Category: Other

Decoding Voyager 1 Telemetry with GNU Radio

Daniel Estévez often posts on his blog about advanced SDR and radio experiments he's worked on. In a recent post he describes how he decoded telemetry from the Voyager 1 spacecraft using GNU Radio. As Voyager 1 is so far away, and the signal so weak, a rather large scale 100 meter dish is required to receive Voyager 1. So he uses publicly available recorded data received by the Green Bank Telescope in 2015.

Using GNU Radio he first converts the telescope's data file discarding most of the 187.5 MHz recorded bandwidth, then decimates the signal allowing the very weak carrier and data subcarriers to be seen in the resulting high resolution FFT plot. Daniel notes how most of the power is spent in the carrier, allowing ground stations to more easily detect the signal and at least measure doppler to determine the spacecrafts trajectory. The rest of the post explains how the carrier is tracked, how to correct for doppler and phase shifts, how to demodulate the data, apply error correction, and finally decode the data packet.

While not something we can easily listen to directly, it is amazing that we can all be NASA engineers right at home with GNU Radio and tutorials like this.

Voyager 1's Spectrum. Strong carrier in the middle, and two data subcarriers.

Arinst Dreamkit SDR now on sale for $230 + Shipping

About a month ago we posted about the Arinst Dreamkit, which was an unreleased Russian made portable receive only SDR with 16-bit ADC, 1 - 3100 MHz tuning range, up to 5 MHz instantaneous bandwidth, and very fast scanning capabilities.

Reader 'sunny' has written in and informed us that the Arinst Dreamkit is now released and available for sale on both eBay and Aliexpress. The pricing is $230 + shipping costs. Sunny notes that the manual is only in Russian, and currently it does not have any digital decoding capabilities, and no preselector on the input.

The Arinst Dreamkit

DragonOS: RF Propagation Analysis with Signal Server GUI

DragonOS is a ready to use Ubuntu Linux image that comes preinstalled with multiple SDR software packages. The creator Aaron also runs a YouTube channel showing how to use the various packages installed. In his latest video Aaron shows how to use the new Signal-Server GUI that has recently been added to DragonOS.

We posted about Signal Server before as it's a very powerful open source tool for creating RF Propagation simulations. With this tool you can determine how a signal from a transmitter might propagate, by taking into account factors like frequency, EIRP, and geographic elevation maps. The resulting propagation map can then be plotted on Google Earth.

Aarons recent work adds thetacoms GUI to the Signal Server install on DragonOS, and his video shows how to use it, including an introduction to RF propagation analysis in general. This version of DragonOS with the GUI is not yet available for download, but it will be in a future version. For now the video also shows how to install the GUI.

DragonOS Focal New Signal Server GUI Setup + Intro to RF Propagation Analysis (Signal-Server) Part 1

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

Arinst SDR Dreamkit: A Portable RX SDR with 16-Bits, 1 – 3100 MHz Range and 5 MHz Bandwidth

Thank you to reader 'sunny' who has written in to share a new software defined radio that he has found being previewed on YouTube. The SDR is the Arinst SDR Dreamkit, a Russian made portable receive only SDR that will have a 16-bit ADC, 1 - 3100 MHz tuning range, up to 5 MHz instantaneous bandwidth, and have very fast processing which can scan the spectrum at 20 GHz per second. It also comes with a built in 3.9" touchscreen and loudspeaker.

Arinst are a Russian company that designs, produces and sells affordable portable spectrum analyzers, vector network analyzers, power amplifiers and antennas.

The Dreamkit is not yet available for sale but reader sunny has indicated that the pricing will be ~$250, although we cannot confirm that information. In a YouTube comment the developer only writes that it will be slightly more expensive than the Malachite SDR, for which an original non-clone unit sells for around $200. 

The Arinst SDR Dreamkit

We have not seen any announcement of the product on their website, but on their first YouTube video for the product they write some specs (translated from Russian):

  • There is no preselector.
    • Possibility to supply preselectors and source repeaters via SMA antenna connector. It also provides for the generation of a code message for each frequency range by pulse modulation of the supply voltage supplied to the antenna connector.
  • Operating frequency range - 1-3100MHz
  • Input impedance 50 Ohm.
  • ADC capacity - 16 bits, effective 13 bits.
  • Instant scan bandwidth - 5 MHz, sampling rate: 2 IQ channels at 6 MHz.
  • Scanning speed over 20 GHz per second.
  • Audio: built-in loudspeaker, headphones, bluetooth (optional).
  • Battery life up to 3 hours.

From the English demo video shown below, the interface looks very slick, customizable and with a very responsive refresh rate. The video shows off the features which include all the standard demodulation modes, an RDS decoder, 12V 100mA bias tee, and the ability to connect to a PC and run it on HDSDR.

It appears that they plan to sell additional preselectors and LNAs that will be powered via the 12V bias tee. An interesting point is that it appears that they will control the external devices via a some sort of modulated pulse on the coax.  

