Category: Amateur Radio

SignalsEverywhere Android Project Updates: Satellite Tracker, HackTV NTSC Transmitter, OBS To HackTV, PacketShare and More

Recently, Sarah Rose Giddings (aka SignalsEverywhere) has been actively developing several radio and SDR based projects for Android, and she would like to provide an update on them.

First, as mentioned in a previous post, Sarah has been developing APRS.chat, an online mailbox system for APRS messages sent over RF. She has also been making progress on various other projects, including various useful Android apps, which she has updated interested people on in her latest livestream.

Hangout Chat | Linux | HackRF NTSC Transmission | Android APPS and More!

Some of the links to the Android software she's working on have been provided below:

Works with Benshi Protocol Radios (VR-N76 UV-PRO etc)

Stuff Created After The Livestream

Help beta test Play Store Releases (Benshi Dash, Benshi Commander, APRS Chat): https://docs.google.com/forms/d/e/1FAIpQLSfNTrCBofQYam6f6CrZ8XxTxZw2vlOiaD6ehGs5NBOAbKkHWw/viewform?usp=header

Screenshots from Sarah's HackTV NTSC Transmitter
Screenshots from Sarah's HackTV NTSC Transmitter

Understanding Single Sideband Modulation Through GNU Radio and RTL-SDR

Thank you to Paul Maine for writing in and sharing his latest tutorial video, which explains how Single Sideband (SSB) modulation works. In the video, Paul explains the concept and mathematical principles behind SSB by showing how to create an SSB receiver using GNU Radio and an RTL-SDR.

Paul writes:

Paul Maine “ The SDR Guy” recently released a video about Single Side Band (SSB). 

The SDR Guy shows how to create a single sideband receiver using GNU Radio and an RTL-SDR. He also shows how to modulate SSB signals. Paul collaborated with Gary Schafer in the production of this video. Gary has created a must read blog post on SSB.

Paul answers the question: What is SSB and what’s the advantage when compared to Amplitude Modulation. He used SDR++ to capture an IQ file using an RTL-SDR and his HF antenna and is included in his resources. This allows you to use the resources he has provided to demodulate SSB even if you don’t have an HF antenna.

In fact, you don’t even need to have an SDR. A GitHub link is provided in the video description to all flowgraphs and IQ files discussed in the video. Lastly, The SDR Guy has included a complete Upper and Lower Side Band receiver that’s implemented in GNU Radio using an RTL-SDR!

Be sure to look at his YouTube Channel (paulmaine6433). He has many other SDR related videos.

E17 Create Single Sideband Receivers with GNU Radio and RTL-SDR

An SSB receiver in GNU Radio
An SSB receiver in GNU Radio

ARPS.Chat – Send and Receive APRS Messages Globally

Thank you to Sarah Rose Giddings (aka Signals Everywhere) for submitting to us her latest project called aprs.chat. This is a web service that allows ham radio operators to have all of their incoming APRS (Automatic Packet Reporting System) messages (regardless of SSID) saved in history on the web platform. This will enable operators to never miss a message, even when their radios are turned off. The service works over the APRS-IS (APRS Internet Service) network, which bidirectionally connects APRS radios to the internet.

Sarah notes that the service currently works through the website, but an Android app is planned for release in the near future. Patreons of Sarah/Signals Everywhere can get early access to the Android app on request.

More information about the service can be found on this post on the Signals Everywhere blog.

aprs.chat website
aprs.chat website

SkyRoof: New Ham Satellite Tracking and SDR Receiver Software

Recently VE3NEA has released a new Windows program called "SkyRoof". SkyRoof is both a satellite tracking and SDR receiver program. It supports the RTL-SDR as well as Airspy and SDRplay devices.

The software is designed for tracking and receiving ham radio satellites, and it can provide detailed information about all ham satellites, tracking them in real time, and provide pass prediction. It also shows a skymap and SDR waterfall display. The receiver software supports demodulation of SSB/CW/FM, and it automatically compensates for doppler. It can also interface with antenna rotators that support hamlib.

