺乏保護環境的意識，以至于自毀家園，其危害不僅于當代，而且嚴重影響了子孫后代的生存。

環境問題在很大程度上是由于人們的不良設計、生活方式造成的后果。于是給設計師們提出了一個

嚴肅的問題：作為設計師，應肩負起保護環境的歷史重任！

工業在為人類創造大量物質財富的同時，也給世界帶來了災難。工業設計在為人類創造了現代生活

方式的同時，也加速了資源、能源的消耗，并對地球的生態平衡造成了巨大的破壞。

所以，作為工業設計師，建立環境意識體現了其道德和社會責任心。設計師必須對自己的設計負責，必須把人類的健康幸福，自然與人類的和諧共存作為設計中心遵循的原則。

設計師還必須掌握必要的材料、工藝、化工、制造等方面的知識，使得其設計不對環境造成危害而 成為可能。

“可持續發展設計” 這一概念的提出，對于人性的回歸及世界真正意義上的發展具有劃時代的意義。他體現了設計師的道德與責任，已成為 21 世紀設計發展的總趨勢。從此，人類傳統工業文明發展模式

轉向現代生態文明發展模式。它是社會進步，經濟增長，環境保護三者之間的協同。

可持續發展是人們應遵循的一種全新的倫理、道德和價值觀念。其本質在于：充分利用現代科技，大力開發綠色資源，發展清潔生產，不斷改善和優化生態環境，促使人與自然的和諧發展，人口、資源 和環境相互協調。

解決可持續反展問題是一個技術創新和行為模式轉變的問題。

可持續發展戰略是解決在不危害未來幾代人的需求前提下，盡量滿足當代人的需求的問題。實現目

前利益與長遠利益的統一，為子孫后代留下發展空間。

目前可持續發展戰略考慮的問題有：循環性、綠色能源、生態效率。

綠色設計源于人們對于現代技術文化所引起的環境及生態破壞的反思。綠色設計著眼于人與自然的

生態平衡關系，在設計過程的每一個決策中都充分考慮到環境效益，盡量減少對環境的破壞。

對工業設計師而言，綠色設計的核心是“ 3R ”，即“減少”（Reduce）、“再循環”(Recycle)和“再 利用”（Reuse)。不僅要盡量減少物質和能源的消耗、減少有害物質的排放，而且要使產品及零件能夠 5 方便的分類回收，并再生循環或重新利用。

綠色設計不僅是一種技術層面的考慮，更重要的是一種觀念 上的變革。

要求設計師放棄那種過分強調產品在外觀上標新立異的做法，而將重點放在真正意義上的創 新上面，已一種更為負責的方法去創造產品的形態，用更簡潔、長久的造型使產品盡可能地延長其使用 壽命。

從材料方面要考慮： 原材料的存量和可再生性，獲取材料時的環境能源的消耗與污染，后續加工時

環境材料的易加工性，低能耗性、低污染性，報廢時的可回收性。

從加工制造方面要考慮：加工制造階段需要將污染減至最少，或將污染消滅在生產過程初始階段。

從包裝、運輸、銷售等方面要考慮：包裝的環境性能、綠色包裝，良好的可運輸性、降低自重、減 少能耗，當地化生產及減少物流過程消耗。

從產品的使用階段考慮： 使用中的能耗、資源消耗。

產品更新換代時環境性能的模塊化、可重組性、產品的使用模式等因素。

從產品的報廢階段考慮：易拆卸性，便于分解和分類，材料可回收性和可再利用性，零部件可重組 性或移作它用等因素。

清潔的能源：如考慮太陽能、水電、風力的清潔燃料；清潔的材料，涉及低污染、無毒、易降解和 可回收性；清潔的制造過程，考慮低能耗、少排放的制造；清潔的產品，涉及使用中節能、環保、報廢 后的回收。

零部件的再生利用濕可持續戰略的有力措施。事實證明： 報廢的產品拆卸后，經分析，其中材料在

改進設計后可重用和經翻新后可重用的比例可以提高。

比如：一輛報廢車中，金屬材料占 80 ％，其中，有色金屬占 3 ％～ 4.7 ％。世界鋼產量中的 45 ％是 由廢鋼鐵生產出的。中國鋼產量的 25 ％是由廢鋼鐵生產的。

產品全生命周期管理是指從人對產品的需求開始，到產品淘汰報廢的全部生命歷程。其中包括產

品需求分析產品計劃、概念設計、產品設計、數字化仿真、工藝準備、工藝規劃、生產測試和質量監控、銷售與分銷、使用、維護與維修，以及報廢與回收等主要階段。將先進的管理理念和一流的信息技術有

