FCC Guidance on Transmitter Modules

Written by: Shane Rismeyer

Shane is currently an EMC Engineer working at LSR located in Cedarburg, WI, where he has worked since 2009. His primary engineering focus is on compliance testing and radio certification. He is a member of IEEE and its EMC society. Shane graduated from the Milwaukee School of Engineering with a bachelor’s degree of science in biomedical engineering.

Transmitter modules enable a company to save time and money. The FCC allows modules to be used in multiple hosts without the need to approve each module individually.

Part 15 FCC Antenna Regulations Summary:

There are two basic transmitter modular designs as categorized by the FCC. A single module is defined as a self-contained RF device that is normally designed with the intention of integration into a host device. A split module has its radio control and radio components separated. Both types fall under 47CFR Part 15.212. Single module requirements are found in 15.212(a)(1) and split module in 15.212(a)(2).1 As single modular transmitters share the majority of their requirements with split modular transmitters, below is a summary of requirements for FCC approval.

1.  The radio elements must have the radio frequency circuitry shielded. Physical components and tuning capacitor(s) may be located external to the shield but must be on the module assembly.

2.  The module must have buffered modulation/data inputs to ensure that the device will comply with Part 15 requirements with any type of input signal.

3.  The module must contain power supply regulation on the module.

4.  The module must contain a permanently attached antenna, or contain a unique antenna connector, and be marketed and operated only with specific antenna(s).

5.  The module must demonstrate compliance in a stand-alone configuration.

6.  The module must be labeled with its permanently affixed FCC ID label or use an electronic display.

7.  The module must comply with all specific rules applicable to the transmitter. The grantee must provide comprehensive instructions to explain compliance requirements.

8.  The module must comply with RF exposure requirements. For any transmitters intended for use in portable devices, SAR compliance must be demonstrated to be independent of the host device.2

Both single and split modular transmitters can qualify for limited approval. Limited approval restricts the implementation of a modular transmitter to a host or environment in which it can satisfy all eight criteria. Once a host is fitted with a module, it must be able to satisfy all pertinent FCC regulations that do not relate to the module. For example, if a module is incorporated into a computer system, it must be able to pass applicable FCC 15B (Unintentional Radiators) sections in order to gain compliance. The host manufacturer is responsible for ensuring this compliance.

When placing a transmitter module in a host unit, the module may or may not be end-user accessible. As described in KDB 996369:

A transmitter can be certified as a module and also marketed as an end product to be used as a stand-alone device or a computer peripheral when it is end-user accessible and plug-in replaceable, and does not provide any control that will cause operation of the device in violation of the regulations.

If an authorized transmitter that is not certified as a modular device is used within a host, it must be user accessible and plug-and-play replaceable. If an authorized transmitter is not accessible and is not plug-and-play replaceable, then the host requires a separate certification under a new FCC ID. 3

These distinctions are important to keep in mind when a wireless product is being developed, as additional time and resources may be required in certain instances. When an approved module (modular or limited approval) is integrated into a host device, various scenarios can occur, depending upon the host system’s labeling. If the FCC ID of the module is labeled on the host system, additional authorization is not needed outside of Radiated Emissions and RF Exposure (SAR), as long as:

·         The final product complies with module device usage and grant conditions.

·         The final antenna configuration(s) and use conditions meet applicable rules.

·         The original module test data represents same characteristics in final product.

·         The final product has module FCC ID label per applicable module policy.

If the modular approval is limited, the radiated emissions must be examined to determine whether a Class I or Class II permissive change is valid. If the module’s FCC ID will not be displayed on the host system, then the system ID takes precedence over the module ID. In this instance, the test data taken for the module cannot be applied to the host system and the module effectively becomes a component in the system. A similar situation occurs when the transmitter does not have modular approval and is integrated into a host system. The resulting product is required to have a new FCC ID assigned (it cannot be the transmitter FCC ID), and any data taken during the certification of the transmitter is not valid for the host system.

When multiple transmitters are incorporated within a single host, the transmitters are considered collocated. In order for the host to be certified, both of the transmitters must have grants that allow for collocation. If a transmitter is being employed and its grant does not allow for collocation, the manufacturer may ask the grantee to file a Class II permissive change. The manufacturer may also file for a new FCC ID or a change in ID.4

Modular transmitters provide a cost- and time-effective solution as components of an end product. It is important to note that the overall compliance of a product is left up to the host manufacturer. However, with basic knowledge of applicable FCC guidelines, modular transmitters can be implemented advantageously into host systems.

LSR provides wireless testing services internationally. Contact us for more information.

Works Cited

1. FCC. Section 15.212 Modular Transmitters. Code of Federal Regulations Title 47 Part 15. Washington, D.C.: United States Government Printing Office, 2009, pp. 811-813.

2. OET KDB Labratory Division. 996369 D01 Module Certification Guide v01r01, February 3, 2011. Retrieved April 15, 2011, from FCC OET KDB: https://apps.fcc.gov/kdb/GetAttachment.html?id=35038

3. Harrington, D.F. Modular Transmitter Basics, October 2009. Retrieved April 19, 2011, from TCB Workshop: http://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=77&tn=246405

4. Szeliga, J. Modular Transmitter Approvals KDB 996369, April 5, 2011. Retrieved April 19, 2011, from TCB Workshop: http://www.fcc.gov/oet/ea/presentatio