SkyRoof Satellite Tracking and SDR Receiver Software Screenshot
SkyRoof Satellite Tracking and SDR Receiver Software Screenshot

Over on YouTube Johnson's Techworld has also recently uploaded a video showing him testing out Skyroof, which may be of interest to some.

Brief review of SkyRoof, the latest satellite tracking software!

SDR Television: DATV TX and RX Software for the PlutoSDR

Recently, Simon Brown (G4ELI), best known for being the author of the popular SDR-Console software, has released a new program called "SDR Television (Beta 2)". SDR Television is a program designed for transmitting and receiving Digital Amateur TV (DATV) signals.

At the moment, the software supports DATV on the QO-100 satellite, but in the future, further terrestrial DATV support has been promised. The software is designed to be used with a PlutoSDR (or PlutoSDR clone or spinoff), but also supports Airspy or SDRplay for receive only.

Over on YouTube, Tech Minds has also posted a great video demonstrating the software's setup and use.

SDR TELEVISION V1.0 - Game Changing DATV Software From G4ELI!

Creating an Open Source DMR Transceiver with a LimeSDR Mini

Thank you to Adrian Musceac for writing and sharing his article detailing how he implemented an open-source DMR (Digital Mobile Radio) transceiver modem with his LimeSDR Mini and GNU Radio.

DMR is a digital voice communications protocol often used by commercial business band radios, as well as by amateur radio hobbyists.

Adrian explains:

I wrote an article about the implementation of an open-source DMR transceiver using the LimeSDR-mini, GNU Radio and Codec2, which could be used for SDR experiments.

The DMR modem was designed to work both in repeater and direct (DMO) mode, and supports voice and other basic features of the ETSI TS 102 361-1 standard.

In the article there is discussion about aspects of the TDMA transmission, time synchronization, as well as how David Rowe's Codec2 can be used to replace the default vocoder.

The work builds upon Jonathan Naylor's extensive DMR implementation which a large number of amateur radio operators are using as part of MMDVM.

DMR TX Flowgraph
DMR TX Flowgraph
Transmitting DMR with the LimeSDR-mini

TechMinds: Testing out the SDRBerry Software on a Pi 4 with Touchscreen

Over on the TechMinds YouTube channel, Matt has posted a video demonstrating the SDRBerry software, which can be used with many SDR devices, including the RTL-SDR, on a Raspberry Pi with a touchscreen.

The SDRberry software is designed to be used on a touchscreen. As Matt points out, it has an aesthetically pleasing user interface and is compatible with almost any SDR software via the Soapy interface. Combining an SDR with a Pi 4 touchscreen and SDRberry results in an excellent hand-held SDR system.

In the video, Matt demonstrates the features of SDRberry, showing its RX features as well as some of its TX features, such as speech transmission and FT8, via a built-in WSjtx tab. He then shows the optional web interface, which is still in the early stages of development. Finally, he shows how to install the software and dependencies onto a fresh Raspbian image. 

SDRBERRY - This User Interface Is Just GORGEOUS! AND IT USES SOAPY TOO!

Setting up a Dual RX System with an SDR and Ham Radio Rig via an SDRSwitch

There are two common options when using an SDR together with a ham radio rig. You can either create an IF tap within your ham radio and connect the SDR to that, or connect the SDR directly to the antenna via a switch that switches the SDR out when transmitting.

Over on YouTube, Ham Radio DX has uploaded a video discussing the latter option and revealing its advantages. In the video, he mentions results by HB9VQQ that show that connecting an Airspy HF+ directly to an antenna via an SDR switch from SDRSwitch.com results in 60% more spots on WSPR, compared to using an IF tap from an FT450D ham radio rig.

He goes on to explain and demonstrate his setup and the recommended switch that he is using, which is the SDRSwitch by N2EME, available at SDRSwitch.com. He notes that this switch is recommended due to its very low insertion loss and high isolation specifications and compares it against an MFJ switch, which has some rather terrible specifications.

Add a SDR Receiver to ANY Ham Radio Rig!