Howto build your BS-11 E1<>RJ45 cable¶

We used a Cat-7 Ethernet cable to build our E1<>RJ45 cable to connect the BS-11 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)