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The article misses to point out an important insight that this could be illegal and FCC governs radio spectrum. You can't just spin up a giant transmitter as a

The article misses to point out an important insight that this could be illegal and FCC governs radio spectrum. You can't just spin up a giant transmitter as a DIY project, you'll need a Ham radio license and can only operate in a certain frequency. Lazy article - readers now think "hah...some nerd in his basement, no big deal." except that it is a federal crime.

amingilani 7y ago
True, but what both the article and you miss out on is that some radio frequencies are unlicensed. You actually can spin up a transmitter as a DIY projected, and even built exactly what this guy did, as long as you use check up your domestic laws and ensure you're using the right frequencies and in the manners prescribed. Specifically, see the ITU recommendations on 315 Mhz for low powered transmitters. You should be good if you don't exceed 10 mW. [0]: https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-SM.2153-2-2011-PDF-E.pdf https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-SM.2153-2-20...
- myself248 7y ago
  Under FCC jurisdiction at least, 315 MHz has strict duty cycle limits -- you can't transmit more than two seconds per hour. There's a really good summary here: https://www.ti.com/lit/an/swra048/swra048.pdf https://www.ti.com/lit/an/swra048/swra048.pdf So, yes, you can buy exactly the parts this guy did, and implement the project differently, and be completely legal. But he implemented it such that the duty cycle violated regulations, and here we see why the duty cycle is supposed to be very limited. What he did was in clear violation, and he did not need fancy test equipment to determine that.
  - crankylinuxuser 7y ago
    Even though he inadvertently caused consternation with people with keyfobs and rc garage doors, he did quit after it was brought to his attention. I'm much much more lenient on someone who's tinkering and causes that accidentally. And if you read into the article, the person who did it was special needs (mentally or physically). They're also likely on a fixed income. Jail would be unconscionable, as would fining someone which lack of payment would lead to jail. Hopefully the result here is "person quits, person reads up on proper RF practice, and does things better next time"
thinkingkong 7y ago
Yeah its pursuable as a crime but there was no malicious intent and it doesnt make sense to charge anyone. Im actually super glad they used good judgement.
myself248 7y ago
That's not accurate. You absolutely can spin up a transmitter as a DIY project, as long as you stay within the power and duty cycle limits. Devices not intended for eventual sale don't even have to be tested or certified, as long as the builder/user makes a good-faith effort to comply with the regulations. A ham license moves you into a different set of limits and gives you more bands to play in, that's all. Take a read of https://www.ti.com/lit/an/swra048/swra048.pdf https://www.ti.com/lit/an/swra048/swra048.pdf for a reasonably cogent summary of the regulations. The FCC's own rules are considerably denser legalese, and the relevant parts are scattered over hundred of pages. That app note brings it all together. More: https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf https://transition.fcc.gov/Bureaus/Engineering_Technology/Do... (See the "Home-built transmitters that are not for sale" section.)
- spectramax 7y ago
  You're probably correct as I do not have any background in Radio. My point was simply that this article should have mentioned something related to radio frequencies and how it is regulated. It does disservice by telling readers nothing about regulations. This is terrible journalism.
- tzs 7y ago
  That TI document is a nice look at the regulations that concern the device designer. There are also some regulations that the device user needs to comply with that you don't automatically get for free by using a compliant device. I didn't see those in the TI document, but may have missed them. Probably the most important are for interacting with other services that share that band. A band might have several services authorized to use it, and these services have different priorities in case of conflict. Generally, the rule is if a higher priority service interferes with you, it is up to you to filter it out or tolerate it. If you interfere with a higher priority service, it is up to you to stop. For example, the lower part of the 2.4 GHz WiFi band overlaps the higher part of the 13 cm ham band. Hams have higher priority. So if I were to use that band for some long range telemetry (I have an Extra class ham license) and that messes with you using the lower WiFi channels, you are the one who has to find a workaround. If your WiFi messes up my telemetry, you are again the one who has to find a workaround. On the other hand, part of 13 cm is an Industrial, Scientific, and Medical (ISM) band. That ISM band has higher priority than the ham band. If your microwave oven messes up my telemetry, I'm the one who has to cope, because microwave ovens are classified as and operated as ISM devices. And if my telemetry messes up cooking your burrito, I'm the one who has to deal with it.

