Essentials - Ch 9 Performing a PSG Study Questions and Answers 100% Accurate

What is the frequency of a wave? Characterized by the number of times it repeats or oscillates in a second; measured in Hz or Cycles per second (cps); the narrower the wave, the faster it is, and therefore the higher the frequency What is the amplitude of a wave? It is directly affected by the voltage of the associated signal; it is the height of the wave What is Time Constant? Also called fall time or fall time constant; the amount of time for a calibration wave to fall from its highest point or peak to 37% of its peak; the time constant performs the same function as the LFF in that they both place limits on the amount of slow wave activity displayed by attenuating (reducing the amplitude) the amplitude of the signals with frequencies below the filter setting What is the Rise Time? The amount of time it takes for the calibration wave to reach 63% of its peak; very short time (usually in the hundredths of a second) *The rise time of a calibration wave increases and decreases with the HFF setting *A decreased LFF setting allows slower waves to enter the signal, which causes the calibration wave to fall more slowly; a decreased LFF setting increases the time constant What does the HFF do? Determines the upper limit of frequencies that a channel will display at full amplitude; the amplitude of electrical signals with frequencies HIGHER than the HFF setting will be greatly attenuated (reduced amplitude) making it difficult to visually detect these waves