I'm really excited to see what will come of this discovery. I will mention OpenTrafficMap [1][2], which leveraged the ESP32-C5 to collect 802.11p V2X communication data (Cooperative Intelligent Transport Systems) from traffic lights, vehicles and other road traffic sensors. This project in particular got me excited about what could be accomplished with these microcontrollers.
So many $1 wireless ICs have a powerful "SDR", but will never be documented due to certification/compiliance/export-control reasons. The projects listed here rightly limited the scope to RX-only but Espressif might be forced to "patch" this away if arbitrary TX too is possible (or starts making headlines). Hope it doesn't come to that, more cheap options for RF-to-bits is always welcome.
On a technical note, not much I can find about the signal quality. Phase noise, images, DC Offset, etc. Have to get my hands on one, ESP32-S31 seems promising.
BlackRabbit1 17 hours ago [-]
I'm pretty sure that that WiFi-7 modems/routers have a similar modes up to 320MHz bandwidth.
The modems could be quite interesting as they are connected via PCIe which can eat a lot of bandwidth.
But they are very difficult (to almost impossible) to find if there isn't anything left in the firmware blob or device driver.
Shhhh. Just some AI hallucinations, nothing to see here.
ErroneousBosh 18 hours ago [-]
> The projects listed here rightly limited the scope to RX-only but Espressif might be forced to "patch" this away if arbitrary TX too is possible
Why would they? It's perfectly legal to operate radio transmitters on any frequency you like, if you hold a suitable licence.
amelius 4 minutes ago [-]
Think of this scenario. What if there is a botnet that these ESP32 modules become a part of, and they all start transmitting garbage, simultaneously ...
(This is why you will never truly own your smartphone, even though you paid for every chip inside it)
ssl-3 17 hours ago [-]
It is legal for a person with an appropriate license, yes. But laws (in the US) about RF transmission differ from how many other laws are structured: We're only allowed to transmit what we have permission to transmit -- and by default, we're forbidden.
But right now, I've got an ESP32 WROOM module on a dev board sitting in my windowsill reporting some sensor values over wifi.
The WROOM itself is registered with the FCC[1]. If I stick to using the documented operation, then I have permission to use it in those documented ways. As a practical concept, I don't need a unique license to use it in the way that I am; I'm granted the ability to use it by Part 15 of the FCC rules.
And that's pretty great: The hardware was inexpensive to buy and very easy to find. I was able to spin this sensor up very quickly and get moving on the software side that deals with those readings. It has been a very rewarding little project with a fantastic cost:benefit ratio.
The fear being expressed here (which I don't necessarily subscribe to) is that things like this WROOM module will become less-available when/if methods to use it in undocumented ways are published and start becoming used.
>>"We're only allowed to transmit what we have permission to transmit -- and by default, we're forbidden."
It is not true that by default you are forbidden to transmit. In fact there are quite open rules in some ways for transmissions. Whenever these discussions about transmission come up there's always people who, without really undrstanding, freak out about transmitting anything and declare that all tranmissions are illegal. Not so.
USA hobbyists can legally transmit without a licence under FCC Part 15, but the limits are pretty low and depend on the frequency. AM, up to 100 mW into the final RF stage, with the antenna, feedline and ground limited to a total of 3 metres. FM maximum field strength of 250 µV/m measured 3 metres away. There are special cases, such as 49.82–49.90 MHz, where home-built transmitters can go to 100 mW on a 1 metre antenna. One-off home-built transmitters don't need FCC certification if for personal use not being sold.
We're granted permission to make the transmissions you speak of; it is otherwise deny-by-default. This is described right there at the top of your first link, in the first three paragraphs.
It's broadly possible to sort any rule (or superset or subset of rules) into one of two different buckets:
One bucket contains the rules about the things things we're not allowed to do. Like a firewall with a blacklist, whereby we can do whatever we want that explicitly isn't blacklisted. It is allow-by-default.
The other bucket contains the rules about things that we are permitted to do. This is like a firewall with a whitelist, where we can do whatever the whitelist explicitly allows us to do and nothing more. It is deny-by-default.
Drug laws in the USA are in the first bucket (blacklisting). Radio transmission rules in the USA are in the second bucket (whitelisting).
(There is no third bucket.)
fc417fc802 2 hours ago [-]
I think your analysis of the situation is correct. I just want to point out that what you are describing resembles a form of tyranny to me. Radio, flight, and food are all everyday domains that I appreciate absolutely require regulation for society to function smoothly however the FCC, FAA, and FDA have to be among the most anti-american institutions (or rather bodies of regulation) I can immediately think of.
