Category: RTL-SDR

RTL-SDR Blog Active L-Band Patch Antenna for Inmarsat, Iridium, GPS Back in Stock

Just a quick note to say that the second batch of our Active L-Band Patch Antenna for receiving Inmarsat, Iridium and other L-Band satellites is now in stock, available to be shipped from our warehouse in China from early next week. Amazon will be stocked within the next 1-2 months as the freighter will take time to arrive.

Please see our store for ordering details.

Apologies as we've had to temporarily suspend sales of this product as a manufacturing defect has been discovered in this batch. The defect is that on a number of units the plastic around the screws is cracking, and this was caused by a factory worker over torqueing a pneumatic screwdriver.

The antenna itself will work fine, and it probably won't even affect weather tightness, but it is certainly a defect. If your unit already shipped out and your unit has these cracks, please let us know at [email protected] and we will get the factory to ship you a replacement enclosure. For unshipped units we will be issuing a refund within the next few days.

Update: The units have been repaired and are available for shipping again.

Pricing remains the same at US$49.95 including free worldwide shipping to most countries. A reminder to EU customers: please order from our Aliexpress or eBay stores as due to the new IOSS laws we need to now use those marketplaces to collect and remit VAT upon your purchase, instead of upon import at the border.

This second batch comes in a gray color as feedback from the previous batch indicated that a lighter color is preferred to avoid excess heating from the sun.

If you are hearing about this patch antenna for the first time, please see our original release post for more information. In short this is an amplified patch antenna designed to be used with bias tee capable SDRs that can provide 3.3V - 5V power, such as our RTL-SDR Blog V3 dongle, Airspy, SDRplay or HackRF.

The antenna allows for reception of L-band satellites that transmit between 1525 - 1660 MHz, such as Inmarsat, Iridium and GPS. Please note it is *not* for receiving weaker signals like HRPT and GOES which require a dish antenna.

The patch comes with useful mounting accessories including a window suction cup, bendable tripod and 3M RG174 coax cable. The patch and active circuitry is enclosed in a weather proof enclosure.

What can you do with this antenna?

SDRA2021 Talks: Electrosense, Neural Network Signal Classification, gr-rpitx, Radio Astronomy and More

The 2021 Software Defined Radio Academy conference was held online this year on June 26/27 and the talks have been recently uploaded to YouTube. There are some interesting talks this year including a presentation on various SDR related topics including Electrosense, gr-rpitx, 21cm radio astronomy with low cost SDR hardware, and using deep learning neural networks for automatic signal identification. Our favorite talks and blurbs are collected below for easy access, and the full set of talks can be found on their YouTube channel.

Dr. Henning Paul: Building a flexible Multi-Antenna-capable SDR using open Source

The availability of Open Source software components enables the ambitious hardware hacker to design their own powerful SDR. This talk is the follow-up to the talk on Scientific SDR and recapitulates the steps towards the current design of a Homebrew SDR based on a Xilinx Zynq SoC using the Linux kernel and other Open Source components. Furthermore, one of its applications, receiving shortwave radio with antenna diversity is presented.

SDRA2021 - 04 - Dr. Henning Paul: Building a flexible Multi-Antenna-capable SDR using open Source

Jean-Michel Friedt: GNURadio compatible gen. purpose SDR emitter using RasPi4 PLL

GNU Radio, the Raspberry Pi single board computer and Digital Video Broadcast Terrestrial receivers make an awesome combination for educational purposes of Software Defined Radio. gr-rpitx aims at complementing these tools with emitting capabilities, combined with the flexibility of GNU Radio.

SDRA2021 - 08 - Jean-Michel Friedt: GNURadio compatible gen. purpose SDR emitter using RasPi4 PLL

Sreeraj Radjendran: Knowledge extraction from wireless spectrum data

In this half-hour talk, the need for large scale wireless spectrum monitoring will be discussed. A short introduction to a large scale wireless spectrum monitoring framework, Electrosense, will be given. Furthermore, how anomaly detection and signal classification can be performed using the collected data will also be discussed. Insights to the major problems with state-of-the-art machine learning models will also be discussed in this context.

