Howtosignalprocessing
- How does Costas loop work?
- What is the advantage of Costas loop?
- What does a loop filter do?
- What type of feedback is used in Costas loop and why?
How does Costas loop work?
The Costas loop1 is based on a pair of quadrature modulators - two multipliers fed with carriers in phase-quadrature. These multipliers are in the in-phase (I) and quadrature phase (Q) arms of the arrangement. Each of these multipliers is part of separate synchronous demodulators.
What is the advantage of Costas loop?
. This translates to double the sensitivity and also makes the Costas loop uniquely suited for tracking Doppler-shifted carriers, especially in OFDM and GPS receivers.
What does a loop filter do?
The loop filter acts to slow the response down. The narrower the loop bandwidth, i.e. the lower the cut-off frequency of the filter, the slower the response of the loop to responding to changes. Conversely if the loop requires a fast response to changes in frequency, then it will need a wide loop bandwidth.
What type of feedback is used in Costas loop and why?
Fig 1 -- In the basic phase-locked loop structure the system relies on feedback formed by mixing a reference signal with a received waveform. received signal are equal in phase and frequency they are locked in sync.
