Implementation of the pulse interval modulation code 3B17P for a 90 Mbit/s LED single mode fibre system

• Published in: Conference Proceeding IEEE Pacific Rim Conference on Communications, Computers and Signal Processing pp. 423 - 426
• Main Authors: VandenBrink, S.R., Goud, P.A., Englefield, C.G.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 1989
• Subjects: Binary codes; Bit error rate; Coaxial cables; Light emitting diodes; Modulation coding; Optical fiber cables; Optical fibers; Optical signal processing; Pulse modulation; Space vector pulse width modulation
• DOI: 10.1109/PACRIM.1989.48392

A modified version of pulse position modulation (PPM), asynchronous digital pulse interval modulation (PIM), is examined. The modulation scheme strengthens the viability of using LEDs as sources on a single mode fiber system, by allowing an increase in the peak power coupled into the fiber. First, an overview of the PIM code is provided. This is then followed by a detailed description of the 3B17P PIM code, which was implemented in an experimental 90-Mb/s communication system. Experimental results of the system's bit error rate (BER) versus the average received power were obtained for both the PIM and NRZ code over a coaxial cable link. The results are compared and discussed. The PIM code has a power advantage of up to 3.5 dB over the NRZ binary code. At a constant peak received power, the effect of the threshold level on the BER is similar for both codes at a high SNR. At a low SNR, there appears to be an optimal threshold level that depends on the duty cycle of the received code.< >