Radio compliance testing is the process of ensuring that radio products meet the necessary regulatory requirements, rules, and standards that apply to the countries where they will be sold. This testing can be a complex and daunting process, especially for those unfamiliar with the intricacies of radio technology and regulations.

By understanding the testing requirements, manufacturers can help ensure their products meet the necessary regulatory standards and reach their intended markets on time.

Preparing the sample for testing

The first step is to ensure the sample is fully ready for testing. When preparing a sample, it’s useful to know the common modes that will most likely be required to put the device in to facilitate the testing. This will then enable you to consider any issues that may arise with each mode, such as:

• Will the channels need to be changed?
• Will the modulation scheme need to be changed? For example, from QPSK to 16QAM
• Have the signal bandwidths been agreed, for example, 5, 10, 20, 40, 160 megahertz
• Does there need to be the ability to change carrier power?
• Will it be necessary to remove modulation and just have a continuous wave to help with the testing?
• Does the device have a receive-only mode or a mode where you completely disable the radio?
• Does the device support multiple antennas/ports? Are all antenna ports accessible for testing?

Consider the type of sample required

The type of sample that will be required should also be considered in advance of testing. Wi-Fi requires much of the testing to be conducted rather than radiated, therefore, a 50 ohm connection on the unit will be required. Others may require extremes of testing, for example, temperature or supply voltage.

Using pre-approved modules

• Pre-approved or pre-certified modules: The module manufacturer’s integration instructions must followed to ensure the final product fully complies, which is especially true with power supply and the antenna type and gain.
• Access to the test mode interface: The test laboratory will need to gain access to the test mode or device test mode interface. If the manufacturer hasn’t designed it themselves, they will need to ask the module manufacturer how it’s put into test mode. If it needs a special interface, like a serial interface, ensure that’s available on the end product so it can be connected to for testing.
• Cellular module integration: The test equipment can control any radio access technology and enable the device under test to switch between modes. For example, it can switch between GSM mode, 3G mode, LTE mode, then go into narrowband IOT mode, or MTC mode for LTE. However, the manufacturer needs to be aware that a soldered down SIM should be a special test SIM and a software SIM needs to have the test mode profile enabled.

Intermodulation

Intermodulation is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities or time variance in a system. This can happen when integrating two pre-approved modules. If, during normal operation, two individual transmitters can operate at the same time, then it needs to be ensured that any intermodulation products are within the limit.

Chipset vs module implementation

When designing a radio product, one of the first points to consider is if it should be designed as a chipset or a module.

• Chipsets tend to mean a lower cost per device as they have a lower component cost, however, they will have an increased design cost and increased certification cost.
• Modules tend to have a high component cost but a reduced design cost, however, the manufacturer must accept that a third party has control and will therefore have to rely on the third party for maintaining quality.

Avoiding the common pitfalls

Often, manufacturers experience testing delays due to sample preparedness but what stops the laboratory from performing the testing?

Some of the most common reasons testing gets delayed include:

• Test modes – the customer does not realize that test modes are required. Make sure you check in advance of testing if you have got the test modes there
• The test mode has not been checked prior to testing
• The test sample hasn’t been configured for continuous transmission. Samples need to transmit continuously to maximize the signal and if it’s only transmitting for a brief amount of time, for example, every 10 seconds, it will be impossible to test
• Support equipment has not been supplied.

Awareness of these common pitfalls and taking steps to avoid them can ensure that samples are ready for testing and avoid unnecessary delays. For more information about how we can support your testing requirements, speak to an expert today.

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