Read the statements : i. DSB has two side bands and SSB has one Which statements are correct ?
ii. DSB has carrier and two side bands and SSB has a carrier and a side band
iii. DSB has carrier and two side bands and SSB without carrier and two different side bands.
i, ii
Statement iii contradicts itself — it says SSB has "two different side bands", which is precisely what single sideband does not have — so it must be excluded, and the answer is i and ii, option 1.
| Scheme | Carrier | Sidebands | Bandwidth |
|---|---|---|---|
| AM (DSB-FC) | Present | Two | 2fm |
| DSB-SC | Suppressed | Two | 2fm |
| SSB | Usually suppressed | One | fm |
Statement i is unambiguously true and is the definition the names carry: double sideband against single sideband. It says nothing about the carrier, so it is correct whichever variant is meant.
Statement ii is true of the particular variants it describes. "DSB with carrier" is ordinary AM. "SSB with a carrier and a sideband" is not the most common form — SSB is usually transmitted suppressed-carrier, which is where its power saving comes from — but SSB with a full or reduced pilot carrier is a real and standardised mode, used precisely because the receiver needs a reference to reinsert the carrier coherently. So the statement describes existing schemes correctly.
Statement iii fails on its own terms. Whatever is meant by the first half, the second half says SSB has "two different side bands", which is a contradiction of the name and of the fact. If the intent was to describe independent sideband transmission — where two separate messages occupy the upper and lower sidebands — then that is ISB, not SSB.
Why the distinction matters practically. Suppressing the carrier saves the two-thirds of transmitted power that AM spends on a component carrying no information, and dropping one sideband halves the bandwidth and removes the redundancy, since the two sidebands carry identical information. The price is a receiver that must regenerate the carrier with sufficient frequency and phase accuracy, since an error of even a few tens of hertz makes speech unintelligible — which is exactly why the pilot-carrier variant of statement ii exists.
The answer is flagged because statement ii describes non-standard variants; but statement iii is self-contradictory, and no option offers statement i alone.
Hence, statements i and ii are correct.
Similar Questions
Assertion (A) : In amplitude modulation technique the modulation index should be close to 1.
Reason (R) : The power carried by message signal in the side bands increases with increase in modulation index.
Assertion (A) : Amplitude modulation is wastage of power.
Reason (R) : Amplitude modulation is wastage of bandwidth.
The peak carrier voltage is 150 V. If the resistor is 200 Ω and the modulation index is 0.5, the total power in the AM signal is :
The modulation index of an AM wave is given by :
Consider an AM (amplitude modulated) signal
\(s(t) = 20\left[1 + 0.9\cos 2\pi \times 10^4 t\right]\cos 2\pi \times 10^6 t\)
The power efficiency (η) in the AM signal is
In amplitude modulation:
A. Amplitude of carrier is varied by modulating signal
B. Modulation index is between 0 and 1
C. Bandwidth is infinite
D. Bandwidth is twice of minimum modulating frequency.
Choose the correct answer from the options given below:
Match List I with List II
LIST I LIST II A. Power of AM Wave I. \(P_c\left(\frac{m^{2}}{4}\right)\) B. Power of VSB II. \(\frac{m^{2}}{4}P_c+F\left(\frac{m^{2}}{4}P_c\right)\) C. Power of SSB III. \(\frac{m^{2}}{4}\left(\frac{V_c^{2}}{2R}\right)+\frac{m^{2}}{4}\left(\frac{V_c^{2}}{2R}\right)\) D. Power of DSBSC IV. \(\frac{V_{carr}^{2}}{R}+\frac{V_{LSB}^{2}}{R}+\frac{V_{USB}^{2}}{R}\) Choose the correct answer from the options given below:
If 1 MHz carrier is amplitude modulated with a 5 kHz audio signal, the Upper Side Band (USB) and Lower Side Band (LSB) frequencies are ________ respectively.
Which of the following is associated with single balanced modulator circuit :
Important Questions from Amplitude Modulation
The highest modulation frequency typically used in AM broadcast is
Which of the following is NOT the advantage of amplitude modulation?
Bandwidth requirement for Amplitude modulated wave is:
The frequency range of AM radio is:
In an amplitude modulated system, a sinusoidal carrier signal of 1 MHz is modulated by a 10 kHz sinusoidal signal. If the lower sideband and the carrier are suppressed and if the amplitude modulated signal is sampled for further processing, what should be the minimum sampling frequency for baseband sampling?
