ASTR 735: Radio Astronomy
Using your SDR

 

Now that you have your shiny new SDR and antenna, its time to try it out and see what it can do. First, we'll start off running a graphical interface that allows you to tune it across its entire frequency range.

If you have a Mac or Linux computer, navigate to GQRX and follow the installation instructxions. If you have a windows computer (which I don't so I can't offer much advice here), there are several options for similar packages. One is CubicSDR which is available from the nooelec SDR download tab at the website above. There appear to be several other options based on google/youtube.

Basically these programs are plug-and-play. Simply connect the antenna on the coax end and plug the USB end into your computer, then start up the program. It should auto-configure but if you have problems, google is your friend and here is my gqrx I/O setting.

I encourage you to simply explore - its fairly intuitive and you won't break anything! First try tuning in to a commercial FM radio station from about 87 to 108 MHz. Here's what it looks like on my computer.

An explanation of the various windows and settings are at the GQRX tips and tricks page. Change the bandwidth over which you receive the signal. What happens if you change from FM to AM and why? Once you've had enough FM radio, move up the dial and see if you can find any signals from the HNL airport tower. These will be AM and lie in the range 118-338 MHz according to radioreferennce.com. (I'm on the windward side and the signals are very faint but I hope they are better town side.) Find a weather channel at 162.4 MHz (AM).

Unfortunately emergency services (police, ambulance, etc) has moved to a different "P25" format that we can't listen to using these tools but there are plenty of other signals as you scroll across the band. Many of these are digital, however, so you won't hear anything (but let me know if you find something). If you want to see an example of how the signals here can be decoded, google "dump1090" for airport tracking software (I'll demonstrate this next time we're back in class).

Take me back to the class website