Category: Amateur Radio

Using SDR For QO-100 Satellite Operation

Es’hailsat, otherwise known as QO-100 is the first geostationary satellite with an amateur radio payload on-board. The satellite contains both a Wide Band transponder for experimental modes and DVB-S Digital Television and a Narrow Band transponder used mostly for SSB voice and some digital mode contacts with other amateur operators. If you’re unfamiliar with this satellite we’ve covered it in previous articles, like in [Es’hail Transponder Now Active]

While many choose to use a transverter connected to a traditional amateur transceiver, others have turned to use Software Defined Radios to complete their satellite ground stations.

[Radio Innovation] posted a video back in March showing his contact on QO-100 using a LimeSDR Mini as the 2.4 GHz transmitter and a 10 GHz LNB for the downlink.

Calling cq on QO-100 with LIMESDR

The PlutoSDR has been frequently seen used for QO-100 satellite operation on the Wide Band transponder due to its ease of DVB-S transmission utilizing software such as [DATV Express] but more recently there have been more and more operators turning to SDR for their day to day satellite operation.

It will be interesting to see how these stations evolve, perhaps by the time North America has access to a similar satellite, we’ll be prepared to operate it.

YouTube Review of the RS-918: A Chinese Clone of a Clone of the mcHF SDR

Over on YouTube Kevin Loughin has uploaded a video reviewing the "Recent RS-918" which is a Chinese clone of the popular mcHF open source SDR transceiver made by Chris (M0NKA). The mcHF is a well known small and inexpensive home brewed open source HF QRP SDR that was started back in 2013. It's sold either as a kit for 236.82 GBP (US$287), or with metal enclosure at 292.78 GBP (US$354). The kit comes with SMD components already soldered, but you still need to solder the through hole components and assemble it into the enclosure. The RS-918 clone can be found fully assembled as a ready to use product on eBay for approximately US$400.

As the "Recent RS-918" is a commercial Chinese clone of an open source project that has restrictions against commercial use, it goes against the spirit and legality of the licence imposed by the original creator. So based on that Kevin cannot recommend the RS-918 SDR. However, from his review Kevin notes that apart from some burning hot areas on the metal after transmitting, the SDR itself works and has a nice minimal design. The design appears to be based on an older version of the mcHF, so the latest upgrades are not available.

Kevin's review just overviews the RS-918 and doesn't go into depth reviewing the radio. For the rest of his video Kevin discusses the lineage of the RS-918, noting that it is actually a clone of the Ailunce HS1, which in turn is a clone of the mcHF. He then goes on to discuss the mcHF itself, noting that we should support all the hard work that Chris has put in (and continues to put in) to the original mcHF rather than these immoral clones.

Ham Radio - The RS-918 clone of a clone of an outstanding open source SDR transceiver, the mcHF.

Slow Scan Moon Bounce Event for 50th Anniversary of the Moon landing

Fifty years ago Neil Armstrong became the first man to step foot on the moon. This weekend on June 20th and 21st 2019 Amateur Radio operators at the [PI9CAM] team have been transmitting Slow-Scan Television images in commemoration of this historic event at the Dwingeloo radio astronomy station in the Netherlands. This station is the oldest rotatable 25-meter radio telescope in the world. 

 Dwingeloo radio astronomy station
Dwingeloo radio astronomy station
An EME SSTV Image
An EME SSTV Image

Slow-Scan Television is a method often employed by ham radio operators to send photos over radio waves. You may be familiar with this from some of our previous articles on the SSTV event held by ARISS for the International Space Station.

Station [S1NDP] has previously sent slow-scan EME images between the PI9CAM team and himself. These images can potentially be heard by anyone within line-of-site with the moon during the operation of this event.

The team transmit in the 23cm band at a frequency of 1296.11 MHz, according to the ARRL even a 2.5 to 3meter dish should be enough for reception assuming you have a 23cm feed for your dish. It will be interesting to see what photos are heard by the end of this event.

Homebrew SDR Transceiver for HF Operation

Traditionally when we think about Software-Defined Radio we’re thinking about little USB adapters that unlock a world of radio in the palm of our hands. This is done by allowing us to directly sample the IQ data from the mixer within the SDR.

However, this isn’t the only way to experience Software-Defined Radio. Ham Radio operator [Charlie Morris] has uploaded a 10 part series on YouTube explaining how he implemented his own HF transceiver, including custom software. Some of the components such as the amplifier and filters are built completely from scratch, other components use a little DSP magic from a “Teensy” microcontroller. 

Charlie actually samples the I and Q data in a similar way that today’s SDRs do and even implemented the transmit side of the radio so he can make contact with other radio operators around the world, and man… it sounds good!

You can find a complete playlist from Charlie with well-explained videos that go over his entire process from planning, schematics, layout and final operation. The channel appears to be quite active and will surely continue to pump out amazing content.

Homebrew SDR SSB Rig – Part 9 First On-Air QSO!

