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An evolution in testing

The European Telecommunications Standards Institute (ETSI) produces globally applicable standards for information and communications technologies and TÜV SÜD currently sits on the ETSI task group.

This task group was involved in the production of the Radio Equipment Directive Harmonised Standard, EN 300 328 – one of the most frequently that’s used standards for approval tests for products with radio technologies.

As of 6th August 2021 the transition for the new requirements of the latest version of EN 300 328 (V2.2.2) ended and the previous version (V2.1.1) will no longer provide ‘presumption of conformity’ to the European Union’s Radio Equipment Directive or UK’s Radio Equipment Regulations.

As a result, manufacturers, distributors or importers which have previously used EN 300 328 as their presumption of conformity will now need to evaluate the changes and update the technical construction file. Failure to continuously ensure compliance may very well result in a variety of enforcement penalties.

The principal changes to the standard relate to receiver blocking requirements, transmitter spurious emissions limits, and the revision of equipment classification “types”.

The EN 300 328 standard covers wideband data transmission equipment which operates in the unlicensed 2.4 GHz ISM band. This includes Wi-Fi, Bluetooth and Zigbee devices, as well as other technologies such as proprietary wideband transmission systems and frequency-hopping spread spectrum (FHSS) devices, and covers both transmitters & receivers.

So this standard affects millions of devices that employ these commonly used technologies.

‘Essential requirements’

It is mandatory that radio equipment meets the ‘essential requirements’ and as EN 300 328 is a harmonised standard, by adhering to it, manufacturers and service providers will be able to demonstrate that they have followed the essential requirements and are able to claim a ‘presumption of conformity’.

Consequently, this allows them to put their products and services on the market in Europe and the UK.

While there is no requirement to involve a European Union Notified Body or UK Authorised Body in the compliance process (i.e. manufacturers can “self-declare” compliance), they can still be involved in the compliance process on a voluntary basis.

The Notified Body or Authorised Body’s identification number can only be used on the product and packaging if a full quality assurance process has been completed. It cannot be used if just a type examination has been performed and certified – the identification mark indicates that a third-party has been involved in the compliance process.

The minimum performance criteria for receiver blocking has been updated to allow for a Frame Error Rate (FER) of less than or equal to 10%. This will result in a more consistent and quantifiable means of test, but it does mean less flexibility for manufacturers, as they may no longer declare an alternative performance criterion, which was permitted in V2.1.1.

For devices that do not facilitate a Packet Error Rate (PER) or FER, the standard mandates that there must be no loss of transmission for the intended use of equipment.

A change in the test requirement mandates that all Receiver Categories (outlined in clause 4.3.1.12.4) should now feature a blocking signal power of -34 dBm at the receiver of the equipment, after having compensated for in-band antenna assembly gain in conducted measurements or power flux density (PFD) in radiated measurements.

This is a much more stringent requirement than previously.

Receiver tests were introduced into the Radio Equipment Directive to ensure the more efficient use of the radio spectrum, and task groups now need to consider the revised level to be more representative of typical levels of interference out-of-band from other sources.

Additionally, all Receiver Categories feature a wanted signal mean power from companion device (WSMPCD) that is derived from a calculation based on the occupied bandwidth (OCBW) of the device. The WSMPCD no longer uses calculations based on the level of the wanted signal at the input of the equipment (Pmin), unless in a radiated test where the wanted signal from the companion device cannot be determined. This will result in a more consistent approach to testing and ensure the minimum receiver sensitivity for all devices.

All Receiver Categories must be tested to new blocking signals defined in V2.2.2 that were not required in V2.1.1. As the frequency of signals have only been adjusted by 500 kHz, this makes it somewhat easier for test laboratories. This means that all equipment will need to be re-assessed (tested) to the revised Receiver Blocking requirements of V2.2.2 and manufacturers cannot self-declare against the previous version of the standard.

FHSS equipment capable of employing both adaptive and non-adaptive modes must comply with the requirements for non-adaptive FHSS equipment. However, as there are an insignificant number of devices using non-adaptive FHSS, this would rarely apply to new devices. For example, it would apply to Bluetooth chipsets that may still need to pair with older Bluetooth devices. In such a case, it could mean further testing is required, as it will need to cover non-adaptive test cases.

Penalties for non-compliance

Equipment must also meet the requirements for Accumulated Transmit Time, Frequency Occupation and Hopping Sequence. If the manufacturer chooses to provide their test laboratory with a statistical analysis that the equipment meets the requirements for Accumulated Transmit Time, this must be included in the test report.

In relation to this process, the new requirement is that if a test report is showing compliance using the ‘statistical analysis’ approach, this must be included in the report. Manufactures may wish to check whether this approach was used and, if it was, check whether the analysis is included in the test report.

The updated standard also relaxes the transmitter unwanted emissions in the spurious domain requirement. Previously equipment had to meet -54 dBm from 470 MHz to 862 MHz and -36 dBm from 862 MHz to 1 GHz (when measured with a Resolution Bandwidth (RBW) of 100 kHz). Therefore, a device which complies with the more stringent limits in V2.1.1 also complies with the limits in V2.2.2.

The measurement procedure for determining the number of operating channels in the hopping sequence previously used an RMS detector. It is now specified that a peak detector must be used. However, as the change of detector type is unlikely to impact the number of channels detected, a device previously deemed compliant against V2.1.1 can therefore be considered compliant with V2.2.2.

Updates to standards can often cause designers and manufacturers of electronics problems, as they may be confused as to what applies to their products and how tests should be applied.

In the case of v2.2.2, if a product was compliant with the old version (v2.1.1) there is no presumption of conformity and new tests must be undertaken regardless. The Technical Construction File and Declaration of Conformity must also be updated to v2.2.2 accordingly.

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.

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.

In any country, the market surveillance authorities can come down hard on manufacturers that supply non-compliant equipment to the market, imposing significant penalties for non-compliance, with goods being held up at national borders if the wrong standards are detailed on the Declaration of Conformity.

Author details: Rob Campling is Manager for Global Market Access at TÜV SÜD

Author
Neil Tyler

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