Tài liệu DS3 FLC Distance Learning pdf

Application Note 1211 Telecommunications Several schools utilize distance learning to meet demands for greater variety in their curriculum. Distance learning entails transmitting a presentation or lecture from one location to several remote locations for students to observe. Distance learning offers several benefits to the traditional classroom setting. It provides for a more effective use of an educator’s time, and allows a specialist's expertise to be spread across a wider audience. In addition, distance learning permits the sharing of resources between institutions and increases the availability of a broader curriculum to the student body. In short, distance learning solves educators’ problem of providing more variety with fewer resources. Several networks, such as DS3, analog or DS1/fractional DS1, exist to facilitate distance learning. Of these, a DS3 network proves to be the best solution. Due to the availability of greater bandwidth, a DS3 network requires less signal compression than a DS1 network. This leads to a higher quality video signal with DS3 transmission than with DS1. Because DS3 transmission requires less compression than DS1, DS3 compression equipment costs significantly less, making the DS3 network a more cost-effective video transmission solution. DS3 video transmission also compares favorably to analog video transmission. Analog transmission distance limitations arise because an analog signal repeater amplifies both the signal and any noise accompanying the signal; a digital signal can be effectively regenerated without amplifying the accompanying noise. This advantage allows a digital signal to be successfully transmitted over longer distances. In addition, analog video transmission requires an analog switch, which is not normally found in a central office. Digital cross-connect systems provide DS3 switching and are frequently available as an integral part of the telephone company network. Therefore, digital video transmission utilizes existing switching capabilities whereas analog video transmission requires purchasing additional switching equipment, making digital video transmission a more cost-effective solution. ® DS3 FLC Distance Learning 2 DS3 FLC Distance Learning Application Note 1211 ADC offers the DS3 Fiber Loop Converter (FLC) as an effective solution for DS3 video transmission. A DS3 FLC system consists of two identical modules interconnected by a pair of singlemode fibers capable of transmitting a standard DS3 rate video signal. The DS3 FLC module converts a DS3 electrical input signal into an optical output signal and converts an optical input signal back into a DS3 electrical output signal. Two separate fiber cables, one for each direction of transmission, provide full duplex communications. The modules are configured in either a 1 + 1 protection mode or as a single non- protected system. In the protection mode, a standby protect system, consisting of an additional DS3 FLC module at each location connected by an additional fiber pair, provides system redundancy. Failures affecting transport with this configuration cause the DS3 signal to switch automatically from the on-line working system to the redun- dant protect system, thereby ensuring continuous service. The DS3 FLC module can be installed in several ADC FLC chassis. The module plugs into either the FLC eight position mounting chassis, the FLC wall mount cabinet, or the DS3 FLC two position horizontal mounting chassis. Each chassis has the flexibility for various configurations. The eight position chassis allows up to four protected systems or four non-protected systems. The four position wall mount cabinet can be configured for up to two protected systems or two non-protected system. The two position horizontal chassis offers up to one protected system or one non-protected system. Description CENTRAL OFFICE 8 POSITION UNIVERSAL HORIZONTAL MOUNTING SHELF SCHOOL #3 SCHOOL #1 SCHOOL #2 D S 3 F L C W D S 3 F L C W 3/3 SWITCH VIDEO CODEC OPTICAL BUDGET = 13 dB OPTICAL BUDGET = 13 dB FOUR POSITION UNIVERSAL WALL MOUNT D S 3 F L C W D S 3 F L C P OPTICAL BUDGET = 13 dB D S 3 F L C W VIDEO CODEC T1 MULTIPLEXER TWO POSITION RACK MOUNT DS3 VIDEO SIGNAL 110V AC 110V AC Q F L C W Q F L C W 8 POSITION UNIVERSAL HORIZONTAL MOUNTING SHELF T1 MULTIPLEXER AC/DC converter D S 3 F L C W D S 3 F L C P VIDEO CODEC D S 3 F L C W Q F L C W Q F L C W Figure 1 3 DS3 FLC Distance Learning Application Note 1211 Application Figure 1 illustrates ADC DS3 FLCs used in a typical distance learning application. An eight position chassis occupies the central office and contains several configurations. The three DS3 FLCs in the central office allow for video transmission, with an optical budget of not less than 13 dB, to three remote schools with a DS3 FLC in either an eight position chassis, a four position wall-mount cabinet or a two position chassis at the school location. The versatility of the fiber loop converter system allows for DS1 signal transmission in addition to DS3 video traffic. The extra slots in the remote chassis may be occupied by other DS3 FLC modules or ADC's Quad Fiber Loop Converter (QFLC) which provides for optical transmission of DS1 voice and data signals. Several combinations of signal transmission exist. The four position wall-mount cabinet has a redundant AC/DC power converter which converts 110V AC power from a standard wall outlet to the necessary -48 V DC. This option saves the expense of buying a rectifier. Advantages ADC’s DS3 FLC offers definite advantages over other DS3 transport systems. The DS3 FLC provides an alternative to OC-3 multiplexers, allowing an economical last mile DS3 transport or point-of-presence hand-off. Configuration options permit the system to maximize facilities utilized for point-to-point or point-to-multipoint network topologies. The DS3 FLC requires no common equipment to operate because it integrates all functions onto a single printed circuit board. This feature reduces both start-up and spare inventory costs. Compared to OC-3 multiplexers, the DS3 FLC offers greater capacity for transporting a clear channel DS3. Up to four protected systems can be hubbed out of one rack mount chassis versus three DS3 systems by an OC-3 Mux. The DS3 FLC is a plug, play, and walk away system. No need exists for hand-held termi- nals or craft interface access for turn-up of service. Installer training is minimal and can be provided either by ADC or your in-house training department using ADC course material. The same DS3 FLC module is interchangeable for the central office terminal and the remote terminal, for either main or protect channels. One module fits all locations and applications, thereby keeping spare inventory costs to a minimum. Each module is a fully integrated system, simplifying trouble-shooting when needed. At the remote end, the FLC customer premises wall mount chassis is perfect for handing off DS3 and DS1 hicaps to end users. Installed in two of the customer premises chassis’ four slots, the QFLC can be used to deliver four protected DS1 hicap circuits; DS3 FLCs can be installed in the other two slots to deliver one protected DS3 hicap. Or, all four slots can be dedicated to DS3 FLCs to provide two protected DS3 hicap circuits. Application Note 1211 11/94 Original © 1994 ADC Telecommunications, Inc. All Rights Reserved An Equal Opportunity Employer Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. 4900 West 78th Street Minneapolis, Minnesota 55435 FAX: (612) 946-3292 For U.S. Sales, Call Toll Free: 1-800-366-3891 ® Telecommunications International Sales Offices: Belgium 32-2-721-5282 • United Kingdom 44-734-441955 • Montreal, Quebec (514) 677-9166 • Vancouver, BC (604) 270-1675 • Toronto, Ont. (905) 629-3104 • Ottawa, Ont. (613) 596-9937 • Singapore 65-225-8228 • Venezuela 58-2-953-1684 • Mexico City, Mexico 525-658-4519 • Sydney, Australia 61-2-975-1499 . cost-effective solution. ® DS3 FLC Distance Learning 2 DS3 FLC Distance Learning Application Note 1211 ADC offers the DS3 Fiber Loop Converter (FLC) as an effective. C W Figure 1 3 DS3 FLC Distance Learning Application Note 1211 Application Figure 1 illustrates ADC DS3 FLCs used in a typical distance learning application.