Data Acquisition Systems Quiz
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What is a key component in the process of data acquisition?

  • Digital signal processing
  • Analog signal modulation
  • Data compression
  • Analog to digital conversion (correct)

    • Which of the following describes the initial step in computer data acquisition?

  • Measuring the data (correct)
  • Applying signal conditioning
  • Transmitting the signals
  • Analog signal conversion

    • Which of the following is NOT typically part of a measurement system architecture?

  • Analog-to-Digital Converter
  • Feedback controller (correct)
  • Measurand
  • Software

    • What forms do signals take in data acquisition systems?

    <p>Digital and analog</p> Signup and view all the answers

    In the architecture of a measurement system, what does the sensor do?

    <p>Measure the measurand</p> Signup and view all the answers

    Which of the following tools is associated with data acquisition software?

    <p>LabVIEW</p> Signup and view all the answers

    What role does signal conditioning play in data acquisition?

    <p>Enhances the quality of the analog signal</p> Signup and view all the answers

    The measurand in a measurement system refers to what?

    <p>The physical quantity being measured</p> Signup and view all the answers

    What is the Nyquist rate according to Shannon's sampling theorem?

    <p>fs &gt; 2fmmax</p> Signup and view all the answers

    Which of the following statements about digital signals is true?

    <p>Digital signals are easier to process further.</p> Signup and view all the answers

    Sampling at a frequency less than the Nyquist rate can result in what?

    <p>Phantom frequencies</p> Signup and view all the answers

    Which signal range is considered standard for digital signals?

    <p>0 or 5V</p> Signup and view all the answers

    What characterizes the sampling process?

    <p>Using a constant sampling rate</p> Signup and view all the answers

    What is the consequence of sampling at a frequency lower than the Nyquist rate?

    <p>Loss of high-frequency information</p> Signup and view all the answers

    What is the main disadvantage of analog signals compared to digital signals?

    <p>Analog signals are more susceptible to disturbance.</p> Signup and view all the answers

    In the context of sampling, what does Ts represent?

    <p>Sampling period</p> Signup and view all the answers

    What is the primary feature of a Flash Analog-to-Digital Converter?

    <p>Employs parallel comparison for fast conversion</p> Signup and view all the answers

    Which factor is NOT considered when selecting an A/D converter?

    <p>Size of the package</p> Signup and view all the answers

    What is one advantage of adding resolution in a Flash A/D converter?

    <p>No increase in conversion time compared to other types</p> Signup and view all the answers

    Which method is used to multiplex analog signals in an A/D conversion system?

    <p>Using transistors or relays and control signals</p> Signup and view all the answers

    In the process of D/A conversion, what is the simplest type of D/A converter mentioned?

    <p>Resistor ladder-network converter</p> Signup and view all the answers

    What is the primary purpose of quantization in Analog to Digital conversion?

    <p>To approximate a discrete signal value to a set of distinct levels</p> Signup and view all the answers

    How does the number of bits affect the resolution in quantization?

    <p>More bits increase the number of distinct levels</p> Signup and view all the answers

    What dictates the highest measurable frequency in a signal?

    <p>The sampling frequency</p> Signup and view all the answers

    In the context of analog to digital conversion, what does the term 'sampling period' refer to?

    <p>The time interval between consecutive samples</p> Signup and view all the answers

    Which of the following could be a potential issue related to analog to digital conversion?

    <p>Increased resolution leads to larger data files</p> Signup and view all the answers

    What is the maximum bandwidth requirement for a distortion-free audio signal?

    <p>It must be half the sampling frequency</p> Signup and view all the answers

    Which factor does NOT influence the selection criteria for an analog to digital converter?

    <p>Signal distortion during transmission</p> Signup and view all the answers

    If a system uses a 16-bit quantization level, how many distinct values can it represent?

    <p>65536 values</p> Signup and view all the answers

    What is the primary component used in a first order low pass filter?

    <p>One resistor and one capacitor</p> Signup and view all the answers

    Which of the following describes the performance of a first order low pass filter?

    <p>Simple to implement, not very effective</p> Signup and view all the answers

    What is one major advantage of the successive approximation A/D converter?

    <p>It is relatively cheap and fast</p> Signup and view all the answers

    What is the role of the sample and hold (S&H) amplifier in the successive approximation A/D converter?

    <p>To maintain and latch the analog input signal</p> Signup and view all the answers

    In the successive approximation A/D converter, when is the end signal set by the control unit?

    <p>When the D/A output equals the analog input</p> Signup and view all the answers

    What does the successive approximation process involve after receiving the start signal?

    <p>An iterative approximation with a digital output</p> Signup and view all the answers

    Why is the D/A converter embedded in the successive approximation A/D converter not considered a disadvantage?

    <p>It is simple and relatively cheap to produce</p> Signup and view all the answers

    Which best describes the process flow of the successive approximation A/D converter?

    <p>Sampling -&gt; D/A conversion -&gt; Comparison</p> Signup and view all the answers

    What does the most significant bit (MSB), 𝑏3, represent in the conversion process?

    <p>The highest weight bit</p> Signup and view all the answers

    What happens when the analog approximation error, 𝓔𝑖, is negative?

    <p>𝑏3 is set to 0</p> Signup and view all the answers

    Which of the following steps is performed last in the successive approximation process?