機融入到現代企業的工業和商業運作中，從而使企業在數字經濟時代能夠有效地調整經營手段和管理方式，以發揮企業前所未有的競爭優勢。幫助企業進行產品創新，贏得市場，并獲得額外利潤，以提高企業產品的價值。

GRAPHIC DESIGN The term graphic design can refer to a number of artistic and professional disciplines which focus on visual communication and presentation.Various methods are used to create and combine symbols, images and/or words to create a visual representation of ideas and messages.A graphic designer may use typography, visual arts and page layout techniques to produce the final result.Graphic design often refers to both the process by which the communication is created and the products which are generated.Common uses of graphic design include magazines, advertisements, product packaging and web design.For example, a product package might include a logo or other artwork, organized text and pure design elements such as shapes and color which unify the piece.Composition is one of the most important features of graphic design especially when using pre-existing materials or diverse elements.Graphic Design spans the history of humankind from the caves of Lascaux to the dazzling neons of Ginza.In both this lengthy history and in the relatively recent explosion of visual communication in the 20th and 21st centuries, there is sometimes a blurring distinction and over-lapping of advertising art, graphic design and fine art.After all, they share many of the same elements, theories, principles, practices and languages, and sometimes the same benefactor or client.In advertising art the ultimate objective is the sale of goods and services.In graphic design, “the essence is to give order to information, form to ideas, expression and feeling to artifacts that document human experience.” During the Tang dynasty(618–906)between the 4th and 7th century A.D.wood blocks were cut to print on textiles and later to reproduce Buddhist texts.A Buddhist scripture printed in 868 is the earliest known printed book.In late 19th century Europe, especially in the United Kingdom, the movement began to separate graphic design from fine art.Piet Mondrian is known as the father of graphic design.He was a fine artist, but his use of grids inspired the modern grid system used today in advertising, print and web layout.In 1849, Henry Cole became one of the major forces in design education in Great Britain, informing the government of the importance of design in his Journal of Design and Manufactures.He organized the Great Exhibition as a celebration of modern industrial technology and Victorian design.From 1892 to 1896 William Morris' Kelmscott Press published books that are some of the most significant of the graphic design products of the Arts and Crafts movement, and 2 made a very lucrative business of creating books of great stylistic refinement and selling them to the wealthy for a premium.Morris proved that a market existed for works of graphic design in their own right and helped pioneer the separation of design from production and from fine art.The work of the Kelmscott Press is characterized by its obsession with historical styles.This historicism was, however, important as it amounted to the first significant reaction to the stale state of nineteenth-century graphic design.Morris' work, along with the rest of the Private Press movement, directly influenced Art Nouveau and is indirectly responsible for developments in early twentieth century graphic design in general.Who originally coined the term “graphic design” appears to be in dispute.It has been attributed to Richard Guyatt, the British designer and academic, but another source suggests William Addison Dwiggins, an American book designer in the early 20th century The signage in the London Underground is a classic of the modern era and used a font designed by Edward Johnston in 1916.In the 1920s, Soviet constructivism applied 'intellectual production' in different spheres of production.The movement saw individualistic art as useless in revolutionary Russia and thus moved towards creating objects for utilitarian purposes.They designed buildings, theater sets, posters, fabrics, clothing, furniture, logos, menus, etc.Jan Tschichold codified the principles of modern typography in his 1928 book, New Typography.He later repudiated the philosophy he espoused in this book as being fascistic, but it remained very influential.Tschichold, Bauhaus typographers such as Herbert Bayer and Laszlo Moholy-Nagy, and El Lissitzky are the fathers of graphic design as we know it today.They pioneered production techniques and stylistic devices used throughout the twentieth century.The following years saw graphic design in the modern style gain widespread acceptance and application.A booming post-World War II American economy established a greater need for graphic design, mainly advertising and packaging.The emigration of the German Bauhaus school of design to Chicago in 1937 brought a “mass-produced”minimalism to America;sparking a wild fire of “modern”architecture and design.Notable names in mid-century modern design include Adrian Frutiger, designer of the typefaces Univers and Frutiger;Paul Rand, who, from the late 1930s until his death in 1996, took the principles of the Bauhaus and applied them to popular advertising and logo design, helping to create a uniquely American approach to European minimalism while becoming one of the principal pioneers of the subset of graphic design known as corporate identity；and Josef Müller-Brockmann, who designed posters in a severe yet accessible manner typical of the 1950s and 1960s era.3 From