Category: Digital Signals

A Web and RTL-SDR Based Trunking Scanner

During the Cyberspectrum Wireless Village talks a few days ago Gavin Rozzi gave a talk about his online RTLSDR-based trunking scanner website at ocradio.live. Recently he wrote in and wanted to share a little more about his system. He writes:

[The talk focuses] on my experience implementing several open source software packages to create an online RTLSDR-based trunking scanner website, https://ocradio.live/ that serves the part of New Jersey that I live in. Using multiple RTLSDR receiving locations, the site is demodulating, recording, and timeshifting multiple talkgroups of local and state trunked radio systems to create a live streaming service and archive of past scanner calls. Data from the site is also accessible over a REST API and we allow the creation of custom scan lists. My presentation is going to center on the advantages the site has over traditional hardware scanners and some of the technical challenges that we had to overcome to get the project off the ground.

In the Cyberspectrum YouTube video, Gavin's talk starts at around 2:40:22 and his slides are available at https://cyberspectrum23.ocradio.live

OCRadio Streams Screenshot
OCRadio Streams Screenshot

Tutorial on using RS to Decode and Plot Radiosondes

A radiosonde is a small weather sensor package that is typically attached to a weather balloon. As it rises into the atmosphere it measures parameters such as temperature, humidity, pressure, GPS location etc, and transmits this data back down to a receiver base station using a radio signal.

Zilog's RS is a free open source radiosonde decoder for Linux and it supports a wide range of radiosonde protocols. Together with an RTL-SDR it is possible to receive radiosonde signals, and decode them using RS.

Over on his website, happysat has recently uploaded a tutorial that shows how to use RS with an RTL-SDR, CubicSDR or GQRX, and FoxtrotGPS, a GPS plotting program for visualizing the location of the radiosonde. The tutorial covers some tricky points like setting up audio piping in Linux, and getting the GPS data into a virtual COM port to use with FoxtrotGPS.

Alternatively, there are also Windows GUI based sonde decoders that can be used with the RTL-SDR such as SondeMonitor which costs 25 Euros, but also covers a wide range of sonde protocols, and RS41 Decoder which is a GUI for the RS41 sonde protocol only. If you are interested we have a tutorial on setting up radiosonde decoding in Windows with SondeMonitor available here.

Plotting the Sonde Location with an RTL-SDR, GQRX, RS and FoxtrotGPS.
Plotting the Sonde Location with an RTL-SDR, GQRX, RS and FoxtrotGPS.

Tutorial on Setting up OP25 for P25 Phase 2 Digital Voice Decoding

Most police departments is the USA have now upgraded or are in the process of upgrading their radio systems to P25 Phase 2 digital radio. The frequencies can easily be received with an RTL-SDR, but a decoder is required to be able to actually listen to the voice. Software like SDRTrunk and DSDPlus can decode P25 Phase 1, but at the moment the only software that is capable of decoding P25 Phase 1 AND 2 is a program called OP25. However, OP25 has a reputation of being fairly difficult to set up as it does not have a simple to use GUI, and requires Linux.

Over on John's Tech Blog, John has uploaded a very helpful step by step tutorial that should help with those trying to get OP25 to work. The tutorial assumes that you have Ubuntu 18.04 already installed, and then starts from downloading and installing OP25. The next steps involve setting up OP25 for the particular system in your area, which mostly involves just editing a spreadsheet to input frequency data from radioreference.com. John also mentions that he's been able to get OP25 running perfectly on a Raspberry Pi 3 B+ as well, with less than 40% CPU usage.

OP25 Running
OP25 Running

In the video below John reviews some of the steps, and shows OP25 running and decoding voice.

OP25 Tracking 2 Control Channels

Video Tutorial About Decoding 433 MHz ISM Devices with rtl_433

Over on his YouTube channel Tech Minds has recently uploaded a video that demonstrates and shows how to use the rtl_433 software with an RTL-SDR to decode 433 MHz ISM band low power devices. Typically these devices include things like home wireless temperature and weather sensors, tire pressure sensors, remote controls, and other various sensors.

In the video he sets up an RTL-SDR and magmount antenna by his window and is able to receive data from several of his neighbors weather stations, and some car key remotes. He shows how to run the software on both Linux and on Windows.

How To Decode 433Mhz Low Power Devices Using RTL433 And A RTL-SDR Receiver

RS41 RadioSonde Tracking Software

A radiosonde is a small weather sensor package that is typically attached to a weather balloon. As it rises into the atmosphere it measures parameters such as temperature, humidity, pressure, GPS location etc, and transmits this data back down to a receiver base station using a radio signal. The RS41 is one of the newer radiosonde modules sold by  radiosonde manufacturer Vaisala, and is currently one of the most popular radiosondes in use by meteorological agencies. The signal is typically found at around 400 MHz and can be received with an RTL-SDR and an antenna tuned for 400 MHz. We have a general tutorial on radiosonde decoding available here.

