Tagged: FT8

Testing the ATS25 Max-Decoder Receiver

Thank you for Manuel Lausmann for submitting his videos where he tests out and upgrades an ATS25 Max-decoder receiver. The ATS25 Max-decoder is a low cost portable HF receiver which has a large number of decoders built in such as RTTY, Hell, FT8 and FT4. Manuel notes that more decoders are still to come, such as SSTV. The built in decoders make it superior to it's predecessors the x1 and x2.

We note that the ATS25 Max appears to be around US$75 on Aliexpress, but these appear to be Max units without the "-decoder" add on. So if you are looking at purchasing one, please make sure to check that you are getting one with the text "max-decoder".

Manuel also notes that older models of the ATS25 can be retrofitted with a decoder PCB and converted into an ATS25 Max-decoder with a firmware update written by Bernhard Binns.

Note that Manuel's videos below are narrated in German, however the YouTube subtitle auto-translate feature works well enough to understand what is being said. In the first video Manuel demonstrates and reviews the ATS25 Max-Decoder, showing off some of the decoding features.

In the second video Manuel shows how to update an old model ATS25 in to the ATS25 Max by soldering on the decoder board.

Alter ATS25 umbauen zum max Decoder Teil 1 Die Hardware

Maverick-603 Project Suspended Indefinitely

Back in December 2022 we posted about the Maverick-603 which was at that stage Crowd Funding on Crowd Supply.

It was to be a US$149 FT8 receiver based on an open source RF chip design, capable of acquiring signals between 7 MHz and 70 MHz (technically 1 MHz to 100 MHz). Shipments were expected to begin in April 2023.

Unfortunately the Maverick team just released today that the project will be suspended indefinitely due to logistical issues. Backers of the project will receive a full refund.

The Maverick-603 project has been indefinitely suspended due to unforeseen logistical obstacles. No funds have yet been spent and all backers will receive full refunds. If you backed this project, your refund will be issued within the next week to the credit card you originally used. If your credit card is no longer valid, please contact Crowd Supply support before midnight UTC on Friday, April 28, 2023 to arrange your refund. If the Maverick-603 project is revived, we will post another update. Thank you for your support and patience.

The Maverick-603 FT8 Receiver
The Maverick-603 FT8 Receiver

Maverick-603: An Affordable FT8 Receiver with an Open Source RF Chip

The Maverick-603 is a US$149 FT8 receiver based on an open source RF chip design which is capable of acquiring signals between 7 MHz and 70 MHz (technically 1 MHz to 100 MHz). It is currently undergoing Crowd Funding on Crowd Supply with 7 days left in the campaign. Shipping is expected to begin in April 2023.

FT8 is a popular weak signal propagation digital mode used by ham radio enthusiasts. FT8 signals can be received and decoded all over the world even with low transmit power and poor propagation conditions thanks to its highly error tolerant encoding. A dedicated FT8 receiver allows enthusiasts to set up a 24/7 FT8 monitor without dedicating more expensive ham radio equipment to the task. Note that a computing device like a PC or possibly a Raspberry Pi 4 will still be required to run the FT8 decoding software as this is a software defined radio.

The Maverick-603 is based on a custom open source RF chip design made possible by the company eFabless. It is now possible to cheaply design and produce custom ASIC chips (at least at the lower end of the technology scale), replacing more costly FPGA designs. The technical specs of the Maverick-603 are:

  • MCU: ATMEGA1608
  • Power Supply: 3.3 V / 10 mA
  • Operating Frequency Range: 1 to 100 MHz
  • Minimum Signal Strength: -25 dBm
  • Input Antenna Impedance: 50 Ohm
  • Data Interface: SPI
  • Board Size: 2" x 1.75"
  • Capable of receiving FT8 signals
  • 7 - 70 MHZ frequency range
  • Low-power operation (1.8 Volts) means no battery or outlet is required
  • USB Connection
  • A compact surface area
The Maverick-603 FT8 Receiver
The Maverick-603 FT8 Receiver

Lon.TV Demonstrates Decoding Various Digital Signals with RTL-SDR

Tech YouTuber Lon.TV has recently uploaded a video demonstrating how to identify and decode various digital transmissions with an RTL-SDR dongle. In the video he explains how to use VB Cable to pipe audio from SDR# into various decoders, and then goes on to show DMR, APRS, POCSAG, L-Band AERO, FT8, and JS8/JS8CALL all being decoded via an RTL-SDR Blog V3 dongle.

