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The FCC Road: Part 15 from Concept to Approval

By Linx Technologies

Contributed By Convergence Promotions LLC


Once your wireless widget is ready for market, how do you get FCC Part 15 approval? Knowing the process and starting it from the beginning helps shorten and smooth out the road ahead.


Many manufacturers have avoided making their products wireless because of uncertainty over the approval and certification process. While it is true that RF increases the effort and cost of bringing a product to market, it also can add significantly to the function and salability of a completed product. Thanks to a growing number of easily applied radio frequency (RF) devices such as those offered by Linx, manufacturers are now able to quickly and reliably add wireless functionality to their products. The issue of legal compliance for the finished product is straightforward when approached in logical steps.

Purpose of this article

This article gives a brief overview of the legal issues governing the manufacture and sale of RF products intended for unlicensed operation in the United States under CFR 47 Part 15. In the United States, the Federal Communications Commission (FCC) is responsible for the regulation of all RF devices. The FCC requires any device that radiates RF energy to be tested for compliance with FCC rules. These rules are contained in the Code of Federal Regulations (CFR), Title 47. Part 15 is the section of the code that deals with devices that emit RF energy and are to be operated without an individual license.

While this article will provide you with a basic understanding of the steps involved in certification, it is strongly recommended that you obtain a full copy of the code from your local government bookstore, the Government Printing office, or the FCC website.

What is “Unlicensed” operation?

Certain bands within the RF spectrum are available for “unlicensed” operation. The term “unlicensed” is often misunderstood. The manufacturer of a product designed for “unlicensed” operation is not exempt from testing and/or certification. Indeed, both the transmitter and receiver must be tested by a qualified testing laboratory. However, once the necessary approvals are received, the end user can then operate the product without further obligation or licensing.

Steps to Part 15 certification

Choose the optimum operating frequency

Part 15 governs a broad range of the radio spectrum ranging from below 1 MHz to in excess of 32 GHz. It is broken into individual sections that govern the use of specific frequencies and bands. For example, section 15.249 covers the 902-928 MHz band. In this frequency range a user is allowed to transmit any analog or digital signal they desire so long as the stipulations governing allowed output power, harmonics, and occupied bandwidth are met. Other sections are not so accommodating. For example, in the 260-470 MHz band, the FCC considers not only RF factors but also the intended function and application.

In order to determine which operational frequency is best for your product, it is necessary to weigh both technical and legal issues. First, you will want to have a clear understanding of which frequencies are legally available, and then choose a specific frequency based on technical issues such as range, propagation, antenna length, power consumption, and potential interference. (If you are not familiar with these technical issues, consult with a Linx application engineer or read Linx Application Notes focusing on those issues.)

Component selection

Once a frequency of operation has been selected, the RF section and antenna must be carefully designed and optimized to comply with the allowed power and harmonic limitations imposed by Part 15. This process is greatly simplified if you are using a Linx module, but it is still important to recognize that the antenna and layout play key roles in the product’s legal operation.

Many modular RF transmitter products, including those manufactured by Linx, have the potential to output RF power in excess of Part 15 limits. This extra power helps designers overcome inefficient antenna styles and take advantage of the FCC’s averaging allowance when modulation techniques such as ASK/OOK are employed. If necessary, output power may be reduced using the module’s level adjust or an external attenuation pad.

Another consideration in antenna selection is that Part 15.203 requires the antenna to be permanently attached or coupled with a unique or proprietary connector. While this requirement leaves room for interpretation, the FCC’s intention is that a user not be able to change the radiated characteristics of the device by easily interchanging the antenna with a higher performance model.

Build production-ready prototypes

After choosing a frequency for operation and a suitable RF stage, you will want to move from concept breadboard prototypes to a production-ready model as rapidly as possible.

Prescreen and optimize

Once a wireless product is finished, its output power and harmonics should be checked to ensure that the RF stage is both optimized and Part 15 compliant. This testing requires a spectrum analyzer and calibrated antennas. If you do not have access to these instruments, consider prescreening services such as those offered by Linx. The prescreening process can result in a cost savings over formal testing and provides an opportunity to maximize product performance.

