I had access to one at the time. My initial problems started showing up here in my home lab, when certain devices operating at 3x0MHz started to malfunction. This included a consumer garage door opener manufactured by a company that primarily does commercial devices (320MHz) and an old X10 RF control system (310MHz.) I tracked it down by scanning the band with a cheap SDR radio and finding a wideband noise source at ~318MHz. This was tracked to the ESP12 devices I had on the bench running life tests, and I confirmed it with my then employer's RF lab, which gave me access to several HP spectrum analyzers. Didn't even need a probe for this, a piece of cable free air was enough to give a peak on the analyzer.
It didn't matter which module I chose, 8266 or 32, shielded or not. They all emit 318MHz. The modules are shielded on one side only, so you get leakage out the back, out the holes for the antenna, off the connections, and off the antenna itself. For all intents and purposes, there is no shielding on these. I can hold an ESP32 within a few feet of my garage door opener and watch the receive lamp come on and stay lit. (it's looking at raw input signal, doesn't care if there's modulation on it.)
The FCC certification falls under part 15C, and covers the WiFi band emissions only. Looking at the test report for 2ANHN-ESP8266, there is a spur at 319.9MHz. Since my SDR radio wasn't very accurate, this is probably closer to what it actually is, and they're seeing it with one module. My test was with 10+, and it was enough to saturate the area with enough noise to knock both the above-mentioned devices off the air. There are multiple other spurs, but since they aren't on restricted frequencies no one cares - they're noted and that's it. But...the module they used is some oddball design, so chances are none of the currently available devices have any certification beyond the ESP chip itself. That there's no ID printed on the shield of the modules with such seems to support that.
So there's nothing I can do. The ESP chipset is great if you don't have any other devices in the general radio spectrum, but as there are commercial devices operating there, they're useless for some applications.
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