Data Acquisition

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Figure 3.7Ideal band pass filter transfer characteristicsThe transfer characteristics of a practical filter for minimum ‘Q’ and maximum ‘Q’ areshown in Figure 3.8.Figure 3.8Practical active band pass filter transfer characteristicsBand stop (notch) filtersNotch filters filter out a certain range of frequencies specified by a start and stopfrequency, and pass all others. These filters combine a high pass and a low pass in parallel,each tuned to the low and high cut-off frequencies respectively. The ideal transfercharacteristic of an active band stop filter is shown in Figure 3.9.
Figure 3.9Ideal band stop filter transfer characteristicsThe transfer characteristics of a practical filter for minimum ‘Q’ and maximum ‘Q’ areshown in Figure 3.10.Figure 3.10Practical active notch transfer characteristicsButterworth filterButterworth filters provide a higher level of low pass filtering, containing two or morelow pass filter stages. The number of stages ‘n’ of the filter determines how sharp theroll-off is at the cut-off frequency. A two-stage filter of this type is known as a secondorder Butterworth filter as shown in Figure 3.11.A fourth order Butterworth filter would have two of the filter sections shown in Figure3.11 cascaded together.
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Practical Data Acquisition forInstr
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Practical Data Acquisition forInstr
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In less than a decade, the PC has b
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PrefaceContentsxvii1 Introduction 1
Page 10 and 11: Contents vii4.2.1 Hardware interrup
Page 12 and 13: Contents ix6.2.3 Functional descrip
Page 14 and 15: Contents xi9.1 Ethernet and fieldbu
Page 16 and 17: Contents xiii12.5.2 Pin assignments
Page 18 and 19: Contents xvType R thermocouple 384T
Page 20 and 21: A data acquisition and control syst
Page 22 and 23: FilteringIn noisy environments, it
Page 24 and 25: are capable of programmed I/O and i
Page 26 and 27: Plug-in expansion boards are common
Page 28 and 29: 50 mRS-232 Communication InterfaceS
Page 30 and 31: speeds are of the order of 1 Mbyte/
Page 32 and 33: 14 Practical Data Acquisition for I
Page 54 and 55: 3PC based data acquisition (DAQ) sy
Page 56 and 57: 3.2.3 FilteringIsolation performs s
Page 58 and 59: The transfer characteristics of a p
Page 62 and 63: Figure 3.11Two-stage Butterworth fi
Page 64 and 65: As individual signal conditioning m
Page 66 and 67: ThermocouplesDigitalTransmitterDigi
Page 68 and 69: Examples of floating signal sources
Page 70 and 71: espect to the measurement system gr
Page 72 and 73: Figure 3.26Opto-coupler isolation o
Page 74 and 75: • Using isolation amplifiers to i
Page 76 and 77: Figure 3.31Physical representation
Page 78 and 79: field or if the field is caused by
Page 80 and 81: Where the shield is grounded (i.e.
Page 82 and 83: mines the amount of noise in the ci
Page 84 and 85: For full-duplex systems using balan
Page 86 and 87: 4.1.1 DOSusually consist of a small
Page 88 and 89: With the advent of Windows as a gra
Page 90 and 91: UNIX shellSimilar to the DOS comman
Page 92 and 93: available to the expansion bus. A l
Page 94 and 95: 4.2.7 Interrupt service routinesIt
Page 96 and 97: Whichever CPU is being used, it mus
Page 98 and 99: • An I/O device requests a DMA tr
Page 100 and 101: Normal DMA using on-board FIFOThe D
Page 102 and 103: ferring samples until the counter r
Page 104 and 105: The read or write command signals (
Page 106 and 107: Shortened 3-BCLK 8-bit memory acces
Page 108 and 109: Extended 6-BCLK 16-bit memory acces
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• A cycle which the expansion boa
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Figure 4.13Timing chart of a shorte
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Figure 4.15Timing chart of an exten
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4.7.2 Expanded memory system (EMS)E
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The IBM PC and early versions of th
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Figure 4.17ISA signal mnemonics, si
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data bus. An example of this happen
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NOWSThe /NOWS (NO wait state) signa
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interrupt lines (1RQ13, 8, 2, 1 and
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one application at a time, it is ne
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The need for PCs to exchange data w
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Figure 4.198-bit 21-line I/O board4
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Address decoding on the 24-line pro
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The write cycle is considered in th
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data acquisition and control system
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Adjustable on-board fixed gain ampl
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level applied at the input. When a
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Each step effectively divides the r
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The operation of a dual slope integ
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Code widthThis is the fundamental q
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(a) Unipolar offset error(b) Bipola
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Changes in temperature result in a
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1 LSB. Therefore, an ideal A/D conv
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• The source and level of interru
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5.3.3 Differential inputsTrue diffe
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A/D board can divide the input rang
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a) DC alias caused by sampling at h
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Figure 5.15Frequency spectrum of or
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ate be a minimum of about five time
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Figure 5.20Many aliases combined wi
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initiated. The data is subsequently
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Figure 5.22Time skew between channe
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For each burst trigger, the A/D boa
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Analog output D/A boardsUnlike high
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Like the weighted-current source ne
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The generation of high frequency si
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• The plug-in connector, which pr
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Latched digital I/OFor applications
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y increasing the resistance of R x
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One advantage of this type of relay
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Figure 5.36Waveforms showing genera
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When a counter is configured to ena
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6The standardization of the RS-232
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A duplex system is designed for sen
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Some examples of the HEX and BIN va
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In summary, the optional settings f
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At the RS-232 receiver the followin
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110 850300 800600 7001200 5002400 2
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• Pin 7: Signal ground (common)Th
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6.2.5 Examples of RS-232 interfaces
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terminating resistors, approximatel
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Another commonly used technique, ba
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• Line controlThis applies to hal
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The calculation of the block checks
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The mechanism of operation of the C
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Figure 6.18, has appropriate intern
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77.1 IntroductionAs with other form
