How does a Costas Loop lock to one of multiple BPSK signals

1. How does Costas loop work?
2. What type of feedback is used in Costas loop and why?
3. What is the advantage of Costas loop?
4. What are the applications of Costas loop?

How does Costas loop work?

A costas loop is an analog circuit that can regenerate a carrier and its phase from an input signal without any or with minimal carrier content. It is a phase-locked loop that relies on frequency content of the input signal sidebands.

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.

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 are the applications of Costas loop?

The Costas loop is a classical analog PLL based circuit for carrier recovery[6–8]. Nowadays, among the applications of Costas loop, there are global positioning systems (GPS)[9, 10], wireless communication[11] and others[8, 12–19].