Extra exam question E7H10
Subelement E7, PRACTICAL CIRCUITS· Group E7H
What information is contained in the lookup table of a direct digital synthesizer (DDS)?
- A.The phase relationship between a reference oscillator and the output waveform
- B.Amplitude values that represent the desired waveform (correct answer)
- C.The phase relationship between a voltage-controlled oscillator and the output waveform
- D.Frequently used receiver and transmitter frequencies
WhyA direct digital synthesizer's lookup table contains amplitude values that represent the desired waveform. A direct digital synthesizer's lookup table stores amplitude values that represent the shape of the desired output waveform (typically one cycle of a sine wave), which the phase accumulator steps through to reconstruct that waveform in digital form, answer B. It doesn't store phase relationships to a reference or VCO, and it isn't a table of frequently used operating frequencies, those aren't what a DDS lookup table actually contains.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.