Category: Digital Signals

A Worldwide Map for HRPT Weather Satellite Receive Stations

Recently Manuel (DO5TY aka Tysonpower from YouTube) wrote in and wanted to share his website that shows HRPT weather satellite receive stations from around the world on a map, and links to their Twitter pages where you can see the latest images that have been uploaded. The database also describes the SDR and antenna equipment used by each station. Currently there are 10 stations on the map, and Manuel encourages other people to submit their stations to the map database too. If you are interested in contributing your station to the map, please see Manuel's blog post for more information.

Since the satellite broadcasts a live image of what is currently being seen by the weather camera, each receiver location receives a live view of their part of the earth only. The end goal of Manuel's HRPT station map is to crowd source and collect multiple images of different parts of the earth to create a large HRPT composite image. In a previous post, Manuel who is based in Germany was able to create a beautiful composite image covering Germany, the Atlantic Ocean and Canada with the help of a station in Canada. With more contributors larger and more complete composite images of the Earth could be created.

HRPT is a high resolution weather satellite image signal that is broadcast from the same NOAA satellites that provide the more commonly received low resolution APT images at 137 MHz. HRPT is also broadcast from the Feng Yun and Metop-A satellites. However, HRPT transmits at 1.7 GHz, so a high gain dish antenna with motorized tracking mount, LNA and high bandwidth SDR like an Airspy is required to receive it.

HRPT Station Map
HRPT Station Map

YouTube Tutorial: Decoding POCSAG and FLEX Pager Messages on Windows with PDW

Pager systems are famously known to be insecure, and due to the lack of encryption and high transmit power anyone with an RTL-SDR or other SDR can receive and decode pager messages. The users of pagers are mostly hospitals and doctors, and IT infrastructure professionals who need to be notified of server warnings and errors quickly. We have a text tutorial on decoding these messages with an RTL-SDR available here, and there are several previous posts discussing how insecure they are. 

If you prefer a video tutorial, M6LME on YouTube has recently uploaded one where he explains the PDW pager decoding software, the VB-Audio 'banana' audio mixing software, and how to use SDR-Console with an RTL-SDR and the aforementioned software to receive and decode the signal.

How to Decode POCSAG & FLEX using an RTL-SDR Dongle

YouTube Tutorial: Eavesdropping on DECT6.0 Cordless Phones with a HackRF and GR-DECT2

Back in December of last year Corrosive from his YouTube channel SignalsEverywhere showed us a demo video of him receiving unecrypted DECT digital cordless phones with his HackRF.

DECT is an acronym for 'Digital Enhanced Cordless Telecommunications', and is the wireless standard used by modern digital cordless phones as well as some digital baby monitors. In most countries DECT communications take place at 1880 - 1900 MHz, and in the USA at 1920 - 1930 MHz. Some modern cordless phones now use encryption on their DECT signal, but many older models do not, and most baby monitors do not either. However, DECT encryption is known to be weak, and can be broken with some effort.

In his latest video Corrosive shows us how to install GR-DECT2 on Linux, which is the GNU Radio based decoding software required to decode the DECT signal. He then goes on to show how the software can be used and finally provides some optimizations tips.

DECT 6.0 Cordless Phone Eavesdropping {Install GR-DECT2 and Decode with HackRF SDR}

Tracking Radiosondes with an RTL-SDR and Radiosonde_Auto_RX

A radiosonde is a small sensor and radio package normally attached to a weather balloon. Meteorological agencies around the world typically launch two balloons a day from several locations to gather data for weather prediction. With an RTL-SDR, appropriate antenna and decoding software it is possible to decode the telemetry signal and gather the weather data yourself. You can also use the GPS data to chase and collect the fallen radiosonde package. We have a tutorial on setting up a basic radiosonde decoder in Windows here.

However, if you want to set up a permanent radiosonde receive station it's possible to create an automatic system with a program called radiosonde_auto_rx. It works by performing an rtl_power scan over the radiosonde frequency range and looking for peaks that might indicate that a radiosonde is currently transmitting. If a peak is found it tries to decode it as a radiosonde, and if successful will begin uploading the weather data to an online aggregation site called sondehub.org. With this sort of system there is no need to know in advance the launch times and exact frequencies that your local meteorological agency uses, as often this information is not public.

