[danner]

I'm spending entirely too much time on this topic but it is what it is.

I called the ARRL and they didn't have much to say because the arduino transmitters aren't ham radio items. Was also told that arduino transmitter modules did not need FCC type acceptance because it is not a finished product, it is simply a part intended to be used with a collection of parts. He also mentioned there are regulatory provisions for hobbyists, which is what I remembered reading previously. Googling that further I found the following which hopefully will put this topic to rest, at least for those of us in the USA.


Part 15.23


Home-Built Transmitters that are Not for Sale


Hobbyists, inventors and other parties that design and build Part 15 transmitters with
no intention of ever marketing them may construct and operate up to five such
transmitters for their own personal use without having to obtain FCC equipment
authorization. If possible, these transmitters should be tested for compliance with the
Commission's rules. If such testing is not practicable, their designers and builders are
required to employ good engineering practices in order to ensure compliance with the
Part 15 standards.

These can be used between 410-470MHz with emissions limits, however, testing is not required as per Part 15.23 but good engineering practices should be employed,with the all encompassing caveat that it may not create interference and must accept interference.

So to summarize. In the USA you can use up to 5 unlicensed non-type accepted transmitters for your own personal use as long as you aren't selling them. And if you're that concerned about emissions limits (that anyone still curious is welcome to google for themselves) then feel free to spend the thousands of dollars required to comply with something you're not expected to test for anyway.

[hornychz]

  Good job, danner!

[zitoune]

Yes very interesting indeed -  "employ good engineering practices"

[wizardgmb]

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.

"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."

Yes those devices are permitted BUT the designs for all of them have been approved by the FCC and can be manufactured/marketed as long as the devices strictly adhere to the approved design. There is no type acceptance for the WeatherDuino or the transmitter module used by it. The modules being purchased on eBay and from a host of Chinese suppliers are a knock off of a nearly 2 decade old design by Radiometrix, a European company. Radiometrix has never attempted to get that particular product FCC type accepted as they have with some other devices.

"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. "

Having had experience with Accurite and La Crosse devices, I can say all of there design and fabrication work is farmed out to Asian companies. The Asian companies use 433 MHz for devices exported to most of the world so they do the same thing for the USA market. These USA companies are heavily populated by marketing, logistics & finance types and short on technologists. They most likely don't have the in house expertise to know they are violating FCC regulations and if told that is the case, they probably don't care.

As far as your basic argument that "Since everyone else is violating the rules there isn't any reason I shouldn't  be able to do it with impunity.", that is just so wrong and an example of much that is wrong in the USA. If you are the eighth car in a line of eight cars stopped for driving 20 MPH over the speed limit, do you thing the traffic court judge will dismiss the ticket when you tell him or her the seven people in front of you were doing the same thing? Not very likely...

Regards,
George

[wizardgmb]

I'm spending entirely too much time on this topic but it is what it is.

I called the ARRL and they didn't have much to say because the arduino transmitters aren't ham radio items. Was also told that arduino transmitter modules did not need FCC type acceptance because it is not a finished product, it is simply a part intended to be used with a collection of parts. He also mentioned there are regulatory provisions for hobbyists, which is what I remembered reading previously. Googling that further I found the following which hopefully will put this topic to rest, at least for those of us in the USA.

Part 15.23

Home-Built Transmitters that are Not for Sale

Hobbyists, inventors and other parties that design and build Part 15 transmitters with
no intention of ever marketing them may construct and operate up to five such
transmitters for their own personal use without having to obtain FCC equipment
authorization. If possible, these transmitters should be tested for compliance with the
Commission's rules. If such testing is not practicable, their designers and builders are
required to employ good engineering practices in order to ensure compliance with the
Part 15 standards.

These can be used between 410-470MHz with emissions limits, however, testing is not required as per Part 15.23 but good engineering practices should be employed,with the all encompassing caveat that it may not create interference and must accept interference.

So to summarize. In the USA you can use up to 5 unlicensed non-type accepted transmitters for your own personal use as long as you aren't selling them. And if you're that concerned about emissions limits (that anyone still curious is welcome to google for themselves) then feel free to spend the thousands of dollars required to comply with something you're not expected to test for anyway.

I'm sorry for being late to followup but I couldn't leave it to rest.

This Part 15 section in addition to your Part 15 quotation is very enlightening:

15.203 An intentional radiator shall be designed to ensure that no antenna other than that furnished by the responsible party shall be used with the device. The use of a permanently attached antenna or of an antenna that uses a unique coupling to the intentional radiator shall be considered sufficient to comply with the provisions of this section. The manufacturer may design the unit so that a broken antenna can be replaced by the user, but the use of a standard antenna jack or electrical connector is prohibited.

The WeatherDuino has the transmitter output connected to a SMA female connector and the mating SMA male connector is definitely standard and very readily available. Therefore the WeatherDuino design fails to meet FCC Part 15 requirements and the hobbyist has failed to meet the requirement for "good engineering practices in order to ensure compliance with the Part 15 standards" . Anyone could connect an amateur radio 70cm base station antenna with 6dBi gain to a WeatherDuino, knock out shipping container operations a mile away and probably piss off a few amateurs.

