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.

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BlackRabbit1 2 hours ago | parent | next [-]

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.

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ErroneousBosh 2 hours ago | parent | prev [-]

> 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.

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ssl-3 2 hours ago | parent | next [-]

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.

[1]: https://fccid.io/2AC7Z-ESPWROOM32

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wewewedxfgdf 5 minutes ago | parent | next [-]

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.

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ErroneousBosh 28 minutes ago | parent | prev [-]

The FCC is relevant in exactly one country in the world.

	▲	TeMPOraL 13 minutes ago \| parent \| next [-]
		Other countries have equivalent organizations and they all tend to be in sync on this stuff.
	▲	22 minutes ago \| parent \| prev [-]
		[deleted]

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mallets 2 hours ago | parent | prev [-]

Legal for end-user, sure. But Espressif might run into trouble with regulators like FCC.

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ErroneousBosh 28 minutes ago | parent [-]

Then sell them in the UK, where the FCC is entirely irrelevant.

We treat RF like your lot treat Mexican fireworks.

	▲	gamblor956 11 minutes ago \| parent [-]
		Our border control confiscates Mexican fireworks.