Frequency shift key /FSK/ approximations

This paper presents approximating equations to the spectrum of PCM/FM or FSK signals when the frequency modulating waveform is a random sequence of binary pulses of duration T. These approximations are intended to add to computational efficiency, implementation and easy interpretation of EMI characteristics. Two particular models are considered: (1) envelope model and (2) algebraic model. The envelope model is implemented by slicing it at a level so that the total area satisfies a power constraint. The algebraic model is a simple algebraic form which approximates the signal in some neighborhood where most of the power is concentrated, while giving way to the envelope at distant frequencies.