Sensing Technologies of IoT

Outline

• One-dimensional barcode
• Two-dementional barcode
• IC card
• RFID
• Sensor
• Positioning and GPS
• Smart device

2.1 One-dimensional Barcode 一維條形碼

One-dimensional Barcode

BarCode 工作原理

• optical machine-readable representation of data.
  相關(guān)的數(shù)據(jù)的光學(xué)機(jī)器可讀表示法.
• varying the widths and spacings of parallel lines.
  改變平行線的寬度和間距來(lái)表示數(shù)據(jù)的.
• Each character is represented by a pattern of wide and narrow bars.
  每一個(gè)字母是用一條細(xì)線代表的。
• As it moves, barcode reader uses a photosensor to convert the barcode into an electrical signal.
  在掃描器移動(dòng)過(guò)程中其能把條碼變成電子信號(hào)。
• Every barcode begins with a special start character and ends with a special stop character.
  每個(gè)條形碼都以一個(gè)特殊的開始字符開始，以一個(gè)特殊的結(jié)束字符結(jié)束。
• Some barcodes may include a checksum character just before the stop character.
  有些條形碼可能在停止字符之前包含校驗(yàn)和字符。

BarCode 具體形式

• UPC-A

  • identifies the manufacturer and specific product
    識(shí)別制造商和具體的產(chǎn)品

    
    
    UPC-A

• UPC-E

  • for labeling small items

  • automatically re-inserting them at the scanner

    
    
    UPC-E

• Codabar

  • for libraries, blood banks

    
    
    Codabar

• EAN-13
  • for marking retail goods. 零售商品

  • 2 or 3 characters countrycodes + 9 or 10 data digits + 1 checksum

    
    
    EAN-13

• Interleaved 2 of 5
  • for warehouse(倉(cāng)庫(kù)) and industries

Interleaved 2 of 5

Interleaved 2 of 5

• Code 39
  • for government and industries

Code 39

• Code 93
  • more compact（緊湊） version of Code 39

Code 93

• Code 128
  • excellent density for all-numeric data and good density for alphanumeric data.
    對(duì)全數(shù)字和字母的數(shù)據(jù)有很好的密度
  • support all ASCII symbols

Code 128

• Bookland EAN (ISBN)

  • for books, video, audio and software

    
    
    Bookland EAN

BarCode Reader 工作原理

• light source, a lens and a light sensor translating optical impulses into electrical ones.
  光源、透鏡和光傳感器將光脈沖轉(zhuǎn)換成電脈沖。
• contain decoder circuitry 譯碼器電路

BarCode Reader 具體形式（不重要）

• Pen-type readers: consist of a light source and photodiode 光源和光電二極管
• Laser scanners: laser beam 激光 mirror 棱鏡反射掃描
• CCD readers: light sensors 光傳感器
• Camera-based readers: camera and image processing
• Omni-directional barcode scanners(全方位的條形碼掃描儀): Laser scanner, for grocery

BarCode System

• encoding module for generating a visually significant barcode
  生成具有視覺(jué)意義的條形碼
• decoding module for receiving an acquired version of a visually significant barcode
  接收可能在典型的文檔處理通道
• recovering the message
  恢復(fù)

2.2 Two-dimentional Code

工作原理

• encode a lot of information in a small space
• contain 100 to about 2000 characters

具體形式

• PDF-417

  
  
  PDF-417

• DataMatrix

• QR Code

2.3 IC card

工作原理

• embedded integrated circuits
  嵌入式集成電路
• provide identification, authentication, data storage and application processing.
  識(shí)別、認(rèn)證、數(shù)據(jù)存儲(chǔ)和應(yīng)用程序處理。

具體形式

• smart card

  
  
  smart card

• chip card

  
  
  chip card

• integrated circuit card

  
  
  integrated circuit card

Contact smart cards 工作原理

• comprising gold plated contact pads
  包括若干鍍金接觸墊
• power is supplied by the card reader.
  電源由讀卡器提供

Contactless smart cards 工作原理 (重點(diǎn))

• RF induction technology 無(wú)線射頻技術(shù)
• not have an internal power source 沒(méi)電
• communicate with a terminal via radio waves
  通過(guò)無(wú)線電波與終端通信
• Contactless smart cards do not contain an ordinary readonly RFID, but they do contain a re-writeable smart card.
  非接觸式智能卡不包含普通的只讀RFID，但它們包含可重寫的智能卡
• used for identification,authentication, and data storage
  可用于識(shí)別、認(rèn)證和數(shù)據(jù)存儲(chǔ)