Send the production-ready product to an FCC authorized testing facility

Once your product is in its finished form, exactly as it will be produced, testing should be conducted by a properly approved laboratory. In most cases, it is not necessary to be present for testing and the laboratory will prepare the filing paperwork.

The FCC has greatly streamlined the approval process by allowing independent laboratories to issue certifications though the Telecommunication Certification Body (TCB) program.

Unless specifically requested pursuant to Section 2.1076, receivers no longer require certification. They just require a quick test and issuance of a Declaration of Conformity (DoC) which should be maintained in the applicant’s files. Transmitter certification is also relatively painless since many labs that are TCB certified are now allowed to issue certifications on behalf of the FCC. Full transmitter and receiver testing can cost around $5,000, transmitter only around $3,500, and the receiver about $1,500. The entire process can now be rapidly completed and many labs can perform other testing at the same time, such as Class A/B.

Label the product and market it

Following successful completion of the approval process, products should be labeled as required by Part 2.925 and 2.926 as well as Part 15.19 or otherwise prescribed by the FCC.

Summary

Bringing a product through the approval process (summarized in Figure 1) involves cost, effort, and in some cases frustration, but in the end your product will have an exciting new dimension of functionality and market appeal. By following the steps outlined in this application note and reviewing a copy of CFR 47 you will be well on your way to RF success. While complying with applicable provisions may seem unnecessarily restrictive, such regulations serve to ensure the availability of usable RF spectrum for every product.

The approval process

Introduction

Here in the United States the Federal Communications Commission (FCC) is responsible for the regulation of all RF devices. The FCC requires any device that radiates RF energy to be tested for compliance with FCC rules. These rules are contained in the Code of Federal Regulations (CFR), Title 47. The first volume of CFR 47 contains parts 0-19. The sections you will be dealing with throughout the approval process are primarily Part 2 and Part 15. Part 2 deals with issues of marking and authorization. Part 15 deals with the operational aspects and requirements for devices that emit RF energy and are to be operated without the end user needing a license. It is strongly recommended that you obtain a full copy of the code from your local government bookstore, the Government Printing office, or the FCC website.

Issues such as frequency selection, antenna compliance, and output power are covered elsewhere, therefore this section moves past those issues to the specific steps involved in the approval process.

Step one: lab selection

The FCC requires that final product testing be conducted by a registered testing facility. Labs that have indicated they are available to perform Part 15 testing for the public are listed on the Domestic Testing Facilities list.

The quality and competence of labs varies widely. Labs appearing on the list are independent. Linx is pleased to make recommendations of test facilities believed to be competent; however, it is the sole responsibility of applicants to select a test lab capable of measuring their specific device.

To pay or not to pay

Once you have chosen a lab, you must decide the extent of the services they will provide. Lab services range from basic testing, to full compliance testing and filing.

Our advice? Have the lab do as much as possible. Taking time to understand the subtleties of the filing process in the middle of trying to get a product to market is a bad idea. Saving a little money doing things yourself can end up costing far more than you save and in some cases might jeopardize your ability to receive approval.

Step two: registering

When your product is completed and ready for testing a Federal Registration Number (FRN) must be obtained. This is free and can be obtained online.

Next, request a grantee code from the FCC. This can also be done online. The grantee code costs $60 and must be paid within thirty days of the application. Form 159 is used for this and can be done online or printed and mailed.

Step three: testing

As previously mentioned, the FCC requires that final product testing be done in a registered test facility. Here, such items as output power, harmonics, and spurious emissions will be tested. This facility will perform separate measurements on the transmitter and receiver as the transmitter and receiver require different types of authorizations from the FCC. The testing will usually take less than two weeks, but the actual time will depend on the test lab’s backlog and schedule. It is a good idea to contact the lab well in advance to make them aware of your project and secure a spot in their testing schedule.

In order to have the best chance at approval it is important to explain the intended function of the product and any special operating characteristics to test lab personnel. If you are using a module that uses a keyed modulation method such as ASK/OOK, be sure your lab remembers to measure or calculate average power, not peak.

