Question

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

• A. 1.003 MHz and 6KHz
• B. 0.997 MHz and 6KHz
• C. 1.003 MHz and 3KHz
• D. 1.003 MHz and 2MHz

Hint:

In amplitude modulation, the upper sideband frequency is the carrier frequency plus the message signal frequency, and the bandwidth is twice the message signal frequency.

Answer 1

The Correct Option is A

Step 1: The upper side band frequency is given by the carrier frequency plus the message signal frequency: \[ f_{US} = f_{carrier} + f_{message} = 1 \, \text{MHz} + 3 \, \text{kHz} = 1.003 \, \text{MHz} \] Step 2: The bandwidth of the modulated signal is twice the frequency of the message signal: \[ B = 2 \times 3 \, \text{kHz} = 6 \, \text{kHz} \] Thus, the correct answer is option (1), 1.003 MHz and 6KHz.