應(yīng)用場(chǎng)景

• Financial: ATM cards, fuel cards, mobile phone SIMs.
• Identifications: driver's license system, students card
• Healthcare: portable medical record

2.4 RFID

定義和特點(diǎn)

• RFID Radio Frequency Identification：Radio-frequency identification is the use of a wireless non-contact system that uses radio-frequency electromagnetic fields to transfer data from a tag attached to an object, for the purposes of automatic identification and tracking.
  射頻識(shí)別:射頻識(shí)別是使用無(wú)線非接觸系統(tǒng)，利用射頻電磁場(chǎng)將數(shù)據(jù)從附著在物體上的標(biāo)簽傳輸?shù)轿矬w上，以實(shí)現(xiàn)自動(dòng)識(shí)別和跟蹤。
• An ADC (Automated Data Collection) technology
  • uses radio-frequency waves to transfer data to identify, categorize, track
  • fast and doesn't require physical sight or contact
  • automatic
  • low cost
  • unique identification

RFID 組件

• RFID tag
• RF Antenna
• Network

• WorkStation

  
  
  RFID Components

RFID tag

• The tag contains electronically stored information.
  標(biāo)簽包含電子存儲(chǔ)的信息，可以從幾米(碼)外讀取
• the tag does not need to be within line of sight of the reader.
  標(biāo)簽不需要在閱讀器的視線范圍內(nèi)
• Tags can be read-only or read-write

RFID Tag 概念圖

RFID

RFID Tag 分類（重點(diǎn)）

• Passive 被動(dòng)

  • Operational power scavenged from reader radiated power
    從讀出器輻射功率中清除的操作功率
  • Tag reflects radio signal from reader
    標(biāo)簽反射來(lái)自閱讀器的無(wú)線電信號(hào)
  • Reader powered
  • Shorter Read Range

• Semi-active 半主動(dòng)

  • Operational power provided by battery

• Active 主動(dòng)

  • Operational power provided by battery - transmitter built into tag
    工作電源由內(nèi)置在標(biāo)簽內(nèi)的電池發(fā)射器提供
  • Tag transmits radio signal
    標(biāo)簽傳送無(wú)線電信號(hào)
  • Battery powered memory, radio & circuitry
    電池供電的存儲(chǔ)器，無(wú)線電和電路
  • High Read Range

• Read-only tags

• Write once, read many tags

• Read/Write tags

RFID Reader （重點(diǎn)）

• 功能

1. Remote power tags 遠(yuǎn)程電源標(biāo)簽
2. Establish a bidirectional data link 建立雙向數(shù)據(jù)鏈路
3. Inventory tags, filter results 庫(kù)存標(biāo)簽，過(guò)濾結(jié)果
4. Communicate with networked server(s) 與聯(lián)網(wǎng)的伺服器通訊
5. Can read 100-300 tags per second 每秒可以讀取100-300個(gè)標(biāo)簽

Frequencies of operations for Readers

RFID 交流模型（重點(diǎn)）

communication

• Host 發(fā)出命令
• Reader 和 Tag 通過(guò)射頻信號(hào)進(jìn)行通信
• Reader 產(chǎn)生 Carrier signal
• Reader通過(guò) Antennas 發(fā)送 Carrier signal
• Carrier signal hit Tag
• Tag recieves 并修改信號(hào)發(fā)送回Reader
• Antennas 接收并發(fā)送到 Reader
• Reader decode
• Reader 發(fā)送結(jié)果到 Host

Electronic Product Code EPC碼

• universal identifier 通用標(biāo)識(shí)符
• RFID tag
• EPCglobal Tag Data Standard
  其結(jié)構(gòu)定義在EPCglobal標(biāo)簽數(shù)據(jù)標(biāo)準(zhǔn)中

EPC Network (PPT 要求理解)

• 定義
  The EPCglobal Network is a computer network used to share product data between trading partners. It was created by EPCglobal.
  EPCglobal網(wǎng)絡(luò)是一個(gè)用于在貿(mào)易伙伴之間共享產(chǎn)品數(shù)據(jù)的計(jì)算機(jī)網(wǎng)絡(luò)。它是由EPCglobal創(chuàng)建的。

• The EPCglobal Network consists of the following components:

2.5 Sensor

定義

A device that responds to a physical stimulus and transmits a resulting impulse.

