This document is not meant to be a complete tutorial on GnuRadio, but to help you start to play around GnuRadio on Orbit Sandbox and to share my experiences on exploring this wonderful toy. 


== What you need to know? ==
 

Before you jump into GnuRadio on Orbit, you should have a clear picture on what GnuRadio is. An excellent starting reading material is Eric Blossom’s Exploring GNU Radio:[http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html]. Eric is the founder of the whole GNU Radio project. Make sure you understand the data flow paths, including the receive path and the transmit path, understand the role that the USRP plays. USRP is a flexible USB device that connects the PC to the RF world. USRP has one motherboard, which connected to the PC via USB 2.0 and can support up to four daughterboard. Each daughterboard has RF ends that can either transmit or receive waveform from the air. There are different types of daughterboard supporting a variety radio range, e.g. for example, Flex400 supports both transmit and receive in the frequency band 400MHz to 500 Mhz. You need to refresh your memory on the sample theory. 

To program GnuRadio, you need to build a radio by creating a graph (as in graph theory) where the vertices are signal processing blocks and the edges represent the data flow between them. The signal processing blocks are implemented in C++. The graphs are constructed and run in Python. If you are not familiar with C++ or Python, find a tutorial online and learn it. 


== What is on Orbit Sandbox5? ==

Sandbox5 consists of two nodes, i.e. node1-1 and node1-2. Each individual node is connected to one Gnuradio motherboard, and each motherboard in turn connects to two Basic RX and two Basic TX as show in the following picture.