Howto build your E1<>RJ45 cable

We used a Cat-7 Ethernet cable to build our E1<>RJ45 cable to connect the BTS with the BSC.

Things you need:

• one Cat-7 Ethernet cable
• two twinax plugs (BR2)
• some heat shrink tube
• soldering-iron
• multimeter (optional)
• a sharp knife :)

Step-by-step guide

One:

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.

Two:

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).

Three:

Sort your twinax plugs to make sure you build them in the right order. ;)
We used heat shrink tube to stabilize our cable around the plugs.

Four:

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.

Five:

Repeat step three and four to build the second plug.

Done.

Detailed pinout

A detailed pinout for your reference:

Signals on the RJ45 plug:
             ____________________ 
            / /               / /|
           / /               / / |
          / /_______________/ /  |
         / ________________  /   |
        / / / / / / / / / / /    |
       / / / / / / / / / / /    / 
      / /_/_/_/_/_/_/_/_/ /    / 
      | | | | | | | | | | |   /
      | |8|7|6|5|4|3|2|1| |  /
      | |_|_|_|_|_|_|_|_| | /
      |___________________|/
            |      |/
            \______/

	1 = RX1
	2 = RX2
	3 = NC
	4 = TX1
	5 = TX2
	6 = NC
	7 = NC
	8 = NC


Signals on the twinax plugs:

     E1 Transmitter:
           ___            
       .-''   '`-.  
     .'           `. 
    /     1      2  \
   :    ##     ##    ;
   |    ##     ##    |
   :                 ;
    \ ############# /
     `. ######### .'
       `-._____.-'

	1 = TX1
	2 = TX2


     E1 Receiver:
           ___            
       .-''   '`-.  
     .'           `. 
    /     1      2  \
   :    ##     ##    ;
   |    ##     ##    |
   :                 ;
    \ ############# /
     `. ######### .'
       `-._____.-'

	1 = RX1
	2 = RX2
     
      Note: The drawings are showing the plugs point of view. 
      Note: This is a differential connection with symetric signals
            so you do not have to care about the polarity.


Cable connection on the BS11:
           
  ~~~~~~~_________~~~~~~
 /        12            \
 \        oo   oo       /
  ~~~~~~~|_______|~~~~~~ 

	1 = RX (connect E1 Transmitter to that port)
	2 = TX (connect E1 Receiver to that port)