AN2931| Application Note
Maxim/Dallas > App Notes > COMMUNICATIONS CIRCUITS
FIBER-OPTIC CIRCUITS
TELECOM
Keywords: T3, E3, STS-1, fiber optic extension, media converter, fiber, fibre
Dec 12, 2003
APPLICATION NOTE 2931
HFTA-09.0: T3/E3/STS-1 Fiber Optic Extension
This application note will describe what is needed to design a T3/E3/STS-1 Fiber to Copper Media Converter. Such a device will take the copper signal and convert it to an optical signal to be transported over a fiber link. A pair of converters will extend the T3/E3/STS-1 signal beyond its copper specification, transparently. This allows, for example, the T3/E3/STS-1 signal to be utilized beyond the intrabuilding length limitation.
Introduction
Typically, T3/E3/STS-1 signals are run over short distances, but some applications require a much longer distance. A T3/E3/STS-1 fiber-to-copper converter takes the copper signal and converts it to an optical signal to be transported over a fiber link. A pair of converters extends the T3/E3/STS-1 signal beyond the copper specification, allowing the T3/E3/STS-1 signal to be used beyond the intrabuilding length limitation. While the standard length for a T3 signal is 380m, an E3 signal length is 440m, and an STS-1 standard signal length is 360m, a fiber connection can reach miles. However, no standard exists for transporting T3/E3/STS-1 over fiber. Typical designs can include single-mode or multi-mode fiber using SC or ST connectors, and different optical wavelengths, such as 850nm, 1310nm, and 1550nm. The optic budget length determines if the engineer needs to enhance the optical component design to satisfy the end user's application. To transmit data via fiber optic cables, the signals must first be converte
d from the electrical domain to the optical domain. At the receiver, the process is reversed. Most designs use two fiber strands for each direction: Tx and Rx. However, because of the unique properties of light, an optical diplexer can be used so that a full-duplex connection can be designed over one strand of fiber, using the same wavelength for both directions. This application note discusses a simple, full-duplex system using two strands of single-mode fiber for longer distances. The STS-1 is the basic unit of transmission in the Synchronous Optical Network (SONET). It is the copper-based version of OC-1. STS-1 is also known as EC-1. Both T3 and E3 are at the third hierarchy within the Plesiochronous Digital Hierarchy (PDH). Table 1 illustrates the respective bit rates. Table 1. Bit Rates vs. Hierarchical Standards Bit Rate Hierarchy
34.368Mbps PDH (E3) 44.736Mbps PDH (T3) 51.840Mbps SONET (STS-1) In a time-division multiplex (TDM) system, the Manchester technique is typically used for the line encoding/ decoding of the clock and data together. As for modulation of the optical signal on the fiber, the laser/LED transmitter/receiver uses the "light on" for a binary 1, and "light off" for a binary 0. As optical receivers detect
AN2931 Application Note maxim Download PDF
Add this permalink to your bookmarks for future download of AN2931 ApplicationNote
Permalink: http://application.emcelettronica.com/maxim/AN2931
