If you’re familiar with the LabVIEW software, there is now an RTL-SDR interface called SDRLab by Beküldte Andris. The software is able to capture the I/Q data from the RTL-SDR, and with that you can do educational experiments in LabVIEW, which is great for students. The author has also implemented a FM demodulator.
Dr. Carles Fernandez-Prades, Dr. Javier Arribas and Dr. Pau Closas have published an academic paper showing how they were able to implement an RTL-SDR based GNSS (Global Navigation Satellite System) receiver in software.
What they have done is use their open source GNSS software receiver program with a RTL-SDR connected to an active GPS antenna. An active GPS antenna requires DC power to be passed to the LNA in the GPS antenna through the antenna connection, so a Bias-T network is required to ensure DC power does not enter the RTL-SDR dongle.
More information can be found on their webpage here.
D-STAR or Digital Smart Technologies for Amateur Radio is a digital voice and data protocol used in amateur radio. I was tweeted a link earlier which shows how the RTL-SDR can decode D-STAR text messages and headers (link is in Italian but Google translate can help, and the pictures show more than enough information). By using SDRSharp and stereo mix you can tune to a D-STAR signal, and pass the audio to a command line based decoding program (dstar.exe) which can be downloaded from the above link, which will then decode D-STAR text messages.
Here is also an older video showing D-STAR decoding with HDSDR in action.
Wavesink is a new SDR Android App, which allows your RTL2832U based dongle to receive FM radio with RDS, Digital Audio Broadcast Radio (DAB) and VHF band Digital Radio Monodial (DRM+). DAB+ support is also to be released by next week, and a station memory will also be added in a future release.
The app is currently in beta development, and only the trial version is released, which will allow you to use the app for 5 minutes at a time. They indicate that the commercial version will be out soon.
To use this with your Android device, you will need a USB OTG (On the Go) cable, and your device must support USB host mode, which most Android devices above 3.1 should support.
I gave the app a quick spin in FM mode, and found that the interface was a little clunky, but the app worked fine, and the FM and RDS signals were decoded correctly.
Oona has written on her blog www.windytan.com about how she used an RTL-SDR to listen in on those wireless devices that are given out at some restaurants and cafes to notify you when your food is ready.
While at a local burger chain she found a label on the back of the device given to her which specified the radio frequency used by the device. By tuning to that frequency with her RTL-SDR, she discovered that the device uses the POCSAG protocol, which is the same protocol that is used by pagers. She then decoded the data packet and found that it contains the device address, which is used to notify the correct device.
Blogger OZ9AEC has written a post on his blog showing how he made a 2-channel AIS receiver using the RTL-SDR, GNU Radio and GNUAis. AIS is a radio protocol used by boats to broadcast their position and speed which is then used to create a type of radar system to help avoid collisions. AIS signals are transmitted periodically on one of two channels. Two channels are used to improve capacity and help avoid interference if two signals from different boats are broadcast at the same time.
Before this, most AIS receiver implementations we’d seen that used the RTL-SDR received only on a single channel. OZ9AEC’s GNU Radio program receives on both channels simultaneously like a commercial AIS receiver does and is thus a better receiver. He eventually plans to get this receiver to run on a Beaglebone.
See his post for instructions and to download the GRC files.
Update: Another AIS decoder known as gr-ais is also capable of 2 channel AIS, and bristromat from Reddit has written a tutorial on setting it up and running it with OpenCPN.
Ettus Research, creators of the high end USRP software defined radios have posted a well produced video on YouTube showing off various applications that an SDR can perform. In the video they go through and explain FM Radio, APRS, AIS, Multi-Channel Decoding, Pagers, ADS-B/Mode S, ACARS, RADAR Analysis and 802.11a decoding.
For these apps they use a USRP B200, which costs $675 USD. Most of the applications shown should also be compatible with other SDRs, such as the cheaper HackRF and BladeRFs. Even the cheap RTL-SDR will at least work for FM Radio, APRS, AIS, Pagers, ADS-B and ACARS. Of course, the USRP is still probably the most top of the line SDR available.
Update: The video creator, Balint has also uploaded a video on his personal YouTube channel which is a longer presentation of the topics that were briefly discussed in the USRP video.
Over on YouTube user adsbrus shows us his project which is an in car ADS-B aircraft tracker using a Raspberry Pi mini computer and an RTL-SDR. The system uses an LCD screen mounted where the car radio usually is to show aircraft identifier, altitude, and speed information in text.
