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سؤال 486

Which describes spread spectrum frequency hopping?

  1. If interference is detected by the receiver, it will signal the transmitter to change frequencies
  2. RF signals are clipped to generate a wide band of harmonics which provides redundancy to correct errors
  3. A binary bit stream is used to shift the phase of an RF carrier very rapidly in a pseudorandom sequence
  4. Rapidly varying the frequency of a transmitted signal according to a pseudorandom sequenceپاسخ درست

توضیح

Frequency hopping keeps the signal narrowband at any single instant but moves the carrier from channel to channel following a pseudorandom pattern that the receiver reproduces in step. Spreading by shifting the carrier phase with a fast chip stream is the direct-sequence method, a different technique.

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شروع تمرین
سؤال 486: Which describes spread spectrum frequency hopping? · FCC Amateur Extra Class (Element 4) · Questena