Over on his latest video Tech Minds' explores the use of TempestSDR to eavesdrop on video monitors with his Airspy Mini. TempestSDR is a program that we've posted about several times in the past. With an RTL-SDR or other compatible SDR like a HackRF it allows you to reconstruct an image from a computer monitor or TV just from the radio waves unintentionally emitted by the screen or cable. SDRs with larger bandwidths like the HackRF or Airspy are better at reconstructing the image as they can collect more information.
In his video Tech Minds shows how to download and setup one of the newer branches of TempestSDR which unlike older versions doesn't require much installation work. Using an Airspy Mini he shows that he is able to view what is on his screen via the emitted RF waves.
Eavesdropping Video Monitors With TempestSDR RTL-SDR
Over on his YouTube channel Frugal Radio has been testing his YouLoop passive magnetic loop antenna on VLF and LF reception with his Airspy HF+ Discovery. In the video Frugal Radio browses the VLF & LF spectrum, making note of some interesting signals, and showing how well the combo receives.
The YouLoop is a low cost passive loop antenna for HF and VHF. It is based on the Möbius loop design which results in a high degree of noise cancelling. However the main drawback is that it is a non-resonant design, which means that it needs to be used with ultra low MDS receivers like the Airspy HF+ Discovery. We have YouLoop stock available in our shop for $34.95 with free worldwide shipping.
Airpsy YouLoop passive antenna review on VLF & LF with an HF+ Discovery and SDR# during storms!
[@aang254] made a custom HRPT decoder and ported HRPT blocks for NOAA, METEOR and MetOp to work with gnuradio 3.8 on Linux. Right now it is the only free and open source decoder for MetOp (that works), and he also thinks about implementing FengYun support. I tested the decoder and it works great.
He's also working on extracting the full data from HRPT, not just the AVHRR/MSU-GS imagery but also all the telemetry and other instrument data.
HRPT is a high resolution weather satellite image signal that is broadcast from the same NOAA satellites that provide the more commonly received low resolution APT images at 137 MHz. HRPT is also broadcast by the FengYun-3, Metop and Meteor satellites. However, HRPT transmits at 1.7 GHz, so a high gain dish antenna with motorized tracking mount (or hand guided tracking), LNA and a high bandwidth SDR like an Airspy is required to receive it.
The YouLoop is a low cost passive loop antenna for HF and VHF. It is based on the Möbius loop design which results in a high degree of noise cancelling. However the main drawback is that it is a non-resonant design, which means that it needs to be used with ultra low MDS receivers like the Airspy HF+ Discovery. However, a high performance HF pre-amp will be available in the future which will allow it to work well with other radios too.
In his video Robin tests the YouLoop on the HF bands with an Airspy HF+ Discovery and he demonstrates excellent noise free reception from his location. In terms of his setup he notes:
I am running Spyserver on a 10 year old Windows 7 laptop in the loft. The same laptop is also running 3 x SDRSharp instances (following 2 digital trunking systems). It runs 4 x simultaneous Zello instances each providing a high quality audio feed to my Network Radio / phone.
In terms of noise-creating equipment nearby, there is
a second laptop used for other duties
a Pi 3B used for ADS-B reception, feeds & a second instance of spyserver
a Pi 3A with MMDVM module performing as a hotspot
a Motorola HT charger
5 x base station scanners
This means there are 10 x switched mode power supplies constantly running, as well as 4 x 24/7 WiFi devices.
All this equipment is within 10ft of the YouLoop antenna, was one of my primary reason for choosing a passive loop.
Since making the video, cable clips have been added provide support to the antenna which means it is now in the correct shape of a loop. That means I am unable to rotate the antenna to make use of the nulls when receiving. However I am very pleased with the performance based on the location, noisy environment, and frugal pricing :-)
$35 Airspy YouLoop Passive Antenna Review : tested on HF using Airspy HF+ Discovery SDR
Over on YouTube Tech Minds has uploaded his latest video that shows how to easily update the firmware on Airspy R2 and Mini units. The Airspy R2 ($169) and Airspy Mini ($99) are two software defined radios that can be considered a step up from an RTL-SDR in terms of performance and price. Recently the Airspy developer updated the firmware, and we show the changelog below.
This release improves the overall phase noise, tuning accuracy, dynamic range and spur responses.
More accurate R820T/2 tuning.
Fast R820T/2 register update by only sending the actual changes. Useful for fast scanning.
The R820T/2 reference clock is now fed directly from the 25 MHz TCXO. No noise contribution from PLL_A at all when using the internal TCXO.
The MCU and ADC reference clock is now using PLL_B of Si5351 in Integer mode with power of two dividers.
EXT_CLK now feeds PLL_A for the R820T/2 and PLL_B for the LPC4370 with optimal Integer Mode and power of two dividers.
Drive level reduced to 2mA per clock. This significantly reduces the spurs.
Tech Mind's YouTube video shows us how to check the current firmware installed, how to download the latest firmware, and finally how to actually flash the new firmware.
AIRSPY R2 & MINI Software Defined Radio Firmware Update Procedure
Over on YouTube SignalsEverywhere/Harold is back with a new video tutorial that shows users how to set up a SDR# SpyServer with an RTL-SDR dongle. SpyServer is a program included with SDR# that allows you to access your Airspy or RTL-SDR dongle remotely through the internet or local network connection. Thanks to it's compression techniques and that it does most processing on the server side, it requires significantly less network bandwidth compared to a raw IQ server like rtl_tcp.
In the video Harold first shows how to access the SpyServer network in SDR# which consists of many remote SpyServers that have been made accessible to the public for free. He then goes on to explain how you can set up your own SpyServer by simply editing a text config file. He notes that you may need to perform port forwarding on your router if you wish to make the server publicly accessible.
RTL SDR Spyserver Remote SDR Setup Tutorial (on Windows)
It's been a good time for ready to use SDR Linux OS images recently, as we've seen the release of two new images, DragonOS and gorizont-rtlsdr over this lock down period. And now the already popular and mature PiSDR image has also been updated.
PiSDR is a ready to use Raspbian based operating system for Raspberry Pi's which comes pre-loaded with many programs for software defined radios. It currently supports the RTL-SDR, LimeSDR, PlutoSDR, Airspy, and Airspy HF+ and has preinstalled software such as SDR Angel, Soapy Remote, GQRX, GNURadio, LimeUtil, and LimeVNA.
The latest update includes various bug fixes as well the following new features:
Three times smaller.
Verified Compilation on GitHub Actions.
New Software: Quisk, CygnusRFI, rpitx, rtl_433, acarsdec, gpredict, multimon-ng, and leansdr
Over on YouTube TechMinds has uploaded a video where he explores the QT-DAB software (formerly known as SDR-J), which is a program capable of decoding Digital Audio Broadcast (DAB) signals. QT-DAB is compatible with several SDRs including the RTL-SDR, HackRF, Airspy and SDRplay units.
DAB stands for Digital Audio Broadcast and is a digital broadcast radio signal that is available in many countries outside of the USA. The digital signal encodes several radio stations, and it is considered a modern alternative or future replacement for standard analog broadcast FM.
In the video TechMinds explains how to download, install and use the software on a Windows machine. He goes on to demonstrate some DAB decoding in action with various SDRs and then shows how to connect QT-DAB to a remote RTL-SDR via rtl_tcp.
DAB Radio Decoder For SDR (RTL_SDR - HACKRF - AIRSPY)