There are several software packages that can decode RS41 data, such as the multi-radiosonde decoder Windows program called SondeMonitor (25 euros), or the free Linux command line software called RS. Recently a new free Windows GUI based RS41 decoder has been released by IW1GIS. The software can display on Google maps the current location and previous path of the radiosonde, as well as it's weather data telemetry.

Main features are:

  • Directly decoding of GFSK signal received by the FM radio receiver (the use of a Software Defined Radio is recommended).
  • Capability to connect and command SDRSharp software by mean of Net Remote Control plugin.
  • Advanced frequencies scan and decode: RS41 Tracker is able to look for RS41 radiosonde signal in a given list of frequencies, starting the radiosonde decoding when a valid signal is detected.
  • Real time showing radiosonde position on google map (internet connection is required)
  • Map auto centered on radiosonde position
  • Map type selectable by user (road, satellite, hybrid, terrain).
  • Burst killer detailed information and launch time estimation.
  • Radiosonde RAW data save
  • Post processing of RS41 RAW data file
  • Tracking information (elevation, bearing, slant range)
  • Radiosonde track saved on kml file
  • Ghost track shown on map (loading from kml file)
  • Shortcut for google maps in browser
RS41 Tracker Software
RS41 Tracker Software

New TETRA Trunk Tracker for use with SDR# and the TETRA Demodulator Plugin

Over on our forums user thewraith2008 has just released news about his new software called TETRA Trunk Tracker. The software works in conjunction with the TETRA demodulator plugin for SDR#. It works by using two dongles, one to monitor a TETRA trunking channel, and the other to decode voice audio, although a single receiver mode is also available which works with a reduced and fixed bandwidth.

TETRA Trunk Tracker
TETRA Trunk Tracker

The post reads:

TETRA Trunk Tracker will follow calls on a TETRA network.

TETRA Trunk Tracker reads DATA that is output from the SDR# plug-in TETRA Demodulator (by TSSDR) via the 'Network Info' calls log window.

It interprets this DATA to determine when a call is set-up, then instructs SDR# (VC) to move to the carrier (frequency) that the call will be on.

It will also watch out for other PDUs to determine when a SSI starts or completes transmissions and when calls are complete (Released).

Features:

  • A basic call recording (All or Selective call recording).
  • Display current call details with list of seen SSIs for that call. (SSI populate as they TX).
  • GSSI holding - will only allow calls with selected GSSI to be heard.
  • Call lockout based on GSSI. Can be unchecked in list to lockout GSSI.
  • Call Priority. (Only normal version)
  • GSSI weighted 0-9, 9 is highest. If on active call and other call event occurs, if new call has higher
  • priority then will switch to it.
  • Collect/Save all seen GSSIs with Labels and Priority, By Network.
  • Collect/Save seen SSIs with Labels and Last seen Date/Time, By Network.
  • Set a call time-out. Returns to idle state if call does not see a release PDU
    after X time in seconds.
  • Log call events to screen and file, if enabled.
  • Log raw CC and VC PDU messages as seen by the 'TETRA Demodulator' plug-in, if enabled.
  • Log GSSI daily call activity. (Simple version does not play calls when this is selected)
  • Set base frequency via UI.
  • Set CC park carrier # via UI.
  • Set VC park carrier # via UI.
  • Suppress some PDUs. (unchecked is mainly for testing only)
  • Suppress lockout messages.
  • Sort SSI and GSSIs/Lockouts (by GSSI). This only occurs on start-up.
  • Country Code label, defined via file (shown as menu item)
  • Network label, defined via file (shown in tool tip where MNC,LA is in 'Call Details' panel)
  • Location Area label, defined via file (shown in tool tip where MNC,LA is in 'Call Details' panel)
    Only shown when Network label used.
  • Ignores Encrypted PDUs (with no reference to them)
  • Set a seen GSSI priority via UI.
  • Update a seen GSSI/SSI label via UI.
  • Call active indicator.
  • Restore SDR# windows to a defined position.

If the TETRA Demodulator does not work for you this program will do nothing to change that.

This is the third release of this program. (TETRA Trunk Tracker v0.99.6)
And 2nd release for (TETRA Trunk Tracker v0.99.6s - Simple)

Two versions are available:

  • Normal (Uses 2 SDR# and 2 Dongles) with TETRA Demodulator and Net Remote plug-ins
  • Simple (Uses 1 SDR# and 1 Dongles with some features not available) with TETRA Demodulator and Net Remote plug-ins

Backup your "Tetra-trunk-tracker.dat" settings file.
Then delete "Tetra-trunk-tracker.dat" as it has changed and old one will cause error on load.

