Tài liệu DSX-3 75 ohm Circuit Termination doc

Overview DS3 Network Elements (NE) such as fiber optic terminals (FOT) or M13 multiplexers (M13) that are cabled to the DSX-3 require a 75 ohm load to stabilize the output signal. This 75 ohm load or "75 ohm termination" prevents the output from oscillating and affecting adjacent channels. When a NE is cross-connected to another NE, the output of each NE is terminated by the input of the other NE. When multiple NEs are installed, many are often unassigned for a period of time until working service is required. Although unassigned, the NEs are powered up "Hot" in a standby mode, waiting to be turned up live as soon as a service order is issued. When DS3 NEs are powered up but not yet cross-connected or assigned to other NEs, a 75 ohm termination is placed at the DSX-3. This 75 ohm termination may be placed in a number of ways as illustrated by the following figures. The 75 ohm termination is also required when disconnecting two NEs from each other for testing or reconfiguration. This termination is provided by a DS3 test set or a 75 ohm termination plug at the DSX-3 OUT jack. DSX-3 75 ohm Circuit Termination application note 2 www.adc.com • +1-952-938-8080 • 1-800-366-3891 3/01 • 1209 DSX-3 75 ohm Circuit Termination Applications DSX-3 and 75 ohm Termination Plug Schematics ININ R2 R3 } PIN Jack } Card Edge Conn LS TL OUT R2 OUT MON R1 OUT BNC/TNC IN BNC/TNC X-CONN -48V LG TL TL BNC/TNC R1 = 93.1 ohm 1/8W Resistor R2 = 75 ohm 1/8W Resistor R3 = 464 ohm 1/8W Resistor DSX Rear Cross-Connect Schematic MON IN IN BNC/TNC OUT BNC/TNC R2 R1 R3 OUT R2 Tracer Lamp PIN Jack IN OUT X-CONN R1 = 93.1 ohm 1/8W Resistor R2 = 75 ohm 1/8W Resistor R3 = 464 ohm 1/8W Resistor Card Edge Connector LS TL } DSX Front Cross-Connect Schematic 75 OHM RESISTOR 75 ohm Termination Plug Schematic 3 www.adc.com • +1-952-938-8080 • 1-800-366-3891 3/01 • 1209 DSX-3 75 ohm Circuit Termination Applications 75 ohm Termination Plug at DSX-3 OUT Jack DSX-3 MON OUT IN X-OUT X-IN 75 OHM TERMINATION PLUG NETWORK ELEMENT 1 (TX) (RX) DSX-3 (TX) (RX) NETWORK ELEMENT 2 X-OUT X-IN OUT OUT IN IN OUT OUT IN IN 75 ohm Termination Provided by the Far-End DSX-3 IN Jack DSX-3 MON OUT IN X-OUT X-IN NETWORK ELEMENT 1 75 OHM TERMINATION 75 OHM TERMINATION (TX) (RX) DSX-3 (TX) (RX) NETWORK ELEMENT 2 X-OUT X-IN OUT OUT IN IN OUT OUT IN IN MON OUT IN PLUG NOTE: 75 OHM TERMINATION PROVIDED INTERNALLY BY JACK OPERATION 75 ohm Termination Plug or Terminating Connector at the DSX-3 Cross-Connect OUT Terminal DSX-3 MON OUT IN X-OUT X-IN NETWORK ELEMENT 1 (TX) (RX) DSX-3 (TX) (RX) NETWORK ELEMENT 2 X-OUT X-IN OUT OUT IN IN OUT OUT IN IN MON OUT IN 75 OHM TERMINATION PLUG (FRONT CROSS-CONNECT) 75 OHM TERMINATING BNC OR TNC CONNECTOR (REAR CROSS-CONNECT) ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 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. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 1209 3/01 Revision © 1998, 2001 ADC Telecommunications, Inc. All Rights Reserved Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891, Ext. 63475 • Outside of North America: +1-952-938-8080 Fax: +1-952-946-3292 For a complete listing of ADC's global sales office locations, please refer to our web site. Applications 75 ohm Termination Provided by the Far-End NE Equipment (Working Configuration) DSX-3 MON OUT IN X-OUT X-IN NETWORK ELEMENT 1 75 OHM TERMINATION IN RECEIVER (TX) (RX) DSX-3 (TX) (RX) NETWORK ELEMENT 2 X-OUT X-IN OUT OUT IN IN OUT OUT IN IN 75 OHM TERMINATION IN RECEIVER MON OUT IN . OUT OUT IN IN 75 ohm Termination Provided by the Far-End DSX-3 IN Jack DSX-3 MON OUT IN X-OUT X-IN NETWORK ELEMENT 1 75 OHM TERMINATION 75 OHM TERMINATION. 75 ohm Termination Plug Schematic 3 www.adc.com • +1-952-938-8080 • 1-800-366-3891 3/01 • 1209 DSX-3 75 ohm Circuit Termination Applications 75 ohm Termination