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I <br />I I <br />RS232 <br />spdal <br />Cable <br />1 170 Traffic <br />FSK <br />Signal Contrd.ler - Modem <br />Con1m17er Cabinet <br />RS-232 <br />I Sedan I <br />1 Cable I <br />DPJS Contrdler FSK Modem <br />------------------- <br />___ - -_ <br />I <br />— — — Network Hub <br />I <br />I <br />I <br />Vi Cable <br />I FSK Mocem <br />I <br />I Centel Server , <br />I <br />1 <br />Figure 5. FSK over Copper Example <br />Ethernet over Cooper <br />The Ethernet communications protocol, defined by the Institute of Electrical and Electronics <br />Engineers (IEEE) 802 family of protocols, may be used with twisted pair copper cable to support <br />higher bandwidth applications than that allowed by FSK over copper. Symmetric high -speed <br />digital subscriber line ( SHDSL) equipment has recently been introduced to the ITS market to <br />provide up to 45 Mbps of bandwidth using Ethernet communications protocols over twisted pair <br />copper cable. The amount of bandwidth that may be achieved varies depending on the distance <br />the data is transmitted, the gage of the twisted pairs, and the number of twisted pairs used: <br />• Bandwidth decreases as the transmission distance (also called reach) increases. <br />• Bandwidth decreases as the gage of the twisted pairs increases. <br />• Bandwidth increases when more twisted pairs are used for transmission. <br />For example, the bandwidth for 24 AWG twisted pair copper cable transmitted at 9,500 feet is <br />approximately 9 Mbps using two twisted pairs, 14 Mbps using four twisted pairs, and 27 Mbps <br />using eight twisted pairs <br />A number of Ethernet access devices (EADs) that use SHDSL equipment are available on the <br />market to provide Ethernet over copper communications. EADs are given varying names by <br />different manufacturers and may include a variety of components such as digital subscriber line <br />access multiplexers (DSLAMs), copper add drop multiplexers (C- ADMs), concentrators, and <br />switches depending on the desired functionality. Figure 6 illustrates an example of using EADs <br />to provide Ethernet over copper communications. Typically one EAD is installed in each <br />controller cabinet and another EAD is installed at the hub to communicate with several <br />controllers. Category 5- enhanced (Cat 5e) cables are used to transmit data between the EAD <br />and the controller or server. Although many newer devices are Ethernet - ready, other devices <br />may require additional equipment to convert serial analog data to IP /Ethernet. For example, the <br />5 In February and March 2005, DKS Associates conducted a 60-day field trial in Livermore, California comparing the ' <br />SHDSL equipment manufactured by Tut Systems and Actelis Networks. Tut Systems provided performance data <br />showing 9.2 Mbps to a range of 9,500 feet using two pairs of 24 AWG twisted copper cable. Actelis Networks <br />provided performance data showing 7.2 Mbps to a range of 9,500 feet using two pairs of 24 AWG twisted copper <br />cable. Actual field observations obtained during the field trial were in line with the performance statistics advertised t <br />by each manufacturer. <br />DKS Assoerates Eugene Master Traffic Communications Plan March 2008 , <br />Page 21 <br />