In order to minimize the noise power a filter is introduced
In order to minimize the noise power that is presented to the demodulator of a receiver, a filter is introduced before the demodulator as shown below.
The last and the first stages in a superheterodyne receiver are respectively
The output signal to noise ratio depends upon .
Output signal to noise ratio (SNR) is more useful measure of noise performance.
SNR depends both on the type of modulation used at the transmitter and the type of demodulation used at the receiver.
Match List-I (Superheterodyne receiver characteristics) with List-II (Features/Cause) and select the correct answer using the codes given below the lists:
A. Double spotting
1. Ability to reproduce all the modulating frequencies equally.
2. Occurs due to inadequate image-frequency rejection.
3. Ability to rejected unwanted signal.
4. Ability to amplify weak signals.
Assertion (A): The figure of merit of a receiver is always more than unity.
Reason (R): The figure of merit must be as high as possible because higher value of figure of merit indicates better noise performance of the receiver.
Assertion is a false statement because figure of merit of a radio receiver can be less than, greater than or equal to 1 depending on the type of modulation.
The sensitivity of a superheterodyne receiver does not depend on
The sensitivity of a superheterodyne receive does not depend on the receiving frequency. The selectivity of a superheterodyne receive, depends on the receiving frequency. It become; somewhat worse when the receiving frequency is raised.
Consider the following statements:
1. The figure of merit of DSB-SC and SSB receivers with coherent detection is 1.
2. The figure of merit of an AM receiver with envelope detection is more than 1.
3. If the average modulated signal power and the average noise power in the message bandwidth is same as that of DSB-SCreceiver then the output SNR and figure of merit of SSB coherent receiver is same as that of the DSB SC receiver.
4. A square-law demodulator operates above threshold on a weaker signal than with an envelope demodulator.
Which of the above statements are correct?
Match List-I (Classification of radio receivers) with List-II (Applications) and select the correct answer using the codes given below the lists:
A. A.M. Broadcast receivers
B. F.M. Broadcast receivers
C. Communication receivers
D. Radar receivers
1. Operate in VHF or UHF bands.
2. Used to receive radio detection and ranging
3. Operate on long, medium and short wave bands.
4. Used for reception of telegraph and short wave telephone signals.
Which of the following is not an uncoded system?
DM (Delta modulated system) is a coded system.
The main function of a radio receiver is to
1. amplify the modulating frequency signal.
2. amplify the selected R.F. (radio frequency) signal.
3. select the desired signal and reject the unwanted signals.
4. intercept the incoming modulated signal by the receiving antenna.
5. detect the modulated signal to get back the original modulating or baseband signal.
Of these, the correct statements are: