Sampling a Sinusoid

For this tutorial, use the Y option when calling doing SSH. First you are going to want to resolve a space on SB3 before continuing on with the tutorial.

ssh -Y username@sb3.orbit-lab.org

Check the current status of the nodes:

omf stat -t all

If one or both of the nodes are in a powered on state turn them off with:

omf tell -a offh -t all

Next to get the latest updated image with updated gnuradio libraries enter:

omf load -t all -i ubuntu-14-04-64bit-sdr-full.ndz

The nodes will be in an off state after imaging. Turn them back on and enter:

ssh -Y root@node1-1

*Note if this doesn't work the first time, the node might 'hiccup' because they recovering from imaging. Wait a few seconds and try again.

Enter on the command line:

gnuradio-companion &

Once opened configure the following with the necessary blocks:

Compile and run the configuration and you will get the following output with a slider to adjust the frequency of the input sinusoid.

Determining Frequencies of Multiple Sinusoids

In the case of when you receive a signal that is made of multiple sinusoidal signals that are summed together and you would like to know the frequencies of the individual signals that make of the signal.

Below is what the received signal looks like:

From this, you wouldn't be able to glance and determine the signals that make it up. But if you view the signals FFT as seen below you can see impulses at the frequencies that make up this signal: