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E8A03

SIGNALS AND EMISSIONS · Fourier analysis; RMS measurements; average RF power and peak envelope power (PEP); analog/digital conversion

E8A03E8A →

Which of the following describes a signal in the time domain?

  1. APower at intervals of phase
  2. BAmplitude at different times
  3. CFrequency at different times
  4. DDiscrete impulses in time order
Why The time domain view plots how a signal's instantaneous amplitude (voltage or current) varies as time advances, which is exactly what an oscilloscope shows with time on the horizontal axis and amplitude on the vertical axis. Fourier analysis is the mathematical bridge that converts that amplitude-versus-time record into the frequency domain, where amplitude is plotted against frequency instead, as a spectrum analyzer does.
Watch out Plotting frequency against time describes a spectrogram or waterfall display, not the basic time domain representation; a series of discrete impulses is just one particular waveform, not a general definition of the domain.
Time domain = scope: amplitude vs time. Frequency domain = analyzer: amplitude vs frequency.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
← E8A02 All of E8A E8A04 →

The rest of E8A

  1. E8A01 What technique shows that a square wave is made up of a sine wave and its odd harmonics?
  2. E8A02 Which of the following is a type of analog-to-digital conversion?
  3. E8A03 Which of the following describes a signal in the time domain?
  4. E8A04 What is "dither" with respect to analog-to-digital converters?
  5. E8A05 What is the benefit of making voltage measurements with a true-RMS calculating meter?
  6. E8A06 What is the approximate ratio of PEP-to-average power in an unprocessed single-sideband phone signal?
  7. E8A07 What determines the PEP-to-average power ratio of an unprocessed single-sideband phone signal?
  8. E8A08 Why are direct or flash conversion analog-to-digital converters used for a software defined radio?
  9. E8A09 How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?
  10. E8A10 What is the purpose of a low-pass filter used at the output of a digital-to-analog converter?
  11. E8A11 Which of the following is a measure of the quality of an analog-to-digital converter?
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