Software Defined Radio Part 2 - Decoding Digital Transmissions with an RTL-SDR USB Radio

DragonOS: Decoding FT8 on Linux with WSJT-X

DragonOS is a ready to use Ubuntu Linux image that comes preinstalled with multiple SDR program. The creator of DragonOS, Aaron, uploads various YouTube tutorials showing how to use some of the preinstalled software. This month one of his tutorials covers how to use a SDRplay RSP1A or a HackRF to receive and decode FT8 with the preinstalled software WSJT-X or JS8Call. Aaron also notes that an RTL-SDR could also be used as the SDR.

In the video he covers how to set up a virtual audio cable sink in Linux for getting audio from GQRX into WSJT-X, setting up rigctld to allow WSJT-X to control GQRX, configuring GQRX, CubicSDR and WSJT-X, and finally downloading and using GridTracker.

DragonOS Focal Receive FT8 w/ WSJT-X (RSP1A, HackRF One, GQRX, CubicSDR, GridTracker)

Comparing Shortwave Antennas with an RTL-SDR and FT8 Monitoring

Eric had an inverted L and T3FD antenna set up in his backyard and he wanted to test both at the same time to see which received HF better overall. Rather than relying on subjective 'by ear' measurements he decided to use the digital FT8 mode as his comparison signal. FT8 is quite useful for this purpose as the decoded data includes a calculated signal-to-noise (SNR) reading which is a non subjective measure that can be used for comparisons. It also contains information about the location of the signal which can be used for determining the DX capability of the antenna. 

To perform the comparison he used two or our RTL-SDR Blog V3 dongles running in direct sampling mode, and also added an additional low pass filter to prevent excessively strong TV and FM signals from overloading the input. Each antenna is connected to it's own RTL-SDR, and a modified version of GQRX with remote UDP control is used to switch between multiple FT8 frequencies so that multiple bands can be covered in the experiment. WSJT-X is used for decoding the FT8 packets.

After logging SNR values for several days he was able to plot and compare the number of packets received by each antenna, the maximum distance received by each antenna. His results showed that his inverted L antenna was best in both regards. He then performed a relative comparison with the SNR readings and found that the inverted L performed best apart from at 14 MHz, where the T3FD performed better.

In further tests he also compared the antennas on which signal headings they were receiving best from. The results showed that Erics inverted L was receiving best from one direction only, whereas the T3FD received signals from more headings.

Eric's post includes full instructions on the software setup and also Python code which can be used to replicate his experiments. We think that this is a great way to objectively compare two types of antennas.

Antenna directionality measurements via FT8 received headings

TechMinds: OpenWebRX Feature Overview And Raspberry Pi Setup

Over on YouTube TechMinds has posted his latest video which shows an overview of the features available in OpenWebRX, and also how to set it up on a Raspberry Pi. OpenWebRX is software which allows you to access your SDR remotely via the internet or local network through a web browser. All major SDRs are supported including RTL-SDRs. The software includes a waterfall display, all the standard demodulators, as well as several digital decoders for DMR, YSF, NXDN, D-Star, POCSAG, APRS, FT8, FT4, WSPR, JT65 and JT9.

In the video TechMinds first demonstrates OpenWebRX in action, showing reception of HF SSB amateur radio signals, decoding FT8 and plotting received grids on a map, decoding and plotting APRS on a map and decoding YSF/DSTAR/DMR digital voice. After this demonstration he goes on to show how to set up the OpenWebRX server on a Raspberry Pi via the installation image.

OpenWebRX Feature Overview And Raspberry Pi Setup

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)