road signs to technical schematics, from interoffice memorandums to reference manuals, graphic design enhances transfer of knowledge.Readability is enhanced by improving the visual presentation of text.Design can also aid in selling a product or idea through effective visual communication.It is applied to products and elements of company identity like logos, colors, and text.Together these are defined as branding(see also advertising).Branding has increasingly become important in the range of services offered by many graphic designers, alongside corporate identity, and the terms are often used interchangeably.Textbooks are designed to present subjects such as geography, science, and math.These publications have layouts which illustrate theories and diagrams.A common example of graphics in use to educate is diagrams of human anatomy.Graphic design is also applied to layout and formatting of educational material to make the information more accessible and more readily understandable.Graphic design is applied in the entertainment industry in decoration, scenery, and visual story telling.Other examples of design for entertainment purposes include novels, comic books, opening credits and closing credits in film, and programs and props on stage.This could also include artwork used for t-shirts and other items screenprinted for sale.From scientific journals to news reporting, the presentation of opinion and facts is often improved with graphics and thoughtful compositions of visual information-known as information design.Newspapers, magazines, blogs, television and film documentaries may use graphic design to inform and entertain.With the advent of the web, information designers with experience in interactive tools such as Adobe Flash are increasingly being used to illustrate the background to news stories.A graphic design project may involve the stylization and presentation of existing text and either preexisting imagery or images developed by the graphic designer.For example, a newspaper story begins with the journalists and photojournalists and then becomes the graphic designer's job to organize the page into a reasonable layout and determine if any other graphic elements should be required.In a magazine article or advertisement, often the graphic designer or art director will commission photographers or illustrators to create original pieces just to be incorporated into the design layout.Contemporary design practice has been extended to the modern computer, for example in the use of WYSIWYG user interfaces, often referred to as interactive design, or multimedia design.Before any graphic elements may be applied to a design, the graphic elements must be originated by means of visual art skills.These graphics are often(but not always)developed 4 by a graphic designer.Visual arts include works which are primarily visual in nature using anything from traditional media, to photography or computer generated art.Graphic design principles may be applied to each graphic art element individually as well as to the final composition.Typography is the art, craft and techniques of type design, modifying type glyphs, and arranging type.Type glyphs(characters)are created and modified using a variety of illustration techniques.The arrangement of type is the selection of typefaces, point size, line length, leading(line spacing)and letter spacing.Typography is performed by typesetters, compositors, typographers, graphic artists, art directors, and clerical workers.Until the Digital Age, typography was a specialized occupation.Digitization opened up typography to new generations of visual designers and lay users.Page layout is the part of graphic design that deals in the arrangement and style treatment of elements(content)on a page.Beginning from early illuminated pages in hand-copied books of the Middle Ages and proceeding down to intricate modern magazine and catalog layouts, proper page design has long been a consideration in printed material.With print media, elements usually consist of type(text), images(pictures), and occasionally place-holder graphics for elements that are not printed with ink such as die/laser cutting, foil stamping or blind embossing.Graphic designers are often involved in interface design, such as web design and software design when end user interactivity is a design consideration of the layout or interface.Combining visual communication skills with the interactive communication skills of user interaction and online branding, graphic designers often work with software developers and web developers to create both the look and feel of a web site or software application and enhance the interactive experience of the user or web site visitor.Printmaking is the process of making artworks by printing on paper and other materials or surfaces.Except in the case of monotyping, the process is capable of producing multiples of the same piece, which is called a print.Each piece is not a copy but an original since it is not a reproduction of another work of art and is technically known as an impression.Painting or drawing, on the other hand, create a unique original piece of artwork.Prints are created from a single original surface, known technically as a matrix.Common types of matrices include: plates of metal, usually copper or zinc for engraving or etching;stone, used for lithography;blocks of wood for woodcuts, linoleum for linocuts and fabric plates for screen-printing.But there are many other kinds, discussed below.Works printed from a single

