Physical & Network Setup
========================

There are important preliminary steps to get the USRPs running, involving a physical and a network setup.

Network Setup
~~~~~~~~~~~~~

Ensure that the USRPs are in the same network. It is advised to change their hostname. This can be done as follows:

.. code-block:: shell

   $ ssh <usrp-ip>
   $ vi /data/network/hostname

Type in your desired hostname and restart the USRP.

We use ZeroMQ for communication between client and server. Therefore, the port `5555` should be opened
for TCP packets.

Physical Setup
~~~~~~~~~~~~~~

Synchronization
    The USRPs are synchronized via PPS signals and a 10 MHz reference radio signal.
    As a generator, we use a Meinberg Clock. Connect their PPS outs to the `PPS in`` of the USRP and the
    10MHz ooutput to `REF IN`. Ensure that the cables are the same length!

   .. image:: images/sync.png

Antennas
    - Note, that receiver ports of the USRP receive signals, although weak, even if no
      antenna is connected! 
    - `TX/RX0` ports of the USRP are transmit antennas by default!
    - if you connect two antennas via cable (to mitigate effects of the channel), make sure to add add
      30dB attenuator at transmit side