Category: RTL-SDR

RTL-SDR Blog V3 Dongle Back in Stock at Amazon + Upcoming Cosmetic Changes in 2023

This is just a quick note to say that the RTL-SDR Blog V3 silver dongles are back in stock at Amazon USA after having taken a bit longer to arrive than usual. Currently only the individual dongle and separate multipurpose dipole antenna sets are in stock, and we expect the dongle+antenna bundled sets to be back in stock in January 2023. 

International customers can continue to order from our webstore and associated marketplaces via our store page at

RTL-SDR Blog V3 (Silver)

Upcoming 2023 Black RTL-SDR Blog V3 Dongles (Cosmetic Redesign)

We also want to give a heads up and note that in the next few months you might start seeing black RTL-SDR Blog V3 dongles in our stores, marketplaces and resellers. Going into 2023 we will be making a cosmetic change to our dongles (note that there is no changes to the highly tuned circuitry). There are two reasons for this cosmetic change.

The first is to try and better differentiate our original product from all the clones that have been popping up recently. Manufacturers of fake RTL-SDR Blog V3 clones have been getting closer and closer to copying our external design exactly. The internal circuitry of the clones however have often been poorly implemented, with broken features and poor performance. This results in a higher support burden, and damage to our brand when the clones inevitably perform poorly.

The second reason is for regulatory compliance with the FCC. Devices like this must have a FCC regulatory statement printed on the body, we have to add the UKCA logo for Brexit UK, and increase the size of the compliance logos as well. Moving forward this will eliminate any possible regulatory problems with Amazon or bulk imports, which are becoming stricter every year.

The new enclosure design uses a special black plating that like our silver models retains full electrical conductivity (normally electrical conductivity is not possible with most black plating's, but we investigated many solutions and finally found an appropriate one). Maintaining electrical conductivity ensures that shielding of the circuitry from interfering signals works properly. The text is also laser etched on, ensuring that it cannot be erased.

New black redesign of the RTL-SDR Blog V3 dongle. Coming in 2023. (Front)
New black redesign of the RTL-SDR Blog V3 dongle. Coming in 2023. (Rear)

DEF CON 30 RF Talks: Biohacking, Designing Antennas, Tracking Military Ghost Helicopters and More

DEF CON is a yearly conference with a focus on information security. At this years DEF CON 30 conference various talks on RF related topics were presented. In the past few weeks talks have been uploaded to YouTube for all to watch. Below we highlight a few we found interesting. The list of all main talks can be found on the Defcon YouTube channel, and talks from the RF Village can be found on the RF Hackers Sanctuary YouTube page

J9 - Biohacking Using SDR When You Don’t Know What You’re Doing

Security Researcher and BioHacker J9 presented an interesting and entertaining talk about how she used an SDR to listen in and decode a wireless pH sensor pill she ingested as part of a medical test.

What would you do if you were implanted with a medical device that broadcasts every 12 seconds?

Starting with loads of curiosity and very little knowledge about RF, how to use a software defined radio (SDR), and no knowledge of how to decode captured RF signals, I embarked on an adventure to teach myself something new. Jumping head first into the RF CTF helped greatly!

This presentation starts with cocaine and ketamine (in a controlled medical setting) and includes a near-death experience and new skills attained by building on the work of those who came before me. The end result of this adventure led me to the US Capitol to sit down with Senate staffers about the security and exploitability of medical devices.

DEF CON 30 RF Village - J9 - Biohacking Using SDR When You Don’t Know What You’re Doing

Erwin Karincic - Have a SDR? - Design and make your own antennas

In this talk Erwin Karincic explains how to design and make custom PCB antennas using home based or low cost techniques.

Most Software Defined Radios (SDRs) process a wide range of frequencies usually ranging from few MHz to multiple GHz where different antennas are used to pick up signals in a specific subset of that range. All applications using SDR require antennas to operate efficiently at very specific frequencies. Most inexpensive commercial antennas are designed either for wider ranges with lower gain over the entire range or very specific known frequencies with higher gain. The problem occurs when the researcher performs an assessment of a device and requires the use of specific frequency for which an antenna with high gain is not readily available. Most security researchers within wireless domain have outlined that their specific attack or exploit could be executed at higher range if antenna had better gain at that specific frequency. This talk focuses on bridging that gap by providing a way for researchers to create their own patch antennas without deep electrical engineering experience.

DEF CON 30 RF Village - Erwin Karincic - Have a SDR? - Design and make your own antennas

Andrew Logan - Tracking Military Ghost Helicopters over Washington DC

In this talk Andrew explains how ADS-B receivers, combined with ATC communications, public announcements and crowd sourced visual identification have helped track the activity of military helicopters operating over the Washington DC area.  