Recently Mark Jessop and Michael Wheeler, the team behind radiosonde_auto_rx, also did a talk at the linux.conf.au conference. The talk explains radiosondes and demonstrates their software in action. They then go on to talk about chasing radiosondes, and re-purposing collected sondes.

[Also seen on Hackaday]

STM32 Development Boards (literally) Falling From The Sky

SDR# TETRA Plugin Now Available At RTL-SDR.RU

Vasilli has recently released the SDR# TETRA plugin on his website RTL-SDR.RU (note that the site is in Russian, but can be translated with the Google Translate option in the top right of the page). Previously it was only available via ever changing forum links, so it's good to see that it has a permanent home now for the latest version. This plugin allows you to listen to TETRA digital voice via SDR#, without needing to set up any complicated GNU Radio based receivers which were necessary in the past.

The features include (note Translated from Russian):

  • Receiving a signal from the BS band 25kHz and modulation Pi / 4-DQPSK;
  • Automatic adjustment of the reception frequency;
  • Displays information about the BS;
  • Displays ISSI, GSSI subscribers in the channels (for open channels only);
  • Displays a service exchange network (for open channels only);
  • It allows you to listen to the channels in manual or automatic mode selection (only open channels);
  • It allows to filter and distribute the listening priority specified for groups (GSSI);
  • It displays a message with the location (just a short message format)

The current features not yet implemented are:

  • And listen to correctly display any encoded information in a network;
  • Display SDS type 4 (short messages);
  • Record audio from the channels (menu added, but does not work);

We also note that as discussed in a previous post there is a companion program for this plugin called TETRA Trunk Tracker.

SDR# TETRA Decoder Plugin
SDR# TETRA Decoder Plugin

Using a LimeSDR / PlutoSDR to Transmit Digital Amateur Television with DATV Express

Over on YouTube Corrosive from channel SignalsEverywhere has uploaded a new video in his series on Digital Amateur Television (DATV). The new video shows us how to use a transmit capable SDR like a LimeSDR or PlutoSDR to transmit DATV with a free Windows program called DATV Express.

In the video he explains the various transmit and video encoding settings, and then demonstrates the signal being received on SDRAngel with an RTL-SDR (which he explained in his previous video)

Transmitting DVB-S DATV Digital Amateur Television with LimeSDR / Pluto on Windows with DATV Express

Video Showing How to Decode Meteor M2 with an SDRPlay in Windows

Thanks to "Lolo sdr" for submitting his videos that show his process for receiving and decoding Meteor M2 weather satellite images in Windows with an SDRplay and SDR-Console V3. Since the SDRplay is not supported by SDR#, it is not possible to use Vasilli's excellent Meteor Demodulator plugin (site in Russian, please use the Google Translate option) which is only available for SDR#.

Lolo's method gets around this limitation by initially recording an IQ file of the satellite pass in SDR-Console V3, then opening that IQ file in SDR# via the Fileplayer plugin, which is also by Vasilli and available here. The process is a bit of extra work, and the image isn't live, but the image comes out clearly in the end.

The videos are shown below, and subtitles are available in English, French and Italian via the YouTube player options.

Recibir y decodificar Satélite Meteor M2 con SDRplay, parte 1 de 2, grabar el pase, con subtitulos.

Recibir y decodificar Satélite Meteor M2 con SDRplay, parte 2 de 2, decodificar imagen y corrección.

Demodulating DVB-S Digital Amateur TV with SDRAngel on Windows with an SDR

Over on YouTube Corrosive has uploaded a new tutorial video showing us how we can demodulate DVB-S DATV (Digital Amateur TV) on a Windows PC with SDRAngel. DATV is a mode used by hams to transmit and receive digital video, and SDRAngel is a multiplatform SDR software platform that supports multiple SDRs such as the RTL-SDR, HackRF, PlutoSDR, LimeSDR and more.

SDRAngel comes with a built in DATV demodulator, but it is necessary to install the FFMPEG video decoder yourself. Corrosive's tutorial shows where to download the decoder, and how to install it into SDRAngel. He then goes on to show how to use SDRAngel to begin receiving and demodulating a DATV signal.

We note that in a previous post Corrosive also showed in another video how to transmit and receive DATV with a LimeSDR and a modified $20 DVB-S receiver.

Decoding DVB-S DATV on Windows with SDRAngel | Works with RTL HackRF Pluto Lime and other SDR