6 ms·

> Because the ISM bands were basically reserved to be a no-man's land that non-communications devices could freely emit into, there are no licensing requirement

> Because the ISM bands were basically reserved to be a no-man's land that non-communications devices could freely emit into, there are no licensing requirements for ISM emissions. Just because there are no formal licensing requirements does not mean that an implied license doesn't exist, nor does it mean that there are no rules. The ISM bands have for a very long time had both transmitter and antenna power limits attached to them. What I think is missing in this article is an understanding that all RF spectrum belongs to the public. The FCC does not own it, it licenses parts of it for coordination so that the spectrum is _usable_ by the public at large. They operate the spectrum on _behalf_ of the public, and their decisions and procedures are based entirely around this concept.

jcrawfordor 5y ago
Yes, the limitations are due to device certification under part 15. However, this is in no way an implied license, as "license" has specific meaning within the context of various parts of the FCC regulations. Part 15 covers unlicensed radiators, so essentially "licensed" and "part 15" are antonyms. This is most significant in that licensing almost always implies some degree of protection from interference (although it may be rather limited), while part 15 devices receive no such protection... when someone interferes with your WiFi, you cannot complain to the FCC (there's some recourse related to the legality of devices, but you cannot for example seek a license modification to address the interference as licensed users generally can to some degree). The existence of "soft licensed" services such as the part 95 services somewhat complicates this as there are services like family radio service (part 95B) that are "licensed by rule," meaning that there is an implicit license, but that somewhat illustrates the point: part 95B radios like the common consumer Motorolas and Midlands are implicitly licensed, WiFi is not! FRS has (limited) regulatory protection from interference, WiFi does not. FRS has limitations on nature of usage, Part 15 has none, but the device must be certified to meet part 15 specs for emissions. The whole "part 15" thing gets more into device certification, which I mentioned in the post I will discuss in the future as it's a topic all of its own. The history of part 15 device certification is closely related to the history of the ISM bands in some ways, but they are not 1:1, as part 15 covers both unintentional/incidental radiators (essentially all electronic devices) as well as intentional radiators which do not have a license... microwave ovens and WiFi are the quintessential examples of the latter. It is of course obvious that RF spectrum belongs to the public, but in the US it is regulated by both the FCC and the NTIA depending on the user and the importance of the ITU cannot be understated as many of these services have at least partial international coordination. Certain radio licenses in the US will also require the approval of either Industry Canada or Mexico's IFT, although this is required under FCC regulations some of which implement treaty obligations. That said, I live in the US and am not a radio technician in the federal government (which is generally exempt from FCC regulations), so I tend to stick to what I know best: 47 CFR! It's also important to understand that in most cases the FCC does not coordinate spectrum usage on a level more granular than services and instead leaves it to other government agencies or private organizations, within the scope of each service. Part 90 is an interesting example, which is FCC licensed on a frequency level but coordinated by private companies for profit (the FCC just approves whatever frequency the private frequency coordinator recommends). I'll probably write on this in the future.
GekkePrutser 5y ago
In Europe there's not only power limitations but also duty cycle on some bands. Eg on 868Mhz you can only transmit 1% of the time. I don't think the equivalent US band of 915Mhz has this, and it has a much higher maximum power which is really nice. Wish we had something like this here.
- vvanders 5y ago
  Yep, you can see this if you go poke into LoRa and associated protocols. 915MHz does have some restrictions on either using spread spectrum, frequency hopping or much lower power limits so it's still quite different than say the ham bands.
- Terry_Roll 5y ago
  Yes the Europeans give away some of their knowledge when looking at radio spectrums, the recent 5G bands causing problems with aircraft at airports in the US is one such example of forward planning or lack of.
- CraigJPerry 5y ago
  There’s also listen-before-talk rules for devices in certain ISM bands in the EU. Affects at least LTE, Wifi and a few other users in 5.8ghz
- usrn 5y ago
  Our band around 400Mhz has a similar limitation.
h2odragon 5y ago
> all RF spectrum belongs to the public. The FCC does not own it, I wish the FCC and more radio enthusiasts also understood that. Its amazing how many epochal inventions in radio have come to the public through getting around the FCC one way or another.
- charcircuit 5y ago
  Not just inventions in radio. Pretty much all electronics nowadays are at least unintentional radiators.

