Advantages of an RF amplifier & Costas receiver

The advantages of using an RF amplifier are

Options:

a) Better sensitivity
b) Improved signal to noise ratio
c) Better selectivity
d) All of the above

Correct Answer: d) All of the above

Explanation:

The RF amplifiers are used in super heterodyne receivers. The advantages of using RF receivers are
- They have better sensitivity i.e. they have improved gain to the signal
- They have better signal to noise ration than other amplifiers
- The selectivity is better as they have better rejection to the adjacent undesired signals.

The costas receiver is used for

Options:

a) FM signal
b) DSB-SC signal
c) PCM signal
d) DM signal

Correct Answer: b) DSB-SC signal

Explanation:

Costas receiver is a synchronous receiver system used for demodulating DSB-SC waves. The incoming modulated carrier is applied at two inputs of the coherent detectors of the receiver. The locally generated carrier applied to the two inputs is however in phase quadrature with each other. The frequencies of the local carriers are adjusted as same as the carrier frequency of the received signal.