In a direct digital synthesizer, what are the unwanted components on its output?

Get ready for the FCC General Radiotelephone Operator License (GROL) exam. Study with flashcards and multiple choice questions, each with hints and detailed explanations. Prepare effectively for your licensing test!

Multiple Choice

In a direct digital synthesizer, what are the unwanted components on its output?

A direct digital synthesizer generates an output by digitally producing a waveform and then converting it to analog. Because this process happens in discrete time and with a finite-resolution DAC, the spectrum of the output contains energy not only at the intended tone but also at specific, fixed frequencies. These unwanted components are called spurs and they appear at discrete frequencies in the spectrum, closely tied to the clock and the digital synthesis process. This is why they’re the correct description: spurs are the predictable, discrete-frequency artifacts you get from the periodic, digitally generated signal as it’s converted to analog, rather than broad broadband noise or random conversion noise. Reconstruction filtering and higher DAC resolution can help reduce their amplitude.

A direct digital synthesizer generates an output by digitally producing a waveform and then converting it to analog. Because this process happens in discrete time and with a finite-resolution DAC, the spectrum of the output contains energy not only at the intended tone but also at specific, fixed frequencies. These unwanted components are called spurs and they appear at discrete frequencies in the spectrum, closely tied to the clock and the digital synthesis process.

This is why they’re the correct description: spurs are the predictable, discrete-frequency artifacts you get from the periodic, digitally generated signal as it’s converted to analog, rather than broad broadband noise or random conversion noise. Reconstruction filtering and higher DAC resolution can help reduce their amplitude.

More practice questions