The test lab will require a number of items to complete the filing. These items will often include:

  • A letter appointing the test lab as your technical agent for certification. The labs will provide a sample letter.
  • The FCC ID Number of the unit. The first three digits are the grantee code obtained earlier. The last 14 digits are up to the applicant.
  • A sketch of the location of the FCC label on your unit as well as a sketch (with dimensions) of the label itself.
  • A block diagram of the unit showing all clock oscillators and their frequencies of operation. The signal path and frequency should be shown at each block.
  • Full schematic diagram.
  • The user’s manual.
  • A brief, non-technical description of the product and its operation.
  • A product sample for testing and photos.

Transmitter testing

A product containing a Linx transmitter is considered by the FCC to be an intentional radiator because it intentionally emits RF energy into free space. Thus, it must be tested and certified before it may be marketed.

Certified transmitters are required to have two labels attached: an FCC ID label and a compliance label. The FCC ID label identifies the FCC equipment authorization file associated with the transmitter, while the compliance label indicates to the consumer that the transmitter may not cause, nor is it protected from, harmful interference. These labels may be combined for convenience.

Receiver declaration of conformity

A receiver is considered an unintentional radiator because, while not specifically designed to radiate RF energy, RF radiation may occur. For this reason the receiver must be tested and authorized by a Declaration of Conformity (DoC). In this simple process an accredited laboratory tests the product to ensure compliance with FCC standards. An FCC filing or submittal is not required unless specifically requested pursuant to Section 2.1076. The test results should be maintained within the applicant’s files.

Conforming products are also required to have a compliance label attached to all items subsequently manufactured or marketed by the responsible party.

Filing confidentiality

Filing for confidentiality is an important and often overlooked issue. Unless otherwise requested the entire contents of your filing will become public information. You may request confidentiality pursuant to 47 CFR 0.459, which can prevent such proprietary items as schematic diagrams from falling into the hands of competitors. When confidentiality is requested, please label all items that are to be kept confidential from the general public “CONFIDENTIAL.” Items that cannot be given confidentiality are: (1) photos of a device (anyone who purchases a device will know what it looks like), (2) test results (the public has a right to review a test report showing compliance with the FCC regulations) and (3) the user’s manual. In general, the only information that is granted confidentiality is patented trade-secret information that if given out could harm a company financially.

Step four: The filing process

The FCC greatly streamlined the approval process. Certifications were once issued by the FCC directly, but independent testing laboratories are now allowed to issue certification though the Telecommunication Certification Body (TCB) program. They can also issue certifications for other countries with which the US has a Mutual Recognition Agreement (MRA). TCB’s must be accredited and comply with Section 2.962.

The filing process is usually done by the test lab as a part of their service. The lab will compile the test report, photographs, and other items listed above. The TCB will review all application materials and, if the device conforms to the requirements, they will upload this information to the FCC. After the FCC receives the report they will add the product and the ID number to their database and their website and issue a Grant of Certification. At this point, the device can be legally marketed and sold. After certification, the FCC or the TCB may request a sample of the product to confirm ongoing FCC compliance.

Consideration for operation within the 260-470 MHz band

Introduction

This section is designed to give the reader a basic understanding of the legal and technical considerations for operation of RF devices in the 260-470 MHz band within the United States. The use of these frequency bands varies considerably worldwide, so it should be recognized that this application note is intended for designers utilizing Linx RF modules and planning to operate in the United States.

When working with RF, a clear distinction should always be made between what is technically possible and what is legally acceptable. Achieving a solution that meets technical objectives but cannot be legally sold or operated serves little use. As such, issues of legality should be given high priority.

Legal considerations

In the United States, the Federal Communications Commission (FCC) is responsible for the regulation of all RF devices. These regulations are contained in the Code of Federal Regulations (CFR), Title 47. Title 47 is made up of numerous volumes; however, all regulations applicable to operation in the 260-470 MHz band are contained in volume 0-19. It is strongly recommended that a copy be obtained and reviewed in its entirety. You can get a full copy of the code from your local government bookstore, the Government Printing office in Washington, or the FCC website.

What is unlicensed operation?

Certain bands within the RF spectrum are available for “unlicensed” operation. The term “unlicensed” is often misunderstood. The manufacturer of a product designed for “unlicensed” operation is not exempt from testing and/or certification. Indeed, both the transmitter and receiver must be tested by a qualified testing laboratory. However, once this has been done and any necessary approvals received, the end user of the product can then operate it without obtaining a license for its use.

