A message signal of 3 kHz is used to modulate a carrier signal frequency 1 MHz using amplitude modulation.…

A message signal of 3 kHz is used to modulate a carrier signal frequency 1 MHz using amplitude modulation. The upper side band frequency and band width respectively are
  1. 1.003 MHz and 6 KHz
  2. 0.997 MHz and 6 KHz
  3. 1.003 MHz and 3 KHz
  4. 1.003 MHz and 2 MHz

Solution

For amplitude modulation, $\begin{aligned} & \mathrm{f}_{\mathrm{m}}=3 \mathrm{kHz}, \mathrm{f}_{\mathrm{c}}=1000 \mathrm{kHz} \\ & \therefore \text { Upper side frequency, } \mathrm{f}_{\mathrm{u}}=\mathrm{f}_{\mathrm{c}}+\mathrm{f}_{\mathrm{m}} \\ & =1000+3=1003 \mathrm{KHz} \\ & =1.003 \mathrm{MHz} \\ & \therefore \quad \text { Band width }=\mathrm{f}_{\mathrm{u}}-\mathrm{f}_{\mathrm{l}}=\left(\mathrm{f}_{\mathrm{c}}+\mathrm{f}_{\mathrm{m}}\right)-\left(\mathrm{f}_{\mathrm{c}}-\mathrm{f}_{\mathrm{m}}\right) \\ & =2 \mathrm{f}_{\mathrm{m}}=2 \times 3=6 \mathrm{kHz}\end{aligned}$

Asked in: AP EAMCET 2024 (19 May Shift 2)

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