Zero-Crossing Based Demodulation of Minimum Shift Keying

摘要

Minimum shift keying (MSK) modulation has features such asconstant envelope, compact spectrum and good error performance, whichare all desirable in many digital applications including mobile radio. Numerous receiver structures to demodulate MSK have been suggested,such as correlation receivers, differential detectors and frequencydiscriminators. MSK is a form of biphase keying and can be detectedby a zero-crossing based phase demodulator which gives near optimumperformance. In this paper, the bit error performance of azero-crossing based coherent MSK demodulator is theoreticallyinvestigated and a closed-form expression for the bit error rate isderived. The results indicate that the demodulator performs within0.8-1 dB of the theoratical optimum for MSK. Towards the goal ofderiving probability of bit error, it is also shown that underadditive white Gaussian noise (AWGN) zero-crossing locations of MSKsignals are Gaussian distributed except at very low signal-to-noiseratios.