Tagged: rtl2832

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 github.com/wizardyesterday/RtlSdrDiags.

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, github.com/wizardyesterday/RtlSdrDiags/blob/master/doc/agcResearch/README.txt

If you get curious how I implemented my AGC, you can look at the file, github.com/wizardyesterday/RtlSdrDiags/blob/master/radioDiags/src_diags/AutomaticGainControl.cc.

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.

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: https://www.qsl.net/do3mla/raspberry-pi-images.html

Here is a link to the Facebook group for the image: https://www.facebook.com/groups/raspberrynoaav2edition

Here is a link to ranged from my off-grid station where this image is running: https://usradioguy.com/science/off-grid-apt-lrpt-satellite-ground-station

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

Car Hacking in the Mr Robot TV Show Explained

Over on YouTube David Bombal has uploaded a video titled "Warning! This is how cars are hacked. Just like in Mr Robot." which explains how the car hacking scenes in Mr Robot worked. Mr Robot is a TV drama series about cybersecurity hackers, and it is known for portraying realistic hacks and scenarios. Back in 2019 we posted about an episode where they used a HackRF and Raspberry Pi to jam a garage door, before using the HackRF as an IMSI catcher. RTL-SDRs were also briefly used in some episodes.

David's video goes into greater detail about how realistic the hacking concepts displayed in the Mr Robot series are and if they would work in real time. In this video he goes into particular detail about car hacking. He uses a HackRF and RTL-SDR and demonstrates attacks like jamming, and signal replay.

This video is a part of a series exploring the hacks shown on Mr Robot. The full playlist can be found here.

Warning! This is how cars are hacked. Just like in Mr Robot.

Guglielmo FM and DAB Receiver Software Updated to V0.4

Thank you to Marco Greco for writing in and noting that V0.4 of his Guglielmo software has recently been released.

Guglielmo is a Linux (and now Windows) based RTL-SDR FM and DAB tuner software that supports SDRs including the RTL-SDR, Airspy, SDRplay, HackRF and LimeSDR. It is designed to be an easy to use program designed for media users, rather than hobbyist technical users.

The latest additions in V0.4 include support for MPRIS controllers, support for the SDRplay V3 API and support for Windows building (although at this time there appears to be no binary file available).

The AppImage can be found here https://github.com/marcogrecopriolo/guglielmo/releases

Guglielmo: Screenshot of the DAB Interface

KrakenSDR now in stock in our shop

As per our previous post we wanted to note that our direct sales KrakenSDR shop is now up and running with immediate shipping available. There is only a limited number of KrakenSDRs and antenna sets that we can sell direct to customers. After this stock is depleted all sales will need to go through Crowd Supply again. Regardless, both Crowd Supply and our direct sales shop are in stock right now.

If you weren't already aware, KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding and passive radar. We successfully crowd funded the device on Crowd Supply.  

KrakenSDR Shop now open
KrakenSDR Shop now open