Receiver procedure

The approval procedures for transmitters and receivers are quite different. The receiver is considered an unintentional radiator and is subject to authorization under the Declaration of Conformity process. This is a simple process in which an accredited laboratory tests the product to ensure that the equipment complies with FCC standards. The test results should be maintained within your files but an FCC filing or submittal is not required unless specifically requested pursuant to Section 2.1076.

Following successful completion of this process, the end product should be labeled as prescribed by the FCC.

Transmitter procedure

The transmitter is an intentional radiator and subject to certification. Certification testing should be performed by properly approved laboratory. In most cases you do not need to be present for testing and your chosen laboratory will prepare the filing paperwork. Certifications were once issued by the FCC directly, but now independent laboratories are allowed to issue certification though the Telecommunication Certification Body (TCB) program which has streamlined the process.

Following successful testing, a report will be produced showing information about the testing and your device. A label displaying your FCC ID number along with FCC prescribed information will need to be placed on your certified product.

The rules for transmitters operating in the 260-470 MHz band are governed by Part 15.231. In some bands the FCC specifies only fundamental power, harmonic levels, and allowed bandwidth. However, in the case of the 260-470 MHz band, the FCC also considers factors such as the intended application and transmission duration.

You will want to review the text of 15.231 in its entirety. When reviewing this section, it is critical to read paragraphs (A)-(D) as a unit, and recognize that paragraph (E) only applies if the rules of paragraph (A) cannot be met. Given the rules’ complexity and application-dependent nature, they are best illustrated in Figure 1.

Functional Requirements

Once you are certain your application is allowed in principle, you will want to focus on understanding the specific functional requirements that must be met in order for your product to receive certification.

Determine and comply with allowed output power

Figure 2 shows the relationship between the fundamental frequency of operation and the allowed output power. Since the output power is allowed to climb as the frequency increases, it might appear that selecting the highest frequency would give the best range performance. This is not the case, however, since free space attenuation increases proportional to frequency. Thus, the regulations equalize the bands propagation characteristics. Antenna size and efficiency should also be considered. Compact or reduced sized antennas will generally not be as efficient at the lower parts of the band.

It is always important to note that the RF level radiated into free space is dependent not only on raw output power, but also factors such as the type of antenna employed, circuit layout and ground plane. Most transmitter modules, including those manufactured by Linx, are capable of producing non-compliant output levels. This extra power helps designers overcome inefficient antenna styles and allows them to take advantage of the FCC’s averaging allowance when modulation techniques such as ASK/OOK are employed. If the module is matched to an efficient antenna, the output power may need to be reduced using the module’s level adjust or an external attenuation pad. For further details, review Linx Application Note #00150.

Part 15 approval process
Figure 1: The Part 15 approval process.


Frequency of operation vs. output power
Figure 2: Frequency of operation versus output power.


In addition to fundamental output power restrictions, the FCC also regulates allowed harmonic levels and occupied bandwidth.

Since this article is oriented toward users of Linx products, little detail is needed on these points as Linx modules are designed to meet these requirements. It is important, however, to note that there are ways in which a user can adversely affect harmonic content, including the use of a poorly matched or tuned antenna, supply/system noise, or layout or bypass issues.

While these considerations of legality may appear formidable, they generally are not. By choosing a correct operational frequency and using a pre-made RF module, a product designer’s burden is greatly reduced. With proper attention to such basics as good layout, clean supply lines, and a properly matched antenna, RF success can be a nearly painless process.

Now that your application has hopefully survived the legal considerations outlined above, let’s consider the actual technical issues of operation in these frequencies.

Benefits of operation in the 260-470 MHz band

First, it should be recognized that the unusual restrictions placed on the band by the FCC do more than just make a designer’s life miserable. The random periodic nature of transmissions resulting from these restrictions helps to keep this set of frequencies clear of sustained interference. Other Part 15 bands are potentially crowded with continuous transmissions of voice, data, video, and even microwave ovens.

