[[Include(WikiToC)]]

== Spectrum visualization with Fosphor ==

=== Description ===

This tutorial illustrates use of [https://archive.fosdem.org/2015/schedule/event/rfnocfosphor/attachments/slides/804/export/events/attachments/rfnocfosphor/slides/804/fosdem2015_rfnoc_fosphor.pdf RFNoC Fosphor block for spectrum visualization]. RFNoC Fosphor block is the FPGA accelerated version of [https://projects.osmocom.org/projects/sdr/wiki/Fosphor gr-fosphor (CPU/GPU version)]. As any other RFNoC blocks, RFNoC Fosphor can be instantiated on 3rd generation USRP devices, and can be used in conjunction with gnuradio-companion(GRC) on the host computer. This tutorial demonstrates GRC RFNoC Fosphor application on USRP-2974 in [wiki:Hardware/sdr/usrp2974 COSMOS testbed]. 

Running a GRC application on a testbed node requires using graphical user interface(GUI) on the node. This tutorial shows how to setup a MobaXterm session with X11 forwarding in order to access the GRC GUI. The node image used in this tutorial also has a desktop environment and chrome remote desktop server installed, enabling platform-independent remote desktop access.

=== Prerequisites ===
In order to access the test bed, create a reservation and have it approved by the reservation service. Access to the resources is granted after the reservation is confirmed. Please follow the process shown on the COSMOS [wiki:GettingStarted getting started] page to get started. 

=== Resources required ===
1 USRP-2974 (sdr2-md1 or sdr2-s1-lg1) on COSMOS SB1 or COSMOS bed.
=== Tutorial Setup ===

Follow the steps below to gain access to the [wiki:/Architecture/Domains/cosmos_sb1 sandbox 1 console] and set up nodes with appropriate images. 
 1. If you don't have one already, sign up for a [https://www.cosmos-lab.org/portal-2/ COSMOS account]
 1. [wiki:/GettingStarted#MakeaReservation Create a resource reservation] on sandbox 1
 1. [wiki:/GettingStarted#LogintoyourReservation Login] into sandbox 1 console (console.sb1.cosmos-lab.org) with an SSH session. SSH session for COSMOS SB1 with MobaXterm can be setup as shown, with remote host = console.sb1.cosmos-lab.org, and username = your COSMOS username. X11 forwarding is enabled to access GUI.
[[Image(mobaxterm_sb1_session.JPG, width=600px)]]
 1. Make sure all the nodes and devices used in the experiment are turned off:
{{{#!shell
omf tell -a offh -t sdr2-s1-lg1  
}}}
 1. Load rfnoc_fosphor_uhd4_4.ndz on sdr2-s1-lg1.  
{{{#!shell
omf load -i rfnoc_fosphor_uhd4_4.ndz -t sdr2-s1-lg1
}}}
 1. Turn the SDR on and check the status
{{{#!shell
omf tell -a on -t sdr2-s1-lg1
}}}
{{{#!shell
omf stat -t sdr2-s1-lg1
}}}
 1. Log into the SDR with -Y for X11 forwarding
{{{#!shell
ssh root@sdr2-s1-lg1 -Y
}}}



[[CollapsibleStart(Configure MobaXterm for node access)]]
Another way to access the SDR is to set up a MobaXterm session directly to the SDR, with the console as the jump host. As shown in the pictures below, for the SSH session, use remote host = sdr2-s1-lg1.sb1.cosmos-lab.org username = root. Enable X11 forwarding in advanced settings. Set up jump host in network settings, with gateway host = console.sb1.cosmos-lab.org, username = your cosmos username. 

[[Image(nodessh.JPG, width=600px)]]
[[Image(jumphost.png, width=600px)]]

The following is displayed when this session runs.
{{{#!shell
     ┌────────────────────────────────────────────────────────────────────┐
     │                        • MobaXterm 20.6 •                          │
     │            (SSH client, X-server and networking tools)             │
     │                                                                    │
     │ ➤ SSH session to root@sdr2-s1-lg1.sb1.cosmos-lab.org              │
     │   • SSH gateway     : ✔  (myusername@console.sb1.cosmos-lab.org)   │
     │   • SSH compression : ✔                                            │
     │   • SSH-browser     : ✔                                            │
     │   • X11-forwarding  : ✔  (remote display is forwarded through SSH) │
     │   • DISPLAY         : ✔  (automatically set on remote server)      │
     │                                                                    │
     │ ➤ For more info, ctrl+click on help or visit our website          │
     └────────────────────────────────────────────────────────────────────┘

Last login: Fri Dec 11 04:49:36 2020 from 10.106.0.21
root@sdr2-s1-lg1:~#

}}}
[[CollapsibleEnd]]

=== Experiment Execution ===


==== RFNoC Fosphor FPGA image ====
Custom USRP-2974 FPGA image /usr/local/share/fosphor_bit/usrp_x310_fpga_XG.lvbitx will be used for this tutorial. This can be verified by looking at the RFNoC blocks as follows.
[[Image(usrp_probe_fosphor.PNG, width=600px)]]

==== Run rfnoc-fosphor GRC application ====
[[Image(launch_grc_fosphor.PNG, width=600px)]]

[[Image(rfnoc_fosphor_grc.jpg, width=800px)]]

Set center frequency, bandwidth and run the application to see spectrum display.

[[Image(rfnoc_fosphor_display.jpg, width=800px)]]