2. INTRODUCTION TO ANALOG COMMUNICATION (Chapter 1) elctronicsa2z.com

3. Elements of a Communication System  Communication involves the transfer of information or intelligence from a source to a recipient via a channel or medium.  Basic block diagram of a communication system: SourceTransmitterReceiverRecipient elctronicsa2z.com

4. Brief Description  Source: analog or digital  Transmitter: transducer, amplifier, modulator, oscillator, power amp., antenna  Channel: e.g. cable, optical fiber, free space  Receiver: antenna, amplifier, demodulator, oscillator, power amplifier, transducer  Recipient: e.g. person, speaker, computer elctronicsa2z.com

5. Frequency Bands BAND Hz  ELF30 - 300  AF300 - 3 k  VLF3 k - 30 k  LF30 k - 300 k  MF300 k - 3 M  HF3 M - 30 M BAND Hz  VHF30M-300M  UHF300M - 3 G  SHF3 G - 30 G  EHF30 G - 300G Wavelength, = c/f elctronicsa2z.com

6. Information and Bandwidth  Bandwidth required by a modulated signal depends on the baseband frequency range (or data rate) and the modulation scheme.  Hartley’s Law: I = k t B where I = amount of information; k = system constant; t = time available; B = channel bandwidth  Shannon’s Formula: I = B log 2 (1+ S/N) in bps where S/N = signal-to-noise power ratio elctronicsa2z.com

7. Transmission Modes  Simplex (SX) – one direction only, e.g. TV  Half Duplex (HDX) – both directions but not at the same time, e.g. CB radio  Full Duplex (FDX) – transmit and receive simultaneously between two stations, e.g. standard telephone system  Full/Full Duplex (F/FDX) - transmit and receive simultaneously but not necessarily just between two stations, e.g. data communications circuits elctronicsa2z.com

8. Time and Frequency Domains  Time domain: an oscilloscope displays the amplitude versus time  Frequency domain: a spectrum analyzer displays the amplitude or power versus frequency  Frequency-domain display provides information on bandwidth and harmonic components of a signal elctronicsa2z.com

10. Non-sinusoidal Waveform  Any well-behaved periodic waveform can be represented as a series of sine and/or cosine waves plus (sometimes) a dc offset: e(t)=C o +  A n cos  n  t  B n sin n  t (Fourier series)