About FOCL And Analog Transmission Prt.1

Introduction

In the last decades of the previous century many methods of different types of signals, data and control commands FOCL-transferring were implemented. For a long time they couldn’t compete with coaxial cable or crossover cable (at least not in ESS field). Coaxial and crossover cables were predominated in security systems, despite such disadvantages as high resistance and capacity, which are set a limit on the transmission range,

The situation is changing nowadays. In a small system, where the signals are transmitted for small distances, coaxial and crossovers cables are still indispensable, but in big or wide-spread systems there are no alternative to the optic fiber.

The case is the optic fiber has became cheaper and the cheapening tendency is stable. This way, the optic fiber can offer not only a durable, but also a cost-effective solution to the security systems client. The using of light ray for signals transmitting and wide bandwidth provides the high-quality signal transmitting for long distance without multiplier and repeater using. The main advantages of using optic fiber:

  • far more wider bandwidth (up to several GHz) if to compare with copper cable (up to 20 MHz)
  • immunities to electrical noise, ground loop absence
  • low transmission loss, the signal quenching is near 0.2-2.5 dB/km
  • no conflict with copper or fiber optic cables
  • good quality of transmitting signal
  • fiber optic cable is miniature and light.