From the FCC document Understanding the FCC Regulations for Low-Power Non-Licensed Transmitters:

https://transition.fcc.gov/Bureaus/Engin...t63rev.pdf

"Home-built transmitters, like all Part 15 transmitters, are not allowed to cause interference to licensed radio communications and must accept any interference they receive. If a home-built Part 15 transmitter does cause interference to licensed radio communications, the Commission (FCC) will require its operator to cease operation until the interference problem is corrected. Furthermore, if the Commission (FCC) determines the operator of such a transmitter has not attempted to ensure compliance with the Part 15 technical standards by employing good engineering practices then that operator may be fined up to $10,000 for each violation and $75,000 for a repeat or continuing violation."

I have FCC amateur and commercial licenses, years of experience and a bench full of equipment to ensure transmissions from my future WeatherDuino meets the the Part 15 requirements (if I don't use it at 433 MHz as an amateur) even if the SMA connector doesn't. You may also have the prerequisites but we are probably among the minority. If one's WeatherDuino isn't built or operated properly or isn't stable there are two possibilities based upon frequency: pissing off a nearby shipping company or amateur radio operator on 433 MHz or having some non-knowledgeable neighbors using 315 MHz remote controls that can't unlock their cars or open their garage doors on the first try. I think the latter is a better choice for WeatherDuino owners in the USA, the chances of getting drawn & quartered by the FCC are much lower on 315 MHz.

Regards,
George

[AllanG]

George,

I'm obviously not going to get into the issue of which module and/or frequency should be used as I'm in the UK, and I *think* the subject has now been comprehensively covered anyway.

I thought I'd just jump in to welcome you to the "WeatherDuino family" and ask if you'd tell us a bit more about your own WeatherDuino project, for example the various sensors and modules (apart from rf obviously) you're planning on using - or maybe *are* already using!!


Allan.

[wizardgmb]

George,

I'm obviously not going to get into the issue of which module and/or frequency should be used as I'm in the UK, and I *think* the subject has now been comprehensively covered anyway.

I thought I'd just jump in to welcome you to the "WeatherDuino family" and ask if you'd tell us a bit more about your own WeatherDuino project, for example the various sensors and modules (apart from rf obviously) you're planning on using - or maybe *are* already using!!


Allan.

Yes Allan, the subject has been fully thrashed. You don't have to drag me off the topic...

I am currently using an old Davis Vantage in a less than optimal location. The US Army withdrew non-military access to the only known accessible scientific grade weather station in Caroline County where I live, so much for the good neighbor policy. It's up to private individuals and a couple of WeatherBug sites at a school & the county EOC to provide weather information for use by NWS and the local media. It's time for me to step up my game!

I have a 5+ meter length of 51 mm pipe with arms at the top that is going into a previously cast cement foundation, if spring ever comes to the USA east coast. Once in place, there will be a 60 x 60 X 24 cm watertight steel enclosure mounted at working level to house instrumentation, radio gear and battery backed power. Conduits for AC power and data have been run from the pole location to underneath my house. There is also a poly tubing loop buried with the conduit that if needed, can be used for geothermal maintenance of the cabinet interior temperature using gamer PC water cooling devices.

All of the commercial/scientific grade instruments are on hand save for CO2 detection and will include:

2 ea   Vaisala HMP233 temperature and humidity monitors, one with a radiation shield
1 pair MetOne cup anemometer and direction indicator
1 ea   Vaisala Ultrasonic wind speed & direction sensor
1 ea   Vaisala barometric pressure sensor with Campbell wind shield
1 ea   Campbell Scientific tipping bucket rain gauge
1 ea   Campbell Scientific solar radiation sensor
1 ea   Personally built moisture sensor
1 ea   Personally built lightning detector
1 ea   TBD CO2 sensor
1 ea   Network attached 720P video camera aimed at a snow measurement platform
1 ea   Network attached 720P video camera aimed at the adjacent vegetable garden

At this point in the plan, there will be a Wyse 5010 Thin Client in the cabinet running either Cumulus or WeatherView with the necessary interfacing, backup battery and solar charge controller. The thin client has a fiber optic Ethernet connection that will feed into the house to avoid noise and lighting impulse transfer. Additional fiber pairs will be used for a KVM remote control of the thin client and a separate USB 2.0 link for SDR units receiving ADS, weather satellites and hopefully a few passing weather balloons. The thin client will also feed amateur 2M & 70 cm cigarette pack APRS transceivers. There will be a last chance cellular SMS communications system. From the outside, the whole assembly is going to look like a radio mast on a modern warship. If space remains, it will house irrigation controls for my wife's vegetable garden.

