Introduction to Communication System
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This document provides an introduction to communication systems, including why modulation is needed, the basic components of transmitters and receivers, and different multiplexing techniques. It discusses how modulation converts information to radio frequencies for transmission, and how receivers convert the signals back down for processing. It also outlines several multiple access techniques used in cellular systems, including FDMA, TDMA, and CDMA, and provides block diagrams of cellular phone components.
Introduction to Communication System
- 1. Electronic Circuit Design CHO, Yong Heui Introduction to Communication System
- 2. 1. Communication Transmission Information Channel bandwidth Base band Inefficient wave radiation Modulation – center frequency Time domain Frequency domain 출처 : RFDH.com
- 3. Why do we need modulation? Transmission efficiency Multiplexing Antenna length: wavelength Wave radiation: comparison with DC Battery: DC Antenna: AC 1. Communication
- 4. Communication transmitter (Tx) Up-conversion: frequency 출처 : RFDH.com 1. Communication
- 5. Communication receiver (Rx) Down-conversion: frequency 출처 : RFDH.com 1. Communication
- 6. Communication transceiver Duplexer: bandpass filter or switch Loss, tx suppression, channel selection IF: superheterodyne No IF: direct conversion 출처 : RFDH.com 1. Communication
- 7. FDMA (FDM Access) Resource: frequency Guard band Simple transceiver Interference 1. Communication
- 8. TDMA (TDM Access) Resource: time Guard time Complicated transceiver 1. Communication
- 9. Synchronization of TDMA Guard time: imperfect sync 1. Communication
- 10. GSM TDMA Global System for Mobile Communication TDMA within FDMA Carrier separation: 200 kHz 1. Communication
- 11. FH(Frequency Hopping)-CDMA Resource: code Precise clock Very complicated transceiver Bluetooth, military applications 1. Communication
- 12. DS(Direct Sequence)-CDMA QPSK: Quadrature Phase Shift Keying 1. Communication
- 13. Block diagram of cellular phone LNA (Low Noise Amplifier), PA (Power Amplifier), Mixer, VCO, switch Filter, duplexer 2. System
- 14. Digital RF system Transmitter and receiver 2. System
- 15. AM receiver Envelope detector Antenna + BPF + diode + capacitor + speaker 2. System
- 16. AM receiver with amplifier 2. System