Answer to Question #245971 in Electric Circuits for aeron vargas

Question

Three (3) AM broadcast stations are spaced at 18 kHz, beginning at 73 kHz. Each station is allowed to transmit modulating up to 6 kHz. Compute for the upper and lower sidebands of each station and plot it in the frequency domain.

Answer 1

Initial frequency f_i = 73 kHz

Final frequency f_f = (73 + 18) kHz = 91 kHz

Let Station 1, Station 2 and Station 3 be A, B and C respectively.

The f_USB of A = 73 kHz + f_m (6 kHz) = 79 kHz

The f_USB of B = 79 kHz + f_m (6 kHz) = 85 kHz

The f_USB of C = 85 kHz + f_m (6 kHz) = 91 kHz

Where: f_USB is the Frequency of the Upper Sidebands, while f_m is the modulating frequency at which each station is allowed to transmit.

Therefore, the frequency of the upper and lower sidebands of each station are given by:

1. For A, f_LSB = 73 kHz and f_USB = 79 kHz;
2. For B, f_LSB = 79 kHz and f_USB = 85 kHz;
3. For C, f_LSB = 85 kHz and f_USB = 91 kHz.

Note: f_LSB means Frequency of the Lower Sidebands.

The plot of the Station A, B and C (i.e. Station 1, Station 2 and Station 3) with their respective frequency domain is given in the diagram below: