How to Prepare for Radio Compliance Testing?

As the use of radio devices grows, it is now more crucial than ever for manufacturers to conduct compliance testing to prove that their products meet the necessary requirements before they can be sold on the market.

What is radio compliance testing?

Radio compliance testing 确保无线电产品符合必要的法规要求的过程, rules, 以及适用于销售这些产品的国家的标准. 这个测试可能是一个复杂而艰巨的过程, 特别是对于那些不熟悉无线电技术和法规的复杂性.

In this article, we will discuss some of the key considerations for manufacturers preparing for radio compliance testing, including sample preparation, the types of testing required, and using pre-approved modules. By understanding these requirements, manufacturers can help ensure that their products meet the necessary regulatory standards and reach their intended markets on time.

Prepare the sample for testing

第一步是确保样品完全准备好进行测试. When preparing a sample, it is useful to know the common modes that will most likely be required to put the device in to facilitate the testing. 这将使您能够考虑每种模式可能出现的任何问题，例如:

Channel

Will the channels need to be changed?

Modulation scheme

Will the modulation scheme need to be changed? For example, from QPSK to 16QAM

Signal bandwidth

信号带宽已经商定了吗，比如5、10、20、40、160兆赫

Carrier power (if tuning is required)

是否需要改变载波功率的能力? 在带的中间以全功率测试信道是可能的, but at the edges of the band some of these tests may be difficult to pass when the transmitters are on full power and may require turning the wick down at the edges of the bands.

Signal type

Will it be necessary to remove modulation and just have a continuous wave to help with the testing?

如果支持，只接收模式/数字设备

设备是否具有仅接收模式或完全禁用无线电的模式?

Number of ports/antennas

Does the device supportmultiple antennas/ports? Are all antenna ports accessible for testing?

It’s also worth considering the instructions and the interface when preparing a sample for testing. It’s not unusual for a product to arrive at Element’s test laboratories to find that there are no, or only very basic, instructions. To prevent delays, comprehensive instructions on how to set up and configure the unit for testing should be prepared and readily available. 

Regarding the interface, 哪一个最好是可拆卸的, commands are typed in and sent down a serial cable to the device to set up in a particular mode. 重要的是要确保电缆可以在必要时断开.

Consider the type of sample required 

所需样品的类型也应在测试前考虑. For Wi-Fi testing, 大部分试验将进行，而不是辐射试验, 需要在设备上连接50欧姆. This means providing samples with a temporary antenna port soldered on where the antenna would have been. A normal sample, with a built-in antenna already installed, 是否也需要进行辐射排放测试.

Some tests may require extremes of testing. 这可能是极端的温度或极端的电源电压. If it's a battery powered device being tested, 为了使电压变化，可能需要连接到工作台电源. If it's a mains device, standards will usually say to test within + or -15% of the nominal value of the mains voltage. For voltage extremes, if it's a USB device, 那么标准给出的极值通常也是USB的极值.

在附加设备方面，考虑是否需要提供适配器进行测试. Element has had instances where the product manufacturer has presumed AC conduct and emissions won’t be applicable because their device is DC powered, 在侧面有直流电源接口，而不是电池. However, if an adapter is not supplied with the device, ANSI建议测试机构从货架上取下适配器来进行交流电源测试. 设备不能因为只有直流电源端口而不受影响.

Using pre-approved modules

When using pre-approved modules, 应仔细遵循模块制造商的集成说明. 当使用预先批准或预先认证的模块, 模块制造商应提供一套全面的集成说明. These need to be read and followed to the letter to ensure that the final product fully complies. 对于电源、天线类型和增益来说尤其如此, 虽然如果设备有一个内置天线的模块, then it will not be an issue. 

You also need to consider how the conducted RF testing can typically be inherited from the module. 这就是为什么预先审批模块的模块集成真的很有帮助. 

Using pre-approved modules will mean that you need to ensure access to the test mode interface. If the module has been brought in, it’s vital to remember that the test laboratory will need to gain access to the test mode or device test mode interface. 如果不是制造商自己设计的, 他们需要询问模块制造商它是如何进入测试模式的. If it's specific software that the module manufacturer doesn't want to release to the customer, 应该有可能让实验室在NDA下得到它, but this can take time and cause delays. If it needs a special interface, like a serial interface, 确保它在最终产品上可用，以便可以连接到它进行测试. 

When integrating a cellular module, Element can control the device under test, including RAT, frequency, and level, by a communication test set. 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.

For 2.4 GHz Wi-Fi，重要的是要注意，对于 FCC authorisation，辐射受限带边缘限(2483).5 - 2500mhz)可能要求在信道边缘处降低输出功率. You therefore need to be aware that a lot of time can be spent carrying out power tuning for Wi-Fi.

Intermodulation

Intermodulation is the amplitude modulation of signals containing two or more different frequencies, 由系统中的非线性或时变引起的. 当集成两个预先批准的模块时，可能会发生这种情况. The two signals can potentially radiate into each other's antenna and any nonlinearities can cause intermodulation products. 

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. 例如，以900mhz和a Zigbee device 在2405mhz发射可以产生1505 MHz的互调产品, 3305 MHz, 4205 MHz and so on. 

Element在测试过程中也经常发现只有一个发射器的问题, 但是天线匹配不佳，这也会导致互调产品. 

Chipset versus module implementation

When designing a radio product, 首先要考虑的一点是，它应该被设计成一个芯片组还是一个模块. Both chipsets and module implementations have their advantages and disadvantages for radio products and their manufacturers.

Chipsets 这意味着每台设备的成本更低，因为它们的组件成本更低. 然而，它们将增加设计成本和认证成本. Chipsets provide the manufacturer with the ability to retain control but can result in an additional quality burden.

模块往往具有较高的组件成本，但降低了设计成本. 继承测试还意味着降低认证成本. However, the manufacturer must accept that a third party has control and will therefore have to rely on the third party for maintaining quality.

最终，芯片组还是模块的选择通常取决于生产规模. If the production numbers are not expected to be that vast then the module is usually the more popular choice but if the quantity is going to be sizeable, 那么芯片组往往是首选的选择.

Avoiding the common pitfalls

Element often finds a manufacturer has booked a laboratory and scheduled the testing on a certain day to discover it can't start because the sample is not ready. 那么，是什么阻止了实验室进行测试呢?

测试延迟的一些最常见原因包括:

• 测试模式-客户没有意识到测试模式是必需的. 如果你有测试模式，请确保在测试前检查
• 测试前未检查测试模式
• 测试样品没有配置为连续传输. 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.

How Element can help

Manufacturers with little RF experience may be more likely to experience issues with test modes, 而那些设计自己的射频部分可能不太可能有这样的问题. 通过意识到这些常见的陷阱，并采取措施避免它们, manufacturers can ensure that their samples are ready for testing and avoid unnecessary delays in the testing process.

Element’s engineering team can support you throughout the entire radio compliance testing process, from generating bespoke test plans and performing pre-compliance investigations through to full formal conformance testing. 我们的目标是针对复杂的产品测试要求提供快速有效的解决方案, enabling you to demonstrate that your products will use the radio spectrum effectively and comply with country-specific regulatory requirements. 

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