electronic communication system unit one
- 2. Elements of an Electronic Communication System An electronic communication system is a set of electronic devices that work together to send information from one place to another.
- 3. Information Source 1. The information source in a communication system is where the message or data originates. It can be a person speaking, a computer sending files, a camera capturing images, or any device or medium that generates the content to be communicated. 2. Transducer The transducer is a device that converts one form of energy into another. In communication systems, it converts physical signals (like sound or images) into electrical signals for transmission. For example, a microphone (transducer) converts your voice (sound waves) into an electrical signal.
- 4. 3. Transmitter It converts the electrical message signal into a form suitable for transmission on the physical medium or channel. It might amplify the signal, modulate it onto a carrier wave (for wireless communication), or otherwise process it to make it suitable for sending over the channel. 4. Channel and Noise The channel is the physical medium through which the message travels from the sender to the receiver. It could be a physical wire (like a coaxial cable), fiber optics, or wireless (like radio waves through the air). Noise is any unwanted random signal that interferes with the transmission and reception of the message signal.
- 5. 5. Receiver It reproduces the message in electrical form from the distorted received signal. 4. Output transducer It converts the received electrical message signal back to its original form. For example, a speaker (output transducer) converts the electrical signals back into sound waves that you can hear.
- 7. Channel
- 8. Classification of Channels/ Transmission Medium
- 9. Guided Medium: Guided media involves a physical path that guides the signal between the transmitter and receiver. The signal is confined within cables or wires. Unguided Medium: Unguided media, also known as wireless media, does not use a physical conductor. Instead, they transmit signals through the air or vacuum, using electromagnetic waves.
- 10. Types of Guided Media / Cable
- 11. Twisted Pair cable Consists of two insulated conductors twisted together to form a spiral. The twisted reduces crosstalk. It can be shielded (STP) or unshielded (UTP). Commonly used in telephone lines and ethernet cables.
- 13. Co-axial cable Consists of the inner conductor and the outer conductor separated by insulating material. The inner conductor is used to transmit the signal while the outer conductor acts as ground and also as a shield against noise. Compared to the twisted pair cable, it offers better noise immunity and better data rates. Costlier than twisted pair but cheaper than optic fibres.
- 15. Optical Fibre cable It consists of an inner glass core surrounded by a glass cladding which has a lower refractive index.
- 17. messages are sent as light signals. Light is shown in at one end of the fiber via a laser or LED. Light hits the boundary between the fiber and the cladding at an angle greater than the critical angle. This ensures that light travels down the cable via total internal reflection.
- 20. Unguided Media
- 23. Classification of Electronic Communication Systems Also called broadband transmission
- 27. Modulation and Demodulation Modulation is the process whereby the transmitter modifies the characteristic of the carrier signal in accordance of the message signal. In the modulation process there are two signals used: the modulating signal or the message signal and the carrier signal Some parameter (amplitude, frequency of phase) of the carrier is modulated in accordance to the modulating / baseband signal. The modulated signal is then transmitted over the medium. The receiver demodulates the original message from the degraded received signal.
- 28. Modulation and Demodulation Modulation is the process whereby the transmitter modifies or changes some characteristic of the carrier signal in accordance with the message signal. The source information is impressed upon a carrier- wave by changing or modifying some characteristic of the carrier wave. .
- 29. Modulation and Demodulation The message signal is called baseband signal and the modulated signal is called the bandpass signal. The modulated signal (bandpass signal) is then transmitted over the medium. The receiver demodulates the original message from the degraded received signal.
- 31. The Need For Modulation
- 37. Analog Modulation Digital Modulation
- 41. Phase Modulation
- 45. Multiplexing Multiplexing is the name given to techniques, which allow more than one message signal to be transferred via the same communication channel at the same time (simultaneously). A channel will offer a specified bandwidth, which is available for a time t. Thus, with reference to the channel there are 2 ‘degrees of freedom’, i.e. bandwidth or frequency and time. .
- 46. A device called a multiplexer (often shortened to "mux") combines the input signals into one signal. When the multiplexed signal needs to be separated into its component signals, a device called a demultiplexer (or "demux") is used.
- 52. Limitations of a Communication System