第五篇：中英文翻譯

Fundamentals This chapter describes the fundamentals of today’s wireless communications.First a detailed description of the radio channel and its modeling are presented, followed by the introduction of the principle of OFDM multi-carrier transmission.In addition, a general overview of the spread spectrum technique, especially DS-CDMA, is given and examples of potential applications for OFDM and DS-CDMA are analyzed.This introduction is essential for a better understanding of the idea behind the combination of OFDM with the spread spectrum technique, which is briefly introduced in the last part of this chapter.1.1 Radio Channel Characteristics Understanding the characteristics of the communications medium is crucial for the appropriate selection of transmission system architecture, dimensioning of its components, and optimizing system parameters, especially since mobile radio channels are considered to be the most difficult channels, since they suffer from many imperfections like multipath fading, interference, Doppler shift, and shadowing.The choice of system components is totally different if, for instance, multipath propagation with long echoes dominates the radio propagation.Therefore, an accurate channel model describing the behavior of radio wave propagation in different environments such as mobile/fixed and indoor/outdoor is needed.This may allow one, through simulations, to estimate and validate the performance of a given transmission scheme in its several design phases.1.1.1 Understanding Radio Channels In mobile radio channels(see Figure 1-1), the transmitted signal suffers from different effects, which are characterized as follows: Multipath propagation occurs as a consequence of reflections, scattering, and diffraction of the transmitted electromagnetic wave at natural and man-made objects.Thus, at the receiver antenna, a multitude of waves arrives from many different directions with different delays, attenuations, and phases.The superposition of these waves results in amplitude and phase variations of the composite received signal.Doppler spread is caused by moving objects in the mobile radio channel.Changes in the phases and amplitudes of the arriving waves occur which lead to time-variant multipath propagation.Even small movements on the order of the wavelength may result in a totally different wave superposition.The varying signal strength due to time-variant multipath propagation is referred to as fast fading.Shadowing is caused by obstruction of the transmitted waves by, e.g., hills, buildings, walls, and trees, which results in more or less strong attenuation of the signal strength.Compared to fast fading, longer distances have to be covered to significantly change the shadowing constellation.The varying signal strength due to shadowing is called slow fading and can be described by a log-normal distribution [36].Path loss indicates how the mean signal power decays with distance between transmitter and receiver.In free space, the mean signal power decreases with the square of the distance between base station(BS)and terminal station(TS).In a mobile radio channel, where often no line of sight(LOS)path exists, signal power decreases with a power higher than two and is typically in the order of three to five.Variations of the received power due to shadowing and path loss can be efficiently counteracted by power control.In the following, the mobile radio channel is described with respect to its fast fading characteristic.1.1.2 Channel Modeling The mobile radio channel can be characterized by the time-variant channel impulse response h(τ , t)or by the time-variant channel transfer function H(f, t), which is the Fourier transform of h(τ , t).The channel impulse response represents the response of the channel at time t due to an impulse applied at time t ? τ.The mobile radio channel is assumed to be a wide-sense stationary random process, i.e., the channel has a fading statistic that remains constant over short periods of time or small spatial distances.In environments with multipath propagation, the channel impulse response is composed of a large number of scattered impulses received over Np different paths，Where

and ap, fD,p, ?p, and τp are the amplitude, the Doppler frequency, the phase, and the propagation delay, respectively, associated with path p, p = 0,..., Np ? 1.The assigned channel transfer function is

The delays are measured relative to the first detectable path at the receiver.The Doppler Frequency

depends on the velocity v of the terminal station, the speed of light c, the carrier frequency fc, and the angle of incidence αp of a wave assigned to path p.A channel impulse response with corresponding channel transfer function is illustrated in Figure 1-2.The delay power density spectrum ρ(τ)that characterizes the frequency selectivity of the mobile radio channel gives the average power of the channel output as a function of the delay τ.The mean delay τ , the root mean square(RMS)delay spread τRMS and the maximum delay τmax are characteristic parameters of the delay power density spectrum.The mean delay is

Where

Figure 1-2 Time-variant channel impulse response and channel transfer function with frequency-selective fading is the power of path p.The RMS delay spread is defined as Similarly, the Doppler power density spectrum S(fD)can be defined that characterizes the time variance of the mobile radio channel and gives the average power of the channel output as a function of the Doppler frequency fD.The frequency dispersive properties of multipath channels are most commonly quantified by the maximum occurring Doppler frequency fDmax and the Doppler spread fDspread.The Doppler spread is the bandwidth of the Doppler power density spectrum and can take on values up to two times |fDmax|, i.e.，1.1.3Channel Fade Statistics The statistics of the fading process characterize the channel and are of importance for channel model parameter specifications.A simple and often used approach is obtained from the assumption that there is a large number of scatterers in the channel that contribute to the signal at the receiver side.The application of the central limit theorem leads to a complex-valued Gaussian process for the channel impulse response.In the absence of line of sight(LOS)or a dominant component, the process is zero-mean.The magnitude of the corresponding channel transfer function

is a random variable, for brevity denoted by a, with a Rayleigh distribution given by

Where

is the average power.The phase is uniformly distributed in the interval [0, 2π].In the case that the multipath channel contains a LOS or dominant component in addition to the randomly moving scatterers, the channel impulse response can no longer be modeled as zero-mean.Under the assumption of a complex-valued Gaussian process for the channel impulse response, the magnitude a of the channel transfer function has a Rice distribution given by

