Tagged: rtl2832

A Portable RTL-SDR and Raspberry Pi Based ADS-B Alarm for Drone Pilots

Pilots of RC planes and drones need to be aware of the area they are flying in, to make sure that they stay well out of the path of manned aircraft. However, this can sometimes be difficult with aircraft like police helicopters that could rapidly show up anywhere. Drones typically do not have ADS-B transmitters due to size/weight and price, but it is still possible for drone pilots to use ADS-B receivers to make their flying safer.

Over on YouTube user xjet has come up with a solution involving the use of a portable ADS-B alarm for drone pilots. The ADS-B receiver consists of a 3D printed enclosure containing a Raspberry Pi Zero 2W, LCD screen and an RTL-SDR dongle connected to an ADS-B whip antenna. xjet notes that when his code and 3D enclosure are finalized, he will release the design for free as open source over on http://www.rcmodelreviews.com.

The idea behind the ADS-B alarm appears to be that drone pilots will receive an alarm when they are within the vicinity of an aircraft. Assuming the drone is not too far away from the pilot (as rules specify drones must be flown within visible distance) the alarm being next to the drone pilot should be sufficient. xjet notes that we cannot rely on live ADS-B aggregation websites like FlightRadar24 due to their censorship of certain aircraft like police, military and some private jets, or due to possible lack of coverage, so a local receiver will be a better solution.

After more than two years of development and testing the ADSB alarm for RC plane and drone flyers is almost ready to go. I will be posting the full build details including an SD-Card image, source code, wiring diagrams and STL/DWG files for the case to the RCModelReviews website in the next week or so. This is a totally open-source project which I give freely to the hobby community so as to increase the levels of safety associated with our activities.

It is through the use of this technology that we can show how taking practical steps towards ensuring safety is every bit as important (if not more so) than blindly following regulations written by those who have probably never even flown an RC plane or drone themselves.

This changes everything (I'm not kidding!)

Guglielmo FM and DAB Receiver Software Updated to Version 0.5

Thank you to Marco, the programmer of Guglielmo for letting us know that his software has recently been updated to Version 0.5.

Guglielmo is a Linux, Windows (and in this recent update x86 MacOS) based RTL-SDR FM and DAB tuner software that supports SDRs including the RTL-SDR, Airspy, SDRplay, HackRF and LimeSDR. It is designed to be an easy to use program designed for media users, rather than hobbyist technical users.

Regarding the release of Version 0.5, Marco writes:

This release sports full mac (x86 only, sorry) and windows installers, DAB and FM scans and a preset editor.

Guglielmo: Screenshot of the DAB Interface

PySDR Guide on DOA & Beamforming

PySDR is a free online textbook created by Dr. Marc Lichtman which explains many digital signal processing (DSP) and software defined radio (SDR) concepts in a clear, concise and easy to understand way. The guide includes multiple images and animations, as well as Python code examples.

In a recent update, Dr. Lichtman has begun adding a new chapter on Direction of Arrival (DOA) and Beamforming which are core concepts for coherent radio direction finding devices like our KrakenSDR. As with the other chapters the guide is made easy to understand with many images and animations.

The introduction reads:

Direction-of-Arrival (DOA) within DSP/SDR refers to the process of using an array of antennas to estimate the DOA of one or more signals received by that array. Once we know the direction a signal of interest is arriving from, we can isolate it from other signals/interference/jamming.

It is just like isolating a signal in the frequency domain by filtering it, except we are now working in the spatial domain (you can certainly combine both!).

We typically refer to the antennas that make up an array as elements, and sometimes the array is called a “sensor” instead. These array elements are most often omnidirectional antennas, equally spaced in either a line or across two dimensions.

DOA is a subset of beamforming techniques, where as the receiver, we are trying to steer a beam (our receiver’s antenna beam) towards the direction of an emitter. We may also steer a beam blindly across a wide range (e.g., 0 to 360 degrees) to figure out what signals are being received and from what direction.

A visual example of what happens to two signals when the interelement spacing of a direction finding antenna array is reduced below half a wavelength.

A Simulated Aircraft RADAR with Real Radar Scope Tube and ADS-B Data from an RTL-SDR

Over on YouTube we've found an interesting project by RingingResonance where he's created a simulated traditional radar scope using a real analog radar scope tube, and ADS-B data gathered from an RTL-SDR running dump1090 on a Raspberry Pi 3B.

The project uses a real radar scope tube which is controlled by SPI signals sent from the Raspberry Pi into a DAC, which is in turn connected to the analog radar scope. RingingResonance has uploaded the open source code to GitHub. He notes that the code currently pushes the Raspberry Pi 3 to it's limits, so the sweep speed is limited.

ADS-B Scope, My Real (Fake) RADAR Scope!