SDRA2021 -11- Sreeraj Radjendran: Knowledge extraction from wireless spectrum data

Stefan Scholl, DC9ST: Classification of shortwave radio signals with deep learning

Automatic mode classification of radio signals in the HF band is a valueable tool for band monitoring, operation of rare transmission modes and future applications of cognitive radio. In recent years, machine learning has established as a general and very powerful approach to classification problems. The presentation first provides an introduction to neural networks and deep learning. Then neural nets are applied to the task of radio signal classification. The result is an experimental deep convolutional neural net (CNN), that can distinguish between 18 different transmission modes occurring in the HF band, such as AM, SSB, Morse, RTTY, Olivia, etc.

Additional Links: Stefan Scholl's post on this topic 

SDRA2021 -12- Stefan Scholl, DC9ST: Classification of shortwave radio signals with deep learning

Marcus Leech: Mapping the sky at 21cm: Gnuradio and Radio Astronomy

We show the results of a year-long sky survey at the 21cm hydrogen line, producing an intensity map of the sky covering a declination range from -35 to +75DEG. We discuss the software tools used, Gnu Radio signal flows, and the hardware aspects of the instrument.

SDRA2021 -14- Marcus Leech: Mapping the sky at 21cm: Gnuradio and Radio Astronomy

DragonOS: Automated Spectrum Analysis with SDR4Space.lite

Over on YouTube Aaron has uploaded a video showing how he is using the SDR4Space.lite package in DragonOS to do some interesting experiments with automated spectrum analysis using a PlutoSDR or RTL-SDR. As a reminder, Aaron is responsible for DragonOS which is a Linux OS with many SDR software programs preinstalled (including SDR4Space.lite).

This video shows how to use the RTLSDR/PlutoSDR with some of the prebuilt SDR4space.lite javascript examples preinstalled in DragonOS Focal.

I start out showing the new IQ recording script w/both the RTLSDR or the PlutoSDR. After a recording is triggered, the saved file can be looked at with inspectrum, SigDigger, etc. The javascript itself can be modified to produce desired results, but by default it's setup to record POCSAG.

The second half of the video shows how to use the wide spectrum analysis javascript to look at 88-108Mhz. The script produces a graphical representation of the RF spectrum along with a spreadsheet containing the corresponding RF information.

Any of these scripts can be modified, new ones can be built, and cron jobs or other scripts could call upon them as needed. I hope to do more videos once I figure out how to take the data and put it into some sort of database.

DragonOS Focal Automate Spectrum Analysis + IQ recording w/ SDR4space.lite (RTLSDR, PlutoSDR) part 1

A Facebook Group about 10GHz Experiments for Beginners

Thank you to Jean Marie (F5VLB) who has written in and wanted to share an invitation to their Facebook group where they are discussing ways for beginners to get into low cost 10 GHz (SHF) experiments. The 10 GHz band is generally considered tough to break into due to the precision required at these frequencies, however Jean notes how they are making use of readily available TV LNBs, RTL-SDRs and free software for their experiments. Jean writes:

I would like to present to you here about a Facebook group that addresses (only) radio enthusiasts, whether it is SWL or loose amateur radio and are interested in the high bands (SHF). On my life of Ham Radio I have never found a site that explains clearly, without big expenses, how to explore these bands.

The purpose of this FB group is to gently take you to this world, reserved for the experts, and yet accessible with reasonable means, with facilities found in the TV SAT store from the corner of the street. For some 50$ you will be ready with a dish, a lnb, a tx module.

The site begins. In 3 weeks 116 members came to join us. We go slowly, step by step.

The result ? It will listen to a satellite at 36000km, listening to tags everywhere around you, emit (if you have the license) on these mythical bands of 10 and 5.7 GHz.

This is aimed at young people aged 7 to 77, without special knowledge.

Want to know more ?

So come on https://www.facebook.com/groups/bzh10ghz this site is for you. And for others who are far in front of us, do not hesitate to bring your comments, simple, kind and taking into account that this site is made for newbies.

10 GHz Equipment and Group (Images provided by Jean Marie F5VLB)

A Physical LED Vehicle HUD for KerberosSDR Radio Fox Hunting

Mark Jessop (@vk5qi) has recently been experimenting with a LED based hardware vehicle heads up display (HUD) that he has created to be used together with our KerberosSDR. The KerberosSDR combined with four antennas in a circular array determines the bearing towards a transmitter, and then the HUD displays this bearing visually on a circle.  

