Thank you to Mitsonobu Saitou for writing in and sharing with us a product that he has created which improves reception on of the Malachite DSP software defined radio and other shortwave radios by up to 20dB by improving the grounding. It appears to work by using the negative USB line as a ground via a modified USB cable with grounding clip on the other end. The product is available via Amazon Japan with international shipping.
The Malachite DSP is a portable battery powered software defined radio with built in screen. It is popular amongst shortwave listeners.
Saitou writes the following summary, and full details about the product are available on his blog (link uses Google Translate to translate from Japanese to English):
Today's item is "Dokodemo Earth KUN". This is an item to pull the ground wire from the charging connector of DCL radios and Mlachite DSPs.
The sensitivity of the receiver will be improved by strengthening the grounding. This is how I applied it.
It is easy to connect by pulling out the ground wire from the charging connector instead of the antenna jack.
It can also be used as a loop antenna by connecting the ground to the antenna.
We have confirmed the effectiveness of this product outdoors. Users who have used this item have experienced a significant increase in sensitivity.
Malachite DSP and SWL Radio USB Grounding Enhancement Cable
Remote SDR V2 is software that allows you to easily remotely access either a PlutoSDR, HackRF or RTL-SDR software defined radio. It was originally designed to be used with the amateur radio QO-100 satellite, but version 2.0 includes multiple demodulation modes, NBFM/SSB transmission capability, CTCSS and DTMF encoders, modulation compression and a programmable frequency shift for relays.
Mark Jessop (@vk5qi) has recently been experimenting with a LED based hardware vehicle heads up display (HUD) that he has created to be used together with our KerberosSDR. The KerberosSDR combined with four antennas in a circular array determines the bearing towards a transmitter, and then the HUD displays this bearing visually on a circle.
The HUD is cleverly designed so that the LEDs reflect on the windshield of the car, allowing for the lights to be safely seen on the windshield while driving. More videos of the HUD being developed and used can be seen on his Twitter feed.
In the video below Mark also shows how he combines KerberosSDR bearing data with his Chase Mapper software, which he uses for tracking down radiosonde weather balloons.
For the last few months I've been piecing together a radio direction finding (also known as 'fox-hunting') system using a RTLSDR-Blog Kerberos-SDR, a custom-made antenna array, and my 'ChaseMapper' software. I have also recently added a 'heads up display' (HUD) box which displays the direction-of-arrival and SNR data from the Kerberos-SDR software.
I hope to put together a longer video showing how the system goes together sometime in the future, but this short clip shows how the system is used in the final approach to a radio transmitter (in this case, a 144 MHz transmitter from one of the Amateur Radio Experimenters Group organised night fox-hunts).
The antenna array consists of two 4-element nested arrays, one with 200mm antenna spacing for the 70cm band, and another with 425mm antenna spacing for the 2m band. The array is mounted to my car roof-racks, with phase-matched coax entering the car through a window-mounted bulkhead.
The red lines on the map indicate a bearing line produced by the Kerberos-SDR software. As we drive around the fox location, bearings are plotted, and we look for where they cross. There are always some inaccurate bearings due to multi-path issues, and misalignment between bearing acquisition time and the position/heading of the car, but it works well enough to be able to allow navigation to the transmitter location. The display can get fairly busy, so there are options to threshold by signal quality, and to 'age out' bearings over time.
The beeping noise you hear in the video is the signal from the radio transmitter, in this case a 144.390 MHz beacon which transmits short CW 'pips'. We were listening to the signal with an Icom IC-705 attached to an omnidirectional antenna so we knew when the transmitter started and stopped (and hence when to trust any bearings produced by the DoA system).
Towards the end of the video you can see the HUD in action, with the blue lights showing the estimated signal arrival direction, relative to the front of the car. As I slowly drive past the transmitter location (which I could see out the side of the car), the bearings swing to the right, and the SNR shows as being very strong. This is exactly what the display was intended for - it's not about getting hyper-accurate bearings, but more knowing when you need to turn left/right, or get out of the car!
Thanks to Will Anthony for capturing the video while I was driving!
Finding a Radio Fox using a Kerberos-SDR + ChaseMapper
KerberosSDR is our 4-channel phase coherent capable RTL-SDR unit that we previously crowdfunded back in 2018. With a 4-channel phase coherent RTL-SDR interesting applications like radio direction finding (RDF), passive radar and beam forming become possible. It can also be used as four separate RTL-SDRs for multichannel monitoring.
