Vojtěch Bubník

Prague, Czech Republic
Joined May 2008
Vojtěch Bubník retweeted
The answer is an SDR that you already own! Let me introduce you to the BirriaSDR! A dual-band 40 Msps SDR (2.4 GHz/5 GHz) based on a mass-produced USB 3.0 Wi-Fi dongle that can export RAW I/Q for under 30 USD. Apologies, I finished the birria long ago... but only got around to writing this now. The idea was to use a chip as cheap as the RTL-SDR (<50 USD), with transport already built in (USB 3.0). Not something that costs four times as much or needs to be paired with an FPGA to export any real amount of data. Now, think for a bit: what kind of mass-produced device fits the bill? Yes, every single USB Wi-Fi dongle!!! It has been clear for a while that a lot of models have internal firmware that can be modified to export RAW I/Q data via their DMA engines. Most units can even run ASM payloads to modify the data. Historically, it would be a pain in the ass to reverse engineer the internal mechanisms of every single chipset in each Wi-Fi dongle (there are many!). But with AI, I can do that from my phone while eating birria at my local restaurant. Before leaving, I connected my MT7921A Wi-Fi dongle to my Raspberry Pi 5 and gave GPT-6 Astra the goal of getting it to export RAW I/Q over USB. Don’t be fooled: this wasn’t a “turn this into an SDR, make no mistakes” prompt. I had to give it leads on how to do this properly. By the way, this is the same chipset that the notorious ALFA AWUS036AXML has. At first, it created a burst exporter that could only record a short snapshot of RAW I/Q. This is an ancient feature that has been known for a long time and is even present in DD-WRT, but it was useless for our purposes. Then, after a couple of hours, it improved it to use the internal packetizing engine to create a stream of four consecutive complex samples per 16-byte block, with I and Q each occupying a 16-bit slot and retaining 14-bit precision. These blocks can be moved out of the device via the DMA engine. The RF front end can tune to both the 2.4 GHz and 5 GHz bands. The tested 40 MHz, 80 MHz, and 160 MHz sample rates work, but with a very prominent filter shape, as expected. The end result was a very capable SDR with dual-band 2.4 GHz/5 GHz reception, 14-bit I/Q resolution, and a nominal complex sample rate of 40 MSps over USB 3.0. Higher sample rates and wider bandwidths are still experimental. That said, I think this is a good proof of concept that needs to be further refined. Using a Wi-Fi dongle as an SDR solves the data interconnect problem and makes it easy to connect an external antenna with RP-SMA. I expect it won't take long for manufacturers to start mass-producing devices with the architecture I'm proposing, with a proper USB port, a tunable RF front end, and heat dissipation. I also want to make the point that you don't need to write a whole new SDR client every time you reverse engineer a Wi-Fi device to be used as an SDR. All you need is a small library that exports the I/Q. To prove this, the whole driver is a single Python script inside a CyberEther flowgraph file. Want to try it? First, buy an MT7921-based Wi-Fi dongle. They’re widely available and cost less than $30. Then, install CyberEther and download the flowgraph from the repository below. Connect the dongle and open the flowgraph in CyberEther to start streaming I/Q data, as shown in the video below. This will be available as a built-in block in CyberEther after some refinement. Download CyberEther: cyberether.org/ BirriaSDR Repo: github.com/luigifcruz/Birria… P.S. This is the same chipset many laptops come with!
Fellas, the answer to cheap SDRs is not in crippled chips that cannot export any real amount of data, or one that also costs hundreds of dollars.
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Vojtěch Bubník retweeted
Early duty here. VU2AAP and VU2LBW. 5060km over the ocean. That is as far as you can make it. The satellite is on both sides just over the horizon, that is why I had to go to the beach at 5am. – at Shimo la Tewa, Kenya
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Vojtěch Bubník retweeted
QMX+ and fork SDR++ by OK1IAK
Panadapter works great on an Android tablet or phone. All you need is a QMX TRX and a USB-C cable. It surprises with its response speed and replaces the missing speaker. Good job!