Borealid 4 hours ago [-]
I believe the default state, in the absence of any law whatsoever, is that you can do whatever you want. Nothing is forbidden by default. You could assault another person, and it would be legal absent a law forbidding it.
Then there are laws that prohibit things like broadcasting radio signals without a license.
Then within those very same laws there are exceptions allowing certain transmissions WITHOUT a license, in specific circumstances.
The "default" is that things are legal unless they are made illegal, and I think it's pointless wordplay to try to argue the default state is somehow the law prohibiting unlicensed operation, and not the part of those same laws that allow unlicensed operation in particular bands with particular transmission power limits.
I understand the point you're trying to make that some parts of U.S. law say that all not-explicitly-mentioned radio transmissions are unlawful, but that's not meaningfully different from drug policies that say that all "harmful substances" are unlawful and so forth. They all just boil down to what the law defines as being within its own scope.
ssl-3 4 hours ago [-]
Yes.
And in the United States of America, at least: Radio transmissions are illegal by law, except where permission is granted by law.
(Try not to overthink it too much. A previous responder provided a citation that did not serve them well.
This situation can seem ugly or fantastic or jubilant or something else -- and it can be changed! -- but it still is just is how it is.)
ErroneousBosh 16 hours ago [-]
The FCC is relevant in exactly one country in the world.
zoobab 46 minutes ago [-]
I created a new country Zooland where there are not RF regulations:
For the same reason, those regulations (FCC radio lockdown etc) stifle innovation in the SDR world.
TeMPOraL 15 hours ago [-]
Other countries have equivalent organizations and they all tend to be in sync on this stuff.
diydsp 21 minutes ago [-]
Yep. Plus there are international, worldwide organizations bt those agencies; the ITU. Internatl Telecom Union.
Prologue. We get it, GP hates the u.s.-centric view. Found on this american website.
Borealid 4 hours ago [-]
Unfortunately the use of the Wi-Fi 5Ghz spectrum is not at all in sync worldwide. See https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_(8... and how meaningfully different the rules are for how you can set up your own home wireless network in different parts of the world...
fc417fc802 2 hours ago [-]
Worse is the OEMs all gradually removing the ability to operate modems intended for general purpose devices as APs in the 5 GHz range. The trend is to lock the firmware to only reply as a client in those bands. Meanwhile it isn't uncommon to encounter cheap dedicated APs that operate under the incorrect regulatory domain for the country they're sold in. So the cure doesn't work yet we lose the ability for P2P outside of 2.4 GHz.
(If they happen to be reading I'd like to offer a hearty fuck you to whoever at Intel and Qualcomm initially decided on these absurd policies.)
16 hours ago [-]
numpad0 8 hours ago [-]
Certified unlicensed radio equipment are required to be reasonably tamper resistant, so that reasonably everything that end users might do would be practically compliant even with a bit of malice. This is one of reasons why iPhone used to use pentalobe screws.
They are not required to be as secure as credit card chips, but they also can't be wide open.
mallets 17 hours ago [-]
Legal for end-user, sure. But Espressif might run into trouble with regulators like FCC.
ErroneousBosh 16 hours ago [-]
Then sell them in the UK, where the FCC is entirely irrelevant.
We treat RF like your lot treat Mexican fireworks.
compiler-guy 14 hours ago [-]
This would mean throwing away a giant market for what are generally pretty niche use cases. Very cool use cases, sure. But not worth giving all those sales up in favor of gray-market importers.
gamblor956 15 hours ago [-]
Our border control confiscates Mexican fireworks.
Joker_vD 5 hours ago [-]
And illegally entering Mexican immigrants too, yes. In practice, neither seems particularly effective.
You don't need much to spam random RF energy into the air. That project just flips a GPIO pin at the right frequency, and gets a signal into the air.
It won't be very powerful, and the harmonics will probably bleed all over the place if you just hang a wire off of it with no filters.....
Gibbon1 5 hours ago [-]
An SX1262 has a frequency range from 150MHz to 960 MHz.
Actual FCC licensed products are supposed to not be naughty. But nothing prevents components from being naughty.
Inside ISM bands there are rules but beyond that anything goes.
BlackRabbit1 18 hours ago [-]
As far as I follow the research process it's currently quite difficult to get all data (like the 80MSPS@10-Bit showcase on Reddit) to a computer without a FPGA+USB3.
With the new ESP32-S31 we most likely can extract the I/Q data over its new 1 GBit/s interface. Guessing something around 20-40MSPS should work.
These hack will most likely will be a revolution for 13cm ham radio. With the new 5GHz ESP32 modules most likely also for 5cm. As all Espressif components are WiFi-qualified we can expect a very very stable and robust radio.
