We’ve just translated OpenRTX into Ukrainian and Polish.
Join the effort: https://hosted.weblate.org/projects/openrtx/openrtx/
Update: German, Czech, Portugese (Brasil), Spanish, and Swedish followed really fast. Thank you!
News feed
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m17-gateway 0.2.10 update
A simple DSP trick added into the most recent version of N1ADJ’s Go M17 gateway reduced MER down from 3.5% to under 2% (tested with a CS7000). A short IIR filter equalizes the frequency response of the CC1200 demodulator, improving the eye diagram. Additionally, the demodulator’s sensitivity has been adjusted for optimal M17 reception.
GitHub: https://github.com/jancona/m17
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OpenRTX updates
Silvano IU2KWO:
Demodulator fixes merged into master, next round of improvements for M17 decode available here: https://github.com/OpenRTX/OpenRTX/tree/m17-ber-threshold
The new demodulator improves M17 symbol timing and slicing. The next planned change will put a threshold on the decoded VIterbi output, based on its metric. That’s where the Codec 2 payload is. Erroneous data will not be played back anymore. This should improve overall user experience with the M17 mode.
Great job so far!
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LinHT at OpenAlt 2025
Vlastimil OK5VAS will be presenting LinHT at OpenAlt 2025 in Brno on Sunday, November 2, at noon.
Update:
Vlastimil’s talk was streamed live: -
LinHT – GRF5604 RF amplifier tests – part II
After receiving a new 10W 40dB attenuator, I decided to give the GRF5604 a spin again. I connected it to my LinHT prototype (Revision A hardware, for the record) and supplied with 5.1V. I’ve set the SX1255’s DAC gain to 0dB and mixer gain to -13.5dB, to prevent the power amplifier from saturating.
Here’s a spectrum plot showing harmonics with the fundamental at 36dBm (M17 signal at 433.475MHz):
Harmonics are below -60dBc, which I would call a good result (the output filter is a MiniCircuits LFCN-490+). The peak to the left is the PLL reference leakthrough (32MHz).
Test setup for the output power and spectrum check Stay tuned for more news.
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LinHT – CQ DL cover article
We are making headlines again, this time with the LinHT – our revolutionary, open-source handheld radio running Linux. Make sure to grab CQ DL issue 11-2025 🙂
Please donate to keep our projects alive: https://www.paypal.com/donate/?hosted_button_id=4HTHZCS8UYPU6
Thank you!
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libm17 1.1.1 is out
This release adds a new function,
sq_eucl_norm, and fixes theunterminated-string-initializationwarning.The squared Euclidean norm (fancy name for a simple sum of squared differences) offers some more robustness, as it doesn’t use
sqrtf, which might be computationally expensive. Calculating pure L2 norm is not always required, as the similarity between two vectors can be estimated without using square roots. -
LinHT – “does it run doom?” act II
Of course it does. We knew that a while ago!
While I’m trying to marry M17 text message decoder with SQLite database and Vlastimil OK5VAS is preparing a test PCB for the upcoming Revision B, Andreas OE3ANC prepared a nice fbDOOM demo. This is an important step, demonstrating the SoM’s capabilities. Stay tuned for more news regarding M17 support in our amazing device.
Extra: quick teaser – M17 message preview. This is not the final design.
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OpenRTX 0.4.2 is out
Changes include GPS and RTC improvements along with some code clean-up.
See the GitHub release page for full changelog: https://github.com/OpenRTX/OpenRTX/releases/tag/v0.4.2
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GRF5604 RF amplifier boards are now available at PCBWay
We designed a universal amplifier block for the 70cm band, that can be used with virtually any mode out there (including M17, of course). Thanks to GRF5604’s good linearity, high PAPR modulations, including SSB, QAM, and OFDM, shouldn’t cause much trouble.
The board should be supplied with 5V. Maximum useful power output (CW) is about 6W. See the chip’s datasheet for more details.
Note: an adequate heat sink is required. The boards do not come with SMA connectors. PCB’s thickness is 1mm. Output lowpass filter is included.
Our “Shared Project”: https://www.pcbway.com/project/shareproject/LinHT_RF_amplifier_ff94e9ca.html
Enjoy!