1. Transmitters and Receivers
Chapter4
Transmitters and Receivers
Generalized Transmitters
AM PM Generation
Inphase and Quadrature Generation
Superheterodyne Receiver
Frequency Division Multiplexing
Huseyin Bilgekul
Eeng360 Communication Systems I
Department of Electrical and Electronic Engineering
Eastern Mediterranean University

2. Generalized Transmitters
Modulating signal
Modulated signal
Transmitter
Any type of modulated signal can be represented by
The complex envelope g(t) is a function of the modulating signal m(t)
Example:

3. Generalized Transmitters
Two canonical forms for the generalized transmitter:
1. AM- PM Generation Technique: Envelope and phase functions are generated to modulate the carrier as
R(t) and θ(t) are functions of the modulating signal m(t) as given in TABLE 4.1

4. Generalized Transmitters
2. Quadrature Generation Technique: Inphase and quadrature signals are generated to modulate the carrier as
x(t) and y(t) are functions of the modulating signal m(t) as given in TABLE 4.1

5. Generalized Receivers
Two types of receivers:
Tuned Radio Frequency (TRF) Receiver:
Composed of RF amplifiers and detectors.
No frequency conversion
It is not often used.
Difficult to design tunable RF stages.
Difficult to obtain high gain RF amplifiers
Receivers
Superheterodyne Receiver:
Downconvert RF signal to lower IF frequency
Main amplifixcation takes place at IF

6. Superheterodyne Receivers
Superheterodyne Receiver Diagram

7. Superheterodyne Receiver

8. Superheterodyne Receivers
The RF and IF frequency responses H1(f) and H2(f) are important in providing the required reception characteristics.

9. Superheterodyne Receivers
RF Response
fIF
IF Response

10. Superheterodyne Receiver Frequencies

11. Superheterodyne Receiver Frequencies