The Rice factor KRice is determined by the ratio of the power of the dominant path to thepower of the scattered paths.I0 is the zero-order modified Bessel function of first kind.The phase is uniformly distributed in the interval [0, 2π].1.1.4Inter-Symbol(ISI)and Inter-Channel Interference(ICI)The delay spread can cause inter-symbol interference(ISI)when adjacent data symbols overlap and interfere with each other due to different delays on different propagation paths.The number of interfering symbols in a single-carrier modulated system is given by

For high data rate applications with very short symbol duration Td < τmax, the effect of ISI and, with that, the receiver complexity can increase significantly.The effect of ISI can be counteracted by different measures such as time or frequency domain equalization.In spread spectrum systems, rake receivers with several arms are used to reduce the effect of ISI by exploiting the multipath diversity such that individual arms are adapted to different propagation paths.If the duration of the transmitted symbol is significantly larger than the maximum delay Td τmax, the channel produces a negligible amount of ISI.This effect is exploited with multi-carrier transmission where the duration per transmitted symbol increases with the number of sub-carriers Nc and, hence, the amount of ISI decreases.The number of interfering symbols in a multi-carrier modulated system is given by

Residual ISI can be eliminated by the use of a guard interval(see Section 1.2).The maximum Doppler spread in mobile radio applications using single-carrier modulation is typically much less than the distance between adjacent channels, such that the effect of interference on adjacent channels due to Doppler spread is not a problem for single-carrier modulated systems.For multi-carrier modulated systems, the sub-channel spacing Fs can become quite small, such that Doppler effects can cause significant ICI.As long as all sub-carriers are affected by a common Doppler shift fD, this Doppler shift can be compensated for in the receiver and ICI can be avoided.However, if Doppler spread in the order of several percent of the sub-carrier spacing occurs, ICI may degrade the system performance significantly.To avoid performance degradations due to ICI or more complex receivers with ICI equalization, the sub-carrier spacing Fs should be chosen as

such that the effects due to Doppler spread can be neglected(see Chapter 4).This approach corresponds with the philosophy of OFDM described in Section 1.2 and is followed in current OFDM-based wireless standards.Nevertheless, if a multi-carrier system design is chosen such that the Doppler spread is in the order of the sub-carrier spacing or higher, a rake receiver in the frequency domain can be used [22].With the frequency domain rake receiver each branch of the rake resolves a different Doppler frequency.1.1.5Examples of Discrete Multipath Channel Models Various discrete multipath channel models for indoor and outdoor cellular systems with different cell sizes have been specified.These channel models define the statistics of the 5 discrete propagation paths.An overview of widely used discrete multipath channel models is given in the following.COST 207 [8]: The COST 207 channel models specify four outdoor macro cell propagation scenarios by continuous, exponentially decreasing delay power density spectra.Implementations of these power density spectra by discrete taps are given by using up to 12 taps.Examples for settings with 6 taps are listed in Table 1-1.In this table for several propagation environments the corresponding path delay and power profiles are given.Hilly terrain causes the longest echoes.The classical Doppler spectrum with uniformly distributed angles of arrival of the paths can be used for all taps for simplicity.Optionally, different Doppler spectra are defined for the individual taps in [8].The COST 207 channel models are based on channel measurements with a bandwidth of 8–10 MHz in the 900-MHz band used for 2G systems such as GSM.COST 231 [9] and COST 259 [10]: These COST actions which are the continuation of COST 207 extend the channel characterization to DCS 1800, DECT, HIPERLAN and UMTS channels, taking into account macro, micro, and pico cell scenarios.Channel models with spatial resolution have been defined in COST 259.The spatial component is introduced by the definition of several clusters with local scatterers, which are located in a circle around the base station.Three types of channel models are defined.The macro cell type has cell sizes from 500 m up to 5000 m and a carrier frequency of 900 MHz or 1.8 GHz.The micro cell type is defined for cell sizes of about 300 m and a carrier frequency of 1.2 GHz or 5 GHz.The pico cell type represents an indoor channel model with cell sizes smaller than 100 m in industrial buildings and in the order of 10 m in an office.The carrier frequency is 2.5 GHz or 24 GHz.COST 273: The COST 273 action additionally takes multi-antenna channel models into account, which are not covered by the previous COST actions.CODIT [7]: These channel models define typical outdoor and indoor propagation scenarios for macro, micro, and pico cells.The fading characteristics of the various propagation environments are specified by the parameters of the Nakagami-m distribution.Every environment is defined in terms of a number of scatterers which can take on values up to 20.Some channel models consider also the angular distribution of the scatterers.They have been developed for the investigation of 3G system proposals.Macro cell channel type models have been developed for carrier frequencies around 900 MHz with 7 MHz bandwidth.The micro and pico cell channel type models have been developed for carrier frequencies between 1.8 GHz and 2 GHz.The bandwidths of the measurements are in the range of 10–100 MHz for macro cells and around 100 MHz for pico cells.JTC [28]: The JTC channel models define indoor and outdoor scenarios by specifying 3 to 10 discrete taps per scenario.The channel models are designed to be applicable for wideband digital mobile radio systems anticipated as candidates for the PCS(Personal Communications Systems)common air interface at carrier frequencies of about 2 GHz.UMTS/UTRA [18][44]: Test propagation scenarios have been defined for UMTS and UTRA system proposals which are developed for frequencies around 2 GHz.The modeling of the multipath propagation corresponds to that used by the COST 207 channel models.HIPERLAN/2 [33]: Five typical indoor propagation scenarios for wireless LANs in the 5 GHz frequency band have been defined.Each scenario is described by 18discrete taps of the delay power density spectrum.The time variance of the channel(Doppler spread)is modeled by a classical Jake’s spectrum with a maximum terminal speed of 3 m/h.Further channel models exist which are, for instance, given in [16].1.1.6Multi-Carrier Channel Modeling Multi-carrier systems can either be simulated in the time domain or, more computationally efficient, in the frequency domain.Preconditions for the frequency domain implementation are the absence of ISI and ICI, the frequency nonselective fading per sub-carrier, and the time-invariance during one OFDM symbol.A proper system design approximately fulfills these preconditions.The discrete channel transfer function adapted to multi-carrier signals results in