KerberosSDR is soon to be replaced with the upgraded KrakenSDR, which will begin crowd funding on Crowd Supply later this year. Be sure to sign up on the Crowd Supply page to be updated once the campaign releases as due to long supply chain crisis related lead times, only a limited amount of stock will be initially available.
The RadioBerry is a HF transceiver board designed to be used as an add on 'hat' for the Raspberry Pi. It uses the same AD9866 chip as the Hermes Lite 2 SDR which gives it a 12-bit ADC with one RX and one TX channel, a maximum bandwidth of up to 384 kHz, and an operating frequency range of 0 to 30 MHz.
In the video TechMinds shows how to connect and setup the Radioberry software on the Pi and how to stream from the Pi to SDR-Console V3 on a PC. He goes on to demonstrate the Radioberry receiving HF signals, noting that the performance is good, although he uses an Ethernet connection and Pi 4 for best performance.
TechMinds notes that he will test the transmit functionality in a future video, once he receives a preamp designed to be used with the Radioberry.
Over on YouTube we've seen a good video from channel Ham Radio DX where presenter Hayden shows how to use an RTL-SDR to receive slow scan television (SSTV) images from the International Space Station (ISS). Often the ISS will transmit SSTV images down to earth on the VHF 2 meter bands as part of an event. With an RTL-SDR and simple antenna it's possible to receive those images.
In the video Hayden discusses the SSTV transmission, and demonstrates some SSTV decoding happening in real time as the ISS passes over his location. If you're looking to get started in ISS SSTV reception, this is a good video to get an idea of what's involved. He finishes the video with some useful tips for reception.
Using a RTL SDR Dongle to receive pictures from the ISS! | Software Defined Radio
In Rob's latest episode of his excellent aviation communications series on his Frugal Radio YouTube channel he shows how to decode aircraft HF ACARS (HFDL) using a software defined radio. HFDL is short for "high frequency data link", and is a method aircraft use for sending text and data communications to ground stations. It is an alternative to VHF or satellite ACARS communications methods.
In the video he shows how he's been able to receive HFDL from all over the world using a simple HF dipole antenna and an Airspy HF+ Discovery. He goes on to show how to find HFDL signals, and how to decode signals using SDR# and the PC-HFDL software. Finally he shows examples of aircraft received, and how to interpret some of the information being received, including location information.
How to decode HF ACARS (HFDL) free with your SDR - Monitoring Aviation Communications Episode 8
In this weeks video Rob from his Frugal Radio YouTube channel shows us how he's turned an old piece of scrap electrical extension cord into an effective HF antenna for his Airspy HF+ SDR. The scrap wire is combined with a US$15 NooElec 9:1 balun which helps improve the impedance match of the antenna. He then stretches the dipole out through his backyard and then hooks it up to his Airspy HF+.
The results show good reception across the 20m, 80m, 40m amateur radio bands, as well as on HF ATC aircraft communications, US coast guard weather information broadcasts and the AM broadcast band.
I made an HF Dipole for free! Reception was good on my AirSpy HF+ Discovery SDR!
In his latest YouTube video Tech Minds explains and demonstrates Remote SDR V2, which is software that allows you to easily remotely access either a PlutoSDR, HackRF or RTL-SDR software defined radio. It is designed to be used with the amateur radio QO-100 satellite, but version 2.0 now include multiple demodulation modes, NBFM/SSB transmission capability, CTCSS and DTMF encoders, modulation compression and a programmable frequency shift for relays.
In his video Tech Minds shows how to install Remote SDR V2 onto an Orange Pi via the SD card image, how to access the web interface, and how to access and use the connected SDR.
Remote SDR V2 with Orange Pi and Transmit Capable
We note that the code is designed to be run on Orange Pi boards, which are low cost single board computers similar to Raspberry Pi's. However over on Twitter @devnulling has indicated that his own fork of the code should run on x86 systems. Aaron @cemaxecuter is also working on including it into a DragonOS release.
The image below demonstrates a typical Remote SDR V2 transceiver setup with two HackRFs.
A full QO-100 Transceiver Setup with Remote SDR V2 and two HackRF's.
