# E7H10 - What information is contained in the lookup table of a direct digital synthesizer (DDS)? **URL:** \ **Category:** Extra Questions\ **Created:** [January 2, 2026, 7:54pm UTC](https://forum.openhamprep.com/t/e7h10-what-information-is-contained-in-the-lookup-table-of-a-direct-digital-synthesizer-dds/1432 "2026-01-02T19:54:18Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![system](https://forum.openhamprep.com/uploads/default/original/1X/a8bc13ef992b522befd6b1d923d2f2a53605a9c7.png) [@system](https://forum.openhamprep.com/u/system)\ **Post date:** [January 2, 2026, 7:54pm UTC](https://forum.openhamprep.com/t/e7h10-what-information-is-contained-in-the-lookup-table-of-a-direct-digital-synthesizer-dds/1432/1 "2026-01-02T19:54:18Z")
## Question What information is contained in the lookup table of a direct digital synthesizer (DDS)? ## Answer Options - **A)** The phase relationship between a reference oscillator and the output waveform - **B)** Amplitude values that represent the desired waveform - **C)** The phase relationship between a voltage-controlled oscillator and the output waveform - **D)** Frequently used receiver and transmitter frequencies **Correct Answer: B** * * * ## Explanation A Direct Digital Synthesizer (DDS) generates a continuous analog waveform (usually a sine wave) entirely from digital data. To do this, the circuit requires a precise map of what the waveform should look like over one complete cycle. The **lookup table** in a DDS contains pre-calculated digital **amplitude values that represent the desired waveform** (typically a sine wave). The DDS phase accumulator cycles through these values, feeding them sequentially to the digital-to-analog converter (DAC), which then reconstructs the smooth analog output signal at the programmed frequency. * * * _This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!_