where the continuous channel transfer function H(f, t)is sampled in time at OFDM symbol rate s and in frequency at sub-carrier spacing Fs.The duration

s is the total OFDM symbol duration including the guard interval.Finally, a symbol transmitted onsub-channel n of the OFDM symbol i is multiplied by the resulting fading amplitude an,i and rotated by a random phase ?n,i.The advantage of the frequency domain channel model is that the IFFT and FFT operation for OFDM and inverse OFDM can be avoided and the fading operation results in one complex-valued multiplication per sub-carrier.The discrete multipath channel models introduced in Section 1.1.5 can directly be applied to(1.16).A further simplification of the channel modeling for multi-carrier systems is given by using the so-called uncorrelated fading channel models.1.1.6.1Uncorrelated Fading Channel Models for Multi-Carrier Systems These channel models are based on the assumption that the fading on adjacent data symbols after inverse OFDM and de-interleaving can be considered as uncorrelated [29].This assumption holds when, e.g., a frequency and time interleaver with sufficient interleaving depth is applied.The fading amplitude an,i is chosen from a distribution p(a)according to the considered cell type and the random phase ?n,I is uniformly distributed in the interval [0,2π].The resulting complex-valued channel fading coefficient is thus generated independently for each sub-carrier and OFDM symbol.For a propagation scenario in a macro cell without LOS, the fading amplitude an,i is generated by a Rayleigh distribution and the channel model is referred to as an uncorrelated Rayleigh fading channel.For smaller cells where often a dominant propagation component occurs, the fading amplitude is chosen from a Rice distribution.The advantages of the uncorrelated fading channel models for multi-carrier systems are their simple implementation in the frequency domain and the simple reproducibility of the simulation results.1.1.7Diversity The coherence bandwidth of a mobile radio channel is the bandwidth over which the signal propagation characteristics are correlated and it can be approximated by

The channel is frequency-selective if the signal bandwidth B is larger than the coherence bandwidth.On the other hand, if B is smaller than , the channel is frequency nonselective or flat.The coherence bandwidth of the channel is of importance for evaluating the performance of spreading and frequency interleaving techniques that try to exploit the inherent frequency diversity Df of the mobile radio channel.In the case of multi-carrier transmission, frequency diversity is exploited if the separation of sub-carriers transmitting the same information exceeds the coherence bandwidth.The maximum achievable frequency diversity Df is given by the ratio between the signal bandwidth B and the coherence bandwidth，The coherence time of the channel is the duration over which the channel characteristics can be considered as time-invariant and can be approximated by

