Question T8A08
From subelement T8 - T8A
What is the approximate bandwidth of a typical single sideband (SSB) voice signal?
Why is this correct?
The correct answer is B (3 kHz). SSB voice signals have an approximate bandwidth of 3 kHz because they transmit only one sideband containing the voice information, eliminating the carrier and redundant sideband. This makes SSB much more spectrum-efficient than other voice modes. Option A (1 kHz) is too narrow for voice communications, while C (6 kHz) represents AM bandwidth with both sidebands, and D (15 kHz) is typical FM repeater bandwidth.
Memory tip
Remember the bandwidth hierarchy: CW narrowest (~150 Hz), then SSB voice (~3 kHz), then FM voice (~10-15 kHz). Each mode trades bandwidth for different advantages—SSB maximizes power efficiency and spectrum usage for weak-signal work.
Learn more
SSB's 3 kHz bandwidth reflects its efficient design for weak-signal communications. By transmitting only essential voice information in a single sideband, SSB enables long-distance contacts with minimal power and spectrum usage. This narrow emission standard makes SSB ideal for crowded HF bands and VHF/UHF weak-signal work, where frequency privileges must accommodate many operators in limited spectrum allocations.
Think about it
Why do you think SSB uses only 3 kHz when human speech contains frequencies well beyond this range, and how does this limitation affect voice quality compared to FM?