Chapter 2 – Basic concepts of Data and Signals Flashcards
Analog signal
• Varies over a continuous range with respect to:
- Sound
- Light
- Radio waves
• Measured in Volts
• Frequency:
- Measured in Hertz (Hz)
• Example:
- Human voice
• Shortcomings of analog data and analog signals:
- Difficult to separate noise from the original wave form
Digital signal
• Has discrete set of values
• Sequence of voltage:
- Represented in binary form
• Examples:
- Computer
- Computer-related equipment
• Easy to separate the original wave form from the noise
• Modulation:
- Digital signal is converted to analog form
• Demodulation:
- Analog signal is converted to digital form
• Device (Modulation & Demodulation):
- Modem
Noise
• Unwanted electrical/electromagnetic energy - Degrades the quality of: ~ Signals ~ Data • Buzzing sound
Noise caused by what?
- Electrical motor
- High voltage line
- Lightning
Transmitting analog data using analog signals
• Analog waveform:
- Transformed to another analog wave form
~ Performed under modulation
• Modulation:
- Process of sending data over a single by either:
~ Amplitude
~ Frequency
~ Phase
• Examples:
- Telephones, FM radio, broadcast TV, cable television
Transmitting digital data with digital signals
• 1s and 0s of digital data: - Converted to the proper physical form ~ Transmitted over a wire or airwave • Digital encoding schemes: - Non return to Zero Digital - Manchester digital ~ Used to convert the 0s of 1s of digital data into the appropriate transmission form
Transmitting digital data with analog signals
• Modem:
- Modules digital data onto an analog signal
- Demodulates the analog data back to digital data
• Modulation technique:
- Converts digital data to an analog signal
• Example:
- Telephone system
Transmitting analog data with digital signals
• Transmit analog data over a digital medium • Digitization: - Convert analog data to digital signal - Example: ~ Recording a CD • Encoding techniques: - Code modulation - Delta modulation
Modem
Convert digital data to an analog data and back again
Modulation & Demodulation
- A communication media
- Data is converted to a signal by a computer device (modem)
- Then transmitted over a communication media
Bandwidth
• Measurement of the network media’s ability to carry data
• Example:
- Network cable
~ Amount of digital signal the cable can carry based on the given time
• Measured in:
- Bits per second (bps)
Analog transmission
• Can support several different frequencies at once
- Many different analogs signals/frequencies representing data can be transmitted at once
Digital transmission
- Supports only one
* Uses the entire bandwidth (in a cable)
Baseband
• Method of transmitting data in:
- A form of digital signal
~ Using the entire bandwidth of a cable
Broadband
• Handles very large volumes of data
• Method of transmitting data in:
- Form of several analog signals at the same time
• Carries more than one frequency at a time