1. TE4201-Communication Electronics 1 1. Introduction  Radio Frequency Radio FrequencyRadio Frequency  Modulation Modulation  Transmission Mode Transmission ModeTransmission Mode

2. TE4201-Communication Electronics 2 Frequency Spectrum 10 0 hertz (Hz), 10 3 kilohertz (kHz), 10 6 Megahertz (MHz), 10 9 Giga hertz (GHz),

3. TE4201-Communication Electronics 3 In the United States, freq. Assignments for free-space radio propagation are assigned by the Federal Communications Commission (FCC) 10 9 Giga hertz (GHz), 10 12 Tetrahertz (THz), 10 15 Petahertz (PHz), 10 18 Exahertz (EHz),

4. TE4201-Communication Electronics 4 Wavelength of Radio Frequency

5. TE4201-Communication Electronics 5 Modulation techniques

6. TE4201-Communication Electronics 6 Transmission can occur in only one direction or one way only either transmission or reception but not both at the same time. Example is radio or television broadcasting. Radio station transmits only and you receive only. Transmission Mode Transmission can occur in bothdirections but not both at the same time. It is two-way alternate. Example is citizens radio or police band radio or walkie-talkie or two-way radio system that use “ push-to-talk. Transmission can occur in bothdirections both at the same time. It is both-way simultaneous between two stations. Example is the standard telephone system. Transmission can occur in bothdirections both at the same time but between more than two stations. One station can transmit to a second station and receive from a third station at the same time. Example is the data communications circuits, postal service in US. 3. Full Duplex (FDX) 3. Full/Full Duplex (F/FDX) 2. Half Duplex (HDX) 1. Simplex (SX)