Category: Applications

Aerial TV: An Android DVB-T Decoder for the RTL-SDR

On the Google Play store a new RTL-SDR compatible app called ‘Aerial TV’ has been released (in beta) by Martin Marinov. Aerial TV allows you to watch DVB-T HD TV on your android device, with an RTL-SDR connected to it via USB OTG cable. Martin is also the author of the popular SDR Touch Android program and the RTL2832U Android driver port. 

The new software requires a different DVB-T driver app to be installed first, which is also provided by Martin. This is because the RTL-SDR needs to be operated in a mode different to the way that the SDR drivers use it in. Martin has also open sourced his Android DVB-T driver and it is available on GitHub.

Aerial TV is currently free on the Google Play store, but looks like it may eventually have some in-app purchases. Also, it is currently marked as ‘Unreleased’ on Google Play, which is essentially a beta version, so you might expect there to be some bugs.

Aerial TV Screenshot
Aerial TV Screenshot

Over on YouTube user GiamMa-based researchers SDR R&D IoT has uploaded a video showing Aerial TV scanning for TV channels, and then eventually playing some video.

APP DVB Receiver Aerial TV (Unreleased) rtl sdr compatible test with oneplus one

HackRF Sweep Spectrum Analyzer for Windows

A few weeks ago the HackRF drivers and firmware were updated and one new feature added was hackrf_sweep. This new feature allows us to scan across the spectrum at up to 8 GHz per second, which means that a full 0 – 6 GHz scan can complete in under a second.

Previously only Linux software such as QSpectrumAnalyzer was compatible with hackrf_sweep, but now over on GitHub user pavsa has released a new Windows based Spectrum Analzyer which is compatible with hackrf_sweep.

We gave the software a test and it ran flawlessly with our HackRF. The features include:

  • Optimized for only one purpose – to use HackRF as a spectrum analyzer
  • All changes in settings restart hackrf_sweep automatically
  • Easy retuning
  • hackrf_sweep integrated as a shared library
  • Peak display
  • High resolution waterfall plot

Remember that to run the software you will need to have updated your HackRF to the latest firmware. The spectrum analyzer software is also Java based, so you’ll need to have the Java JRE for Windows x64 installed.

Wintelive YouTube Demo

Over on YouTube use radiosification has uploaded a video showing the Windows TETRA decoder ‘wintelive’ in action. Wintelive is a Windows port of the popular RTL-SDR compatible Linux based ‘telive’ TETRA decoder. Back in October 2016 we posted about its release and we have a tutorial for telive and the RTL-SDR available here

The install instructions for wintelive are available on the authors webserver.

TETRA decoding on Windows!

T——o SDR: A MultiMode SDR Receiver Program

Recently a reader of RTL-SDR.com wrote in and submitted a link to T——–o SDR, which is an RTL-SDR compatible multimode SDR decoder program for Windows. (The website is in Italian but is easily translated with Google Translate). In terms of operation it appears to be quite similar to SDR#, and other programs like SDR-Console and HDSDR.

Like all other general purpose receiver software it is capable of decoding NFM/AM/WFM/SSB/CW modes. It also has digital noise reduction built in as well as an S-Meter and frequency manager list.

Update: Unfortunately we have been informed by the developer of SDR# that this software was illegally decompiled from a relatively new SDR# version and is thus stolen work. We looked further into the software and it is essentially an exact clone of SDR#, just with a different skin. Please do not use this software, and respect software legality. 

Essentially it appears that they took the closed source SDR# program, decompiled it then reskinned it and then made it open source under a new name.

Obviously this is unacceptable behavior, so out of respect for the original SDR# developers hard work we’ve removed links and references to this software on our website.

Real-Time decoding of Meteor-M2 on Linux

Recently RTL-SDR.com reader Mark wrote in and wanted to share his modified version of otti-soft’s GNU Radio flowgraph for decoding Meteor-M2 weather satellite images on Linux. The modified version allows for real time decoding, whereas the original version requires several offline decoding steps to be performed after recording the signal.

Mark writes:

I have modified one of otti-soft’s gnuradio flowgraphs so that they work with RTL-SDR and output the demodulated symbols to a TCP socket, from which the new version of LRPT Analizer (from robonuka.ru) can decode the data in real-time.

First, one needs to download and extract the AMIGOS version of the LRPT analyzer from robonuka.ru: ftp://meteor2soft:[email protected]/AMIGOS/AMIGOS2.zip.

(AFAIK, only the AMIGOS version is able to decode the data from a socket, which is required for real-time decoding).

The program is to be run under a 32-bit version of Wine.

When the satellite is overhead, open and run the flowgraph (attached) in gnuradio-companion and leave it running. You might need to adjust the gain.

Then, run the LRPToffLineDecoder.exe executable from the extracted archive.
It should display a constantly-updating constellation diagram. When the data is decoded, the channel images will start to appear in each section of the window.

That’s it, when the image is decoded, one can save it and close the windows of gnuradio-companion and the decoder.

Notes: when running the flowgraph, no other processes (rtl_sdr, rtl_power, gqrx, …) should use the SDR device.

The modified GRC file is available here.