An RTL-SDR and Pi 3 Based Ground Station for Simulated CubeSats

CubeSats are small and light satellites that can these days be built and launched into orbit by almost anyone with a small budget of roughly $40,000. They are a great way for schools and other organizations to get into a space based technology project. A "simulated" CubeSat is one that is not designed to be really launched into space, and is made from low cost hardware. The idea is that simulated CubeSats can be used as tools to help demystify the inner workings of satellites to the public and help CubeSat builders get experience and competence before building the real thing.

A Simulated CubeSat made from a Solar Panel board, Pi Zero, UPS and Tranceiver.
A Simulated CubeSat made from a Solar Panel board, Pi Zero, UPS and Transceiver.

A team from AMSAT have been working on creating open source CubeSat simulator hardware and software. In order to demonstrate the RF capabilities of the simulator a ground station simulator is also required. Recently the team have uploaded instructions on creating a Raspberry Pi and RTL-SDR based ground station.

If you're interested in the CubeSat simulator hardware itself, there was a presentation held back in 2018 that may be of interest to you. According to the presentation somewhere between 30% - 50% of CubeSats fail as soon as they're deployed, so building competence with simulated hardware is a good goal.

2018 AMSAT William A. Tynan W3XO Memorial Space Symposium - Saturday Sessions

Decoding FT8 with an RTL-SDR Blog V3 in Direct Sampling Mode

Over on YouTube user ModernHam has uploaded a useful tutorial showing how to use our RTL-SDR Blog V3 dongles for FT8 monitoring. The RTL-SDR Blog V3 has a built in direct sampling circuit which allows for reception of HF signals without the need for any upconverter. FT8 is an amateur radio weak signal digital communications mode which can be received all around the world even with low transmit power.

In his setup he uses SDR# and Virtual Audio Cable to pipe audio to the WSJT-X decoder. His video goes through all the steps and settings that need to be set and then shows a demo of some signals being received. ModernHam also has another video uploaded a few days earlier which is a more general introduction to FT8 decoding.

If you're interested we uploaded a tutorial last year that shows how to set up a Raspberry Pi 3 based FT8 decoding station with a V3 dongle.

Decoding FT8 with a RTL-SDR (Software defined Radio)

Hermes-Lite: A Low Cost Amateur Radio SDR Made from A Repurposed Cable Modem Chip

The HPSDR Hermes SDR is an open source amateur radio SDR transceiver project that was released as far back as 2011. More recently Steve Haynal has been working on a Hermes-Lite project which is intended to be an opensource open hardware low cost amateur radio HF transceiver which is based on the HPSDR Hermes SDR project software and FPGA DSP implementation.

The Hermes-Lite is able to be very low cost (less than $300) because it is based on the AD9866 chip which is a mass produced RF front end (LNA + ADC & DAC) used in cable modems. Because it is a mass produced commodity, the chip only costs approx. US$35-$25 on Mouser depending on quantity. The chip has a 12-bit 80 MHz ADC and DAC, meaning that if used without any analog mixer front end (like in the Hermes-Lite) it can receive the entire spectrum between 0.1 to 38 MHz all at once.  

The Hermes-Lite is also a lot more than just the RF chip, as it contains a set of switched RF filters and a 5W power amplifier for TX. It also interfaces with a PC via Ethernet and has a built in FPGA for DSP processing.

Recently Steve presented at the FOSSi Foundation Latch-Up conference on May 4-5, and a YouTube recording of his presentation is shown below.

[First seen on The SWLing Post]

Hermes-Lite: Amateur Radio SDR

Decoding Es’Hail-2 DVB-S2 Realtime in Linux with LeanDVB

Last week we posted about M Khanfar's YouTube video that showed how to decode Es'Hail-2/QO-100 DVB-S2 on Ubuntu with the LeanDVB decoder. However, the method he showed was not in real time as it involved recording an IQ file in GQRX first, then decoding that IQ file. Similarly we also posted last week about a Windows based real time decoder.

M Khanfar recently wrote in again and wanted to show that real time decoding is possible with LeanDVB. The method is to simply pipe the output of the rtl_sdr command line decoder in LeanDVB, and then into VLC. He notes that his PC isn't actually fast enough to decode in real time without lag, but a modern i5 CPU would work well. The actual terminal command is shown in his YouTube video description.

This is Realtime live DVB-S2 Decoding done , without need to record .RAW file , its live and easy method by one click ! In this video i decoding 2MS symbol rate from wideband transponder of QO-100 beacon , you can decoding 1MS , 0.5MS , 333KS , 125KS symbol rate ! The lower Symbol, the faster speed for decoding! , the Amateurs operators on QO-100 Uplink DATV DVB-S2 at 0.5 , 333 , 125Ks , so its easy to Live Decoding Now ! With very low SNR ! , so the normal SDR can coverage wideband beacon of 2Ms symbol and all Ham uplink ! , if you have an SDR that can coverage 27.5 mb of bandwidth, so you can easy decoding Live a standard commercial satellite channels! But it need a high speed Pc .

QO-100 Realtime Live DVB-S2 Decoding