The HUD is cleverly designed so that the LEDs reflect on the windshield of the car, allowing for the lights to be safely seen on the windshield while driving. More videos of the HUD being developed and used can be seen on his Twitter feed.

In the video below Mark also shows how he combines KerberosSDR bearing data with his Chase Mapper software, which he uses for tracking down radiosonde weather balloons.

Mark's custom KerberosSDR HUD seen on Twitter

Mark writes:

For the last few months I've been piecing together a radio direction finding (also known as 'fox-hunting') system using a RTLSDR-Blog Kerberos-SDR, a custom-made antenna array, and my 'ChaseMapper' software. I have also recently added a 'heads up display' (HUD) box which displays the direction-of-arrival and SNR data from the Kerberos-SDR software.

I hope to put together a longer video showing how the system goes together sometime in the future, but this short clip shows how the system is used in the final approach to a radio transmitter (in this case, a 144 MHz transmitter from one of the Amateur Radio Experimenters Group organised night fox-hunts).

The antenna array consists of two 4-element nested arrays, one with 200mm antenna spacing for the 70cm band, and another with 425mm antenna spacing for the 2m band. The array is mounted to my car roof-racks, with phase-matched coax entering the car through a window-mounted bulkhead.

The red lines on the map indicate a bearing line produced by the Kerberos-SDR software. As we drive around the fox location, bearings are plotted, and we look for where they cross. There are always some inaccurate bearings due to multi-path issues, and misalignment between bearing acquisition time and the position/heading of the car, but it works well enough to be able to allow navigation to the transmitter location. The display can get fairly busy, so there are options to threshold by signal quality, and to 'age out' bearings over time.

The beeping noise you hear in the video is the signal from the radio transmitter, in this case a 144.390 MHz beacon which transmits short CW 'pips'. We were listening to the signal with an Icom IC-705 attached to an omnidirectional antenna so we knew when the transmitter started and stopped (and hence when to trust any bearings produced by the DoA system).

Towards the end of the video you can see the HUD in action, with the blue lights showing the estimated signal arrival direction, relative to the front of the car. As I slowly drive past the transmitter location (which I could see out the side of the car), the bearings swing to the right, and the SNR shows as being very strong. This is exactly what the display was intended for - it's not about getting hyper-accurate bearings, but more knowing when you need to turn left/right, or get out of the car!

Thanks to Will Anthony for capturing the video while I was driving!

Software used:

AREG Fox-hunt Activities: https://www.areg.org.au/archives/category/activities/fox-hunting

Finding a Radio Fox using a Kerberos-SDR + ChaseMapper

KerberosSDR is our 4-channel phase coherent capable RTL-SDR unit that we previously crowdfunded back in 2018. With a 4-channel phase coherent RTL-SDR interesting applications like radio direction finding (RDF), passive radar and beam forming become possible. It can also be used as four separate RTL-SDRs for multichannel monitoring.

KerberosSDR is soon to be replaced with the upgraded KrakenSDR, which will begin crowd funding on Crowd Supply later this year. Be sure to sign up on the Crowd Supply page to be updated once the campaign releases as due to long supply chain crisis related lead times, only a limited amount of stock will be initially available.

SDR Videos from DEFCON 29

Recently some videos from this years (mostly virtual) DEFCON 29 conference have been uploaded to YouTube. Defcon is a major yearly conference all about information security, and some of the talks deal with wireless and SDR topics. Some interesting talks that we've found from the main Defcon and Villages are posted below.

You can view all the talks directly as well as the many others via the main stage DEFCON YouTube channel, the ICS Village Channel, RF Village Channel and the Aerospace Village. There are also several talks from the Ham Radio Village recorded on Twitch. Did we miss any interesting talks? Please let us know in the comments.

Smart Meters: I'm Hacking Infrastructure and So Should You (Hash Salehi)

Why Smart Meters? This is a question Hash is often asked. There's no bitcoin or credit card numbers hiding inside, so he must want to steal power, right? Openly analyzing the technology running our critical infrastructure and publishing the findings is something Hash is passionate about. In the wake of the great Texas freeze of 2021, we can no longer "hope" those in power will make decisions that are in the people's best interest. This talk will present research on the Landis+Gyr GridStream series of smart meters used by Oncor, the largest energy provider in Texas.