amingilani 7y ago

True, but what both the article and you miss out on is that some radio frequencies are unlicensed. You actually can spin up a transmitter as a DIY projected, and even built exactly what this guy did, as long as you use check up your domestic laws and ensure you're using the right frequencies and in the manners prescribed. Specifically, see the ITU recommendations on 315 Mhz for low powered transmitters. You should be good if you don't exceed 10 mW. [0]: https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-SM.2153-2-2011-PDF-E.pdf https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-SM.2153-2-20...

myself248 7y ago
Under FCC jurisdiction at least, 315 MHz has strict duty cycle limits -- you can't transmit more than two seconds per hour. There's a really good summary here: https://www.ti.com/lit/an/swra048/swra048.pdf https://www.ti.com/lit/an/swra048/swra048.pdf So, yes, you can buy exactly the parts this guy did, and implement the project differently, and be completely legal. But he implemented it such that the duty cycle violated regulations, and here we see why the duty cycle is supposed to be very limited. What he did was in clear violation, and he did not need fancy test equipment to determine that.
- crankylinuxuser 7y ago
  Even though he inadvertently caused consternation with people with keyfobs and rc garage doors, he did quit after it was brought to his attention. I'm much much more lenient on someone who's tinkering and causes that accidentally. And if you read into the article, the person who did it was special needs (mentally or physically). They're also likely on a fixed income. Jail would be unconscionable, as would fining someone which lack of payment would lead to jail. Hopefully the result here is "person quits, person reads up on proper RF practice, and does things better next time"

thinkingkong 7y ago

Yeah its pursuable as a crime but there was no malicious intent and it doesnt make sense to charge anyone. Im actually super glad they used good judgement.

myself248 7y ago

That's not accurate. You absolutely can spin up a transmitter as a DIY project, as long as you stay within the power and duty cycle limits. Devices not intended for eventual sale don't even have to be tested or certified, as long as the builder/user makes a good-faith effort to comply with the regulations. A ham license moves you into a different set of limits and gives you more bands to play in, that's all. Take a read of https://www.ti.com/lit/an/swra048/swra048.pdf https://www.ti.com/lit/an/swra048/swra048.pdf for a reasonably cogent summary of the regulations. The FCC's own rules are considerably denser legalese, and the relevant parts are scattered over hundred of pages. That app note brings it all together. More: https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf https://transition.fcc.gov/Bureaus/Engineering_Technology/Do... (See the "Home-built transmitters that are not for sale" section.)

spectramax 7y ago
You're probably correct as I do not have any background in Radio. My point was simply that this article should have mentioned something related to radio frequencies and how it is regulated. It does disservice by telling readers nothing about regulations. This is terrible journalism.
tzs 7y ago
That TI document is a nice look at the regulations that concern the device designer. There are also some regulations that the device user needs to comply with that you don't automatically get for free by using a compliant device. I didn't see those in the TI document, but may have missed them. Probably the most important are for interacting with other services that share that band. A band might have several services authorized to use it, and these services have different priorities in case of conflict. Generally, the rule is if a higher priority service interferes with you, it is up to you to filter it out or tolerate it. If you interfere with a higher priority service, it is up to you to stop. For example, the lower part of the 2.4 GHz WiFi band overlaps the higher part of the 13 cm ham band. Hams have higher priority. So if I were to use that band for some long range telemetry (I have an Extra class ham license) and that messes with you using the lower WiFi channels, you are the one who has to find a workaround. If your WiFi messes up my telemetry, you are again the one who has to find a workaround. On the other hand, part of 13 cm is an Industrial, Scientific, and Medical (ISM) band. That ISM band has higher priority than the ham band. If your microwave oven messes up my telemetry, I'm the one who has to cope, because microwave ovens are classified as and operated as ISM devices. And if my telemetry messes up cooking your burrito, I'm the one who has to deal with it.