Question
What is an effect of excessive phase noise in an SDR receiver’s master clock oscillator?
Answer Options
- A) It limits the receiver’s ability to receive strong signals
- B) It can affect the receiver’s frequency calibration
- C) It decreases the receiver’s third-order intercept point
- D) It can combine with strong signals on nearby frequencies to generate interference
Correct Answer: D
Explanation
Phase noise is unwanted, rapid, random variations in the phase of a signal, effectively manifesting as sidebands spreading out from the nominal frequency. In a Software Defined Radio (SDR), the master clock oscillator is a critical frequency reference, and any noise in its phase affects the entire down-conversion or sampling process.
Excessive phase noise in the master clock causes a phenomenon called reciprocal mixing. This effect means that the noise sidebands of the oscillator clock, instead of sitting quietly, can combine with strong signals on nearby frequencies to generate interference directly within the desired receiver passband. This noise then masks the weak desired signal, effectively reducing the receiver’s dynamic range.
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