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E1-to-RJ45 » History » Version 13

laforge, 02/21/2016 11:16 AM

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h1. Howto build  your E1<>RJ45 cable
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We used a Cat-7 Ethernet cable to build our E1<>RJ45 cable to connect the BTS with the BSC.
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Things you need:
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* one Cat-7 Ethernet cable
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* two twinax plugs (BR2)
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* some heat shrink tube
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* soldering-iron
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* multimeter (optional)
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* a sharp knife :)
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h2. Step-by-step guide
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h3. One
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Take your cable and cut off one of the RJ45 connectors.  Now use a ruler and make a slice so you can strip around 15 cm from your cable.
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!{width:40%}IMG_0960-1.JPG! !{width:40%}IMG_0960-2.JPG!
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h3. Two
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Split the wires from your cable.  We need pin 1 and 2 for *RX* and pin 4 and 5 for *TX*, Use a Multimeter to determine the correct pairs. Cut off the other wires we do not need them (yet).
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!{width:30%}IMG_0960-4.JPG! !{width:30%}IMG_0960-5.JPG! !{width:30%}IMG_0960-7.JPG!
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h3. Three
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Sort your twinax plugs to make sure you build them in the right order. ;)
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We used heat shrink tube to stabilize our cable around the plugs.
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!{width:30%}IMG_0960-9.JPG! !{width:30%}IMG_0960-11.JPG!
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!{width:30%}IMG_0960-12.JPG! !{width:30%}IMG_0960-17.JPG!
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h3. Four
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Now you can put everything on the first part of the cable and assemble it.  Use a soldering-iron to fixate each of the two pins of the plug with your wires.  You do not have to worry about the polarity inside the twinax plug.
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!{width:50%}IMG_0960-19.JPG!
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h3. Five
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Repeat step *three* and *four* to build the second plug.
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h3. Done
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!{width:50%}IMG_6379-1.JPG!
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h2. Detailed pinout
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A detailed pinout for your reference:
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<pre>
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Signals on the RJ45 plug:
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             ++++++++++ 
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            / /               / /|
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           / /               / / |
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          / /+++++++_/ /  |
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         / ++++++++  /   |
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        / / / / / / / / / / /    |
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       / / / / / / / / / / /    / 
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      / /_/_/_/_/_/_/_/_/ /    / 
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      | | | | | | | | | | |   /
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      | |8|7|6|5|4|3|2|1| |  /
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      | |_|_|_|_|_|_|_|_| | /
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      |+++++++++_|/
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            |      |/
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            \+++/
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	1 = RX1
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	2 = RX2
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	3 = NC
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	4 = TX1
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	5 = TX2
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	6 = NC
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	7 = NC
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	8 = NC
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Signals on the twinax plugs:
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     E1 Transmitter:
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           +_            
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       .-_   '@-.  
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     .'           @. 
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    /     1      2  \
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   :    ##     ##    ;
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   |    ##     ##    |
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   :                 ;
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    \ ############# /
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     @. ######### .'
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       @-.++_.-'
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	1 = TX1
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	2 = TX2
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     E1 Receiver:
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           +_            
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       .-_   '@-.  
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     .'           @. 
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    /     1      2  \
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   :    ##     ##    ;
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   |    ##     ##    |
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   :                 ;
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    \ ############# /
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     @. ######### .'
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       @-.++_.-'
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	1 = RX1
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	2 = RX2
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      Note: The drawings are showing the plugs point of view. 
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      Note: This is a differential connection with symetric signals
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            so you do not have to care about the polarity.
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Cable connection on the BS11:
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  ---~++++_---
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 /        12            \
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 \        oo   oo       /
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  ---~|+++_|--- 
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	1 = RX (connect E1 Transmitter to that port)
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	2 = TX (connect E1 Receiver to that port)
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</pre>
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