The real-time Meteor M2 GNU Radio script for Linux
The real-time Meteor M2 GNU Radio script for Linux

—–Hz: A New STD-C Inmarsat Decoder

UPDATE: Unfortunately we have been informed that the code base of this software was illegally decompiled and reused in an almost unchanged way from an already available closed source decoder. This means the program itself is illegal and totally unethical.

Please respect the original developers hard work and do not download this software.

A new STD-C Inmarsat decoder called —-Hz has recently been released. The decoder is Windows based and simply listens to the demodulated Inmarsat STD-C audio from a program such as SDR#. This means that it is compatible with the RTL-SDR, and any other SDR that can receive Inmarsat. 

We gave the software a brief test and it ran very well, and managed to decode several SafeteNET messages without issue, maintaining a good lock most of the time. The author writes that he plans to improve on the software in the future by creating a web service based version of the software.

Currently there are two other Inmarsat decoders available. One is called InmarsatDecoder and the other is the Tekmanoid decoder. The InmarsatDecoder is generally regarded as the best, but the Tekmanoid decoder was recently updated for improved performance. The new software appears to be about the same as the Tekmanoid decoder.

Inmarsat STD-C messages are broadcast from geostationary satellites in the L-band at around 1.5 Ghz. They send mostly marine based messages such as the following quoted from the ——Hz website:

  • Safety: high seas, tropical storm warnings, ice accretion…
  • Shipping activity: moving oil rigs, submarine cable deployment and repairs…
  • Distress reports: MOB, ships lost at sea, migrant ship reports…
  • Military exercises (firing practice, no fly zones…)
  • Pirate at sea reports…

If you are interested in learning how to decode STD-C we also have a tutorial available here

The b4000Hz Inmarsat STD-C Decoder
The ——Hz Inmarsat STD-C Decoder

re-DECTed: An RTL-SDR DECT Decoder

Over on GitHub programmer ‘znuh’ has uploaded a new RTL-SDR compatible GNURadio based tool for DECT decoding. DECT is an acronym for ‘Digital Enhanced Cordless Telecommunications’, and is the wireless standard used by modern digital cordless phones. In most countries DECT communications take place at 1880 – 1900 MHz, and in the USA at 1920 – 1930 MHz. So in order to receive these frequencies you’ll need an RTL-SDR with an E4000 chip, or some other compatible SDR that can tune this high.

It appears that the decoder is not actually able to decode audio (at least not yet or without extra work perhaps), but it can at least output the DECT packets to Wireshark for analysis. This may be of interest to those wanting to learn more about the DECT protocol.

Update: Over on the Reddit thread for this software the original poster ‘sanjuro’ has given a hint on how to (in theory) decode the audio, he writes:

In theory you only need to dump B-field data into a file and then play with g726 codec. See documentation from previous de-DECTed project http://wiki.securityweekly.com/wiki/index.php/Episode158

The re-DECTed decoder outputting packets to Wireshark.
The re-DECTed decoder outputting packets to Wireshark.

Simple NOAA/Meteor Weather Satellite Antenna: A 137 MHz V-Dipole

Over on his blog Adam 9A4QV (seller of various RTL-SDR related goods including the LNA4ALL) has just made a post detailing a build of a high performance super simple NOAA/Meteor M2 weather satellite antenna. Most antenna designs for polar orbiting weather spacecraft are based on circularly polarized turnstile or QFH designs. However, Adams antenna is based on a very simple linearly polarized dipole, which makes construction almost trivial.

The idea is that by arranging a dipole into a horizontal ‘V’ shape, the radiation pattern will be directed skywards in a figure 0 (zero) pattern. This will be optimal for satellites travelling in front, above and behind the antenna. Since polar orbiting satellites always travel North to South or vice versa, we can take advantage of this fact simply by orienting the antenna North/South. 

There is also another advantage to Adams design. Since the antenna is horizontally polarized, all vertically polarized terrestrial signals will be reduced by 20 dB. Most terrestrial signals are broadcast in vertical polarization, so this can help significantly reduce interference and overloading on your RTL-SDR. Overloading is a big problem for many trying to receive weather satellites as they transmit at 137 MHz, which is close to the very powerful FM broadcast band, air band, pagers and business radio. In contrast a circularly polarized antenna like a QFH or turnstile only reduces vertically polarized terrestrial signals by 3 dB.

As the satellites broadcast in circular polarization there will be a 3 dB loss in Adams design from using a linear polarized antenna. But this can be considered as almost negligible. Adam also argues that the home construction of a QFH can never be perfect, so there will always be at least a ~1dB loss from inaccurate construction of these antennas anyway.

The final advantage to Adams design is that construction is extremely simple. Just connect one element to the center coax conductor, and the other to the shield, and spread apart by 120 degrees.

Adam 9A4QV's V-Dipole for 137 MHz Weather Satellites.
Adam 9A4QV’s V-Dipole for 137 MHz Weather Satellites.

Adam has tested the antenna and has gotten excellent results. If you want more information about the antenna design, Adam has also uploaded a pdf with a more indepth description of the design and his thoughts.

DIY 137 MHz WX sat V-dipole antenna

137 MHz NOAA WX sat reception using V-dipole antenna