Amateur ExtraE8D03
Which describes spread spectrum frequency hopping?
D
Answer
Signals, modulation, and digital modes
Type
A
If interference is detected by the receiver, it will signal the transmitter to change frequencies
B
RF signals are clipped to generate a wide band of harmonics which provides redundancy to correct errors
C
A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence
D
Rapidly varying the frequency of a transmitted signal according to a pseudorandom sequence
Answer Notes
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies. Both the transmitter and the receiver must be synchronized and use the exact same pseudorandom sequence to know which frequency to jump to next.
The distractor describing a binary bit stream used to shift the phase of an RF carrier actually defines Direct Sequence Spread Spectrum (DSSS). It is important to distinguish between hopping between distinct frequencies (FHSS) and mathematically spreading a single carrier using phase shifting (DSSS).
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What spread spectrum communications technique uses a high-speed binary bit stream to shift the phase of an RF carrier?
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What is the primary effect of extremely short rise or fall time on a CW signal?