Changes between Initial Version and Version 1 of Tutorials/k0SDR/Tutorial01a

Timestamp:

Jun 12, 2015, 4:07:16 PM (9 years ago)

Author:

nilanjan

Comment:

—

Tutorials/k0SDR/Tutorial01a

@@ +1 @@
+== Simple radio example with GNURADIO benchmark scripts ==
+
+[[TOC(Tutorials/k0SDR*)]]
+
+=== Description ===
+This short example will utilize GNU Radio benchmarks scripts to transfer packets over a radio link between two nodes.
+
+=== Hardware / Software Resources utilized ===
+ 1. Grid nodes with a USRP2 connect via Ethernet.
+ 2. ''ubuntu-14-04-64bit-sdr.ndz'': disk image loaded onto nodes. This image has all the precompiled - software required to configure the USRP2s and all the required GNU Radio software libraries. The USRP2's interface with the node is already configured.
+ 3. GNU Radio - software library to create SDR. Click here for [http://gnuradio.org/redmine/projects/gnuradio/wiki/WhatIsGR additional info].
+ 4. USRP2 - hardware platform for SDR. Click here for [http://gnuradio.org/redmine/projects/gnuradio/wiki/Hardware#Ettus-Research-USRP-Devices more info].
+
+=== Set up ===
+ * Before you can access the testbed, you need to [https://www.orbit-lab.org/schedule make a reservation] and get it approved by the  [wiki:Documentation/Scheduler reservation service]. After receiving the reservation's confirmation (approval) email:
+
+ * [[CollapsibleStart(Login into reserved domain: ssh username@grid.orbit-lab.org)]][[Include(Documentation/Short/Login)]][[CollapsibleEnd]]
+ * [[CollapsibleStart(Load an image on the nodes: omf load -i ubuntu-14-04-64bit-sdr.ndz -t node19-19\,node20-20)]] [[Include(Documentation/Short/LoadImage)]][[CollapsibleEnd]]
+ * [[CollapsibleStart(Turn on the nodes: omf tell -a on -t node19-19\,node20-20)]] [[Include(Documentation/Short/TellOn)]][[CollapsibleEnd]]
+
+
+
+=== Running GNU Radio benchmark scripts ===
+ * From two different terminals ssh into node19-19 and node20-20. Then change to the benchmark script's directory. For this example use node19-19 as the receiver and node20-20 as the transmitter.
+{{{
+username@console.grid:~$ ssh root@node19-19
+root@node19-19:~# cd gnuradio/gr-digital/examples/narrowband
+}}}
+
+ * Start the receiver benchmark script
+{{{
+root@node19-19:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_rx.py -f 2.41G -m bpsk --rx-gain 10 -r .250M
+}}}
+ The parameters passed to the receiving script are as follows:
+
+  '-f 2.41G' ------> the carrier frequency to 2.41GHz
+
+  '-m bpsk'  ------> the modulation mode to binary phase shift keying.
+
+  '-r .250M' ------> the bitrate to 250000 bits /sec
+
+  '--rx-gain 10' -->  receiver front end gain to 10dB.
+
+
+ * Start the transmitter benchmark script
+{{{
+root@node20-20:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_tx.py -f 2.41G -m bpsk --tx-gain 10 -r .250M --tx-amplitude .5
+}}}
+ The values passed to the transmitting script must be similar to the receiver script with the exception of radio specific parameters.
+
+  '--tx-gain 10' -->  transmitter front end gain to 10dB.
+
+
+=== Outputs from transmitter and receiver ===
+ * Once a successful radio link has been established, the transmitted packets are received, decoded and verify by the gnu scripts.
+ A sample output of the receiver is shown below.
+{{{
+root@node19-19:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_rx.py -f 2.41G -m bpsk --rx-gain 10 -r .250M
+linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.008.002-86-g566dbc2b
+
+Using Volk machine: avx_64_mmx_orc
+-- Opening a USRP2/N-Series device...
+-- Current recv frame size: 1472 bytes
+-- Current send frame size: 1472 bytes
+ok =  True  pktno =    1  n_rcvd =    1  n_right =    1
+ok =  True  pktno =    2  n_rcvd =    2  n_right =    2
+ok =  True  pktno =    3  n_rcvd =    3  n_right =    3
+ok =  True  pktno =    4  n_rcvd =    4  n_right =    4
+ok =  True  pktno =    5  n_rcvd =    5  n_right =    5
+ok =  True  pktno =    6  n_rcvd =    6  n_right =    6
+ok =  True  pktno =    7  n_rcvd =    7  n_right =    7
+ok =  True  pktno =    8  n_rcvd =    8  n_right =    8
+ok =  True  pktno =    9  n_rcvd =    9  n_right =    9
+ok =  True  pktno =   10  n_rcvd =   10  n_right =   10
+ok =  True  pktno =   11  n_rcvd =   11  n_right =   11
+ok =  True  pktno =   12  n_rcvd =   12  n_right =   12
+ok =  True  pktno =   13  n_rcvd =   13  n_right =   13
+ok =  True  pktno =   14  n_rcvd =   14  n_right =   14
+ok =  True  pktno =   15  n_rcvd =   15  n_right =   15
+ok =  True  pktno =   16  n_rcvd =   16  n_right =   16
+ok =  True  pktno =   17  n_rcvd =   17  n_right =   17
+ok = False  pktno =   18  n_rcvd =   18  n_right =   17
+^C
+}}}
+
+ For the transmitter output should be similar to this:
+{{{
+root@node20-20:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_tx.py -f 2.41G -m bpsk --tx-gain 10 -r .250M --tx-amplitude .5
+linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.008.002-86-g566dbc2b
+
+Using Volk machine: sse4_2_64_orc
+-- Opening a USRP2/N-Series device...
+-- Current recv frame size: 1472 bytes
+-- Current send frame size: 1472 bytes
+................................................................................................................................................................................................................................................................................................................................................................................................................................................^C
+}}}
+
+=== Troubleshooting ===
+ * If the receiving script is not showing any activity, it most likely the script parameters need to be tweaked. USRP radios (any radio in general) are not made the same due to variations in HW component quality and tolerances. Each radio has it's own sweet spot for best transmission and reception. For different USRPs on the grid (or other sandboxes) raising or lowering gains, amplitude, and/or other parameters is required to establish a solid radio link.
+As an example if the gains are set too hi, signal can become saturated, clipped and distort at the analog-digital interface. If the gains are set too low, the signal will just blend in to the noise floor especially for simple modulation schemes. For a description of other parameters, use the --help command get a listing.
+{{{
+root@node19-19:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_rx.py --help
+}}}
+