Second, longer transmission distances are achieved with less power. The free space propagation of frequencies in this range is significantly better than at higher frequencies such as 900 MHz or 2.4 GHz. Therefore, lower output power is needed to attain any particular distance and power consumption is significantly reduced.

Third is cost effectiveness. The components used at these frequencies are lower in cost than those designed for higher frequencies.

Fourth is international regulatory compatibility. If your product will be sold abroad, you will want to plan for international compatibility. Band allocation and regulations vary from country to country. For additional information you may wish to refer to Linx Application Note #129.

Common frequencies within the band and their uses

As you review Linx product offerings, you will notice three standard frequencies within the 260-470 MHz band. These frequencies are 315, 418, and 433.92 MHz.

  • 315 MHz is commonly used for gate/garage door openers, security, and keyless entry systems.
  • 418 MHz is a very clean frequency here in the US and also appropriate for operation in Canada.
  • 433.92 MHz is used throughout all of Europe. While it is allowable for use here in the US and Canada, interference from amateur radio, the nearby pager band and active RFID tags may sometimes pose a problem.

Summary

The 260-470 MHz band is ideal for transmitting control, command, or status signals. It should also be given consideration for control signals accompanied by data such as time, temperature, or pressure.

Considerations for operation within the 902-928 MHz band

Introduction

This section is designed to give the reader a basic understanding of the legal and technical considerations for operation of RF devices in the 902-928 MHz band. The use of these frequency bands varies considerably worldwide, so it should be recognized that this application note is intended for designers utilizing Linx RF modules and planning for operation within the United States.

When working with RF, a clear distinction should always be made between what is technically possible and what is legally acceptable. Achieving a solution that meets technical objectives but cannot be legally sold or operated serves little use. As such, issues of legality should be given high priority.

Legal considerations

In the United States, the Federal Communications Commission (FCC) is responsible for the regulation of all RF devices. These regulations are contained in the Code of Federal Regulations (CFR), Title 47. Title 47 is made up of numerous volumes; however, all regulations applicable to operation in the 902-928 MHz band are contained in volume 0-19. It is strongly recommended that a full copy of the code be obtained from your local government bookstore, the Government Printing office, or the FCC website.

What is unlicensed operation?

Certain bands within the RF spectrum are available for “unlicensed” operation. The term “unlicensed” is often misunderstood. The manufacturer of a product designed for “unlicensed” operation is not exempt from testing and/or certification. Indeed, both the transmitter and receiver must be tested by a qualified testing laboratory. However, once the necessary approvals are received, the end user can then operate the product without further obligation or licensing.

The frequencies from 902-928MHz are allocated for a wide variety of unlicensed applications. These include unlicensed products operating under Part 15 as well as Part 18 Industrial/Scientific/Medical (ISM) devices.

What must I do to be unlicensed?

Part 15 requirements for many bands are somewhat obscure and difficult to interpret. Thankfully, the regulations of Part 15 for the 902-928 MHz band are very straightforward. There are no restrictions on the application, content or duration of transmissions, only on factors such as power output, bandwidth, harmonic and spurious emissions.

While Linx modules are inherently designed to meet these requirements, it is important to note that external factors such as layout, antenna type, and output power can affect both the module’s performance and compliance. While these issues may appear formidable, they are generally not. By choosing the correct operational frequency and using a pre-made RF module, a product designer’s burden is greatly reduced. Since the approval procedures for transmitters and receivers are quite different, let’s look at each separately.

Receiver procedure

The receiver is considered an unintentional radiator and is subject to authorization under the Declaration of Conformity process. This is a simple process in which an accredited laboratory tests the product to ensure that the equipment complies with all applicable FCC standards. An FCC filing or submittal is not required unless specifically requested pursuant to Section 2.1076. The test results should be maintained within the applicant’s files.

Following successful completion of this process, the end product should be labeled as prescribed by the FCC.

Transmitter procedure

The transmitter is an intentional radiator and subject to certification. In most instances, users of modules manufactured by Linx will seek certification under part 15.247 for Spread Spectrum modules or under 15.249 for narrowband modules. An exception to this is RF modules which have been pre-certified by Linx under the modular approval process. In instances where certification is required, testing will need to be performed by a properly approved laboratory. In most cases it is not necessary to be present for testing and the laboratory will prepare the filing paperwork. Certifications were once issued by the FCC directly, but now independent laboratories are allowed to issue certification though the Telecommunication Certification Body (TCB) program which has greatly streamlined the process.

