Filters and Frequency Control Flashcards
6 cards from real GROL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Filters and Frequency Control flashcards as text
What is the primary function of a low-pass filter in a radio transmitter?
Answer: To pass frequencies below a cutoff frequency while attenuating higher frequencies
A low-pass filter allows signals below its cutoff frequency to pass while attenuating signals above that frequency, commonly used to suppress harmonics.
Which type of filter passes a specific band of frequencies while attenuating frequencies both above and below that band?
Answer: Band-pass filter
A band-pass filter has both a lower and upper cutoff frequency, allowing only the frequencies between them to pass through.
What type of crystal is most commonly used in oscillators and filters for precise frequency control?
Answer: Quartz
Quartz crystals exhibit the piezoelectric effect and have extremely stable resonant frequencies, making them ideal for precise frequency control.
What is the Q factor of a filter or resonant circuit?
Answer: The ratio of resonant frequency to bandwidth
Q (quality factor) is defined as the resonant frequency divided by the 3 dB bandwidth, with higher Q indicating a sharper, more selective filter.
In a series LC circuit at resonance, what is the impedance?
Answer: Minimum impedance (approaches zero)
At resonance in a series LC circuit, the inductive and capacitive reactances cancel each other, leaving only the small series resistance, resulting in minimum impedance.
What is the purpose of a notch (band-stop) filter?
Answer: To sharply attenuate a specific frequency or narrow band
A notch or band-stop filter is designed to reject a specific frequency or narrow frequency band while passing all others, often used to eliminate interference.