Question

AM broadcast station transmits modulating frequency upto 6KHz. If transmitting frequency is 810KHz, then maximum and lower sidebands are ________

(a) 816KHz and 804KHz

(b) 826KHz and 804KHz

(c) 916KHz and 904KHz

(d) 822KHz and 816KHz

The question was posed to me in a job interview.

The above asked question is from Single Tone Modulation topic in portion Amplitude Modulation of Analog Communications

Answer 1

Right answer is (a) 816KHz and 804KHz

Easy explanation: Maximum frequency = 810 + 6 = 816KHz and Minimum frequency = 810 – 6 = 804KHz. Moreover it has a bandwidth of (816 – 804) = 12KHz.

( Formula:  Fmax = fc + fm,

  Fmin = fc-fm,

  Bandwidth = 2*fm = Fmax = Fmin,

fc = Carrier frequency, fm = message signal frequency).