We have discussed before the effect of a phase offset on the received signal. We have also seen a logical approach to solve this problem as well as one of the earliest algorithms for phase synchronization known as a Costas loop. Here, the purpose is to explain how a Rx detects whether the Phase Locked Loop (PLL) has acquired the lock. A receiver is simply a blind machine which can implement a PLL but can never get to know how it is actually doing. A lock detector is a logic signal used in the Rx to indicate successful synchronization after
Continue reading![A BPSK constellation in a the presence of a carrier phase offset. A hypothetical QPSK constellation is also shown for comparison](https://wirelesspi.com/wp-content/uploads/2020/12/figure-phase-sync-phase-rotation-bpsk.png)