Cyber attacks on Industrial Control Systems (ICS) differ in scope and impact based on a number of factors, including the adversary's intent, sophistication and capabilities, and familiarity with ICS and automated indutrial processes. In order to understand, identify and address the specific points that can prevent or stop an attack, a systematic model known as "Cyber Kill Chain" is detailed, a term that comes from the military environment and registered by the Lockheed Martin company. While most are familiar with terms and theoretical diagrams of how security should be implemented, in this talk we want to present live how an attack chain occurs from scratch to compromise industrial devices, the full kill chain, based in our experiences. The goal is to land these threats into the real world without the need to carry out these attacks with a nation-state budget.

Smart Meters: I'm Hacking Infrastructure and So Should You (Hash Salehi)

DEF CON 29 - Paz Hameiri - TEMPEST Radio Station

TEMPEST is a cyber security term that refers to the use of electromagnetic energy emissions generated by electronic devices to leak data out of a target device. The attacks may be passive (where the attacker receives the emissions and recovers the data) or active (where the attacker uses dedicated malware to target and emit specific data).

In this talk I present a new side channel attack that uses GPU memory transfers to emit electromagnetic waves which are then received and processed by the attacker. Software developed for this work encodes audio on one computer and transmits it to the reception equipment positioned fifty feet away. The signals are received and processed and the audio is decoded and played. The maximum bit rate achieved was 33kbit/s and more than 99% of the packets were received.

Frequency selection not only enables maximization of signal quality over distance, but also enables the attacker to receive signals from a specific computer when several computers in the area are active. The software developed demonstrates audio packets transfers, but other types of digital data may be transmitted using the same technique.

[Slides Link] [Whitepaper]

DEF CON 29 - Paz Hameiri - TEMPEST Radio Station

DEF CON 29 RF Village - cemaxecuter - RF Propagation and Visualization with DragonOS

"Today's presentation will start with a brief history of DragonOS, where it started and where it's at today. After a short introduction, I'll dive into the subject of visualizing RF propagation with DragonOS. I'll be showing a fresh OS install and the necessary steps to generate a rough estimate of a transmitter based on SRTM-3 elevation data, as well as a new feature enabling visualization/calculations of the path between transmitter and receiver .

Topics and hands on (pre-recorded) demonstrations will include the following,

  • SPLAT! is an RF Signal Propagation, Loss, And Terrain analysis tool for the electromagnetic spectrum between 20 MHz and 20 GHz.
  • Signal Server Multi-threaded RF coverage calculator
  • Dr. Bill Walker's role
  • Signal Server and DragonOS integration
  • DF-Aggregator Developer / Modifications for visualization

I’ll conclude talking about future improvements to RF propagation and visualization tools."

DEF CON 29 RF Village - cemaxecuter - RF Propagation and Visualization with DragonOS

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SignalsEverywhere: Testing SDR++ A Hands on Overview

On on YouTube on the SignalsEverywhere channel Sarah has uploaded a new video where she gives a hands on overview of the SDR++ software. Last week we posted about the release of SDR++ V1.0.0, which is an open source, cross platform, C++ based GUI general receiver program for various SDRs including the RTL-SDR.

In the video Sarah shows it's basic usage in action and highlights many of the great features that SDR++ has. Overall Sarah notes that she is very impressed with SDR++, praising it as one of the best SDR applications released in a while, and we agree.

SDR++, The Cross-Platform bloat-free SDR software | A Hands on Overview

OpenWebRX Updated to V1.1.0

Thank you to Jason for writing in and letting us know that OpenWebRX Version 1.1.0 has been released on August 03. OpenWebRX is an open source program that allows users to make RTL-SDRs, KiwiSDRs and other SDRs accessible over the internet via a web browser. It is is currently available as a Raspberry Pi SD card image, in the Debian + Ubuntu repositories, as a docker image, or for manual installation. 

The latest version adds an AMBE voice data decoder, new decoders and metadata displays for NXDN and D-Star, and crisper SVG graphics.

Since we last posted about OpenWebRX updates in early 2020, there has also been support added for the Perseus-SDR, RadioBerry 2, Hermes HPSDR, Funcube Dongle Pro+ software defined radios. New decoders and support for external decoders such as JS8Call, FreeDV, Wideband FM, DREAM DRM,  FST4, FST4W, Q65 and M17 digital voice have been added.

There is also now a site called Receiverbook.de that aggregates a list of publicly available OpenWebRX receivers.

OpenWebRX Interface