Below you’ll find a listing of the most frequently asked questions that Linx receives. Should you have any questions that are not found here, or need help with any of Linx’s products, please reach out to one of our technical service representatives at firstname.lastname@example.org. Also, be sure to check out our Wireless Made Simple blog for answers and updates to the latest innovations in the world of wireless.
Since 1996, the Federal Communications Commission (FCC) has set regulations and guidelines on all wireless communications devices sold in the United States. The wireless products must meet minimum guidelines for safe human exposure to radio frequency energy. The limits established in the guidelines are designed to protect the public health with a very large margin of safety.
The Specific Absorption Rate (SAR) is a measure of the rate at which energy is absorbed by the human body when exposed to radio frequency (RF) energy. The general population exposure limits set by the FCC for the frequency range that is utilized by smart meters and other devices like cordless phones and baby monitors, is 0.6 milliWatts per centimeter squared (mW/cm2) at 902 MHz and 1.0 mW/cm2 at 2.4 GHz. Products used within 20cm of the human body must undergo SAR testing to ensure that the rate is below the limits
The FCC has outlined exclusions where the power is low enough that SAR testing is not warranted. In Knowledge Database (KDB) article 447498 this is outlined as:[(max power of channel, including tune-up tolerance, mW)/(min test separation distance, mm)]*[√f(GHz)] ≤ 3.0 for 1-g SAR and ≤ 7.5 for 10-g extremity SAR.
As an example, use the LR Series at 433.92MHz. The maximum output power that the module is capable of is a little under 10mW. Assume a separation of 5mm as a reasonable separation distance through an enclosure. The calculation is:
(10mW / 5mm) * (√0.43392GHz) = 1.3
This is less than 3.0 and would be excluded from SAR testing.
This is a difficult question to answer because of the large number of countries and the way in which some of these countries number their rules. And some countries have different rules for different applications, not just frequency. Here are some of the countries that we get asked about most often. Please note that these can change at any time and these links may not get updated. Please confirm any rules with the agency websites.
Australia – Australia Communications and Media Authority (ACMA) – AS/NZS 4268, LIPD Class License and Fact Sheet
Please contact Linx if you have questions about other countries that are not on this list.
The following Linx Modules have FCC and Industry Canada Certification. The TT Series, HumRC Series and HumPRC Series modules are designed for remote control applications. The HumPRO Series and Amplified HumPRO Series are designed for data applications. There are some restrictions on implementation required to maintain the module certification. These are listed in the module’s data guide.
All of our wireless remote handheld and keyfob transmitters are certified.
It should be noted that there is no modular certification for a receiver. All products must be tested as unintentional radiators regardless of whether or not they contain radios. This must be done on the final product as it will go to market. Any testing on the module itself would be irrelevant since the testing needs to include everything else inside the product as well. This means that while the transmitter portion of the radios is tested and done, the manufacturer is still responsible for performing Unintentional Radiator testing on the end product as it will go to market.
Europe does not have a certification or modular approval. Instead, a Declaration of Conformity (DoC) is used where the manufacturer of the equipment declares that the equipment conforms to all requirements under the Radio Equipment Device (RED) directive. A product placed on the market must be tested and fully assessed against the essential requirements of the RED directive to support that declaration.
The manufacturers are required to test the equipment it all possible configurations and use environments to ensure that they will conform in all likely ways that the end user will install and operate the equipment. This gets easier the closer to the end user you get. For example, a company making a USB dongle that plugs into a computer needs to test against all operating conditions like voltage, temperature and orientation. This is fairly straightforward since the number of variables in a computer are small (as long as the antenna is integrated into the dongle). For the manufacturer who makes the radio, they would have to consider the USB dongle use case as well as every other product that could use their radio and the typical operating conditions of each. This gets overwhelming very quickly. Even then, the RED directive requires some testing on the final product itself, so it is inevitable that some testing would get repeated. While some testing could be done on the module or subassembly and carried through to the end product, it is extremely limited and most likely would not have a significant reduction on the cost of testing.
