Initially, I was very excited about adding wireless capabilities to my product, and I was even more excited to find a plethora of available solutions in China. I could get any kind of remote, receiver, transceiver, encoder or decoder, FSK, OOK, ASK, in any frequency band 315MHz, 433MHz, 900MHz, 2.4GHz, at any power level. I found someone who had a remote with six buttons, which was exactly the kind of remote I needed. They had a matching receiver module, which had the decoder for handling the transmitted signal. I was even able to hook the receiver up to my product without any changes to the microcontroller firmware; it integrated directly into the same circuit as the rest of the buttons. And I contacted the manufacturer of the remote and was told I would even be able to customize the printing on the buttons and change the color of the remote. It was a perfect solution.
Well, it was a perfect solution for a prototype. The realities sank in and caused me a lot of delays. Here are some important notes on building wireless products if you are going to sell them in the United States, Canada, or Europe.
In the United States, the governing body for wireless products is the FCC. In Canada it’s the IC, and in Europe, it’s ETSI. Each has slightly different rules, but in general passing FCC means you should be ok anywhere else, and each region wants imported products to follow those rules.
- Antenna design is a black magic that few people understand, and I’m one of the ignorant many. To get a consistent and optimized range and performance out of the transmitter/receiver pair is very difficult, and requires finely tuned and precisely valued components. This is not likely in extremely cheap products, and the range and bandwidth suffers. You will need to consult with an expert in wireless technologies in order to optimize your solution for your product.
- You may be transmitting at a certain frequency, but depending on the circuit, you are probably also transmitting at harmonic frequencies or other spurious frequencies. This happens more the cheaper the parts are. Your intentional frequency power levels may be below limits, but transmissions outside of the band must be at significantly lower power levels, and it’s easy to violate those.
- Certification is done using the exact parameters of your final product. You don’t want to submit to a certification house anything but the final version of your board, because any change to it can significantly affect the output of the antenna, leading to violations of power levels or harmonics. Any change during production requires recertification as well, so you want to make sure you are in complete control and confidence of your factory. If they change a part, it can put you out of compliance.
- The FCC has a lot to say about intentional transmitters. First, most frequencies are off limits, except for a few called ISM or unlicensed bands. If you will be doing international sales, the most consistently available frequencies are 900MHz and 2.4GHz. These frequencies are unlicensed, meaning you don’t need a license to operate devices at those frequencies, but they are NOT unregulated. Think of it like a city playground. Everybody is allowed to use it, but if you start throwing sand at people, you’re going to get in trouble.
- The FCC wants you to not throw sand in other people’s faces. They’ll let hobbyists do their own thing within certain limits, but anyone developing a product for sale has a lot of rules to follow. This means filling out some paperwork if you are developing a product that says you will be transmitting at certain frequencies and powers from certain locations. It also means no beta test units going out to early customers. You can’t sell, you can’t even market, and you can barely develop a product if you don’t have FCC certification for transmitters.
- In order to make the FCC happy, you have to take your transmitter to an approved testing house which has a special anechoic chamber used to measure transmission levels at all frequencies. The product is put in this chamber, and powered on and put in a test mode to continuously transmit, and then rotated around as the meter gathers data about what emissions are coming out of it. This typically takes a few hours, after which the testing house will compile a report which is then filed.
- Very few Chinese products have any kind of certification. It costs too much for the factory to pursue it, and then they’d have to amortize the cost into the cost of the product. Wasted if the product is being developed for China or any country that doesn’t care about FCC.
- If you want to pay for the certification, you risk that your factory will at some point change a part and put you out of spec and make your certification invalid.
- If they do have certifications, they are sometimes fake. It’s helpful to look up the cert in the FCCs databases. The neat thing about the FCC database is the submitted documents sometimes have the exact part list, schematic, and board layout of the thing being tested. It’s easy to tell if the FCC number being used is not for the product being claimed.
The Good News
It’s not all FCC misery, though. The good news is that there are companies that develop modules that have modular FCC approval. This means you can drop these modules into your design and they have already passed FCC testing and you don’t need to go through that process. Naturally these modules are more expensive, but in lower volumes and faster time to market, it’s not a bad solution. There are lots of modules for any purpose, so it’s not too hard to find one that will do what you need, without having to design your own and fight through the black magic and bureaucracy of the FCC and wireless antenna design.