I ordered a few and waiting for Ali to deliver them to my lab.
rasz 13 hours ago [-]
>FPGA+USB3 80MSPS@10-Bit
>compresses to about 1.2 bytes per pair, around 95–100 MB/s
No mention what FPGA platform/board used, FT600 USB chip is ~$10 alone.
Now you can replace all of it with one of those silly $5 FX2LP USB 2.0 dev boards. CY7C68013A-56 supports 16bit interface and will happily pump 30MB/s all day long for a fraction of the price. $10 total for 2.4GHz ~12MSPS@10-Bit SDR.
rmast 12 hours ago [-]
The GitHub README says the FPGA used: Alchitry Au (Artix-7 XC7A35T, 256 MiB DDR3)
1e1a 5 hours ago [-]
This is absolutely fantastic! Testing with an esp32-s3, it looks like the tuning range is roughly 2.2GHz to 2.8Ghz, which covers far more than just WiFi. It should be possible to receive and demodulate S-band satellite downlinks using this < $2 chip with a dish.
xd1936 17 hours ago [-]
Very exciting!
> However, the current prototype uses the FPGA to clock the ESP32, which results in poor phase noise.
The ESP32S3 support PSRAM, can we redirect the sample to PSRAM, then hooking Logic Analyzer on PSRAM, thus getting the sample directly, not through any digital interface.
(There is cache before PSRAM, but should be trivial to sync).
cellular 10 hours ago [-]
Any way to finagle a LORA type system (ultra reliable using precise timing) using a few of these on each end?
ErroneousBosh 18 hours ago [-]
> undocumented feature that lets the firmware bypass the fixed WiFi and Bluetooth functionality and instead capture raw IQ baseband samples
So kind of like those TV USB sticks that you can adapt into proper SDRs?
wiml 16 hours ago [-]
The ones that the website hosting this article is named after?
brcmthrowaway 17 hours ago [-]
Yep, Matt Ettus converted that to hundreds of millions of dollars
I have a couple of Kanga Finningley SDRs bought through the G-QRP club, but they appear to have almost entirely vanished from the Internet.
CamperBob2 16 hours ago [-]
Not with RTL-SDR specifically but by introducing one of the first open-architecture SDRs, the USRP.
RTL-SDR is the cheapest imaginable commodity implementation of SDR technology, while USRP was... well, pricy enough to bring in some solid revenue and get his company bought. More power to him, it was (and is) an incredibly useful platform.
iamtheamerican 16 hours ago [-]
[dead]
Rendered at 12:17:13 GMT+0000 (Coordinated Universal Time) with Vercel.
[1]: https://opentrafficmap.org/
[2]: https://www.cnx-software.com/2026/05/24/opentrafficmap-esp32...
On a technical note, not much I can find about the signal quality. Phase noise, images, DC Offset, etc. Have to get my hands on one, ESP32-S31 seems promising.
The modems could be quite interesting as they are connected via PCIe which can eat a lot of bandwidth.
But they are very difficult (to almost impossible) to find if there isn't anything left in the firmware blob or device driver.
https://espargos.net/espsdr/ straight up shows its an ADC/DAC debug interface working both ways.
Why would they? It's perfectly legal to operate radio transmitters on any frequency you like, if you hold a suitable licence.
(This is why you will never truly own your smartphone, even though you paid for every chip inside it)
But right now, I've got an ESP32 WROOM module on a dev board sitting in my windowsill reporting some sensor values over wifi.
The WROOM itself is registered with the FCC[1]. If I stick to using the documented operation, then I have permission to use it in those documented ways. As a practical concept, I don't need a unique license to use it in the way that I am; I'm granted the ability to use it by Part 15 of the FCC rules.
And that's pretty great: The hardware was inexpensive to buy and very easy to find. I was able to spin this sensor up very quickly and get moving on the software side that deals with those readings. It has been a very rewarding little project with a fantastic cost:benefit ratio.
The fear being expressed here (which I don't necessarily subscribe to) is that things like this WROOM module will become less-available when/if methods to use it in undocumented ways are published and start becoming used.
[1]: https://fccid.io/2AC7Z-ESPWROOM32
It is not true that by default you are forbidden to transmit. In fact there are quite open rules in some ways for transmissions. Whenever these discussions about transmission come up there's always people who, without really undrstanding, freak out about transmitting anything and declare that all tranmissions are illegal. Not so.