Many modules have a CE mark indicating that they have been tested and comply with the RED directive. This is accurate for the test board used by the manufacturer for the testing and the conditions on that board. This may not apply to the end product depending on voltages, temperatures and antenna implementation. It is a good idea to consult an accredited test lab to get clarification on if any of the test data supplied by the module manufacturer can be applied to the end device testing.
It is ultimately the responsibility of the end equipment manufacturer to assess all possible installation environments and ensure that the equipment complies with the directive. While summaries are great, there is no substitution for reading and understanding the ETSI standards and how they apply to the end product.
The receivers must be issued a Declaration of Conformity (DOC) by an approved test lab. This is far less complicated and expensive than a transmitter certification. There is not an actual filing with the FCC, just keep these documents in your company files.
Recognizing that new uses of low-power transmitters often generate questions that are not directly addressed in the regulations, the FCC accepts inquiries or requests for specific interpretations. Occasionally, the FCC proposes changes to its regulations, generally to address industry concerns and/or as new uses of low-power transmission equipment appear. The FCC accepts questions through their website.
The FCC reviews thousands of applications a year. Depending on your presentation, an inspector may misinterpret information. If you feel you have complied with the regulations, you will want to exercise your rights in accordance with CFR 47 2.923 and petition for reconsideration and review.
In the FCC’s own words: IDENTICAL. However, identical is further defined as identical within the variations that can be expected to arise as a result of quantity production techniques. One of the advantages of using Linx modules is the tight production control and testing procedures to which the modules are subject. Similar controls over the rest of your product’s production will make compliance with these requirements straightforward.
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The FCC maintains an electronic copy of the FCC rules and regulations on their website. Refer to the FCC Resource Document for a copy of the sections applicable to Linx products. For a printed copy, you should contact the Government Printing Office in Washington, D.C., and indicate that you need a copy of Title 47 of the Code of Federal Regulations (47CFR). If your need is for equipment authorization, you will require Volume 1 which contains Parts 0-19. Their telephone number is (202) 512-0132. You can also contact the Government Printing Office in your local area for a copy of the rules. The telephone number for the GPO in your area can be obtained from your telephone directory or operator. It would be listed under the federal government.
For applications like amateur HAM radio, the FCC requires that the end user have a license to operate the radio equipment. For the portions of the spectrum governed by Part 15, the end user does not need a license. Instead, the product manufacturer must have the equipment tested in an FCC authorized facility and receive certification and an FCC ID number for the transmitter and a Declaration of Conformity (DOC) for the receiver before the product can be legally sold in the United States. In this sense, the equipment must get the license so that the end user does not need one.
The FCC makes available a list of FCC authorized test labs and updates it monthly. This information is at the FCC website. It is not necessary to be present at the lab during testing, so the lab you choose can be located nationwide. Linx highly recommends Compatible Electronics, which offers special pricing and exceptional service to our customers.
The FCC has greatly streamlined the approval process in recent years. The entire process can now be completed in less than 30 days. In fact, receivers no longer require certification — just a quick test at an approved lab through the Declaration of Conformity (DOC) process. Transmitter certification is almost as painless since many labs that are TCB certified are now allowed to issue certifications on behalf of the FCC. Linx maintains a close working relationship with Compatible Electronics Compatible Electronics, which extends excellent service and special pricing to Linx customers.
This depends on the radio technology and how much you have the test lab do. Full transmitter and receiver testing for a single channel radio can cost around $5,000. The transmitter only is around $3,500, and the receiver Declaration of Conformity is about $1,500. Multi-channel transmitters, such as FHSS systems, require more testing and lab time, so are more expensive. This is generally closer to $10,000 for the full certification.
Including a certification for Industry Canada will increase the cost, but generally not much. The testing is mostly the same, so there is an additional filing fee and a little more time for the report. Testing for Europe CE is much more expensive and can run around $15,000 for a multi-channel device. The testing is very different from FCC test requirements, so not much of the lab tests or time can cross over between the two.
The test time can usually be done in about a week, depending on the backlog of the test lab. The FCC has authorized private Telecommunications Certifications Bodies (TCB) to issue identity numbers on its behalf so the grants are typically issued within 3 to 4 weeks.
Linx maintains a close working relationship with Compatible Electronics, which extends excellent service and special pricing to Linx customers.