Summary

This blog by Rick Lyons explains why inserting zeros into a time sequence (zero stuffing) to increase sample rate produces multiple replicated spectra in the frequency domain. Readers will learn the underlying DTFT/DFT reasoning for spectral imaging and how proper interpolation filtering removes the unwanted image bands.

Key Takeaways

• Explain why time-domain zero stuffing produces replicated spectral images via DTFT/DFT periodicity and sampling-rate change
• Demonstrate how the upsampling factor determines the number and spacing of spectral images in the frequency domain
• Show how lowpass interpolation (anti-imaging) filters suppress the unwanted images and restore a single-band spectrum
• Apply FFT analysis and filtering considerations when designing interpolation stages for audio, radar, or communications signals

Who Should Read This

DSP engineers, signal-processing students, and system designers working on multirate systems, interpolation, or FFT-based spectral analysis who need a practical explanation of zero-insertion imaging and how to mitigate it.

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