There's a running joke around Washington D.C. that the "State Bird" is the helicopter. Yet 96% of helicopter noise complaints from 2018-2021 went unattributed: D.C. Residents can not tell a news helicopter from a black hawk. Flight tracking sites remove flights as a paid service to aircraft owners and government agencies; even in the best case these sites do not receive tracking information from most military helicopters due to a Code of Federal Regulations exemption for "sensitive government mission for national defense, homeland security, intelligence or law enforcement." This makes an enormous amount of helicopter flights untraceable even for the FAA and leaves residents in the dark.

What if we could help residents identify helicopters? What if we could crowd source helicopter tracking? What if we could collect images to identify helicopters using computer vision? What if we could make aircraft radio as accessible as reading a map? What if we could make spotting helicopters a game that appeals to the competitive spirit of Washingtonians? And what if we could do all of this... on Twitter?

DEF CON 30 - Andrew Logan - Tracking Military Ghost Helicopters over Washington DC

SDR Special Tool Kit: A Ruggedized Enclosure for two RTL-SDR V3 Dongles

Terminal Armament, one of our resellers of RTL-SDR V3 dongles in the USA has created a companion product called the SDR Special Tool Kit (SDR-STK) which is a tactical ruggedized enclosure for two RTL-SDR V3 dongles. The SDR-STK consists of a two port USB hub enclosed in a water-resistant housing, and a rugged screw on USB-A cable. Two SMA connectors protrude out the top. The design is open source with designs and software due to be released on their GitHub in time.

The SDR-STK is estimated to ship within 5-7 weeks, and is available for pre-order via the Terminal Armament website.

The RTL-SDR dongle has long been the standard for an entry-level software defined radio. And while we do love it, the USB dongle form-factor is simply not suited for rigorous outdoor use. This is why we've developed the SDR-STK.

The SDR-STK is a ruggedized two-port USB hub specifically designed to fit two standard RTL-SDR dongles, and provide a durable, water-resistant housing. Having two dongles also grants capabilities not available with just one; these go beyond simply increasing the bandwidth. With one receiver acting as a tuner, you can have the second one preforming other tasks such as wide-band scanning, listening to a trunked radio control channel, or simply receiving other information such as ADS-B packets.

The SDR-STK isn't just a one-off hardware product. In the coming weeks while the pre-order is active, we will be releasing various software utilities for the SDR-STK on our GitHub, as well as the PCB schematic files. We're firm believers in Open-Source hardware software, and we hope to use this launch to kickstart several other communication related products and projects such as better Android SDR applications, and other SIGINT tools.

The SDR-STK includes itself, and a custom 1.5 foot USB Type A Male cable. Antennas and RTL-SDR's are not included unless specified or ordered in conjunction with the SDR-STK.

The RTL-SDR Just Got Better - Terminal Armament SDR-STK

A Software Based VGA AGC Implementation for the RTL-SDR

Thank you to Chris G for writing in and sharing with us his software VGA ADC controller for the RTL-SDR. AGC or 'automatic gain control' is an algorithm that attempts to automatically adjust the gain on the RTL-SDR in order to maximize the signal to noise ratio. The built in hardware AGC's on the RTL-SDR are intended for wideband TV signals, and work poorly with the narrower signals that SDR users typically deal with. However, it's possible that a software AGC implementation could be used instead.

Initially, I wanted to see how well things would work if I could manually control the VGA gain to avoid A/D overload within the 2832 chip.

I liked how things worked so I said: let's make things automatic! I implemented two variants of my AGC. One variant (my favorite) is an implementation of an AGC by Harris and Smith. It is an LMS algorithm that has equal transient response to a sudden increase in input signal magnitude and a sudden decrease in signal magnitude.

Since I'm doing this stuff in software, I operate on blocks of IQ data rather than operating on a sample by sample basis.

Initially, I observed limit cycles for at least two reasons:

  1.  The (approximately) 3.5dB step size in VGA gain adjust.
  2. The fact that when I receive a block of IQ data, another block is in transit.

This resulted me adjusting the gain while a block of data was in transit.

For item 1, I allow the deadband go be settable.

For item 2, I allow a "blanking time" to be settable. For my use case, If the AGC just made an adjustment, I skip making an adjustment while the next black is in transit.

Here is output of my 'get agcinfo' command.

AGC Internal Information
AGC Emabled : Yes
AGC Type : Harris
Blanking Counter : 0 ticks
Blanking Limit : 1 ticks
Lowpass Filter Coefficient: 0.800
Deadband : 1 dB
Operating Point : -12 dBFs
IF Gain : 11 dB
Signal Magnitude : 27
RSSI (After Mixer) : -24 dBFs

Note that my setpoint and gain adjustment works in decibels. That way, I treat the AGC as a linear system (it's actually uses an LMS algorithm) to simplify processing.

Now, I have used the same algorithm for my HackRF software.

I should mention that I implemented a pretty nice software squelch system for the rtl-sdr (and HackRF of course) if you have any interest in that.

I have a github repository at

I've thought about adding an I2C DAC whose output is connected to the VGA analog gain control line, but I really hate to butcher my v3 dongle. Having 1dB (or less) gain resolution would be nice though.

