Pulse time modulation techniques for low cost analog signal transmission systems

Pulse time modulation techniques (PTM) have been proven to be attractive techniques for achieving low cost analog optical transmission systems. To facilitate future design of such transmission systems, a review of these modulation techniques is made. Spectrum expressions of PPM, PWM, PFM, and SWFM are derived and given. The results are used to predict the requirement for minimum carrier frequency and transmission bandwidth as well as the signal to noise ratio performances of optical transmission systems employing such techniques.