So where does WeatherDuino fit into the "plan"? While pretty austere by PC standards, the 20 watt quiescent power requirement of the thin client is a substantial drain on solar batteries if grid and onsite emergency backup power is lost. Relocating Cumulus to a shared thin client indoors, doing measurement only with a WeatherDuino and using a second Arduino for housekeeping chores considerably reduces the solar power consumption. Having Davis Vantage emulation is a big plus when it comes to connecting to APRS and other devices.

I'm also evaluating the establishment of an amateur radio emergency preparedness network of preinstalled radios and antennas at strategic locations. Having a cost effective basic weather station that could be installed with the radios would provide a data source for periodic test communications and a remote data display could be an enticement to the building owner/occupant to let us use the building.

At this point, I'm trying to evaluate the WeatherDuino's transmitter and receiver boards to see if I can substitute a fiber optic driver and receiver for the RF devices (I avoid polluting the radio spectrum whenever possible). Given the schematics aren't available until after the purchase of boards, working from parts lists and photographs is slow going. So far, it appears the data lines from and to the respective Arduinos can be connected to logic level interfaced fiber devices. I haven't looked at the CO2 sensor board yet.

You asked...

Regards,
George

[AllanG]

I did ask George, and I'm glad I did - that's a very impressive setup you have planned!! Here in the UK I live in an urban area about 10 miles east of the city of Liverpool so my station is for my own personal interest only. I do know that some other members of the "WeatherDuino family" are in much more remote locations though, and so like you their stations are much more a necessity than mine is.

Good luck with the project and I look forward to hearing progress reports...

Allan

[uncle_bob]

At this point, I'm trying to evaluate the WeatherDuino's transmitter and receiver boards to see if I can substitute a fiber optic driver and receiver for the RF devices (I avoid polluting the radio spectrum whenever possible). Given the schematics aren't available until after the purchase of boards, working from parts lists and photographs is slow going. So far, it appears the data lines from and to the respective Arduinos can be connected to logic level interfaced fiber devices.

Hi George and welcome.

I'd be very interested in how you go with interfacing to fibre optics. I take it we would need some TTL to fibre media converters.

BTW I think the old schematics are available, they should give you a good idea how it works (besides the ESP8266 stuff that's been added since).

Cheers UB

[wizardgmb]

At this point, I'm trying to evaluate the WeatherDuino's transmitter and receiver boards to see if I can substitute a fiber optic driver and receiver for the RF devices (I avoid polluting the radio spectrum whenever possible). Given the schematics aren't available until after the purchase of boards, working from parts lists and photographs is slow going. So far, it appears the data lines from and to the respective Arduinos can be connected to logic level interfaced fiber devices.

Hi George and welcome.

I'd be very interested in how you go with interfacing to fibre optics. I take it we would need some TTL to fibre media converters.

BTW I think the old schematics are available, they should give you a good idea how it works (besides the ESP8266 stuff that's been added since).

Cheers UB

Actually the interfacing is pretty straight forward. I will be installing 850nm 62.5/125 cable because I have a enough to wrap around my house 100x and using type ST connectors (fiber version of the RF ST). The first number, 850nm, is the wavelength of light used and 62.5/125 refers to the size of the fiber core and outer reflective cladding respectively. This is the most readily available short distance cable and the ST connectors while out of favor today are  still easy to find inexpensively. Since I have the bulk cable, connectors and the required tooling, I will assemble my own cables but ready made cables can bought inexpensively on eBay.

Several decades ago, HP had an optical division and one of the products they developed was the HFBR series fiber optic transmitters and receivers. HP sold or spun the business off to Avayo and Broadcom eventually bought Avayo. The HFBR series are still being manufactured by Broadcom and thousands of them are for sale on eBay. Here is a HFBR device with its dust cap.



This is a typical link schematic:

https://drive.google.com/open?id=1-avEwP...49ly4n4Sxw

This circuit is TTL level in and out and capable of direct interfacing with a 5V Arduino, level shifters are required for 3V Arduinos. The base devices are usable from DC to 5 MBd, orders of magnitude more data rate than needed for a WeatherDuino interconnect. An HFBR pair is good for 1500 meters at 5 MBd and longer distances at lower data rates. If anyone is interested in the specific devices, the 5MBd transmitter with ST connectors is HFBR1412 and the companion receiver is HFBR2412.

If you take apart an older 850nm fiber device such as a 10BaseT to fiber converter from the 1980-90's, the odds are pretty good that you will find HFBR transmitters and receivers. I have a couple of those adapters I may scavenge for HFBR pairs.

Another alternative is to connect a MAXIM RS-232 driver to the transmit and use it to drive a commercial "off the shelf" RS-232 to fiber adapter. The down side of this approach is the need for another power supply for the adapter and the reverse channel goes unused. Yet another approach would be to use audio TOSLINK transmitters, receivers and manufactured cables. They are unidirectional but aren't as sturdy as the HFBR devices with ST connectors and 62.5/125 cable and the absolute maximum distance is 10 meters with 5 meters being the typical maximum.

Regards,
George

P.S. I'm sorry for the link rather than an actual schematic. I tried to embed the schematic image from my Google drive but the forum software couldn't handle the link.