Demodulation of single-sideband (SSB) signals Which one of the following circuits cannot demodulate an SSB signal into intelligible audio?

Introduction / Context:SSB signals have no carrier and just one sideband. Demodulation requires a locally generated carrier (or a product detector) to translate the SSB spectrum back to audio. FM detectors are designed for frequency variations, not for amplitude/phase-coherent detection needed by SSB.

Given Data / Assumptions:

• SSB reception requires carrier reinsertion or coherent detection.
• Receiver has access to a beat-frequency oscillator (BFO) or product detector.
• Phase discriminator is an FM detector type.

Concept / Approach:A product detector multiplies the incoming SSB with a locally generated sinusoid near the original carrier frequency to shift the spectrum to audio. An FM phase discriminator responds to instantaneous frequency/phase deviations and does not recover amplitude-encoded SSB audio.

Step-by-Step Solution:Identify detectors viable for SSB: product detector; mixer plus BFO; synchronous detectors.Recognize that an FM phase discriminator requires a frequency-modulated input to produce audio.Since SSB is not FM, a phase discriminator cannot demodulate it properly.

Verification / Alternative check:Communications receivers implement SSB modes via BFO/product detectors; FM detectors are disabled in SSB/AM modes, confirming the incompatibility.

Why Other Options Are Wrong:Product detector / BFO + mixer: Standard SSB demodulation methods.

Balanced modulator as synchronous detector: When driven by a reinserted carrier, it functions as a coherent detector.

Synchronous envelope detector: With a locked carrier, it will demodulate SSB/AM.

Common Pitfalls:Assuming any “detector” works for all modulation types; detectors are modulation-specific.

Final Answer:Phase discriminator (FM detector)