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Questions and Answers
What type of signal uses a continuous range of values to represent information?
What type of signal uses a continuous range of values to represent information?
Which of the following is an example of a digital signal?
Which of the following is an example of a digital signal?
Which technique does Arduino use to generate analogue signals?
Which technique does Arduino use to generate analogue signals?
What is meant by digitalizing a signal?
What is meant by digitalizing a signal?
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What defines the width of the pulse in pulse width modulation?
What defines the width of the pulse in pulse width modulation?
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Which type of signals are most suitable for audio and video transmission?
Which type of signals are most suitable for audio and video transmission?
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What happens to the appearance of an analogue signal when the changes in pulse width are fast enough?
What happens to the appearance of an analogue signal when the changes in pulse width are fast enough?
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Which of the following best describes digital signals?
Which of the following best describes digital signals?
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What does the time period (T) of a signal represent?
What does the time period (T) of a signal represent?
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How is frequency (f) related to the time period (T) of a signal?
How is frequency (f) related to the time period (T) of a signal?
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What does the duty cycle (D) of a signal measure?
What does the duty cycle (D) of a signal measure?
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Which value corresponds to a 100% duty cycle in PWM?
Which value corresponds to a 100% duty cycle in PWM?
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What Arduino function is used to generate a PWM signal?
What Arduino function is used to generate a PWM signal?
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To determine the PWM value for a desired duty cycle of 75%, what would be the correct formula to use?
To determine the PWM value for a desired duty cycle of 75%, what would be the correct formula to use?
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How does manipulating the PWM signal affect an LED's brightness?
How does manipulating the PWM signal affect an LED's brightness?
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When using the function analogWrite(pin#, 127), what percentage of the duty cycle is being set?
When using the function analogWrite(pin#, 127), what percentage of the duty cycle is being set?
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Study Notes
Signal Types
- Analogue signals are continuous signals with infinite possibilities, while digital signals represent information using a pattern of bits (0s and 1s).
- Analogue signals are depicted by sine waves, whereas digital signals are represented by square waves.
Characteristics Comparison
- Analogue signals utilize a continuous range of values, making them suitable for audio and video transmission.
- Digital signals employ discrete data, making them ideal for computing and digital electronics.
Examples of Signals
- Examples of analogue signals include the human voice, natural sounds, FM radio signals, and analogue devices like temperature sensors and photocells.
- Digital signals can be found in computers, optical drives (CDs and DVDs), and electronic components like pushbuttons and LEDs.
Arduino and Signal Processing
- Arduino can process digital signals but requires digitalization to read analogue signals.
- Digitalization involves representing infinite values with finite numbers.
Analogue Output with Arduino
- Arduino generates analogue signals using Pulse Width Modulation (PWM), which uses digital pulses to create an analogue effect.
- The width of the pulse is defined by its 'on' time, and modifications to the pulse width create a perception of an analogue signal.
Duty Cycle and Frequency
- The duty cycle (D) represents the ratio of 'on time' to the time period (T), with values ranging from 0% to 100%.
- Frequency (f) is the number of complete cycles per second, measured in hertz (Hz) and is inversely related to the time period (f=1/T).
PWM Signal Generation
- The PWM signal can simulate voltages between 0V (off) and 5V (on) by adjusting the duty cycle.
- In Arduino, duty cycle values are scaled from 0 to 255, where 255 represents 100% duty cycle.
- The function
analogWrite(pin#, Value)is used for generating PWM signals, wherepin#is a designated pin on the Arduino.
Calculating PWM Values
- To derive the PWM value for a specific duty cycle:
PWM Value = (desired duty cycle * 255) / 100 - Example: For 50% duty cycle, calculate
PWM Value = (50 × 255)/100resulting in approximately 127 (rounded).
Controlling LED Brightness
- LEDs can be controlled with both
digitalWriteandanalogWritefunctions. - The digital function sets LEDs to either fully on or off, while the analogue function allows for varying brightness levels.
- To set an LED to half brightness, use
analogWrite(pin#, 127).
Practical Application
- Students will write code to manipulate the voltage across an LED to control its brightness directly from Arduino, applying concepts learned about PWM and duty cycles.
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Description
This quiz explores the key differences between analogue and digital signals, focusing on their characteristics and applications. Students will also learn how to read and generate these signals using a microcontroller-based board. Get ready to enhance your understanding of signal processing!
