05-02-2013, 12:59 PM
Radio Receiver
Radio Receiver.ppt (Size: 369 KB / Downloads: 58)
Definition:
Radio receiver is an electronic equipment which pick ups the desired signal, reject the unwanted signal and demodulate the carrier signal to get back the original modulating signal.
Functions of radio receivers
Select desired signal and reject unwanted signal
Amplify the R.F. signal
Demodulate the selected signal
Classification of radio receivers
Radio receivers are classified according to the type of traffic they are designed to handle.
A.M. broadcast receivers
F.M. broadcast receivers
T.V. receivers
Radar receivers
Selectivity:-
Radio receiver should have good selectivity and selectivity of radio receiver is its ability to differentiate desired signal from unwanted signals.
Drawbacks of TRF Receiver
TRF receivers are simple to design and allow the broadcast frequency 535 KHz to 1640 KHz. But at the higher frequency, it produces difficulty in design.
It has poor audio quality.
Super Heterodyne Receiver
The shortcomings of the TRF receiver are overcome by the invention of the super heterodyne receiver.
A super heterodyne receiver converts all incoming radio frequency (RF) signals to a lower frequency known as an intermediate frequency (IF).
Image Frequency
Definition: In radio reception using heterodyning in the tuning process, an undesired input frequency that is capable of producing the same intermediate frequency (IF) that the desired input frequency produces.
It is given by signal frequency plus twice the intermediate frequency