Question 3-55G3

Human speech is highly dynamic, characterized by significant variations in amplitude, frequency, and duration. In a single-sideband (SSB) signal, the modulating voice directly translates its peaks (loudest sounds like vowels or plosives) and valleys (quieter sounds, pauses) into the signal envelope. Peak Envelope Power (PEP) is the maximum power reached by the signal envelope at any instant, corresponding to the loudest parts of the speech. Average power is the power averaged over a period, typically a speech syllable. Because speech is not a constant-amplitude signal, the dynamic range inherent in human voice—the difference between the loudest and quietest sounds—creates a substantial difference between PEP and average power. Therefore, the specific characteristics of the speech being transmitted (how loud, soft, continuous, or punctuated it is) dictate this ratio. * **A) The frequency of the modulating signal:** While frequency content is part of speech, the *dynamic variation* across frequencies and amplitudes, rather than a single frequency, determines the ratio. * **B) The degree of carrier suppression:** Carrier suppression is key to SSB efficiency but does not affect the inherent dynamic range of the modulating signal or its PEP-to-average ratio. * **D) The amplifier power:** Amplifier power sets the *absolute* PEP and average power levels, but not their *ratio*, which is determined by the input signal.