Category: Amateur Radio

DIY Software Defined Ham Transceiver With eBay Parts

YouTuber jmhrvy1947, has recently uploaded a number of videos giving an overview of how he built his own HF SDR transceiver using what he calls the “Lego build method”. The idea of the Lego build method was to build a transceiver with parts picked and pulled from eBay so that it could be easily reproduced by others. There are a few scratch made components however those designs are available on his GitHub page. The SDR only functions within about 100 kHz of spectrum at a time however for amateur radio HF work this is more than sufficient. Bare bones the radio puts out a mere 100 mW and although the output power is small, he’s made contacts up to 450 miles away using CW (Morse code). You also have the option of adding an amplifier on  your output if you are looking for more power than that. His final revision currently puts out 100 Watts.

Using modified versions of fldigi and Quisk he is able to easily work various digital modes and sync the transmitter and receiver together. The only real down side to this radio is that you must switch out your receive and transmit filters whenever you wish to operate on different bands, a process that really only takes a moment or two.

Check out his videos on the project – it’s really amazing to see what can be done with a small budget these days in radio and with how far software defined concepts have brought us.

DIY SDR CW Xcvr Project

In the video below you’ll see an explanation of the software involved in this build.

DIY SDR CW Software

 

Using Two PlutoSDR’s for Full Duplex Packet Radio Communications

Over on his channel SignalsEverywhere, Corrosive has uploaded a video showing us how we can create a full duplex packet radio communications system using two PlutoSDRs. Full duplex is the ability to transmit and receive at the same time. A single PlutoSDR is only half-duplex/simplex because it can only either receive or transmit at any one time. The PlutoSDR is a low cost (typically $99 - $149) RX/TX capable SDR with up to 56 MHz of bandwidth and 70 MHz to 6 GHz frequency range. 

On his video Corrosive explains how full duplex operation is desirable for amateur packet radio communications as it allows for faster and more continuous exchanges.  Demonstrations are performed with his PlutoSDR, SoundModem, EasyTerm, and SDRAngel. Later in the video he also speculates how it might be possible to do things like IP networks via the amateur radio bands with full duplex SDRs.

Full Duplex Radio Communication with PlutoSDR Tutorial

Reducing HF Electrical Noise by Using a Faraday Cage for Switch-Mode Power Supplies

Over on his blog, DXer OH2-2192 was frustrated by lots of local electrical noise showing up on the HF bands on his Airspy + Spyverter SDR receiver. He discovered that the majority of the noise he was seeing was coming from the switch mode power supplies that power the electronic devices used in his setup. Switch mode power supplies are very common in the modern world, with almost every electronic device using one to efficiently convert wall AC into DC power. However, they convert power by rapidly switching on and off, and these on/off square wave pulses cause a lot of RF noise especially on the HF spectrum.

Instead of changing to noise free linear regulators which are expensive, very heavy and big, OH2-2192 decided that he'd try creating a Faraday cage shield out of metal mesh to enclose all his switch-mode power supplies. Using a simple AM loop antenna and Airspy's Spectrum Spy software he measured the amount of noise produced by a switch-mode supply placed inside and outside of the cage. The results he saw were very promising with the shielded supply eliminating the noise almost entirely.

Faraday Cage Shield for Switch Mode Power Supplies
Faraday Cage Shield for Switch Mode Power Supplies (Right image shows the results of a switching supply placed outside and inside the Faraday cage)

Amateur Radio on the Es’hail-2 Satellite Explained on YouTube

Over on YouTube Tech Minds has posted a video explaining what Es'hail-2 satellite is and why it is interesting for hams and SDR users. Briefly Es'hail-2 is a recently launched geostationary TV satellite that covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia.

What's special about it is that apart from the TV transmitters, it also contains the worlds first amateur radio transponder in geostationary orbit. So amateur radio users within the region covered by the satellite can simply point their antennas to a fixed position in the sky to transmit to the satellite, and the signal will be rebroadcast over the entire covered area. With a simple LNB, satellite dish and SDR the signals can be received.

After explaining Es'hail-2 Tech Minds also shows a demo of Es'hail-2 radio traffic using a public WebSDR.

The Worlds First Geostationary Satellite For Ham Radio - Es'Hail 2 - Qatar OSCAR-100

RedPitaya Announces Pre-order for STEMLab HF SDR Transceiver

RedPitaya has just announced their next SDR platform, the STEMlab 122.88-16 which is a software defined radio intended to be used as an HF transceiver on the amateur radio bands.

The SDR is advertised to cover HF + 6m (50MHz) and includes two 16 bit 50 ohm input ADCs and two 14 bit outputs. Based on the Xililinx Zynq 7020 FPGA running an ARM cortex A9 processor it’s plenty powerful to handle the various modes frequently seen in the amateur bands and then some while supporting an impressive 122.88 MS/s sample rate.

The RedPitaya – 3D Rendering

This hardware is also fully compatible with the HPSDR software platform which is an open source project for amateur radio SDR operation.

While this radio is built with amateur operation in mind, it is still a very capable platform that could be used for experimentation albeit with a more restricted frequency range that what you may be used to with traditional software defined radios.

The radio retails for $499 euros and will be available for pre-order from RedPitaya until March 31st of 2019.

Using an Airspy HF+ with SDR# and WSJT-X to Decode FT8 + SpyServer FT8 Decoding Demo

Over on YouTube user TheGazLab has uploaded a video that reviews the Airspy HF+, and also shows how to use the HF+ with SDR# and WSJT-X in order to create a FT8 monitor. The Airspy HF+ is high dynamic range HF/VHF receiver designed for DXing.

In the video TheGazLab demonstrates to us the decoding in real time, and explains the CAT control SDR# plugin that he's using. The CAT control plugin when combined with a virtual serial port driver allows the WSJT-X program to automatically tune SDR# to the FT8 frequency selected in WSJT-X.

Later in the video he also discusses the SpyServer network which allows SDR# users to connect to remote public Airspy and RTL-SDR units over the internet. He demonstrates connecting to a public server in the UK, and decoding FT8 via the remote server. The video also shows the new SpyServer interface by  which nicely lays out the world SpyServer network on a map, making it easy to choose a desired location to listen to.

Airspy HFPlus, SDR# and WSJT-X with full CAT control decoding FT-8

Video Tutorial: Using Universal Radio Hacker, an RTL-SDR and a Microcontroller to Clone 433 MHz Remotes

Over on YouTube user hubmartin has uploaded a video showing how to use an RTL-SDR and the Universal Radio Hacker (URH) software to reverse engineer and clone a 433 MHz remote control. URH is used to extract the signal timing and modulation characteristics as well as the binary/hex code.

Then in order to clone the signal hubmartin uses a cheap IoT microcontroller with button and 433 MHz transmitter attachments. Some C code is then used to program the microcontroller and 433 MHz transmitter with the extracted signal information and to transmit on a press of the button. In his example hubmartin uses his cloned dongle to control a wireless power plug and a motorized projector screen.

Universal Radio Hacker SDR Tutorial on 433 MHz radio plugs

Using a LimeSDR / PlutoSDR to Transmit Digital Amateur Television with DATV Express

Over on YouTube Corrosive from channel SignalsEverywhere has uploaded a new video in his series on Digital Amateur Television (DATV). The new video shows us how to use a transmit capable SDR like a LimeSDR or PlutoSDR to transmit DATV with a free Windows program called DATV Express.

In the video he explains the various transmit and video encoding settings, and then demonstrates the signal being received on SDRAngel with an RTL-SDR (which he explained in his previous video)

DATV DVB-S Transmitter With a LimeSDR or Pluto SDR and DATV Express