Another thing that I noticed is that, when writing to the tuner registers, the I2C repeater is enabled and you hear a spike in the demodulated audio. This may also occur (I haven't done that experiment) when disabling the repeater. Maybe not......

I have composed a report in,

If you get curious how I implemented my AGC, you can look at the file,

The header file is in radioDiags/hdr_diags/AutomaticGainControl.h.

RTL-SDR Blog L-Band Patch, Bullseye, YouLoop Sale

This Black Friday we are offering a discount on our L-Band Patch, Bullseye and YouLoop antennas in our store and marketplace listings! The sale will run until the end of November.

Our L-Band patch is an active design for receiving L-band satellites such as Inmarsat, Iridium, GPS and other satellites that transmit between 1525 - 1660 MHz (please note that you cannot use it for weak signals that require a dish like HRPT or GOES).

The Bullseye LNB is a TCXO stabilized LNB for the QO-100 geostationary amateur satellite and other Ku-band satellites.

The YouLoop is a super portable passive HF/VHF loop antenna designed for super low NF/MDS receivers like the Airspy HF+ Discovery.

  • L-Band Patch Antenna: US $59.95 $49.95
  • Bullseye LNB: US $29.95 $24.95
  • YouLoop: US $39.95 $31.96

Pricing includes free shipping to most countries. Please note that pricing does not include VAT and/or taxes which may be added for your country.

SDRplay RSPdx Black Friday and Holiday Season Sale Now Active

SDRplay have today announced a sale on their "RSPdx" product which runs from today until December 31st. The new pricing is  £130/€156/$169.95 plus shipping and any applicable taxes. This pricing is available for direct sales from SDRplay, and at any participating resellers. The pricing on SDRplay's direct sales platform before the sale was US$214 plus shipping.

Note that individual resellers may be offering slightly different prices depending on if free shipping is offered. For example Ham Radio Outlet in the USA is offering the RSPdx for $179.95 including free shipping.

The RSPdx is designed for high performance DX reception and SDRplay note that it achieves this with additional filtering, improved intermodulation performance, a DAB notch filter, additional attenuation steps, and high dynamic range enhancements for frequencies under 2 MHz.

At SDRplay, we recognise that times are very tough for a lot of people. In view of the economic pressures that people are facing, we want to lend a helping hand by offering the very popular RSPdx at a special low price for this holiday buying season. After discussions with our dealer network, from Black Friday until the 31st December, we (along with participating dealers) plan to offer the RSPdx at a holiday discounted suggested retail price of £130/€156/$169.95 plus shipping and any applicable taxes. This represents a substantial discount of more than one fifth when compared to the normal retail price.

Starting midnight EST, Thursday November 24th visit  to purchase an RSPdx at the special price or contact your local SDRplay dealer for more details.  Please also note that stocks are limited and this offer will certainly end on the 31st December and prices will revert to normal commercial levels thereafter.

This is a great opportunity to get the RSPdx as a gift for a newcomer or a returning radio enthusiast at a price which won’t be repeated, as our suppliers are already increasing their prices for the new year.

  • Prices shown are prices offered when buying direct from SDRplay. Shipping and taxes are extra.  SDRplay ships from the UK to most countries in the world.  However some countries will require import duty to be paid on top.
  • SDRplay dealers who usually include free shipping will adjust the prices accordingly
  • Check with your local dealer to see if they are participating.
  • Links to both the SDRplay direct purchasing page and our list of authorised resellers can be found here
SDRplay - Special RSPdx Holiday Promotion

Raspberry NOAA V2 Edition 2023 Image Released

Thank you to Manuel Lausmann for submitting news about the release of the "Raspberry NOAA V2 Edition 2023" image for Raspberry Pi's. This image has been created by Jochen Köster (DC9DD), and contains a few enhancements over the previous image, mainly by including a program that allows users to create composite images of images from the Meteor weather satellites. Manuel writes:

This is based on the well-known Raspberry Noaa V2. In this image, however, the latest MeteorDemod has been added, which makes it possible to generate composite images, which was previously only possible under Windows with Meteorgis.

Furthermore, the image has an additional FTP uploader. The image was created by Jochen Köster DC9DD. It's available from today. This image is also part of my off-grid station in Northern Norway.

Download link for the image:

Here is a link to the Facebook group for the image:

Here is a link to ranged from my off-grid station where this image is running:

An example of a composite image from multiple Meteor satellite images.

GNU Radio Conference 2022 Talks Available on YouTube

During September 26 - 30 GNU Radio Conference 2022 was held in Washington DC. GNU Radio Conference (aka GRCon) is an annual conference centered around the GNU Radio Project and community, and is one of the premier software defined radio industry events. GNU Radio is an open source digital signals processing (DSP) tool which is used often with SDRs.

A few days ago videos of all the presentations were released on their YouTube channels, and all the talks can be found on this playlist. The videos contain a mix of in person and remote talks. A schedule of all talks can be found on the GNU Radio website.

GRCon22 - GNU Radio Project Update