Some work as gone into trying to make TETRA Trunk Tracker easier to run once the initial setup has been done.

A MCC (Country Code) label file is included for your convenience "TETRA_mcc.txt".

It has only been tested on Windows 7 - Professional SP1 (32 bit), English

You MUST have a PC that is capable of running SDR# x 2 with the TETRA plug-in. (Not overloaded CPU usage.)

It is in alpha stage. This means is may contain errors that may cause issues with the other programs it
works with. i.e. crashing them or itself.

The TETRA plug-in currently been developed by TSSDR is also in early development. Because of this
any changes made in plug-in releases most likely will break this program.

I have created it to suit my needs. And it currently works for me with the TETRA network I monitor.

I make no claim that it will work for other networks.

Please read the provided files for set-up and usage:

  • TTT_set-up_manual.pdf
  • TTT_Features_and_Usage.pdf

I have tried to be as thorough as possible with the documentation to explain usage and features.
I believe any questions can be answered by reading these files.
These files most likely are not complete and contain errors and are not laid out as good as they could be.

It only works with the provided TETRA plug-in supplied in zip. (2018-June-06).
This version uses a custom compiled version of 'Net Remote' supplied in zip

It is only meant to be a temporary solution until something better comes along.

Hopefully all goes well for you setting it up.

Download link

MD5 HASH 6f33fcf9662573b77e177e899793b9f9

Video showing starting it and it running
Video showing starting it and it running - Simple version

Video on Hacking 433 MHz Devices with an RTL-SDR and Raspberry Pi

Over on YouTube user Andreas Spiess has uploaded a video showing how to use an RTL-SDR to reverse engineer 433 MHz ISM band devices such as Internet of Things (IoT)/home automation sensors and actuators. 

Andreas decided to do this because he has a 433 MHz remote controlled actuated outdoor awning which he wants to have automatically retract when the wind speed gets too high. To do this he wanted to use a wireless 433 MHz ISM band weather station with wind speed sensor. But unfortunately he discovered that it has a proprietary protocol that can't talk to his awning, which also has it's own proprietary protocol.

Andreas' solution is to use an RTL-SDR and Raspberry Pi running the rtl_433 decoder software to receive the weather station data. The rtl_433 software already contained a decoder for his weather station, so no further reverse engineering was required. The data is then converted into MQTT which is a common TCP/IP protocol for IoT devices. MQTT is then read by Node-RED which is a flowgraph based programming environment for IoT devices.

Next, unlike the weather station rtl_433 did not already have a decoder implemented for his awning. So Andreas had to reverse engineer the signal from scratch using the Universal Radio Hacker software. Using the reverse engineered signal information, Andreas then uses an ESP32 processor/WiFi chip and cheap 433 MHz transmitter to implement a clone of the awning's remote control signals. The ESP32 is programmed to understand the MQTT data sent from the Raspberry Pi via WiFi, so now the weather station can control the awning with a little bit of logic code in Node-RED.

How to Hack your 433 MHz Devices with a Raspberry and a RTL-SDR Dongle (Weather Station)

An Update on the PantronX Titus II SDR

The PantronX Titus II is a yet-to-be-released portable Android tablet based SDR that we've been following since 2016. The device will feature a 100 kHz - 2 GHz tuning range, and software that focuses on HF digital DRM decoding, as well as DAB on VHF. 

Thomas from the excellent SWLing blog got curious about the Titus II as he had not heard any updates from the team in a while, so he emailed them requesting an update. Mike from PantronX wrote the following reply:

As you might be aware, we have joined up with Fraunhofer to include their MMPlayer app standard on Titus–what a difference a professional decoder, for both analog, DRM(+), and DAB(+), makes! MMPlayer is full featured even including reliable one way file downloads with DRM.

We are attempting also to license HD to include on the app for North America, making a truly worldwide receiver. Some deficiencies in our version of Android have caused issues as well as MMPlayer. All of which have caused delays leading to some serious business decisions – as you can imagine. You are correct that broadcasters have made large orders that will be fulfilled first. There are units in the field testing and such and continuing resolution of the software issues.

One of the issues that folks seem to have a hard time understanding is that we can not just build a few hundred or even thousands of units. Our minimum run is 10,000pcs! To do that everything has to be 100% – including the software. We simply will not ship units that are not 100%. Titus works, MMPlayer works – its that last 5% that takes the most time to resolve. These facts preclude any incremental production attempts. All that being said, we are very hopeful that the first production run is ready by last quarter of this year.

The Titus II
The Titus II