[danner]

That's inaccurate. Operation of unlicensed Part 15 Devices is permitted between 420 and 450 MHz and more specifically there is a sub-band from 433.5-434.5MHz that arduino transmitters use with the caveat that applies to all devices:

(1) This device may not cause harmful interference.

(2) This device must accept any interference received,including interference that may cause undesired operation.

I beg to differ on both points ...

There is no "blanket" part 15 permission whatsoever for operation between 420 MHz and 450 MHz. You may be confusing the 70cm band with the 33cm band, 902-928 MHZ, where amateurs share the band with Part 15 devices. This is also the case between 2.3 GHz and 2.5 GHz as well as 5.6 GHz to 5.9 GHz.

Part 15 section 240 permits the operation of RF ID devices ONLY between 433.5 MHz and 434.5 MHZ. Transmission of any kind other than RFID or one controlled by an amateur radio operator is strictly prohibited. Operation of WeatherDuino devices doesn't come close to meeting the requirements of this section. Here is the first subsection of the rule:

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§ 15.240 Operation in the band 433.5-434.5 MHz.

(a) Operation under the provisions of this section is restricted to devices that use radio frequency energy to identify the contents of commercial shipping containers. Operations must be limited to commercial and industrial areas such as ports, rail terminals and warehouses. Two-way operation is permitted to interrogate and to load data into devices. Devices operated pursuant to the provisions of this section shall not be used for voice communications.
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This exception is based upon a need to have a common RFID frequency throughout the world and the USA acceded to the majority of countries using these frequencies for unlicensed devices.

My apologies for not referencing the RFID exception in my original post.

The bottom line still is that operation of a WeatherDuino on 433 MHz in the USA by anyone other than a licensed amateur radio operator is a violation of FCC rules and subject to a cease & desist order as well as fines.

Regards,
George

I'm not going to argue with you. It is, and has been for a long time, perfectly legal in the USA long before the RFID thing you posted above even existed. Many devices that are not RFID devices are sold which use 433.92MHz for unlicensed transmitters, including commercially sold weather stations that have been sold for decades in the US and are still sold to this very day. Call the ARRL and ask them about it or do a little more research on the subject.