The rising trend for manufacturers to add wireless modules into products, beyond the more traditional market of laptops and mobile phones, means that they are now being included in everything from domestic fridges to industrial machinery.
In the European Union (EU) it is mandatory that radio equipment meets the ‘essential requirements’ of the Radio and Telecommunications Terminal Equipment Directive 1999/5/EC (R&TTE), which will be superseded by the Radio Equipment Directive (2014/53/EC) in June 2016*.
In order to reduce both costs and time to market for new products, many manufacturers are relying on the use of wireless modules which already meet some or all of the R&TTE essential requirements. Many assume that because the wireless module is compliant as an independent unit, no further action is required. However, this may not be the case.
For example, if a wireless module is fully integrated into a standard television, the television will fall within the scope of the R&TTE Directive and the manufacturer will need to draw up their Declaration of Conformity (DoC) with the Directive’s essential requirements.
The manufacturer of the final product is responsible for its overall compliance and must therefore take responsibility for the wireless module compliance as well as for the final host product.
Ideally, the manufacturer of the wireless module should provide clear instructions about the correct integration of the module to the host manufacturer, including details of how to comply with the wireless regulations.
As the R&TTE Directive does not make specific reference to modules, there are no strict rules to follow when integrating them into other equipment, so best practice should always be followed.
The R&TTE Compliance Association has issued guidance on the use of wireless modules (Technical Guidance Note 01 on the R&TTED compliance requirements for a Radio Module and the Final Product that integrates a Radio Module, May 2013). This has been updated several times over the last few years, so the situation is subject to change.
This guidance states that when an R&TTE compliant module is integrated into a final host product, no further radio testing is necessary, provided the module is integrated in accordance with its manufacturer’s instructions. But, the host product must always meet the other essential requirements of the Directive, namely the safety and EMC aspects.
However, integrating a wireless module is not always as straightforward as it may seem. The most common method of demonstrating compliance with the R&TTE essential requirements is by using ‘Harmonised Standards’. These are written and published under an EU mandate, and provide a ‘presumption of conformity’ (or compliance), provided they are applied in full. Harmonised Standards are always evolving, so manufacturers must keep abreast of them if they are to continue placing products on the EU market.
The USA and Canada have formal approval processes in place, so the routes to compliance are laid down and are reasonably clear compared to Europe. However, the Federal Communications Commission (FCC) rules can be difficult to understand. So, for those wishing to export products to North America, it may be prudent to seek guidance from an authorised test laboratory or from an FCC-designated Telecommunications Certification Body, such as TÜV SÜD.
The FCC rules on module integration are laid down in CFR 47 Pt15.212. For further clarification, the FCC has also issued a guidance document (KDB996369). A wireless module must meet the particular part of the FCC rules which applies and must also meet certain criteria in order to gain modular approval. These include requirements such that the module must have shielded circuitry, a unique antenna connector, be compliant in a stand-alone configuration, and meet RF exposure requirements.
When all of these requirements are met and the device is certified, the FCC grant will state that the device has modular approval. The grant will also stipulate certain conditions of use. For example, most modules are for use in mobile applications where the host product must not be used less than 20cm from the human head or body, and the module may not be co-located in the product with another wireless transmitter.
Provided the conditions of the grant are adhered to, there should be no further testing or certification required for the intentional radiator part of the host equipment, but a label should be displayed stating that an approved wireless module is contained within the host.
Where multiple modules are integrated together, the rules can become more complex. This is particularly so if the host device is to be used in a portable application within 20cm of the human head or body and RF exposure becomes a major issue. Where the conditions of the modular grant cannot be adhered to when integrated into the final host, additional testing and certification is therefore usually required.
In all cases, the module manufacturer must provide the integrator with comprehensive integration instructions, so that they can fully understand the conditions and limitations for authorised use of the modular transmitter. The Industry Canada rules for modules are broadly similar to those of the FCC and are laid down in RSS-GEN Section 3.
With different rules applying to the global marketplace, manufacturers are advised to follow some basic guidelines when integrating wireless modules into products.
For European compliance, ensure that the wireless module you are integrating is fully compliant with the latest Harmonised Standards and is integrated in accordance with the manufacturer’s supplied instructions. While the module manufacturer should be aware of the integration rules, as a minimum the final or host product manufacturer should check the module’s DoC to ensure that it lists Harmonised Standards which are current.
It is also important for the host product manufacturer to have access to the module manufacturer’s technical file in case they are asked to prove compliance by a country’s market surveillance authority. This should involve checking the EU Official Journal to see if the standard to which the wireless module was tested has an expiry date and, if so, take action well in advance.
It is important to remember that products containing wireless transmitters must comply with national radio regulations no matter where in the world they are used. A product containing a wireless transmitter must not be shipped to a non-EU country without checking the regulations.
For USA and Canada, host product manufacturers should check the conditions of the module grant and ensure that the product is not breaking those conditions. Once again, follow the module manufacturer’s guidance on integration.
In any country, the market surveillance authorities can come down hard on manufacturers that supply non-compliant equipment to the market and ignorance of the rules is no excuse.
* The R&TTE Directive will be superseded by the Radio Equipment Directive (RED) in June 2016. The essential requirements of the RED are largely identical to those of the R&TTE Directive, so the situation regarding wireless modules will remain unchanged.