PCM Data Transmission System Using Split Phase Code

The LAMPF control system specifies transmission of both data and timing signals between the control room and the local control points throughout the machine for data collection and equipment control information. A balanced system is used to reduce noise pickup. The transmitter receives a timing pulse train and the digital data in a "non return to zero" (NRZ) format. The two signals are combined to form a split phase code and transformer coupled to the transmission line. The receiver uses a minimum energy content circuit (integrator) preceding the decoder to reduce noise sensitivity. The number of timing pulses in the incoming pulse train is known as is the time duration of the transmission. This information is used to further reduce the probability of error.