Efficient M-PSK lock detectors and SNR estimators

We present new structures for carrier lock detection for M-PSK (M-ary Phase Shift Keying) receivers. The lock detectors are NDA (Non Data Aided) and are shown to have the following advantages: (1) they have a compact fixed-point hardware implementation suitable for implementation in ASICs (Application Specific Integrated Circuits); (2) they require only 1 sample/symbol; (3) relatively few symbol intervals are needed in order to achieve good detection and false alarm probabilities; and (4) the decision thresholds for the lock detectors are simple to calculate and are resilient to imperfections in the AGC (Automatic Gain Control) circuit. It is shown that the lock detection metric can be used to estimate the channel SNR (Signal to Noise Ratio). Theoretical, simulation, and laboratory results are presented.