Thank you to José Carlos Rueda for submitting his project called "a-radio: a web virtual reality radio power spectrum analyzer". The idea behind the project is to first use an RTL-SDR together with rtl_power and heatmap.py to generate a heatmap image of the RF spectrum. This image is then projected into a 3D 360 degree view and hosted on a web server via José's script for the a-frame VR web framework, allowing the heatmap to be viewed with a virtual reality (VR) smartphone headset. José' recommends using a cheap VR headset like Google Cardboard which can be used with your Android smartphone.
José notes that the project is just a proof of concept, but he hopes to inspire future work around the combination of RF and VR.
Over on his YouTube channel Tech Minds has recently released a new video demonstrating how to use an RTL-SDR portably via an Android tablet and an OTG cable. In the video he goes through the various Android software options available including general receiver software such as RF Analyzer (free) and SDR Touch (£5.99) as well as AVARE ADSB for ADS-B aircraft reception. He goes on to demonstrate each program in action.
Portable RTL - SDR Software Defined Radio with Android
Android developers have a new RTL-SDR driver wrapper available to use called "RTL-SDR CP Driver". This driver by Evgeni Karalamov is designed to have an additional feature over the current Android RTL-SDR drivers in that it implements client application permission management. The overview reads:
RTL-SDR CP Driver utilises the rtl-sdr codebase and is meant to be kept in sync with the developments there. The provided interface mirrors the functionality of rtl_tcp in an Android way. Instead of via a TCP socket, the communication is carried out through file descriptors returned by a ContentProvider.
Since some potentially sensitive information could be captured through the SDR receivers, like indications of the device location, the RTL-SDR CP Driver implements permission control similar to that of the Android framework. Prior to accessing receivers, client applications have to ask the user for permission to access the driver by starting the driver's permission flow via startActivityForResult. Once the user grants access, their answer is remembered and they are not prompted again. The user has the ability to later revoke the permission from the driver's UI, accessible via the Android launcher.
SignalID is a new Android app available on the Google Play store which offers Shazam-like radio signal identification. Just like Shazam does for music, you simply tune to an unknown signal with your SDR, play the raw audio, and let the app listen to it for five seconds. It then computes an audio fingerprint and checks to see if it knows what the signal is.
We tested the app but unfortunately we were unable to get it to detect any signals. Please write in the comments if you have success. As it uses audio fingerprinting, the app is probably highly dependant on choosing the correct demodulator (AM/FM/SSB etc), and also the tuning and signal quality. We note that most of the signal sources seem to come from our sister site the Signal ID Wiki. Searching through the wiki is a good alternative if automated solutions fail.
However the the app is new and we expect improvements and more signals to be added in the future. Currently the following signals can be recognized:
In political news 75 year old Buffalo protestor Martin Gugino has been generating controversy due to a video of him being pushed to the ground by a police officer, then subsequently lying motionless while bleeding from the head and being ignored by other officers.
Trump's tweet reads "Buffalo protester shoved by Police could be an ANTIFA provocateur. 75 year old Martin Gugino was pushed away after appearing to scan police communications in order to black out the equipment @OANN
I watched, he fell harder than was pushed. Was aiming scanner. Could be a set up?".
We're not entirely sure where this theory from OAN came from as there is no need to get so close in order to listen to police radio communications, since if unencrypted, they can be listened to from anywhere in the city. It's also unclear as to what microphones police would be using, and how these could be "skimmed" with an RTL-SDR. As for blacking out the equipment, an RTL-SDR cannot transmit so it would be impossible to use to jam the radios. An illegal jammer could be used after scanning, but police frequencies are already well known anyway, and there would be no need to scan for them so close even if low power comm links were used.
The video also shows that he appears to be filming police badge numbers with his phone before he was pushed, so it is unlikely that he was using an RTL-SDR and running SDR Touch at the same time as the camera app. No cables, antenna or dongle can be seen in the video either.
EDIT: Please note that this is not a political post or blog. We only post it to highlight the severe lack of understanding that can surround SDR and our technical hobbies. Comments inciting violence against protestors or anyone are NOT OK, and will be removed. Please keep discussions technical and civil in nature.
Back in February 2019 we first posted about Radwave, an Android SDR App for RTL-SDR dongles. It has some interesting features not found in other Apps like the ability to easily zoom, pause and rewind the spectrum at any time.
The author has decided to make use of these spectrum browsing enhancements by providing access to full SETI (Search for Extraterrestrial Intelligence) spectrum data sets which can be browsed via the app for a small fee. From a post on our forums the author of Radwave writes:
This data comes from Breakthrough Listen. These datasets are quite large, and Radwave does all the bulk downloading, processing and hosting of the datasets, allowing you to easily navigate your way through the spectrum. If you find something cool, you can tag it and share it.
Currently there are three datasets available in the first bundle ($10 USD): Voyager 1 and two 'Oumuamua collections (surveys of the the first observed interstellar object in our solar system). The data is big, and is hosted in AWS. That gets pricey, so I'll be adding more collections to this first bundle as funding permits. If there are certain datasets you're interested in seeing, definitely let me know.
Over on YouTube Ian Grody has uploaded two videos demonstrating an early alpha project that he is working on which combines Android Tasker with RTL-SDR frequency scanning. Tasker is an Android automation app which allows users to define a task based on a context. For example, you could set it to turn on WiFi and open an app (task) every time you arrive at a certain location (context).
Ian's idea is to create a Tasker application that performs an rtl_power scan with the RTL-SDR whenever a certain context is detected. The current version of his Tasker app can perform an rtl_power scan over a certain frequency range at the tap of a button, detect the strongest frequencies in that range, and plot a marker at the current location on a Google map which displays the strongest frequency detected at that location. He eventually hopes to turn the application into a wardriving application that will scan 27 MHz - 1.7 GHz for active signals while on the move.