Following successful testing, a report will be produced showing information about the testing and the device. A label displaying the applicant’s FCC ID number along with FCC prescribed information will need to be placed on the certified product.

Now that a basic overview of legal issues has been covered, it is time to consider the technical issues of operation in these frequencies.

Benefits of operation within the 902-928 MHz band

The first benefit of the 902-928 MHz band is freedom from the tight limitations and application restrictions the FCC places on some other bands. In this band virtually any analog or digital signal can be sent without restrictions on content or duration.

Second, higher legal output power allows the potential for much longer transmission distances.

Third, the propagation of frequencies in the 900 MHz range is better than at higher frequencies such as 2.4 GHz. Therefore, lower output power is needed to attain any particular distance, reducing transmitter power consumption.

Fourth is antenna size and compactness. A useful byproduct of higher frequency is shorter wavelength. This allows a 1/4-wave antenna in the 900 MHz range to typically be less than 3.25 inches in length. In fact, Linx’s Antenna Factor division offers tiny surface mount antennas that are less than 0.65 inches in length, allowing for easy concealment in compact portable products.

Drawbacks to the 902-928 MHz band

The first drawback is the band’s popularity (good in rock and roll, bad in RF). Products such as cordless phones have migrated to higher frequencies, but the growth of wireless and the benefits of the band make it likely to remain crowded.

Second is the potential for higher level interferers. In addition to its allocation for narrow-band devices, the 902-928 MHz frequency range is also allocated for higher power devices. While Linx employs a variety of techniques to minimize the possible impact of such interference, it should be considered.

Third is export. Allowed uses of the 900 MHz band vary outside the US and a products operation may not be legally allowable in other areas. Fortunately, nearby frequencies are standardized in the large European market. Linx offers a selection of footprint compatible products which accommodate domestic and export requirements with just a change of modules and antennas. For additional information you may wish to refer to Linx Application Note #129. Check the regulations for each country to which export is desired in order to assure the product will be legal.

Summary

The 902-928 MHz band is highly favorable due to minimal legal restrictions and excellent propagation characteristics. It is an ideal choice for analog or digital links, especially those that require reliability over long distances or which might be prohibited in other bands.

For additional information on FCC regulations you may wish to contact the FCC directly.

Federal Communications Commission
Office of Engineering and Technology
7435 Oakland Mills Road
Columbia, MD 21046
Phone: (301) 362-3000
Fax: (301) 344-2050
E-mail: labhelp@fcc.gov

You may also wish to visit the Linx Technologies website at www.linxtechnologies.com. where a list of testing facilities and applicable sections of FCC regulations are available for review and download.

Frequently asked questions

How can I obtain more information on the approval process?

You may wish to obtain additional literature and application notes from Linx by visiting our website at www.linxtechnologies.com. You may also visit the FCC’s website at www.fcc.gov, email them at fccinfo@fcc.gov or call them at 1-888-CALL-FCC.

Where can I obtain a copy of the FCC Rules and Regulations?

The Rules and Regulations can be found online at:

http://www.fcc.gov/searchtools.html#rules
CFR Title 47, Parts 2 and 15 cover the use of Linx products. Excerpts from these parts are contained in this document. For a paper copy, you should go to the Government Printing Office’s website at:
http://bookstore.gpo.gov/

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 866-512-1800 and email is ContactCenter@gpo.gov. You can also contact the Government Printing Office (GPO) in your local area for a copy of the rules. The telephone number for the GPO in your local area can be obtained from your telephone directory or operator, listed under the Federal Government.

I wish to locate a test laboratory in my area. Is there a list of laboratories in my area?

The FCC Laboratory makes available such a listing and it is updated monthly. This information is online.

How long will it take to receive an approval?

The testing will depend on the current backlog of the test facility that you choose. If your product passes the testing, the TCB will generally issue a Grant of Certification within a few days.

What does testing and certification cost?

