Category: Other

Tech Minds: Reviewing the Malahit DSP1 SDR Receiver 50KHz – 2GHz

Over on the Tech Minds YouTube channel, Matt has uploaded a new review and demonstration of a Malahiteam DSP1 SDR Receiver 50KHz - 2GHz. This particular unit appears to be a Chinese clone unit which is actually called a 'Malahit SDR'. The Russian company Malahiteam makes the original units, and they come in a different enclosure and feature the full Malahiteam logo.

In the video Matt shows this version of the Malahit DSP1 in action, noting that the built-in speakers sound great and that RF performance seems to be good. He does however note that the enclosure is a bit cheap, being built out of PCB boards, and that the top encoder knob sometimes doesn't work properly. Overall Matt mentions that he probably wouldn't buy it at the current ~US$180 price point, noting that better newer models like the DSP2 and DSP3 already exist. 

Malahiteam DSP SDR Receiver 50KHz - 2GHz

New Tool to Convert Between SDR# and SDR++ Frequency List Formats

Thank you to 'thewsoftware' over on our forums who has shared with us his SDR# <-> SDR++ frequency list converter (sdrfc) software. SDR# and SDR++ are two popular SDR programs often used with the RTL-SDR, but each uses a different format for storing custom frequency lists.

The new sdrfc tool allows users to easily convert frequency lists between SDR# and SDR++ formats, so you don't need to manually type out a frequency list for both programs.

The sdrfc is a Windows command line tool and instructions for using it can be found on the GitHub Readme. A release zip file is available on the GitHub Releases page.

SDR# <-> SDR++ Frequency Converter Readme

Great Scott Gadgets URTI: Phase Two Progress Report

Over on their GitHub, Great Scott Gadgets, creators of the popular HackRF SDR, have created a phase two progress report for their upcoming URTI product. URTI (Universal Radio Test Instrument) is their next generation software defined radio which will work not only as a full-duplex SDR transceiver, but also as a vector network analyzer, spectrum analyzer and more.

In the phase two update they note that they have completed fabrication of an initial prototype board and have confirmed that all components on the board are functional. They note that much of phase four was already completed in parallel, which means the firmware and gateware development is also close to completion. So hopefully we will see more updates soon.

More information about URTI can be found at greatscottgadgets.com/urti.

URTI (Universal Radio Test Instrument) First Prototype Board

Tech Minds: Testing Meshtastic Compatible Lilygo LoRa Devices

In the latest video on the Tech Minds YouTube channel Matt tests out the Meshtastic software running on varius Lilygo LoRa devices. Meshtastic is software that can run on cheap LoRa hardware that enables off-grid mesh network based communications.

Being mesh network based means that there are no central repeaters, and instead each device can extend the range of the network by being a repeater itself. Meshtastic can run on various cheap 'Lilygo' branded LoRa devices that come in 433, 868 or 915 MHz license free frequencies depending on your regional band plan.

In his video Matt tests out various models in the Lilygo range, including a ESP32 based wrist watch and he also shows how to install the firmware on each using the online flasher.

Meshtastic Compatible Lilygo Lora Devices

Spacewalker LNA 434 MHz In Prelaunch at CrowdSupply

Thank you to Zoltan and team for submitting news of the prelaunch of their Spacewalker LNA 434 MHz. Spacewalker LNA is designed to improve reception of PocketSat and Cubesat satellite signals when received with SDR devices like the RTL-SDR. Often these relatively weak signals are drowned out by strong interfering terrestrial signals like DVB-T and GSM. To solve this the triple filter and dual amplification design used in the Spacewalker LNA can help to isolate the satellite signals.

The team write that prototype versions of the LNA are already successfully in use around the world with SatNOGS stations. The device uses two state of the art QPL9547 LNA with 0.2 dB noise figure and 25 dB gain at 434 MHz and three 434 MHz SAW filters. The design also uses an interesting coax stub for ESD protection. It can be powered with 5V USB-C or via bias tee.

The LNA is currently in the prelaunch stages with CrowdSupply, so it will likely be released for crowd funding within the next few months. If you are interested in being notified when the campaign launched, be sure to sign up on the Crowd Supply page for updates.

Spacewalker LNA 434 MHz. Designed for PocketSat and CubeSat signals amidst strong DVB-T, TETRA, FM, and LTE signals from densely packed transmitter towers.
Spacewalker LNA 434 MHz. Designed for PocketSat and CubeSat signals amidst strong DVB-T, TETRA, FM, and LTE signals from densely packed transmitter towers.

An HF Ham Radio SSB/AM/FM/CW Transmitter made from a Raspberry Pi Pico and not much more

Over on Hackaday we've seen a story about a Raspberry Pi Pico based software defined radio transmitter that is capable of transmitting SSB, AM, FM and CW anywhere between 0.5 - 30 MHz.

The design generates an oscillator signal using the Pico's Programmable IO. For AM/SSB it uses the PWM output pins to generate an RF envelope which gets mixed together with the oscillator using an analog multiplexor. A small microphone is also connected to the Pico for voice transmissions. The designer notes that the output power is far too low to be used on the air, but adding an output amplifier would help.

The software is all open source and provided on GitHub, and more information about the design can be found on the designer's '101things' website.

The Raspberry Pi Pico is a low cost microcontroller board, and we note it cannot run Linux like standard Raspberry Pi boards. This means that software like RpiTX cannot be used.

Build a Ham Transmitter with a Raspberry Pi Pico

Tech Minds: Testing the Jstvro Handheld Spectrum Analyzer

In one of his latest videos Matt from the Tech Minds YouTube channel tests out the "Jstvro" handheld spectrum analyzer which can be found on sites like Banggood and Aliexpress (the device is cheaper on Aliexpress) for about US$127.50 for the single antenna model, and US$165 for the dual antenna model including shipping. The device appears to be a clone of the RF Explorer, which is a spectrum analyzer that has been on the market for several years.

A spectrum analyzer can be used to visualize the RF spectrum and find frequencies that are active. It cannot demodulate signals like an SDR.

The Jstvro spectrum analyzer covers 240-960 MHz on the first port and 15 - 2700 MHz on the second port, with a total visible bandwidth of anywhere between 112 kHz to 600 MHz. It comes with a single color illuminated LCD screen.

In the video Matt gives an overview of the spectrum analyzer and shows it operating. He notes that the USB-C connection to the PC does not appear to be working and Matt was unable to find the PC software or firmware updates mentioned in the manual. In the rest of the video Matt demonstrates the 2.4G WiFi analyzer feature, the spectrum analyzer feature and goes over the settings.

Visualize the RF Spectrum With This Handheld Spectrum Analyzer

SDU-X: Software Defined Data Transmission with Ultrasonic Transducers

Damian needed to get telemetry from his off-grid solar system 150 feet away, but didn't want to spin up another unreliable WiFi device. Instead he came up with a clever solution that involves using ultrasonic transducers as the physical layer of a software defined communications system instead of RF transmitters and receivers.

Having worked on RF communications systems before, Damian knew that the same  concepts apply no matter what the physical layer of communication is. His system called SDU-X uses two ultrasonic transducers mounted on 3D printed parabolic dish's to increase the directional gain, and an Arduino Nano with amplifiers and a Digital to Analog (DAC) converter for the ultrasonic transmission.

His post explains the hardware and protocol implementation, as well as explaining the Arduino code that he's released for free. The code and 3D printer models can be found on Thingiverse.

SDU-X: A software defined ultrasonic communications system.
SDU-X: A software defined ultrasonic communications system.