Signal processingLesson 1 of 1 in the course Sampling

Sampling: Nyquist Limits, ADC Errors, and Multidimensional Methods

5 flashcards · 5 quiz questions · 5 match pairs · 2 fill-in sentences · English

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Summary

A continuous-time signal is defined at every point in time. For example, a microphone converts changing air pressure into a continuously varying electrical signal. A sample is the value of that signal at a particular point in time (or, for spatial signals, at a particular location).

A sampler is a system or operation that extracts these values. An ideal sampler would measure the signal's instantaneous value at precisely specified times. Real devices approximate this ideal.

All flashcards

What does an ideal sampler produce from a continuous-time signal?
A sequence of signal values measured at specified instants, such as s(nT)s(nT).
What is impulse sampling?
A model in which each sample weights an impulse at its sampling time.
What conditions support ideal reconstruction by interpolation?
The signal must be suitably band-limited and sampled at an adequate rate.
What is quantization error in an ADC?
The error introduced when continuous input values are mapped to a finite set of digital levels.
What is bandpass undersampling?
Sampling a known band-limited signal below the ordinary Nyquist rate when its aliases do not overlap.

Quiz questions

  1. How does aperture error differ from jitter in a practical sampler?Answer: Aperture error involves measurement over a short time region; jitter is variation in sample timing.
  2. When can bandpass undersampling recover a signal whose band lies above zero frequency?Answer: When the signal band is known and its sampled aliases do not overlap.
  3. For a suitably band-limited real signal with highest frequency BB, what complex sampling rate can an appropriate I/Q representation use?Answer: BB complex samples per second.
  4. What can oversampling do in a suitable converter system?Answer: Ease some filter requirements and move certain effects outside the useful band.
  5. What does bit depth describe in digital audio?Answer: The number of bits used to represent each sample's amplitude.

Based on the Wikipedia article Sampling (signal processing), licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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