jcrawfordor 5y ago

Yes, the limitations are due to device certification under part 15. However, this is in no way an implied license, as "license" has specific meaning within the context of various parts of the FCC regulations. Part 15 covers unlicensed radiators, so essentially "licensed" and "part 15" are antonyms. This is most significant in that licensing almost always implies some degree of protection from interference (although it may be rather limited), while part 15 devices receive no such protection... when someone interferes with your WiFi, you cannot complain to the FCC (there's some recourse related to the legality of devices, but you cannot for example seek a license modification to address the interference as licensed users generally can to some degree). The existence of "soft licensed" services such as the part 95 services somewhat complicates this as there are services like family radio service (part 95B) that are "licensed by rule," meaning that there is an implicit license, but that somewhat illustrates the point: part 95B radios like the common consumer Motorolas and Midlands are implicitly licensed, WiFi is not! FRS has (limited) regulatory protection from interference, WiFi does not. FRS has limitations on nature of usage, Part 15 has none, but the device must be certified to meet part 15 specs for emissions. The whole "part 15" thing gets more into device certification, which I mentioned in the post I will discuss in the future as it's a topic all of its own. The history of part 15 device certification is closely related to the history of the ISM bands in some ways, but they are not 1:1, as part 15 covers both unintentional/incidental radiators (essentially all electronic devices) as well as intentional radiators which do not have a license... microwave ovens and WiFi are the quintessential examples of the latter. It is of course obvious that RF spectrum belongs to the public, but in the US it is regulated by both the FCC and the NTIA depending on the user and the importance of the ITU cannot be understated as many of these services have at least partial international coordination. Certain radio licenses in the US will also require the approval of either Industry Canada or Mexico's IFT, although this is required under FCC regulations some of which implement treaty obligations. That said, I live in the US and am not a radio technician in the federal government (which is generally exempt from FCC regulations), so I tend to stick to what I know best: 47 CFR! It's also important to understand that in most cases the FCC does not coordinate spectrum usage on a level more granular than services and instead leaves it to other government agencies or private organizations, within the scope of each service. Part 90 is an interesting example, which is FCC licensed on a frequency level but coordinated by private companies for profit (the FCC just approves whatever frequency the private frequency coordinator recommends). I'll probably write on this in the future.

GekkePrutser 5y ago

In Europe there's not only power limitations but also duty cycle on some bands. Eg on 868Mhz you can only transmit 1% of the time. I don't think the equivalent US band of 915Mhz has this, and it has a much higher maximum power which is really nice. Wish we had something like this here.

vvanders 5y ago
Yep, you can see this if you go poke into LoRa and associated protocols. 915MHz does have some restrictions on either using spread spectrum, frequency hopping or much lower power limits so it's still quite different than say the ham bands.
Terry_Roll 5y ago
Yes the Europeans give away some of their knowledge when looking at radio spectrums, the recent 5G bands causing problems with aircraft at airports in the US is one such example of forward planning or lack of.
CraigJPerry 5y ago
There’s also listen-before-talk rules for devices in certain ISM bands in the EU. Affects at least LTE, Wifi and a few other users in 5.8ghz
usrn 5y ago
Our band around 400Mhz has a similar limitation.

h2odragon 5y ago

> all RF spectrum belongs to the public. The FCC does not own it, I wish the FCC and more radio enthusiasts also understood that. Its amazing how many epochal inventions in radio have come to the public through getting around the FCC one way or another.

charcircuit 5y ago
Not just inventions in radio. Pretty much all electronics nowadays are at least unintentional radiators.