[wizardgmb]

I'm really impressed with WeatherDuino and it fits in well with my plans to replace my old Davis weather station. However the choice of wireless frequency is inappropriate for use in the USA.

In the USA, 433MHz is nearly in the middle of the 70CM amateur radio band. Legally, any transmissions on that frequency can only be made by a licensed amateur radio operator. Anyone transmitting on that frequency without holding a valid amateur radio license is in violation of Federal Communications Commission (FCC) rules and is subject to hefty fines if caught. The FCC doesn't drive up and down streets trying to detect transmissions of a few miliwatts on 433 MHz so it can dish out a fine. However, the 433 MHz transmitters used by WeatherDuino aren't known for frequency stability or doing a good job of suppressing unwanted harmonics of 433 MHz. If one's WeatherDuino transmissions annoy a nearby amateur radio operator or its insufficiently suppressed 866MHz second harmonic invades the radio system of your local police department, they are well within their right to file a complaint with the FCC and expect an investigation, remediation and punishment.

There are transmitter and receiver parts with identical footprints and interface characteristics that operate on 315 MHz. Operation on this frequency falls within the FCC rules allowing low power remote control and data exchange. In the USA garage door openers, vehicle remote controls, personal weather stations and wireless cooking thermometers among others use 315 MHz and adjacent frequencies. Anyone in the USA contemplating building a WeatherDuino should purchase the 315 MHz version and anyone in the USA with an operational WeatherDuino should replace the 433 MHz transmitters/receivers. The transmitter/receiver pair can be purchased for $1 or less on eBay so cost shouldn't be an issue. If problems do develop with the transmitter operating out of spec the FCC is much more forgiving if one is operating on an appropriate frequency. Currently the second harmonic of 315 MHz falls within USA TV channel 40 and after the FCC finishes reshuffling all the TV channels in the country to 36 or less, it will be within a cellular phone band. Either one is much less likely to incur somebody's wrath.

Regards,
George Bean
Amateur Radio Operator - AI4VJ

[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.

[wizardgmb]

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:

-----------------------------------------------------------------
§ 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.
----------------------------------------------------------------

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

[werk_ag]

The WeatherDuino can use radio modules operating in the 433Mhz or the 315Mhz frequency, without any modification in the software or hardware. Performance is almost identical. So, using 433Mhz or 315Mhz its a user choice, considering local regulations.

In Europe the use of 433Mhz radio in devices like WeatherDuino is perfectly legal. Indeed, almost all radio weather station, alarms etc, operate in 433Mhz (some in 866Mhz).

If there are any issue using 433Mhz in the USA, users can opt for the 315Mhz radios

[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:

-----------------------------------------------------------------
§ 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.
----------------------------------------------------------------

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.

[danner]

Here's a list from a searchable FCC database of unlicensed intentional radiators that are completely legal and transmit within the 70cm ham band at 433.92MHz.

Everything from remote tire pressure sensors to doorbells, weather stations, gate openers, wireless light switches, driveway alert systems, LITERALLY everything under the sun operate completely legally and unlicensed there. No ham radio license is required, even though I have one of those too.

"Operation of unlicensed Part 15 Devices is permitted between 420 and 450 MHz."


https://fccid.io/frequency-explorer.php?...per=433.92

[werk_ag]

Nice information, thank you danner.

[Shred]

The potential for interference with other devices is something constructors should consider when building the WeatherDuino.  Some countries place limits on EIRP - the power actually radiated from the antenna.  In Australia, this is only 30mW - running a 10mW radio module into an antenna with a bit of "gain" can easily exceed this.

Add to that the fact that the WeatherDuino is very chatty - particularly when combined with an RX relaying to WD units, it consumes a lot of air time.  It's very different to a device like a garage door remote that transmits for a fraction of a second only twice a day.

Authorities can and do investigate harmful interference.  A work colleague moved to Australia from Canada, bringing with him a wireless baby monitor that operates in Canadian unlicensed spectrum.  He received a knock on the door one night from a radio inspector - the baby monitor was transmitting in expensive licensed spectrum here in Australia and interfering with a cellular phone service.  Considering that there are no radio inspectors based in my State, considerable time, money and expense had been incurred tracking down his baby monitor as the source of the interference.  He wasn't fined, but he was lucky.

Here's some documentation for Australian constructors:
https://www.acma.gov.au/theACMA/spectrum...ed-devices

[AllyCat]

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.

Everything from remote tire pressure sensors to doorbells, weather stations, gate openers, wireless light switches, driveway alert systems, LITERALLY everything under the sun operate completely legally and unlicensed there.

