Characteristics of Manchester-Coded FSK

In this paper, the Manchester-coded frequency-shift-keyed (MCFSK) signal is shown to be representable in terms of an in-phase
(I)
and a quadrature
(Q)
carrier term. The
I
-term carries the bit timing and the
Q
-term carries the message information. Based on this representation, a simple derivation of the power spectral density for MCFSK is presented. The effect of premodulation pulse shaping on the spectral occupancy of MCFSK is then investigated using trapezoidal, triangular and cosine-squared pulses. Formulas for the power spectral density are derived and curves of fractional in-band power are obtained which will be useful for band occupancy determination. Finally, the bit error rate (BER) performance for MCFSK in an ideal channel is derived and shown to be the same as that for coherent FSK.