    <p>Turn off the conversion process</p> Signup and view all the answers

    If 𝓔𝑖 is positive after setting 𝑏3 to 1, what is the next bit that is set to 1?

    <p>𝑏2</p> Signup and view all the answers

    Which part of the iterative process is repeated until the approximation error is near zero?

    <p>Setting the bits based on error</p> Signup and view all the answers

    What is the initial setting of the bits when 𝑏3 is set to 1?

    <p>𝑏2 = 0, 𝑏1 = 0, 𝑏0 = 0</p> Signup and view all the answers

    What can be inferred if 𝓔𝑖 is approximately zero?

    <p>The analog signal matches the digital output.</p> Signup and view all the answers

    How is the bit 𝑏2 affected if the approximation error 𝓔𝑖 is found to be negative?

    <p>It is set to 1.</p> Signup and view all the answers

    Study Notes

    Course Information

    • Course: EE429: Mechatronics
    • Chapter: 8 Data Acquisition
    • Fall 2024
    • Instructor: Dr. Mohammed Morsy Farag

    Data Acquisition Definition

    • The process of measuring and storing or transmitting analog signals from sources such as physical systems, control systems, mechatronic systems, network control systems, telemetry, remote sensing, etc., using a digital computer, is known as computer data acquisition.
    • Data acquisition involves these steps:
      • Sensing or measurement
      • Analog-to-digital conversion

    Data Acquisition in Mechatronic Systems

    • Microprocessors, microcontrollers, single-board computers, and personal computers are prevalent in mechatronics.
    • Engineers should understand direct access to environmental data using these devices.
    • Analog signal processing techniques include recording with analog devices (e.g., chart recorders) and displaying with oscilloscopes.
    • Analog-to-digital conversion transforms analog signals into coded digital values, starting with sampling—numerically evaluating the signal at discrete instants in time.
    • Digitized signals are sequences of numbers approximating analog signals, where sampled data points form a data array.
    • Analog signals are in physical form, and digital signals are converted into numbers

    Signals Come in Two Forms

    • Analog signals have continuous values over time, represented by a smooth curve and typically observed as a wave.
    • Digital signals are discrete (non-continuous), using finite-level digital numbers (0s & 1s or multiples).

    Signals, Voltage, and Current

    • Analog signals for voltage include 0...10V, 0...5V, etc.,
    • Analog signals for current include 0...20mA, 4...20mA,
    • Digital signals are 0 or 1 (or multiples)

    Sampling Theory and Aliasing

    • Sampling rate should not be less than 2 times the maximum frequency to avoid aliasing.
    • Aliasing is a distortion caused by sampling at a rate less than the Nyquist rate (2 times the maximum frequency). It creates false information or errors in the reproduced signal.

    Analog to Digital Conversion

    • This is the process of approximating a continuous signal by assigning distinct pre-assigned binary values to represent a digital signal.
    • This is a key first step in analog-to-digital conversion.
    • This is defined as quantization.

    Components

    • A measurement system has several components:
      • Measurand: the physical quantity being measured.
      • Sensor: converts measurand into another, typically electrical, quantity.
      • Signal Conditioning: processes sensor signal before conversion.
      • Analog-to-Digital Converter (ADC): translates analog signal to digital signal.
      • Software: software to control acquisition and process/display data.
      • Driver: driver that controls the hardware, and interacts with the software.
      • Application: for example, data visualization or analysis software to display collected data

    Architectural overview

    • The order in which instruments are used for signal conditioning.
    • Starting from the sensor converts a physical quantity into an electrical signal (e.g., voltage or current), which then can be processed by different steps in signal conditioning

    Amplification

    • Used for low-level signals to increase their amplitude within the range of the DAQ device to enhance accuracy. Increases signal-to-noise ratio (SNR).

    Attenuation

    • Decreases the signal amplitude to fit within the range of the DAQ device (Data Acquisition Device). A necessity when input signals are greater than the maximum input voltage range for the DAQ device.

    Filtering

    • Filters unwanted noise from measured signals to isolate the desired frequencies.
    • Commonly used for noisy signals so the desired signal components can be isolated and amplified

    Low-Pass Filter

    • Passband is for low frequencies, stopband for high frequencies.
    • Cutoff frequency: signal amplitude reduces by -3 dB (or 0.7).
    • RC filter: simple to implement but not very effective. The cutoff frequency is equal to 1/(2πRC).

    Successive Approximation A/D Converter

    • A practical converter that iteratively approximates the analog input using a D/A converter to see if it matches the analog input.

    Flash A/D Converter

    • Fastest type, does parallel comparison
    • Easily converted to binary output
    • Adding resolution increases the number of comparators, increasing the complexity and required time.
    • Multiplexing analog signals switches among different input signals, reducing system cost.

    Digital-to-Analog (D/A) Converter

    • The process reverses the analog-to-digital conversion, converting a digital value to an analog signal.
    • There are several methods like resistor ladder networks to perform D/A conversion, differing in approach and effectiveness.

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    Chapter 8 Annotated PDF - EE429 Mechatronics Fall 2024

    Description

    Test your understanding of data acquisition systems with this quiz. Cover essential concepts from measurement system architecture to the roles of different signal types and sampling theories. Perfect for students or professionals looking to assess their knowledge in this field.

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