This depends largely on the test lab and how many of their services you choose to utilize. Full transmitter and receiver testing can cost around $5,000, transmitter only around $3,500, and the receiver about $1,500. The entire process can now be rapidly completed and many labs can perform other testing at the same time.

What if my application is denied and I don’t think the FCC correctly understood my product?

The FCC sees thousands of applications a year. Depending on your presentation, an inspector may misinterpret information. It is possible. If you feel you have fairly complied with the regulations, you will want to exercise your rights in accordance with CFR 47 2.923 and petition for reconsideration and review.

What happens if I change my design? Like a case, board or antenna?

For certified equipment (generally your transmitter), the holder of the grant of certification, or the holder’s agent, can make minor modifications to the circuitry, appearance, or other design aspects of the transmitter. Minor modifications are divided into two categories: Class I Permissive Changes and Class II Permissive Changes. Major changes are not permitted.

Minor changes that do not increase the radio frequency emissions from the transmitter do not require the grantee to file any information with the FCC. These are called Class I Permissive Changes (Note: if a Class I Permissive Change causes your product to look different from the one that was certified, it is strongly suggested that photos of the modified transmitter be filed with the FCC).

Minor changes that increase the radio frequency emissions from the transmitter require the grantee to file complete information about the change along with results of tests showing that the equipment continues to comply with FCC technical standards. In this case, the modified equipment may not be marketed under the existing grant of certification prior to acknowledgement by the Commission that the change is acceptable. These are called Class II Permissive Changes.

Major changes require that a new grant be obtained by submitting a new application with complete test results. Some examples of major changes include changes to the basic frequency determining and stabilizing circuitry; changes to the frequency multiplication stages or basic modulator circuit; and major changes to the size, shape, or shielding properties of the case.

No changes are permitted to certified equipment by anyone other than the grantee or the grantee’s designated agent except that changes to the FCC ID without any other changes to the equipment may be performed by anyone.

The receiver is covered by a Declaration of Conformity (DoC), which states that the product was tested by the Grantee and found to comply with the applicable technical standards. The test data should be kept on file by the responsible party as defined in CFR 47 2.209, but nothing is actually filed with the FCC. This means that you will just need to have data on your product on file that shows that the modified product still complies with the regulations. Nothing needs to be filed with the FCC for changes in products covered by a DoC.

Where can I look up information on equipment if I know the FCC ID number?

The FCC maintains a database that can be searched on the Internet. The database contains information on all equipment that was granted through the Equipment Authorization process.

What happens if one sells or uses noncompliant low-power transmitters?

Bad idea. The FCC rules are designed to control the marketing of low-power transmitters and, to a lesser extent, their use. The act of selling or leasing, offering to sell or lease, or importing a low-power transmitter that has not gone through the appropriate FCC equipment authorization procedure is a violation of the Commission’s rules and federal law. Violators may be subject to an enforcement action by the Commission’s Field Operations Bureau that could result in:

  • Forfeiture of all non-compliant equipment.
  • A $100,000/$200,000 criminal penalty for an individual or organization.
  • A criminal fine totaling twice the gross gain obtained from sales of the non-compliant equipment.
  • An administrative fine totaling $10,000/day per violation, up to a maximum of $75,000.

What if my intended use or application does not seem to have been clearly addressed by the FCC?

Recognizing that new uses of low-power transmitters often generate questions that are not directly addressed in the regulations, the FCC generally welcomes 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. Any questions can be directed to the FCC at fccinfo@fcc.gov or 1-888-CALL-FCC.

How close to the products tested are production units required to be?

In the FCC’s own word: 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 subjected. Similar controls over the rest of your product’s production will make compliance with these requirements straightforward.

Does the receiver need to be certified?

The receivers must be issued a Declaration of Conformity (DoC) by an accredited 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.

This document is not endorsed nor approved by the FCC and no affiliation between Linx and the FCC is meant to be inferred.

Disclaimer: The opinions, beliefs, and viewpoints expressed by the various authors and/or forum participants on this website do not necessarily reflect the opinions, beliefs, and viewpoints of Digi-Key Electronics or official policies of Digi-Key Electronics.

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Linx Technologies

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