If the S/N of the input signal is 4 and the intelligence signal is 10 kHz, determine the deviation
A) 200 kHz
B) 100 kHz
C) 145 kHz
D) 160 kHz

Question

Quizplus · Accepted Answer

The deviation can be calculated using Carson's rule, which states that the total bandwidth (BT) of an FM signal is approximately BT = 2(Δf + fm), where Δf is the frequency deviation and fm is the maximum modulating frequency. Given that the S/N (signal-to-noise ratio) for FM is proportional to (Δf/fm)^2, and assuming a linear relationship for simplicity, a S/N of 4 implies that Δf/fm = 2 (since 2^2 = 4). Given fm = 10 kHz, solving for Δf gives Δf = 2 * fm = 2 * 10 kHz = 20 kHz. However, without direct information on bandwidth or a clear method to apply the given S/N ratio directly to find deviation in the options provided, and considering typical FM calculations, the answer provided might not directly follow from the given explanation. The correct calculation should involve understanding that the deviation ratio is directly related to the quality of the signal and its bandwidth, but the specific values provided do not directly lead to a clear answer without additional context or assuming specific conditions that are not provided in the question. Therefore, the selection of "C" as the correct answer is incorrect based on the explanation provided, and there seems to be a misunderstanding in the application of the given information to solve for frequency deviation. The correct approach to determine the deviation would involve more specific information or formulas directly relating S/N ratio to deviation, which is not clearly provided in the question or the explanation.

If the S/N of the Input Signal Is 4 and the Intelligence