Electronics and Communication Engineering - Communication Systems - Discussion
Discussion Forum : Communication Systems - Section 1 (Q.No. 30)
30.
A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. Which of the following frequency is least likely to be present in the output?
Answer: Option
Explanation:
Frequency present in the sidebands is equal to = fc ± fm, fc ± 2fm , fc ± 3fm .
Discussion:
15 comments Page 2 of 2.
Nikhitha said:
9 years ago
fc+fm, fc, fc-fm are frequency components then in maximum cases we find 1000 in qusetion they are not specifying the type of modulation technique.
Gaurav kumar said:
1 decade ago
In amplitude modulation, simple case i.e. no ssb, no dsb or vsb carrier frequency is also present in the output. So according to me 1000 Khz should also be there.
Arnab Bhattacharya said:
1 decade ago
This is a case of amplitude modulation with multi-tone frequencies. Here the multi-tones are 300 Hz (0.3 KHz), 800 Hz (0.8 KHz) and 2 KHz.
Now the spectrum would consist the following bands (1000+-0.3) = 1000.3/999.7, (1000+-0.8) = 1000.8/999.2 and (1000+-2) = 1002/998.
Now from the options provided, only 1000 KHz is left out. So the correct answer is B 1000 KHz.
Now the spectrum would consist the following bands (1000+-0.3) = 1000.3/999.7, (1000+-0.8) = 1000.8/999.2 and (1000+-2) = 1002/998.
Now from the options provided, only 1000 KHz is left out. So the correct answer is B 1000 KHz.
(1)
Sujith k said:
1 decade ago
Least likely means with less probability.
Manish said:
1 decade ago
I think it should be 998 khz.
Because we want to find least frequency it is given by Fc-Fm.
1000-2 = 998 khz.
Because we want to find least frequency it is given by Fc-Fm.
1000-2 = 998 khz.
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