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A coherent QPSK demodulator is required on the ground for receiving data from an LEO satellite. What should be the optimum order of PLL in the carrier phase tracking loop?

A coherent QPSK demodulator is required on the ground for receiving data from an LEO satellite. What should be the optimum order of PLL in the carrier phase tracking loop? Correct Answer 3<sup>rd</sup> order

Concept:

QPSK: QPSK is a phase modulation technique that sends two bits of digital information called digits.

  • It converts digits into pair so that data bit rate decrease to half which allows space for better use.
  • For the same data Rate, QPSK requires half Bandwidth.
  • QPSK is used in satellite communication due to its high spectral and power efficiency.

 

PLL:  PLL i.e. phase-locked loop is a demodulation technique of FM signal.

It generates an output signal whose phase is related to the phase of the input signal.

 

Explanation:

A 3rd order in the earner phases tracking loop is required for a coherent demodulator for receiving data from an LEO satellite.

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