A sensor is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an (today mostly electronic) instrument.
傳感器是一個(gè)轉(zhuǎn)換器，它測(cè)量一個(gè)物理量，并將其轉(zhuǎn)換成一個(gè)信號(hào)，該信號(hào)可以被觀察者或(今天主要是電子)儀器讀取。

分類

Classification

Input & Output

• Input: stimulus or measurand (temperature, pressure, light intensity)
• Output: electrical signal (voltage, current, frequency, phase)
• Relation:
  • Linear or nonlinear; single/multiple
  • inputs, single output;

Range and Span

Example: a sensors is designed for: ?30 °C to +80 °C
to output 2.5V to 1.2V
Range: ?30°C and +80 °C
Span: 80? (?30)=110 °C
Input full scale = 110 °C
Output full scale = 2.5V-1.2V=1.3V

Error

• Error Source

• Error 分類

一堆概念（重點(diǎn)）

• Resolution(分辨力): the minimum increment in stimulus to which it can respond.
  最小感知單元的大小
• Accuracy(準(zhǔn)確度): how closely the output will match the true value.
  感知信息的準(zhǔn)確程度

• Precision(精確度): how close the measured values are to each other.

  
  
  Accuracy & Resolution
  
  
  Accuracy & Precision
• Reliability(可靠性): reproducibility, indicates the ability of the device to perform its stated function.
  也稱為再現(xiàn)性:在不同時(shí)間測(cè)量時(shí)，傳感器在相同條件下不能表示相同的值(即刺激或輸入)。
  對(duì)設(shè)備質(zhì)量的一種統(tǒng)計(jì)測(cè)量，它表明設(shè)備在正常運(yùn)行條件下，在規(guī)定的一段時(shí)間或若干個(gè)周期內(nèi)不發(fā)生故障的情況下，執(zhí)行規(guī)定功能的能力。
• Sensitivity(靈敏度): represents the slope of the transfer function.
  傳感器的靈敏度定義為給定輸入變化(通常是輸入的單位變化)的輸出變化。靈敏度表示傳遞函數(shù)的斜率。
• Hysteresis(滯后程度): the deviation of the sensor’s output at any given point when approached from two different directions
  滯后程度:當(dāng)傳感器從兩個(gè)不同的方向接近任意給定點(diǎn)時(shí)，傳感器輸出的偏差
• Linearity(線性度)： the deviation of the output from a best-fit straight line for a given range of the sensor
  線性度: 在給定的傳感器范圍內(nèi)，輸出與最佳擬合直線的偏差
  Response time(響應(yīng)時(shí)間): delay time, indicates the time needed for the output to reach steady state for a step change in input.
  表示輸出達(dá)到穩(wěn)態(tài)所需的時(shí)間。
  Calibration(校準(zhǔn)): the experimental determination of thetransfer function of a sensor.
  校準(zhǔn):傳感器傳遞函數(shù)的實(shí)驗(yàn)測(cè)定。
  通常，當(dāng)傳遞函數(shù)未知時(shí)，
  當(dāng)設(shè)備必須在低于制造商規(guī)定的公差下運(yùn)行時(shí)。
  例如，在0到100°C的溫度范圍內(nèi)，使用容忍度為5%的熱敏電阻來(lái)測(cè)量溫度。

2.6 Positioning and GPS

定位基本原理（重點(diǎn)）

Signals in the electromagnetic spectrum
Signal time transit from known points converted to distance
Distances/ directions to known points are solved for the unknown position

電磁波譜中的信號(hào)
信號(hào)時(shí)間從已知點(diǎn)轉(zhuǎn)換為距離
由多個(gè)已知點(diǎn)的距離/方向由未知位置求出

• Cellular positioning- EOTD 細(xì)胞定位

Cellular positioning

GPS

• Global Positioning System
• GPS provides:
  ① Location or positional fix
  ② Velocity
  ③ Direction of travel
  ④ Accurate time
• GPS Basic Steps:

• Range from each satellite calculated
  range = time delay * speed of light

• Sources of Errors