USRP Radar Relay
================

About
-----
This is a framework that provides real-time continuous streaming of signal 
waveforms through SDR (Software Defined Radio) devices.

We at Neratec Solutions AG developed it as an utility to test DFS radar 
detection at physical layer. We are testing with Ettus Research USRP N200 [1] 
equipped with the XCVR2450 transceiver board [2].

Beside its initial designation for DFS testing, with the provided interface it 
is generic enough to utilize the SDR for the output of arbitrary patterns and 
is therefore usable for a broader application radius.

Background
----------
Typically SDR devices are used with GNURadio [3] that abstracts the underlying 
hardware with a high-layer interface to access devices over a generalized set 
of functions. With various applications provided (including fully GUI based 
signal generation), it enables quick start using the SDR.

While the tools greatly help to get first hands-on results, they become 
inflexible as soon as the provided functionality set does not suffice the 
target application.

For applications that need continuous real-time streaming of signal data (like 
for DFS testing) the UHD (USRP Hardware Driver) [4] provides an Ettus device 
specific low-level interface. At this layer, the application feeds the device 
with waveform samples over Ethernet to be radiated.

Working at the UHD layer gives full control over timings and at the same time 
demands for carefully designed processing schemes that ensure isochronous data 
flows.

The framework at hand implements a server component that takes care on those 
requirements and provides a JSON-RPC interface to clients to configure the SDR 
and set radar patterns to be radiated.

Functional Description
----------------------
Upon successful building, server and client applications are provided.

The 'radar_server' component creates a virtual instance of the USRP device 
with an initial configuration and then waits for RPC commands to be executed.

The 'radar_client' component reads a JSON-RPC formatted file and after 
verification sends it to the server for execution.

For the command format please have a look in the RPC-commands folder.

Building
--------
The framework has been used so far with Linux systems. It depends on the UHD 
libraries being installed, as described in [5]. You most probably have this 
prerequisite met if you are using the USRP with GNURadio. As second requirement 
the CMake build-system must be installed. Again, if you built UHD and/or 
GNURadio from sources, you have that already installed. CMake will check for 
UHD and refuse to build on errors.

Build steps:
1) create <my_build_dir> and cd to it
2) in <my_build_dir> run: cmake <path_to_source>
3) on success, in <my_build_dir> run: make
4) on success, you should find radar_server and radar_client in <my_build_dir>

Using
-----
1) Start the server component from a shell window and check for errors.
2) In an other shell, run the client component with a valid JSON-RPC file as 
   command line parameter, e.g.:
   ./radar_client <path_to_source>/RCP-commands/pattern_single_ETSI_type1.txt

Per default, the tools are built with debug output enabled and the server will 
display how it interprets the received command. With the above command the USRP 
will fire a one-time burst of 7 pulses with 1ms interval time and a width
of 1usec.

External Dependencies
---------------------
Following external dependencies are used and included in the 
external_projects folder:
 * json-c v0.9, Copyright (c) 2004, 2005 Metaparadigm Pte Ltd

Contact
-------
Please report bugs to <zefir.kurtisi@neratec.com>.


References
----------
[1] https://www.ettus.com/product/details/UN200-KIT
[2] https://www.ettus.com/product/details/XCVR2450
[3] http://gnuradio.org/redmine/projects/gnuradio/wiki
[4] http://code.ettus.com/redmine/ettus/projects/uhd/wiki
[5] http://files.ettus.com/uhd_docs/manual/html/build.html