RSGB 2022: The UK Meteor Beacon Project

During last years Radio Society of Great Britain (RSGB) 2022 convention, Brian Coleman (G4NNS) presented a talk about the UK Meteor Beacon Project. The idea behind the project is to use a transmit beacon and a network of user-run receivers to help detect and study meteors. The talk has recently been uploaded to YouTube.

Radio signals can reflect off the meteor and the ionized trail left behind when it enters the atmosphere. This trail is highly RF reflective, so it can allow distant radio stations to be briefly received.

In the talk Brian explains the meteor detection, and explains the project in more detail.

The UK meteor beacon project is a collaborative project between the amateur radio and radio astronomy communities to collect data on meteor events over the UK. Phase I has been to establish a transmit beacon and Phase II is to create a network of receivers to monitor the radio echoes from meteors and stream data over the internet to support the study of meteor events and their impact on the ionosphere. Another key objective is to make possible a range of accessible radio-related STEM projects building on the interest in space and astronomy.

RSGB 2022 Convention presentation - The UK Meteor Beacon Project

TXAdvance: An RF Transmitter Manager Android App that uses RTL-SDR

Recently we came across a new RTL-SDR app on the Google Play store called TXAdvance which appears to be designed for professional sound engineers working in TV/film/stage/music production industry. The app uses an RTL-SDR to display the RF spectrum, helping sound engineers manage the RF spectrum for all their wireless sound recording devices, ensuring there is no overlapping signals, interference or intermodulation from other transmitters that could corrupt audio.

More information about the app can be found on their website at www.compasseur.com and the app itself can be purchased from the Google Play Store.

TXAdvance RTL-SDR Android App for Profressional Sound Engineers
TXAdvance RTL-SDR Android App for Professional Sound Engineers

Receiving TPMS Tire Pressure Data from a Mazda CX 5 with an RTL-SDR

Over on YouTube Robert from the Robert Research Radios channel has uplaoded a video showing how he has been using an RTL-SDR and rtl_433 to measure his Mazda CX5's wireless tire pressure sensors. The Mazda CX5 comes with TPMS tire pressure sensors in each tire, however when there is a low pressure warning, it does not actually tell you which tire in particular is low.

Robert used his RTL-SDR, rtl_433 and a custom script to read the wireless TPMS data coming from his tires and then matched the ID from each reading to the correct tire.

To go along with the video, Robert has uploaded a blog post explaining his setup and script.


An OpenWebRX fork with additional built in decoders

Thank you to Stefan for letting us know about a relatively modern OpenWebRX fork by luarvique that comes with additional built in decoders and features, such as SSTV, AIS, CW, RTTY, an MP3 recorder and SSTV image browser.

OpenWebRX is an open source web based SDR receiver program that allows you or others (if you allow them to), to access your SDR over the internet. It is compatible with KiwiSDR, RTL-SDR, Airspy, SDRPlay and many other software defined radio hardware. It was originally developed by Andras Retzler, but since abandoned by him, with a semi-official fork being maintained at openwebrx.de. However, other forks like luarvique can exist that implement a new set of features.

The full set of additions and improvements reads as follows:

This is the package repository for the improved version of the OpenWebRX online SDR. The new and original features available in this version of OpenWebRX:

  • Built-in SSTV decoder with background decoding.
  • Built-in AIS decoder.
  • Built-in CW decoder.
  • Built-in RTTY decoder.
  • Built-in MP3 recorder for received audio.
  • Image browser for received SSTV images.
  • Adjustable noise filtering based on spectral subtraction.
  • Adjustable tuning step.
  • Improved touch screen operation, with panning and zooming.
  • Improved scroll wheel support, with tuning and zooming.
  • Improved tuning in CW mode.
  • Bandpass filter adjustable with scroll wheel.
  • More reliable SDRPlay devices operation.
  • Better map information, with distances.
  • Better APRS map information, with weather.
  • Configurable session timeout, with a policy page.
  • HTTPS protocol support (requires SSL certificate).

The code comes packaged for Ubuntu 22.04 (amd64, arm64) and Debian 11 (amd64 arm64, armhf). There is also a ready to use Pi 4 SD card image available, linked on the GitHub readme. The original forked code can be found at https://github.com/luarvique/openwebrx.

According to discussion over on the OpenWebRX groups.io, the fork also runs on a Pi 3. In the image Neil Howard from the groups.io forum demonstrates an SSTV image he received with an SDRplay clone using the luarvique fork of OpenWebRX.

SSTV Image received by the luarvique fork of OpenWebRX. Credit: Neil Howard
SSTV Image received by the luarvique fork of OpenWebRX. Credit: Neil Howard

Stefan also notes:

The maker of OpenWebRX+ Marek and also the maker of the original version of OpenWebRX Jakob are reachable via a Telegram channel: https://t.me/openwebrx_chat