Category: Mobile

SDR ProTrack: Android Radio Direction Finding with RTL-SDR and Directional Antennas

Thank you to Alexandre Gellibert for writing in and sharing his new Android App, "SDR ProTrack." SDR ProTrack is a radio direction-finding app that uses an RTL-SDR and directional antenna to determine a bearing towards a transmitter.

Interestingly, Alexandre notes that this app was initially developed to track Asian hornets, a bee-killing pest. With hornet tracking, a miniature RF transmitter is attached to a caught hornet, and the hornet brings it back to the nest. RF tracking techniques can then be used to find the nest.

It's possible to determine the bearing toward a transmitter by using a receiver such as an RTL-SDR paired with a directional antenna like a Yagi. Directional antennas have high sensitivity in one primary direction and significantly lower sensitivity in all others. By rotating the antenna until the strongest signal is identified, you can establish the precise bearing angle. Typically, following this bearing will guide you directly toward the signal's origin.

Alexandre wrote in an email to us the following:

Just to let you know we just launched a new Android app compatible with RTL-SDR dongles (though mostly tested on RTL-SDR v4).

App is free to use. Advanced features (like Compass to point the signal potential source) are for premium users.

It's plug and play, easy to use, much more user friendly than SDR++.

Any feedback is really appreciated :)

If you want to know more about the project or the 2 developers behind it (we develop it in France to be able to track asian hornets that kill all the bees), please feel free to contact us.

And the Android page describes SDR ProTrack in the following way:

Unlock the power of radio tracking with SDR ProTrack!
Transform your Android smartphone into a signal-tracking powerhouse using an RTL-SDR dongle and a directional antenna. Affordable, versatile, and perfect for enthusiasts, researchers, pros or anyone tracking signals—like Asian hornets or wildlife.

★ Key Features ★

• Automatic RTL-SDR dongle recognition and connection (free)
• Spectrum Visualization (Free): View signal shapes in the frequency domain effortlessly.
• Compass (Premium): Pinpoint the strongest signal direction with precision.
• Signal Strength Display (Premium): Monitor signal power with an intuitive interface.
• Custom Settings (Premium): Adjust bitrate, sample rate, and frequency sensitivity to your liking.

★ Requirements ★

• Requires an external RTL-SDR device.
• Check compatibility: https://osmocom.org/projects/rtl-sdr/wiki

Need an RTL-SDR dongle, emitters, receptors, or antennas?
Visit our website: https://www.intuite.fr/en_GB/pricing

★ About Us ★

Intuite is a company specialized in locating Asian hornet nests. We developed SDR ProTrack to provide a robust, cost-effective solution for radio signal tracking, combining innovative technology with our expertise in signal detection.

★ Open Source Community ★

Join our mission to advance radio tracking! Our open-source library, RTL-SDR Bridge Android Lib, powers SDR Pro Track.
Contribute to development, report issues, or explore the code at https://github.com/alexandreGellibert/RTL-SDR-Bridge-Android-Lib.
Support our work and help shape the future of signal tracking!

Download SDR ProTrack today and start tracking signals like a pro!

SDR ProTrack Screenshot
SDR ProTrack Screenshot

DragonOS: LTE IMSI Sniffing using the LTE Sniffer Tool and an Ettus X310 SDR

DragonOS creator Aaron recently uploaded a video on YouTube showing how to capture IMSI data from an LTE-enabled phone by using the open-source LTE sniffer tool and Ettus X310 software-defined radio.

In the video, Aaron uses a simulated environment involving a Signal SDR Pro to simulate the LTE cell phone, a B205 Mini operating as the eNodeB (base station), and an Ettus X310 SDR for the actual LTE sniffing. The SRSRAN software running on DragonOS is used to simulate the LTE network environment.

Aaron goes on to show how the LTE sniffer software passively decodes the physical downlink control channels and captures IMSI numbers from user cell phones.

An IMSI is a unique identifier associated with a cell phone user's SIM card. IMSI sniffing cannot be used to listen to or decode voice, text, or data as they are all encrypted. However, bad actors can use IMSI sniffing to track the movement of devices/people.

DragonOS Noble Sniff + Passively Capture LTE IMSI (x310, b205mini, SignalSDR Pro)

Spectrum SDR: New Android App for RTL-SDR FM/AM Decoding and Spectrum Viewing

Thank you to James Mainwaring of Knowle Consultants for submitting news of the release of his latest Android app called "Spectrum SDR" for RTL-SDR. Knowle Consultants have previously released a range of RTL-SDR Android apps for FM, Airband, Ham FM and ADS-B reception. The new Spectrum SDR app has a spectrum viewer, as well as the ability to demodulate AM and FM signals.

James writes the following about Spectrum SDR:

This application is about having a bit of fun with those amazing little RTL-SDR dongles, whilst listening to AM/FM radio signals. It's nice and easy to use so why not give it a try?