USA hobbyists can legally transmit without a licence under FCC Part 15, but the limits are pretty low and depend on the frequency. AM, up to 100 mW into the final RF stage, with the antenna, feedline and ground limited to a total of 3 metres. FM maximum field strength of 250 µV/m measured 3 metres away. There are special cases, such as 49.82–49.90 MHz, where home-built transmitters can go to 100 mW on a 1 metre antenna. One-off home-built transmitters don't need FCC certification if for personal use not being sold.
It's pretty interesting to read if you are a radio head: https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A...
https://www.ecfr.gov/current/title-47/section-15.209
"operation within these frequency bands is permitted under other sections of this part, e.g., §§ 15.231 and 15.241."
-->
0.009-0.490Mhz 0.490-1.705Mhz 1.705-30.0Mhz 30-88Mhz 88-216Mhz 216-960Mhz Above 960Mhz
It's broadly possible to sort any rule (or superset or subset of rules) into one of two different buckets:
One bucket contains the rules about the things things we're not allowed to do. Like a firewall with a blacklist, whereby we can do whatever we want that explicitly isn't blacklisted. It is allow-by-default.
The other bucket contains the rules about things that we are permitted to do. This is like a firewall with a whitelist, where we can do whatever the whitelist explicitly allows us to do and nothing more. It is deny-by-default.
Drug laws in the USA are in the first bucket (blacklisting). Radio transmission rules in the USA are in the second bucket (whitelisting).
(There is no third bucket.)
Then there are laws that prohibit things like broadcasting radio signals without a license.
Then within those very same laws there are exceptions allowing certain transmissions WITHOUT a license, in specific circumstances.
The "default" is that things are legal unless they are made illegal, and I think it's pointless wordplay to try to argue the default state is somehow the law prohibiting unlicensed operation, and not the part of those same laws that allow unlicensed operation in particular bands with particular transmission power limits.
I understand the point you're trying to make that some parts of U.S. law say that all not-explicitly-mentioned radio transmissions are unlawful, but that's not meaningfully different from drug policies that say that all "harmful substances" are unlawful and so forth. They all just boil down to what the law defines as being within its own scope.
And in the United States of America, at least: Radio transmissions are illegal by law, except where permission is granted by law.
(Try not to overthink it too much. A previous responder provided a citation that did not serve them well.
This situation can seem ugly or fantastic or jubilant or something else -- and it can be changed! -- but it still is just is how it is.)
https://www.zoobab.com/zooland
For the same reason, those regulations (FCC radio lockdown etc) stifle innovation in the SDR world.
Prologue. We get it, GP hates the u.s.-centric view. Found on this american website.
(If they happen to be reading I'd like to offer a hearty fuck you to whoever at Intel and Qualcomm initially decided on these absurd policies.)
They are not required to be as secure as credit card chips, but they also can't be wide open.
We treat RF like your lot treat Mexican fireworks.
You don't need much to spam random RF energy into the air. That project just flips a GPIO pin at the right frequency, and gets a signal into the air.
It won't be very powerful, and the harmonics will probably bleed all over the place if you just hang a wire off of it with no filters.....
Actual FCC licensed products are supposed to not be naughty. But nothing prevents components from being naughty.
Inside ISM bands there are rules but beyond that anything goes.
With the new ESP32-S31 we most likely can extract the I/Q data over its new 1 GBit/s interface. Guessing something around 20-40MSPS should work.
These hack will most likely will be a revolution for 13cm ham radio. With the new 5GHz ESP32 modules most likely also for 5cm. As all Espressif components are WiFi-qualified we can expect a very very stable and robust radio.
I ordered a few and waiting for Ali to deliver them to my lab.
>compresses to about 1.2 bytes per pair, around 95–100 MB/s
No mention what FPGA platform/board used, FT600 USB chip is ~$10 alone.
Now you can replace all of it with one of those silly $5 FX2LP USB 2.0 dev boards. CY7C68013A-56 supports 16bit interface and will happily pump 30MB/s all day long for a fraction of the price. $10 total for 2.4GHz ~12MSPS@10-Bit SDR.
> However, the current prototype uses the FPGA to clock the ESP32, which results in poor phase noise.
Looks like this was solved five days ago:
https://github.com/h0m3us3r/eSpDR/commit/41a0ffe279119df942e...
SDR in this context is software defined radio.
So kind of like those TV USB sticks that you can adapt into proper SDRs?
I remember the Ettus devices to be much much much more powerful.
I have a couple of Kanga Finningley SDRs bought through the G-QRP club, but they appear to have almost entirely vanished from the Internet.
RTL-SDR is the cheapest imaginable commodity implementation of SDR technology, while USRP was... well, pricy enough to bring in some solid revenue and get his company bought. More power to him, it was (and is) an incredibly useful platform.