Arinst SDR Dreamkit V1D

An Expansion Board with SMA Output for the Raspberry Pi and RPiTX

Thank you to Ihar Yatsevich for writing in and sharing his open source project called "rpitx-coax-pcb" which is an expansion board for the Raspberry Pi that converts the GPIO pin used by RPiTX into a coaxial SMA connector for easily connecting the output to an antenna. He notes that there are two revisions. One includes a filter in the in the GP1212 / GP731 case and the other does not. Filters in this type of enclosure can be found from Minicircuits. Finally he notes that he has not yet fully tested the design, but believes that there will be no problems.

The GitHub contains the EasyEDA design files, schematics and gerbers which you can use to print and build the PCB yourself.

If you are unfamiliar with it, RPiTX is a program for Raspberry Pi single board computers that allows you to transmit almost any type of signal on frequencies between 5 kHz up to 1500 MHz with nothing more than a wire connected to a GPIO pin. However, it is highly recommended that appropriate filtering be used if you are transmitting with an amplifier or longer range antenna as the RPiTX contains harmonics that can cause interference with other devices.

RPiTX Coaxial PCB Expansion Board for the Raspberry Pi

Migou: A Low-Power Hybrid Radio Platform

Thank you to Ramiro Utrilla Gutiérrez a PhD Candidate researcher at Universidad Politécnica de Madrid for writing in and sharing his research groups work on a low power SDR radio platform called "Migou". The basic idea is to combine software defined radio which is flexible but power hungry, with less flexible but power efficient hardware radios. The design files and BOM are creative commons licensed, and free to download. The radio is capable of operating in the 433 MHz, 868 MHz and 2.4 GHz bands at sample rates of up to 4 MSPS in SDR mode. Ramiro writes:

I'm the main developer of the MIGOU platform. This platform uses the Microchip AT86RF215 transceiver (like TinySDR and iotSDR) and a Microchip SmartFusion2 flash-based FPGA SoC.
 
The particularity of our work is what we have called the hybrid radio approach, which proposes to provide low-resource devices with the ability to operate both as a current mote, using a hardware transceiver, and as an SDR system. This is possible using only the AT86RF215 transceiver. With these capabilities, hybrid radio end-devices can exploit the SDR hardware flexibility for those sporadic tasks that strictly require it, and still benefit from the energy efficiency of hardware transceivers for all other tasks.
 
Our platform is not a commercial product, it is an open-source research tool. If you are interested, you can read more about our work in this article in Sensors journal, where we present the hybrid radio approach and the MIGOU platform, and in this article in IEEE Access journal, where we approach a Cognitive Radio problem from the perspective of our hybrid radio platform. Both articles are also open access.

The B105 Electronic Systems Lab also appear to have a website for the design which provides a summary:

MIGOU is a low-power wireless experimental platform designed to simultaneously address the energy-efficiency requirements of resource-constrained end-devices and the hardware flexibility demanded by the current Cognitive Radio (CR) and edge computing paradigms. This platform relies on the SmartFusion2 SoC that integrates an ARM Cortex-M3 processor and a flash-based FPGA, where high-speed processing tasks can be offloaded and computed more efficiently via hardware acceleration. In addition, at the radio level, the platform can operate both as a traditional node, which demands lower energy resources and development time, and as a Software-Defined Radio (SDR) system, which allows for the implementation of custom CR features. Moreover, the ability to dynamically switch between these two modes of operation opens the possibility for developing new hybrid strategies, taking advantage of both the flexibility offered by the SDR and the efficiency of the transceiver’s highly optimized baseband cores.

The power consumption of our platform was measured in transmit, receive, and sleep modes. These measurements were compared with the corresponding ones of other representative tools and systems: YetiMote, a traditional IoT end-device; MarmotE SDR, a low-power SDR system; and B200mini and B210 USRPs, two widely used high-performance SDR platforms. Moreover, all these devices were compared in terms of their hardware features. The results obtained confirmed that a state-of-the-art tradeoff between hardware flexibility and energy efficiency was achieved. These features will allow researchers to develop appropriate solutions to current end-devices’ challenges, and to test and evaluate them in real scenarios.

Migou: Low-Power Hybrid Radio Platform

Evil Crow RF: An Open Source CC1101 Based Device for Pentesting

The CC1101 is a popular RF silicon chip as it can handle many common digital modulation modes such as OOK/ASK, FSK, GFSK, and MSK within it's hardware. It is not a software defined radio, but rather a hardware radio that can be easily software controlled. Over the years we've seen the CC1101 and it's cousin the CC1111 with embedded microcontroller used in several pentesting/RF reverse engineering tools such as the Flipper Zero, Yard Stick One and PandwaRF.

There is now a new open source CC1101 implementation called the "Evil Crow RF". This hardware marries two CC1101 modules with an ESP32 WiFi and Bluetooth microcontroller. It is capable of operating in the 300 MHz - 348 MHz, 387 MHz - 464 MHz and 779 MHz - 928 MHz bands. As it has two CC1101 modules it can receive or transmit on two different frequencies at the same time. 

The firmware running on the ESP32 allows you to control the device via a simple web interface. Currently built in are interfaces for receiving, transmitting and brute forcing.

The device hardware is completely is open source so anyone can build it, however the creators are selling a ready to use version on Aliexpress, however at the time of this post it appears to be out of stock.

Over on Twitter creator @JoelSernaMoreno has uploaded a short video of it working.

The Evil Crow RF Open Source CC1101 Based Radio