Category: Other

Comparing the Malahit DSP-2 Russian Original vs Chinese Clone

Over on the SWLing.com blog guest poster Dan Robinson has posted an article comparing  the Russian made original "Malahit" DSP-2 (~$200) vs the Chinese clone who have upped the version number to DSP-3, but will be referred to as the "HFDY V3" (~$180). The original Malahit DSP-2 from "Malahiteam" is a portable SDR with built in speaker and touchscreen. It has a frequency range spanning between 50 kHz to 50 MHz, 50 MHz to 250 MHz and 400 MHz to 2 GHz.

There are several clones out there, but Dan notes that the Chinese "HFDY V3" version appears to be superior in terms of build quality with its high quality metal construction, high quality knobs, two antenna jacks for AM and FM, good internal shielding, and front firing speaker with beautiful gold grill. These are all improvements over the Russian made version, however it's important to note that the Chinese clone version comes with older firmware that must be carefully updated first, in order to obtain the same features as the original DSP-2.

Overall in terms of performance, after the firmware upgrade, Dan finds no difference in performance between the two. Dan goes on to mention that both the clone and original suffer from grounding problems and sensitivity to touch especially with shortwave. 

Finally he notes how Malahiteam are planning a new higher end more expensive product which will include an optional add-on for enabling reception up to 6 GHz. The estimated cost of the new version will be $480 with the 6 GHz add-on, and $42o without.

The HFDY Malahit DSP SDR V3 (Chinese Clone)

Is the Titus II Portable Android Tablet Shortwave SDR Close to Release?

The PatronX Titus II SDR is something we've been posting about several times since 2016, but in the end it was never released and assumed to be vaporware. However, we found that the website for the Titus II SDR was updated only a few weeks ago, and pricing details have been added advertising $120 and $150 for two versions of the product. But on the new website there is no store, just an email link to contact sales for ordering information. We contacted that email two weeks ago for more information but have not received a reply back yet.

The PantronX Titus II was advertised to be a portable Android tablet based SDR that would feature a 100 kHz - 2 GHz tuning range, and software that focuses on HF digital DRM decoding, as well as DAB on VHF. Computer rendered images show the tablet housed in a portable carry enclosure with two speakers. Their new website writes:

The design of rTablet / rTab defined radio receiver started in 2014. It soon became evident that electronic products available on the market could not be modified to incorporate the advanced features requested by potential buyers. This initiated the process of the innovative design of the Titus SDR (Software Defined Radio) unit. The engineering team started with a general purpose computer unit and embedding it in a broadband radio receiver module.

All types of applications, including RF software, could be installed. For example, DRM capabilities could be added as DRM is an open source. Dream Linux app was converted to run under Android mobile operating system.

The Titus rTablet / rTab being introduced to the market, is a low cost, high performance platform with many RF and PC factory installed applications.

Key feature of rTablet / rTab is the compatibility with analog (SW, AM, FM) and digital standards (DRM, DRM+, DAB, DAB+, HD). Consequently the market of rTablet / rTab is global.

The updated website with pricing and an ordering email makes us think that it might be finally on the way, but the lack of email reply is concerning. If anyone has any further information about the rTab/Titus II please be sure to share with us in the comments!

Titus II SDR updated website
Titus II Specs

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