Phasor explanation of error mechanisms for MSK transmission over a slightly dispersive radio channel

The paper presents some insight into the error mechanisms of minimum shift keying (MSK) transmitted over a slightly dispersive radio channel with sampling at the average mean delay. The authors elucidate the error mechanisms at infinite signal-to-noise ratio (SNR) by the means of phasor diagrams and error circles in the channel constellation diagram. They show that errors occur deterministic related to the channel condition and only for certain bit combinations. Errors occur only if the ratio of instantaneous signal power (within a bit) to average signal power (long term mean) fades below a threshold, dependent on the normalized delay spread S/T_bit