Over on YouTube user knoxieman has uploaded a video that provides a few tips on using DSD+ and an RTL-SDR for listening to DMR digital voice signals. The video is designed as a companion to Tech Minds' video which shows a full set up procedure for DSD+.
Knoxieman's video includes some tips on SDR# settings, virtual audio cable setup, and using a program called "DisplayFusion" to keep the DSD+ event windows permanently on top of the SDR# window.
Tips on using SDR Plus and DSDPLUS to listen to DMR/DIGITAL conversations.
Over on YouTube user ModernHam has uploaded a video showing how to perform a replay attack on a car key fob using a Raspberry Pi running RPiTX and an RTL-SDR. A replay attack consists of recording an RF signal, and then simply replaying it again with a transmit capable radio. RPiTX is a program that can turn a Raspberry Pi into a general purpose RF transmitter without the need for any additional hardware.
The process is to record a raw IQ file with the RTL-SDR, and then use RPiTX V2's "sendiq" command to transmit the exact same signal again whenever you want. With this set up he's able to unlock his 2006 Toyota Camry at will with RPiTX.
We note that this sort of simple replay attack will only work on older model cars that do not use rolling code security. Rolling code security works by ensuring that an unlock transmission can only be utilized once, rendering replays ineffective. However, modern rolling code security systems are still susceptible to 'rolljam' style attacks.
In the video below ModernHam goes through the process from the beginning, showing how to install the RTL-SDR drivers and RPiTX. Near the end of the video he shows the replay attack in action.
Unlock Cars with a Raspberry Pi And SDR - Replay attack
Over on GitHub, Rakesh Peter (r4d10n) has uploaded a new terminal/ssh based console application called "retrogram~rtlsdr". This program uses an RTL-SDR and terminal window to display a spectrum analyzer drawn in ASCII art. Because it is terminal based, it is even possible to view the spectrum of a remote device over an SSH connection. The program is based on software designed for Ettus USRP SDRs, and has been adapted for RTL-SDR.
For other SDRs r4d10n has also worked on a "retrogram~soapysdr" version which should work with any SoapySDR compatible SDR, and "retrogram~plutosdr" for PlutoSDR SDRs.
Giuseppe notes that using an Android TV box for SDR is as simple as installing the Martin Marinov Android RTL-SDR drivers from the Google Play store, and then downloading the SDR apps that interest you. No extra USB OTG cable is required, just plug the dongle into the back of the device. In his post he shows screenshots from apps like SDRTouch, welle.io DAB+, RTL-SDR AIS and SDRoid all running smoothly on his Android TV box.
With a system like this is it probably also a good idea to connect a wireless keyboard/mouse combination into a USB port as well.
SatNOGS is an open source project that aims to make it easy for volunteers to build and run RTL-SDR or other SDR based RF ground stations that automatically monitor satellites, and upload that data to the internet for public access. The antennas used in a typical home based SatNOGS station are small enough for a single person to handle, however recently the SatNOGS team have been working on setting up a monitoring station at the Dwingeloo Radio Observatory in the Netherlands.
Dwingeloo has a large 25 meter satellite dish antenna, and they connect it to an RTL-SDR on a laptop running the SatNOGS software. In the video they show it tracking the PRISM amateur radio satellite, and note that the use of this large dish will only be used in special circumstances. They write:
This week the Dwingelooradio Observatory tested their 25 meter dish as a SatNOGS station! Although not set up as a permanent SatNOGS station it is great to see this historic observatory linked to the network. Dwingeloo radio observatory was built between 1954 and 1956 near the village of Dwingeloo in the Netherlands. Since 2009 this single 25 meter dish has been a national heritage site.
Dwingeloo Radio Observatory as a SatNOGS 📡 station
Dwingleloo Satellite Antenna in the Netherlands [Source: Wikipedia]
At the beginning of last month we posted about an update to JAERO which allows us to now listen to AERO C-Channel voice audio. AERO is a satellite based communications service used by modern aircraft, and it's possible to easily receive the signals with an RTL-SDR, L-band patch antenna and LNA. The C-Channel conversations are typically about Medlink which is a support line for medical emergencies, but other conversations may be heard too.
While it is possible to listen to these conversations, due to legal reasons regarding patents it is necessary to compile the audio decoder manually from source, and this can be quite an involved multi-step process on Windows. Fortunately, YouTuber Corrosive, who has been making SDR related videos for some time now has put up a three part video series on the process.
The Reverse Beacon Network is a project that monitors the amateur radio bands by using volunteer stations to continuously and autonomously collect data on what/when stations are being received, and how good the signal is. The data is made public on the internet and this allows amateur radio operators to easily determine overall propagation conditions. It is currently working mostly with CW (morse code) stations, and mostly on HF, although it is expanding to VHF+ as explained below.
During October, John Ackermann (N8UR) did a talk at the "Microwave Update 2018" conference held in Dayton, Ohio. His talk was about setting up a VHF+ reverse beacon network monitoring station, using multiple RTL-SDR dongles for monitoring. The RTL-SDR dongles run on a Raspberry Pi which runs the rtl_hpsdr software. This allows multiple RTL-SDR dongles to emulate a multi-band HPSDR receiver over Ethernet. They can then be accessed on a PC by the CW Skimmer program which decodes the received CW signals, and then logs it online on the reverse beacon network's website.
The talk slides can be found here, and the video is shown below. More talks from the conference can be found on this YouTube playlist.
Four RTL-SDR.COM V3 dongles used in a VHF+ Reverse Network Setup
John Ackermann, N8UR - The VHF+ Reverse Beacon Network
Over on the AWS blog Jeff Barr has blogged about Amazon's new rentable ground station system called "AWS Ground Station". AWS, or Amazon Web Services is the server farm division of Amazon. They allow customers to rent out server capability on demand. In a similar sense, AWS Ground Station is aiming to allow customers to rent out satellite ground stations on demand.
Launching low cost micro/nano satellites has become very affordable in recent years and it's now common to see high schools, colleges, organizations and hobbyists designing, fabricating and launching their own satellites. Once launched, a ground station is required to receive the satellite's radio transmission as it passes over. Most low cost satellite owners will not have the budget to deploy ground stations all around the world for continuous monitoring of the satellite. This is where AWS Ground Station can take over, allowing a ground station on the other side of the world to be rented temporarily during a pass.
Currently the service is just starting, and only has 2 ground stations, but by 2019 they hope to have a total of 12. More information available on the official AWS Ground Station website.
Alternatively, there are other free open source services that could be utilized such as SATNOGS. SATNOGs relies on volunteer ground stations running antenna rotators that can be built with a 3D printer, some low cost motors and electronics, and an RTL-SDR. The antenna rotator carries a Yagi antenna and will automatically track, receive and upload satellite data to the internet for the public to access.