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Vojtěch Bubník retweeted
Just because Donald Trump acts goofy doesn’t mean his presidency wouldn’t be dangerous. And you don’t have to take my word for it. Lately, some of the people who know Trump the best have been saying in no uncertain terms that he should not be president again.
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Vojtěch Bubník retweeted
Physics In History
@PhysInHistory16 Aug 2023
The science of global warming beautifully and simply explained by Dr. Carl Sagan, ca. 1985.
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Vojtěch Bubník retweeted
LOL, you mentioned only plate name and 3rd party printer profiles. But you actually have merged all my the entire OrcaSlicer code base.
Dear customers! The public beta for Bambu Studio 1.7.0 is now live on GitHub! We added more third-party printer support and also implemented several long-awaited features. bit.ly/3mSAUrz
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URESAT-1, will be ejected from the OTV about 12:10 UTC, over Antarctica. Once ejected from the OTV, the satellite will deploy the antenna 2 minutes after receiving sunlight, starting transmissions immediately. Uplink: 145,975 MHz Downlink:  436,888 MHz Good luck !!
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Vojtěch Bubník retweeted
To je toho, tak bude trochu tepleji... Aneb tohle 🧵vlastně ani číst nechcete. Určitě ne před spaním. Nebude se po něm dobře usínat. Jenže je potřeba o tom mluvit. Amazonský deštný prales, zdá se, umírá. A to dost fofrem. Depresivní #vesmírníček CIAT - Amazon17, CCBYSA 2.0
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Vojtěch Bubník retweeted
Replying to @Chmee2
Vynikajicí vlákno, díky. Lula ve svém předchozím prezidenství deforestaci výrazně omezil. Doufejme, že se mu podaří obrátit trend, co zas nastartoval Bolsanaro. Byť jeho síla nyní není taková. Měl by v tom mít max mezinárodní podporu.
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Vojtěch Bubník retweeted
Very happy with the outcome of the custom firmware for the 4$ Xiaomi Thermometer. Made a video about it. so you can get it yourself. youtu.be/NXKzFG61lNs Please give a thumb up :)
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Vojtěch Bubník retweeted
For you guys out there using @JLCPCB assembly service: I created an alternative component catalog browser which isn't a pain to use: - parametric search - sortable columns - full-text search - fast To use it: yaqwsx.github.io/jlcparts/ More info: github.com/yaqwsx/jlcparts
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Vojtěch Bubník retweeted
Replying to @Prusa3D
this is a big deal! thanks PrusaSlicer team!
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New sign for the radio corner. Testing @Prusa3D PrusaSlicer monotone top layer finish. Big difference in comparison to the rectilinear pattern.
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Vojtěch Bubník retweeted
GitHub Trending Archive, 14 Oct 2020, C++. Devilx86/ImpostorModmenu, Ubpa/GAMES102, Yaxser/CobaltStrike-BOF, TixiaoShan/LIO-SAM, InsightSoftwareConsortium/ITK, wang-xinyu/tensorrtx, AnkerLeng/Cpp-0-1-Resource, prusa3d/PrusaSlicer, diasurgical/devilutionX github.motakasoft.com/trendi…++
Vojtěch Bubník retweeted
One of the biggest PrusaSlicer updates is live as 2.3 Alpha 1 🥳 Looking forward to hear what you guys think 🤓 – at Prague, Czech Republic
PrusaSlicer 2.3 alpha 1 is out! 🎉 This version includes many improvements including: Paint-on custom supports and seams Ironing and monotonic infill Adaptive cubic infill Standalone G-code Viewer Notification center in the 3D scene and much more! github.com/prusa3d/PrusaSlic…
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Vojtěch Bubník retweeted
Důležitá výzva. 3 vteřiny. Ty má každý z vás. Prosím o tzv. retweet.
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Vojtěch Bubník retweeted
So Original Prusa SL1 resin 3D printer is out now 😍 Great workhorse at sweet price just like MK3 for FFF printing ☺️ Get more info here prusaprinters.org/introducin…
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