If the duration of the transmitted symbol is larger than the coherence time, the channel is time-selective.On the other hand, if the symbol duration is smaller than , the channel is time nonselective during one symbol duration.The coherence time of the channel is of importance for evaluating the performance of coding and interleaving techniques that try to exploit the inherent time diversity DO of the mobile radio channel.Time diversity can be exploited if the separation between time slots carrying the same information exceeds the coherence time.A number of Ns successive time slots create a time frame of duration Tfr.The maximum time diversity Dt achievable in one time frame is given by the ratio between the duration of a time frame and the coherence time, A system exploiting frequency and time diversity can achieve the overall diversity

The system design should allow one to optimally exploit the available diversity DO.For instance, in systems with multi-carrier transmission the same information should be transmitted on different sub-carriers and in different time slots, achieving uncorrelated faded replicas of the information in both dimensions.Uncoded multi-carrier systems with flat fading per sub-channel and time-invariance during one symbol cannot exploit diversity and have a poor performance in time and frequency selective fading channels.Additional methods have to be applied to exploit diversity.One approach is the use of data spreading where each data symbol is spread by a spreading code of length L.This, in combination with interleaving, can achieve performance results which are given for

by the closed-form solution for the BER for diversity reception in Rayleigh fading channels according to [40]

Whererepresents the combinatory function，and σ2 is the variance of the noise.As soon as the interleaving is not perfect or the diversity offered by the channel is smaller than the spreading code length L, or MCCDMA with multiple access interference is applied,(1.22)is a lower bound.For L = 1, the performance of an OFDM system without forward error correction(FEC)is obtained, 9

which cannot exploit any diversity.The BER according to(1.22)of an OFDM(OFDMA, MC-TDMA)system and a multi-carrier spread spectrum(MC-SS)system with different spreading code lengths L is shown in Figure 1-3.No other diversity techniques are applied.QPSK modulation is used for symbol mapping.The mobile radio channel is modeled as uncorrelated Rayleigh fading channel(see Section 1.1.6).As these curves show, for large values of L, the performance of MC-SS systems approaches that of an AWGN channel.Another form of achieving diversity in OFDM systems is channel coding by FEC, where the information of each data bit is spread over several code bits.Additional to the diversity gain in fading channels, a coding gain can be obtained due to the selection of appropriate coding and decoding algorithms.中文翻譯 1基本原理

這章描述今日的基本面的無線通信。第一一個的詳細說明無線電頻道，它的模型被介紹，跟隨附近的的介紹的原則的參考正交頻分復用多載波傳輸。此外，一個一般概觀的擴頻技術，尤其ds-cdma，被給，潛力的例子申請參考正交頻分復用，DS對1。分配的通道傳輸功能是

有關的延誤測量相對于第一個在接收器檢測到的路徑。多普勒頻率

取決于終端站，光速c，載波頻率fc的速度和發病路徑分配給速度v波αp角度頁具有相應通道傳輸信道沖激響應函數圖1-2所示。

延遲功率密度譜ρ（τ）為特征的頻率選擇性移動無線電頻道給出了作為通道的輸出功能延遲τ平均功率。平均延遲τ，均方根（RMS）的時延擴展τRMS和最大延遲τmax都是延遲功率密度譜特征參數。平均時延特性參數為

有

圖1-2時變信道沖激響應和通道傳遞函數頻率選擇性衰落是權力頁的路徑均方根時延擴展的定義為 同樣，多普勒頻譜的功率密度（FD）的特點可以定義

在移動時變無線信道，并給出了作為一種金融衍生工具功能的多普勒頻率通道輸出的平均功率。多徑信道頻率分散性能是最常見的量化發生的多普勒頻率和多普勒fDmax蔓延fDspread最大。多普勒擴散是功率密度的多普勒頻譜帶寬，可價值觀需要兩年時間| fDmax|，即

1.1.3頻道淡出統計

在衰落過程中的統計特征和重要的渠道是信道模型參數規格。一個簡單而經常使用的方法是從假設有一個通道中的散射，有助于在大量接收端的信號。該中心極限定理的應用導致了復雜的值的高斯信道沖激響應過程。在對視線（LOS）或線的主要組成部分的情況下，這個過程是零的意思。相應的通道傳遞函數幅度

是一個隨機變量，通過給定一個簡短表示由瑞利分布，有

是的平均功率。相均勻分布在區間[0，2π]。

在案件的多通道包含洛杉磯的或主要組件除了隨機移動散射，通道脈沖響應可以不再被建模為均值為零。根據信道脈沖響應的假設一個復雜的值高斯過程，其大小通道的傳遞函數A的水稻分布給出

