Pre-Compliance Anechoic Chamber Testing Streamlines Design Process

An anechoic chamber is a shielded room that is fabricated with materials like ferrite tiles and conductive carbon to inhibit external interference. These chambers create the ideal quiet environment needed for electronics testing by eliminating electromagnetic emanation and radio frequency reflection signals. Eliminating external factors allows developers to effectively measure device performance and troubleshoot design constraints. All devices, wireless or wired, must undergo testing at an official certification lab prior to deployment to ensure governmental compliance. (Governmental regulations vary depending on application and geographic location.) However, waiting to perform device testing just prior to deployment has a number of drawbacks. It is recommended that developers undergo pre-compliance device testing throughout the development cycle or prior to official lab testing to avoid costly re-work and redundancy in submission for final certification. Connected Development (CD) offers in-house pre-compliance anechoic chamber testing services (Figure 1) that simplify the complex analysis that goes into device prototyping while offering peace of mind prior to entering official certification labs.

Figure 1: Connected Development’s anechoic testing chamber used for antenna, radio, and RF testing.

What are the benefits of pre-compliance anechoic chamber testing?

Connected Development is one of few design houses that offers in-house pre-compliance anechoic chamber testing. Offering a Fixed Price Pre-Compliance Testing Service option, Connected Development is able to provide full transparency on pricing before getting started. Two major drawbacks of waiting to perform testing just prior to deployment at official certification labs, is that they are often booked and charge high hourly/shift rates. Addressing design constraints early on allows developers to get devices certified sooner at official labs and thus accelerate time to market. Developers can benefit from expedited design validation, prototype and pre-certification testing, performance measurement, and production sampling through pre-compliance testing.

Pre-testing also provides a means of knowing if official lab test results are representative of the product. In many cases, having pre-test data allows test results and methods to be reviewed and compared for errors. There are many occasions where lab operators have structured device testing in a manner that is not representative of the device’s intended use case. Implementing framework of an intended outcome from the beginning of the test and measurement phase enables proper preparation for analyzing results.

RF testing can be incorporated from the beginning of a development process with pre-compliance anechoic chamber testing. Connected Development has extensive experience in this process and can assist in managing devices through to official testing. In the United States, cellular device approvals are normally required to meet carrier Over-the-Air (OTA) (Figure 2) and Radiated Spurious Emissions (RSE) (Figure 3) requirements. Pre-compliance OTA and RSE testing is advantageous as it removes risk by verifying the performance before official lab entry. OTA requirements are set by individual carriers, and the test method is determined by PTCRB, CTIA, or the carrier. OTA and transmitter RSE are two of the most failed areas in RF approvals for host integration of a certified module. It is therefore beneficial to perform pre-testing to eliminate subsequent funding during the development process.

Figure 2: Equipment used in OTA anechoic chamber testing.

Figure 3: Example RSE measurement graph of transmitter harmonics in EMQuest Viewer.

Types of pre-compliance electronics testing offered at CD

Connected Development can assist with device test and measurement for a wide range of technologies, including LTE (NB-IoT and all categories inclusive of CAT-M), LoRa®, GPS, Wi-Fi, and Bluetooth/Bluetooth Low Energy (BLE). Connected Development’s pre-compliance electronics testing follows CTIA methods with automation in the testing of Transmit Radiated Power (TRP) (Figure 4) and Total Isotropic Sensitivity (TIS).

Figure 4: Example TRP measurement graphs and corresponding data shown in EMQuest Viewer.

Pre-Compliance Testing Services:

a) RF/Antenna performance testing

b) Passive antenna pattern testing:

• Antenna design, matching, or tuning

• Performance of antennas throughout the design phase

• Verification of an un-licensed spectrum certified modules’ antenna gain limits set by the module vendor or the FCC limits for the radio type and service.

• PCB trace antenna gain and efficiency measurements

c) PTCRB/CTIA OTA pre-testing:

• TRP and TIS

• Custom automated test campaigns

d) Other performance or quality testing:

• Temperature testing

• Un-intentional radiated measurement testing

• RSE testing for harmonics of the transmitter using the same chamber and automation

• Pre-testing for CE Immunity tests

• Detailed current consumption analysis

• Software quality and robustness testing

• Design reliability testing

• Environmental and accelerated life testing

Common applications suitable for pre-compliance testing

Pre-compliance test and measurement is beneficial in any of the following circumstances:

• Any program with OTA performance requirements for Carrier acceptance.

• Any program with an un-intentional radiation emission requirement.

• Any device that engineering has deemed a risk for emissions.

• Where the ground plane does not meet antenna requirements for OTA.

Test methods and limits may vary for RSE, un-intentional emissions, and different test areas like part 15 FCC limits and transmitter harmonics for PTCRB, or carrier requirements. If different test methods and limits need to be applied, the approval process may be impacted.

Examples of device categories that benefit from pre-compliance testing:

• Vehicle tracking device

• Medical device

• Industrial sensors (Figure 5)

• Wirelessly-enabled water meters

• Wearable devices

• Smart home

• Other IoT devices

Figure 7: IoT sensor device example in test chamber.

Conclusion

Evaluation in a pre-compliance chamber serves to ease the extensive process of device certification. Designers can benefit from applications testing in a pre-compliance anechoic chamber, as this route reduces costs and the need for additional engineering time down the line. Pre-compliance testing also allows for earlier examination of device samples to address design issues prior to entering an official lab. Once it is time to conduct certification testing at an accredited commercial lab, designers can be rest-assured that minimal adjustments will be needed to finalize the production process–ultimately accelerating time-to-market. In addition to benefitting from Connected Development’s in-house pre-compliance testing, developers can leverage CD’s other engineering design services, including end-to-end product design, prototyping, development, implementation, and more.

Contact Connected Development to set up pre-compliance testing for your latest design.

About Connected Development

Founded in 2009, Connected Development is a leading wireless, M2M, and IoT engineering firm. Having worked with companies like Ericsson, Motorola, Sony Ericsson, Sierra Wireless, and Nokia–Connected Development specializes in hardware and software design services and can provide support from design reviews to fulfillment of an entire product development cycle. CD’s expertise in regulatory and carrier certification requirements offers customers an advantage in relation to the time and cost-efficiency of an approval process.