- Covers the full frequency range of your RTL-SDR dongle
- AM and FM, wide and narrow
- FFT display
- Sample rates 240000 Hz to 2160000 Hz
- Bias tee control
- 75 presets over 5 pages
- Gain controls
- Squelch
- Built-in help

Spectrum SDR Android App Screenshot
Spectrum SDR Android App Screenshot

Updates to Knowle Consultants RTL-SDR Android Apps

Thank you to James Mainwaring, who wanted to write in and share that he has made some updates to his suite of Android apps, which include ADS-B Radar (RTL-SDR), FM Radio (RTL-SDR), Airband Radio (RTL-SDR) and HAM FM Radio (RTL-SDR).

James notes that all his apps now support the ability to connect to an rtl_tcp instance running remotely. He also writes that the ADS-B app now automatically downloads and displays photos of the aircraft being tracked via the API connection to planespotters.net.

ADS-B Radar (RTL-SDR) Android App now shows aircraft images.

Setting up an ADS-B Radar in a Vehicle Android Head Unit

Over on YouTube channel 'TAKEAPART' has uploaded a short video showing how he tracks aircraft via an RTL-SDR Blog V3 dongle and his car's Android head unit. The head unit is capable of running the ADS-B Radar App available on the Google Play store.

Once the app is installed, it's a simple matter of plugging in the RTL-SDR Blog V3 unit and running the app to start tracking aircraft.

How to ADS-B Radar in the CAR - Tracking Planes...

A KrakenSDR to TAK Interface Converter

Thank you to RTL-SDR.COM reader Aaron, who recently found a Kraken-to-TAK converter made by "SignalMedic" and "dngrssgnls" which converts the KrakenSDR bearing output data to "Cursor on Target" (COT) or XML format, allowing common TAK interfaces to read and display the data. Currently the converter allows a line of bearing to be displayed in a TAK app, with arbitrary length. The converter consists of a single json file for Node Red. The GitHub readme reads:

Convert data from a Kraken SDR to TAK endpoints

The software will parse information collected by Kraken, convert to COT and XML and send to common TAK interfaces. The length of the line is arbitrary. The line is 6km long, but has no correlation besides bearing to the transmitter. Intersecting bearing lines are necessary for determining the geolocation of a transmitter.

Planned improvements include:

  • Button for persisting the current line and generating a new UID
  • Work on filtering out by DOA Angle node
  • Dashboard for easier updating of Kraken and TAK endpoints
  • Simplified deployment

We note that most TAK apps may be a little limited for direction finding purposes as they cannot calculate bearing intersections over time, or calculate a bearing grid like the KrakenSDR Android app, and KrakenSDR online web mapper does. However, often a single line of bearing is enough information, especially if there are multiple distributed units contributing bearing data.

If you weren't already aware, KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding. It can be purchased on Crowd Supply.

TAK (Tactical Assault Kit) is software used by the military and other organizations for visualizing geospatial information such as enemy and friendly positions. Civilian versions of TAK also exist, such as ATAK for Android. Previously we posted about how ATAK has the ability to plot aircraft positions via an RTL-SDR receiving ADS-B.

KrakenSDR bearing data displayed on a TAK app.

SDR++ Android APK now supports the RTL-SDR Blog V4

Thank you to SDR++ developer Ryzerth who has let us know that RTL-SDR Blog V4 support has recently been added to the nightly build of the APK. With this release, Android is now fully supported by the RTL-SDR Blog V4 via Martin Marinov's SDR Driver app (which many SDR applications connect to), SDRAngel and now SDR++.

A reminder: With SDR++ you may find that you will need to close (using the task manager on Android) and reopen the app a couple of times before it will detect an RTL-SDR dongle. 

If you enjoy SDR++ please consider supporting the developer on Patreon.

Blog V4 Receiving Broadcast FM on Android with SDR++
Blog V4 Receiving Broadcast FM on Android with SDR++

SignalsEverywhere: Review of SDR++ on Android

In our last post we mentioned that a 'pre-release' public version of SDR++ for Android was recently released. Now over on the SignalsEverywhere YouTube channel Sarah has uploaded a new video where she reviews and demonstrates the new SDR++ Android App. 

In the video Sarah demonstrates how to connect and start a SDR, shows SDR++ in action, then tests listening to NOAA weather audio reports, Inmarsat reception via the bias tee support, P25 and broadcast FM. She also shows how it's possible to use the split screen multitasking feature on Android to send audio from SDR++ into APRSdroid for APRS decoding.

She goes on to show how to fine tune the screen PPI resolution for different sized devices, and how to set up multi-VFO listening on the HF bands. Next, she compares the audio decoding quality between SDR++, SDRTouch and RFAnalyzer. Finally she shows that a HackRF running at a wideband 20 MHz of bandwidth can run smoothly. 

The Android SDR App That Beats Them All! Supports RTL-SDR Airspy HackRF and Many More!