Introduction to Communication System

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A communication system is for transmitting and receiving the information that users want to exchange. To make up a communication system, we can adopt the FDMA, TDMA, CDMA, and so on. In this presentation, we introduce a simplified communication blocks with which we can understand a modern system.

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Introduction to Communication System

  1. 1. Electronic Circuit Design CHO, Yong Heui Introduction to Communication System
  2. 2. 1. Communication Transmission  <ul><li>Information </li></ul><ul><ul><li>Channel bandwidth </li></ul></ul><ul><ul><li>Base band </li></ul></ul><ul><ul><li>Inefficient wave radiation </li></ul></ul><ul><li>Modulation – center frequency </li></ul>Time domain Frequency domain 출처 : RFDH.com
  3. 3. Why do we need modulation?  <ul><li>Transmission efficiency </li></ul><ul><ul><li>Multiplexing </li></ul></ul><ul><ul><li>Antenna length: wavelength </li></ul></ul><ul><ul><li>Wave radiation: comparison with DC </li></ul></ul>Battery: DC Antenna: AC 1. Communication
  4. 4. Communication transmitter (Tx)  <ul><li>Up-conversion: frequency </li></ul> 출처 : RFDH.com 1. Communication
  5. 5. Communication receiver (Rx)  <ul><li>Down-conversion: frequency </li></ul> 출처 : RFDH.com 1. Communication
  6. 6. Communication transceiver  <ul><li>Duplexer: bandpass filter or switch </li></ul><ul><ul><li>Loss, tx suppression, channel selection </li></ul></ul>IF: superheterodyne No IF: direct conversion 출처 : RFDH.com 1. Communication
  7. 7. FDMA (FDM Access)  <ul><li>Resource: frequency </li></ul><ul><li>Guard band </li></ul><ul><li>Simple transceiver </li></ul><ul><li>Interference </li></ul>1. Communication
  8. 8. TDMA (TDM Access)  <ul><li>Resource: time </li></ul><ul><li>Guard time </li></ul><ul><li>Complicated transceiver </li></ul>1. Communication
  9. 9. Synchronization of TDMA  <ul><li>Guard time: imperfect sync </li></ul>1. Communication
  10. 10. GSM TDMA  <ul><li>Global System for Mobile Communication </li></ul><ul><li>TDMA within FDMA </li></ul><ul><li>Carrier separation: 200 kHz </li></ul>1. Communication
  11. 11. FH(Frequency Hopping)-CDMA  <ul><li>Resource: code </li></ul><ul><li>Precise clock </li></ul><ul><li>Very complicated transceiver </li></ul><ul><li>Bluetooth, military applications </li></ul>1. Communication
  12. 12. DS(Direct Sequence)-CDMA QPSK: Quadrature Phase Shift Keying 1. Communication
  13. 13. Block diagram of cellular phone <ul><li>LNA (Low Noise Amplifier), PA (Power Amplifier), Mixer, VCO, switch </li></ul><ul><li>Filter, duplexer </li></ul> 2. System
  14. 14. Digital RF system Transmitter and receiver  2. System
  15. 15. AM receiver  <ul><li>Envelope detector </li></ul>Antenna + BPF + diode + capacitor + speaker 2. System
  16. 16. AM receiver with amplifier  2. System

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