CWS Basic RF Principles Flashcards
7 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 CWS Basic RF Principles flashcards as text
What is the SNR of a signal received at -65 dBm with a noise floor of -95 dBm?
Answer: 30 dB
SNR = Signal level − Noise floor = −65 dBm − (−95 dBm) = 30 dB.
Which multipath effect causes rapid, short-term fluctuations in received signal strength as a mobile client moves?
Answer: Fast fading (Rayleigh fading)
Fast fading (Rayleigh fading) results from constructive and destructive interference of multipath components as the receiver moves even small distances.
A cable with 3 dB of loss cuts transmitted power by approximately:
Answer: Half
3 dB of loss corresponds to a power ratio of 2, so 3 dB loss means half the power is lost.
Which 802.11 band is generally more susceptible to interference from microwave ovens?
Answer: 2.4 GHz
Microwave ovens operate near 2.45 GHz and directly overlap the 2.4 GHz Wi-Fi band.
What is the primary purpose of antenna diversity in wireless systems?
Answer: To mitigate multipath fading by selecting or combining signals from multiple antennas
Antenna diversity uses multiple antennas to combat multipath fading by selecting the best signal or combining signals.
In the Friis transmission equation, doubling the distance between transmitter and receiver causes received power to:
Answer: Decrease by 6 dB
Free-space path loss follows an inverse-square law, so doubling distance quadruples path loss, which is a 6 dB decrease in received power.
Which modulation scheme encodes data by shifting the phase of the carrier signal?
Answer: PSK (Phase-Shift Keying)
PSK encodes information by varying the phase of the carrier wave rather than its amplitude or frequency.