- 2076 Asoj · 4 marks
Analog and digital communication systems
Short answer
Analog system directly modulates a carrier (AM/FM) with a continuous signal; simple but noise adds. Digital system samples, digitizes, source and channel codes, then modulates (e.g., PSK); regeneration prevents noise, errors can be corrected, and encryption is possible, but wider bandwidth and synchronisation are needed.
Discuss analog communication system and digital communication system with an appropriate block diagram.
Analog communication system
Information is a continuous signal (voice, video) that modulates a carrier continuously (AM, FM, PM).
Source -> Transducer -> Modulator -> Transmitter -> Channel (+ noise)
Destination <- Transducer <- Demodulator <- Receiver <-----+
- Noise adds to the signal and cannot be removed; quality degrades with distance.
- Simple equipment, less bandwidth.
- Examples: AM/FM radio, analog TV, old telephone.
Digital communication system
Information is converted to bits, coded and sent as discrete symbols.
Source -> Sampler/ADC -> Source encoder -> Channel encoder
-> Modulator (ASK/FSK/PSK) -> Channel (+ noise)
Destination <- DAC <- Source decoder <- Channel decoder <- Demodulator
- Blocks: source encoding (compression, PCM), channel coding (error detection/correction), modulation, channel, and the reverse at the receiver.
- Signals can be regenerated by repeaters so noise does not accumulate; errors can be corrected; easy encryption, multiplexing (TDM), and processing.
- Needs more bandwidth and synchronisation; complex equipment.
- Examples: mobile phones, Ethernet, digital TV, Bluetooth.
| Point | Analog | Digital |
|---|---|---|
| Signal | Continuous | Discrete bits |
| Noise immunity | Poor | Good, with error control |
| Bandwidth | Less | More |
| Security and processing | Low | High |
✓ Answer checked by Claude Sonnet 5.5
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