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inserted in the device. This is its
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How frequently logged data is uploa
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The following hardware components d
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In a typical stand-alone data acqui
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The maximum battery life that can b
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Input termination resistors, typica
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Figure 7.13 shows the standard conn
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interface, even at high speed, the
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• Use different data formats so t
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Command errors are reported immedia
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• Channel scalingThis automatical
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The channel scan for this type of s
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Data is logged in a fixed non-ASCII
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7.9 Stand-alone logger/controllers
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88.1 IntroductionThe communications
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Figure 8.2GPIB connector (IEEE 488)
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• TalkersA talker is a one-way co
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controller in charge (CIC). The IFC
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Each device connected to the GPIB h
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One of the additional features that
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• The controller temporarily conf
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Table 8.4IEEE 488.2 commandsThe SCP
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Figure 8.9SCPI instrument modelThe
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99.1 Ethernet and fieldbuses for da
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cabling tray etc and the transceive
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transceiver in the MAU and this is
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Advantages of the system include:
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of a cell as well, but these are ig
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Figure 9.8CSMA/CD collisionsAssume
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• PreambleThis field consists of
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of this figure. Some manufacturers
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Grounding has safety and noise conn
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Just as with any technology, each o
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information. The packet is then pla
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There are two types of connectors,
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HOSTClient SoftwareManages Interfac
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Figure 10.6USB connector pinsThere
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The idle states for low- and high-s
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The interrupt transfer type is used
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than in spending a lot of time and
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• The sensitivity of the output/i
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term error (m) in the system and ad
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11.2 Capturing high speed transient
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12IntroductionThe PCMCIA (PCMCIA st
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adapter on a full size computer has
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Pager cards are used in offices and
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Size 85.6 mm × 54.0 mmType I 3.3 m
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The memory only interface is conver
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The AIMS interface supports large d
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12.8 FutureThe card information str
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A/D conversion timeAddressAddress r
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Back-planeBand pass filterBandwidth
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BufferBusBWCache memoryCCDCCIRCCITT
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pixel is subjected to a mathematica
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data between the computer memory an
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FrameFrame grabberFringingFull dupl
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so that they interlock. The PAL sta
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Lux-secondSI unit of light exposure
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NTSCNull modemNumber of channelsNyq
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PortPPIPre-triggerProgram I/OProgra
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whereby the first gray level of eac
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allowing the user to control basic
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input.TrunkUARTUnipolar inputsUnloa
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Appendix BThe information in this s
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Table B.4Controller 2: 16-bit (AT o
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B.5 8253/8254 Counter/timer
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Table B.8Memory map for PC/XT/AT
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Table B.10BIOS data area
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Table B.15ROMTable B.16AT extended
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← ↔ ← ← ← ↔
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Figure B.1Card dimensions for PC/XT
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Appendix CThis section contains bri
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the control register of the 8255. T
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The bits A7 (MSB) down to A0 (LSB)
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Table C.6Instructions for reading o
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The program could also enable the I
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Group AConfiguration Informationto
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C.11 Single-bit set/resetAny of the
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Figure C.15Bi-directional bus (mode
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Figure D.18254 Block diagramFigure
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Figure D.3TCCTRL registerThe functi
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This is the data register of the fi
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• A simple read operation• A co
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The null count bit indicates if the
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For even counts: the output is init
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Appendix EThe IPTS-68 standard defi
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Number of ranges = 2Range #1 -270 t
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Range #2 0 to 1372°COrder of polyn
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Number of Ranges = 4Range #1 -50 to
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Appendix FF.1 IntroductionAll activ
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Table F.3 gives the conversion betw
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The conversion between binary and h
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F.8 Internal representation of info
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12 which is equivalent to: 1100-4 S
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DCDCASDCISDCLDDDIODTDTASDTISENDEOIE
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STBSTRSSWNST(T)TETACSTADSTAGTCATCST
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404 IndexDuplex:full duplex 178half
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406 IndexOpen loop control 285see a
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THIS BOOK WAS DEVELOPED BY IDC TECH
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Data Acquisition

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