"Unlicensed" simply means that it is not necessary to apply (and maybe pay) for a "Broadcasting" License to operate the specified equipment, it does NOT mean that you can transmit whatever you like.  The equipment must still comply with ALL the relevant broadcasting regulations for the band.

To me, a key phrase is "are Sold"; the equipment will (should) have been designed to comply with all the regulations and may have been submitted to a professional "Test House" for confirmation of its compliance with the complex regulations (you cannot simply cut-and-paste the bits that you like).

Also, that list above is certainly not "Everything", ALL those examples are designed to broadcast for very brief periods of time.  The regulations typically specify a "Duty Cycle" of 1%, sometimes 0.1% or 10% depending on the power level (ERP), for example.  Unfortunately the "averaging" period is not normally specified, so it might be minutes, hours or days, but it is clear that a baby alarm or wireless headphones, etc. would not comply (there is another band allocated for them).  Often the regulations will specify "data" or "voice" and exclude the other.

Actually, even "pushbutton" type devices like door bells/openers may further restrict their transmission time by using "start" and "stop" commands rather than broadcasting continuously whilst a button is pushed.  I've not studied the transmitting duty cycle of the Weatherduino software, but the overall repetition rate of 3 seconds (or less) is very considerably shorter than most/all commercial sensors, which typically transmit for less than  a few hundred ms approximately every minute or more.

Cheers,  Alan.

[danner]

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.

Everything from remote tire pressure sensors to doorbells, weather stations, gate openers, wireless light switches, driveway alert systems, LITERALLY everything under the sun operate completely legally and unlicensed there.

"Unlicensed" simply means that it is not necessary to apply (and maybe pay) for a "Broadcasting" License to operate the specified equipment, it does NOT mean that you can transmit whatever you like.  The equipment must still comply with ALL the relevant broadcasting regulations for the band.

To me, a key phrase is "are Sold"; the equipment will (should) have been designed to comply with all the regulations and may have been submitted to a professional "Test House" for confirmation of its compliance with the complex regulations (you cannot simply cut-and-paste the bits that you like).

Also, that list above is certainly not "Everything", ALL those examples are designed to broadcast for very brief periods of time.  The regulations typically specify a "Duty Cycle" of 1%, sometimes 0.1% or 10% depending on the power level (ERP), for example.  Unfortunately the "averaging" period is not normally specified, so it might be minutes, hours or days, but it is clear that a baby alarm or wireless headphones, etc. would not comply (there is another band allocated for them).  Often the regulations will specify "data" or "voice" and exclude the other.

Actually, even "pushbutton" type devices like door bells/openers may further restrict their transmission time by using "start" and "stop" commands rather than broadcasting continuously whilst a button is pushed.  I've not studied the transmitting duty cycle of the Weatherduino software, but the overall repetition rate of 3 seconds (or less) is very considerably shorter than most/all commercial sensors, which typically transmit for less than  a few hundred ms approximately every minute or more.

Cheers,  Alan.

Not sure what part of unlicensed transmitters are allowed in the 70cm ham band you don't seem to understand? I'm not going to search out all the relevant regulation bits which state that hobbyists aren't expected to be able to fully test their equipment for compliance but should still try to comply as best they can, as I've already researched it and this topic is becoming tedious. Feel free to google to your hearts content.  

Acurite, FO, and La Crosse have marketed and sold weather instruments using 433.92MHz for decades that isn't on that list I posted a link to. I have a LaCrosse weather station console I got in the 90s that operated on 433.92MHz that is sitting on the desk behind me that isn't on that list.  I'm sure there are many other devices operating on 433.92MHz that aren't on that list. With an SDR and an external VHF/UHF antenna I can view countless devices that are operating on and around 433.92MHz in my neighborhood. The idea that a 10mw or 20mw arduino transmitter with a rubber ducky antenna is going to cause the world to come to an end is absurd. It is even sillier to assert the FCC is going to come after anyone with the sheer number of unlicensed devices operating on that frequency in the states.

The FCC caveat always applies that if one operates there you must be willing to accept interference and may not cause interference, that goes for ALL of the radio spectrum in America.

A couple of years ago NASA was running a wind profiler radar that was causing interference in the 50MHz ham band. We complained about the interference and NASA fixed the problem they had with their radar. That is a basic regulation that applies to all RF operation in the USA. Might also be worth mentioning that the 70cm ham band isn't a primary frequency allocation in the US, it is a shared spectrum.

It's quite simple. If you think you're right then don't operate your arduino radio on 433.92MHz.