賴斯因素KRice是由占主導地位的路徑權力的威力比分散的路徑。I0是零階貝塞爾函數的第一階段是一致kind.The在區間[0，2π]分發。

1.1.4符號間（ISI）和通道間干擾（ICI）

延遲的蔓延引起的符號間干擾（ISI）當相鄰的數據符號上的重疊與互相不同的傳播路徑，由于不同的延遲干涉。符號的干擾在單載波調制系統的號碼是給予

對于高數據符號持續時間很短運輸署<蟿MAX時，ISI的影響，這樣一來，速率應用，接收機的復雜性大大增加。對干擾影響，可以抵消，如時間或頻域均衡不同的措施。在擴頻系統，與幾個臂Rake接收機用于減少通過利用多徑分集等，個別武器適應不同的傳播路徑的干擾影響。

如果發送符號的持續時間明顯高于大的最大延遲運輸署蟿最大，渠道產生ISI的微不足道。這種效果是利用多載波傳輸的地方，每發送符號的增加與子載波數控數目，因此，ISI的金額減少的持續時間。符號的干擾多載波調制系統的號碼是給予

可以消除符號間干擾由一個保護間隔（見1.2節）的使用。

最大多普勒在移動無線應用傳播使用單載波調制通常比相鄰通道，這樣，干擾對由于多普勒傳播相鄰通道的作用不是一個單載波調制系統的問題距離。對于多載波調制系統，子通道間距FS可以變得非常小，這樣可以造成嚴重的多普勒效應ICI的。只要所有子載波只要是一個共同的多普勒頻移金融衍生工具的影響，這可以補償多普勒頻移在接收器和ICI是可以避免的。但是，如果在對多普勒子載波間隔為幾個百分點的蔓延情況，卜內門可能會降低系統的性能顯著。為了避免性能降級或因與ICI卜內門更復雜的接收機均衡，子載波間隔財政司司長應定為

這樣說，由于多普勒效應可以忽略不擴散（見第4章）。這種方法對應于OFDM的1.2節中所述，是目前基于OFDM的無線標準遵循的理念。

不過，如果多載波系統的設計選擇了這樣的多普勒展寬在子載波間隔或更高，秩序是在頻率RAKE接收機域名可以使用[22]。隨著頻域RAKE接收機每個支部耙解決了不同的多普勒頻率。

1.1.5多徑信道模型的離散的例子

各類離散多與不同的細胞大小的室內和室外蜂窩系統的信道模型已經被指定。這些通道模型定義的離散傳播路徑的統計信息。一種廣泛使用的離散多徑信道模型概述于下。造價207[8]：成本207信道模型指定連續四個室外宏蜂窩傳播方案，指數下降延遲功率密度譜。這些頻道功率密度的離散譜的實現都是通過使用多達12個頻道。與6頻道設置的示例列于表1-1。在這種傳播環境的幾個表中的相應路徑延遲和電源配置給出。丘陵地形導致最長相呼應。

經典的多普勒頻譜與均勻分布的到達角路徑可以用于簡化所有的頻道。或者，不同的多普勒譜定義在[8]個人頻道。207信道的成本模型是基于一個8-10兆赫的2G，如GSM系統中使用的900兆赫頻段信道帶寬的測量。造價231[9]和造價259[10]：這些費用是行動的延續成本207擴展通道特性到DCS1800的DECT，HIPERLAN和UMTS的渠道，同時考慮到宏觀，微觀和微微小區的情況為例。空間分辨率與已定義的通道模型在造價259。空間部分是介紹了與當地散射，這是在基站周圍設幾組圓的定義。三種類型的通道模型定義。宏細胞類型具有高達500?5000米，載波頻率為900兆赫或1.8 GHz的單元尺寸。微細胞類型被定義為細胞體積約300米，1.2 GHz或5 GHz載波頻率。細胞類型代表的Pico與細胞體積小于100工業建筑物和辦公室中的10 m階米室內信道模型。載波頻率為2.5 GHz或24千兆赫。造價273：成本273行動另外考慮到多天線信道模型，這是不是由先前的費用的行為包括在內。

CODIT [7]：這些通道模型定義的宏，微，微微蜂窩和室外和室內傳播的典型案例。各種傳播環境的衰落特性是指定的在NakagamiSS）的不同擴頻碼L是長度，如圖1-3所示的系統。沒有其他的分集技術被應用。QPSK調制用于符號映射。移動無線信道建模為不相關瑞利衰落信道（見1.1.6）。由于這些曲線顯示，辦法，AWGN信道的一對L時，對MC-SS系統性能有很大價值。

另一種實現形式的OFDM系統的多樣性是由前向糾錯信道編碼，在這里，每個數據位的信息分散在幾個代碼位。附加在衰落信道分集增益，編碼增益一個可因適當的編碼和解碼算法的選擇。