Over-the-Air (OTA) testing explained

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Do you ever wonder how your smartwatch or smart home appliances work so efficiently? Why do they always connect to the right device instantly? Well, it’s because of over-the-air (OTA) testing. In this guide, we will talk in detail about over-the-air testing, how it works, why it is important, and what its benefits are.

Over-the-air testing is becoming increasingly important with the surge in the number of IoT and wireless devices. It ensures the safety and quality performance of any wireless device, but how is it done? Let’s dive into its details!

What is Over-the-Air testing?

Over-the-air (OTA) testing is a technique for evaluating a cordless device's performance and reliability in the actual world. The testers use a test chamber with an open vacuum of space to represent real-world scenarios.

It is put through a series of tests to determine how the device will respond to various systems. By analyzing the whole signal route and antenna functionality, OTA antenna testing helps to confirm that the equipment developed or chosen will function as expected.

Why is OTA testing important?

It can be tricky to fine-tune an inbuilt antenna for effectiveness. Nearby parts, incompatible transmission systems, inadequate partial ground dimensions, and other factors — all of which are decided upon in a design, can interfere with radiofrequency radiation.

Additionally, a variety of in-situ variables are relevant. For instance, the existence of body parts and other obtrusive signals might cause an antenna to be detuned from its ideal frequencies.

Before a device is on the market, OTA testing identifies and fixes these problems. It lowers development costs, enhances wireless efficiency, and lessens the possibility of unplanned delays. In addition, there are a few more benefits:

Points out design errors

Several variables significantly impact device performance, including material selection, component placement, and intended use case. It pinpoints those design problems.

Provides analysis between variants

Different variants or successors can have different connectivity flaws. The test enables comparison of product versions and helps to eliminate them.

Increases brand value by customer satisfaction

Customers consider wireless connectivity a key factor when selecting an IoT product. A working device guarantees customer value and fosters brand trust.

OTA testing preparations

Basic test

Some basic checks are performed before the test, like ensuring the device is fully charged. It should have proper web access.

Given the regularity of the testing, this is a critical step to complete because specific devices automatically turn off and on if they cannot establish a connection. Confirming that the test simulator is operating as it should be is crucial.

Equipment check

Preparing and checking the testing chamber is also necessary before conducting the over-the-air antenna test. The testers must choose the appropriate testing equipment and connect all required cables. Before the assessment, experts look at all the essential devices and equipment for proper functioning.

Reference testing

Reference testing means the antennas, whose performance and measurements are known, are re-evaluated in the chamber when prepared for the test. If the test results match the initial findings, everything has been installed correctly; if they do not match, something is not working correctly.

The outcome will indicate whether everything is working as it should. Reference testing guarantees precise, high-quality test results. The actual OTA antenna testing can start after the reference testing is finished.

How is OTA testing performed?

The device manufacturer typically specifies the test methods and criteria. However, it can be performed at any point in the product's manufacturing cycle.

OTA testing is usually performed using an anechoic chamber, a room designed to minimize reflections of electromagnetic waves. The experts initiate the process by measuring the signal strength in the chamber with no device present. This measurement is used as a baseline reference point.

The device under test is placed in the center of the chamber and surrounded by antennas that emit electromagnetic waves. The waveforms and power levels are carefully controlled and monitored to ensure that they meet the device's specifications under test. The data from the tests are used to assess the device's performance in its intended environment.

OTA testing measurements

1. Efficiency

One of the most often used metrics for RF effectiveness is efficiency. It is significant because it shows the ratio of powers granted to the antennas to the energy it radiates. For example, if your device, let's say a smartwatch, is not powerful enough, it will not pick up the signals efficiently from the Bluetooth device within meters.

There are some frequencies where a particular antenna performs pretty well because antennas are typically made to work over a broad range of frequencies. Improved performance aids in reducing battery depletion brought on by wireless connections.

2. Gain

The amount of radiation released in a specific direction is referred to as an antenna's gains. As the gain increases, the antenna’s efficiency will also increase.

3. Directivity

Pattern metrics, like directivity, demonstrate radiation directions. This measurement shows how RF energy leaves the antenna. This is crucial to understand in the context of handheld and wearable devices.

Manufacturers can optimize the antenna positioning because consumers are expected to use the gadget in a specific way. For instance, the directivity in a wearable should be directed away from the user.

4. TRP

The amount of power an antenna radiates is measured by the Total Radiated Power (TRP). The measurement is done uniformly in all directions by adding up the antenna received signal power from all possible orders.

5. RSE

Radio frequency that a device does not intentionally emit or transmit is called radio spurious emissions (RSE). Testing professionals detect spurious emissions to ensure that your product complies with legal requirements. RSE examinations are more challenging than others, especially for cell phones.

The marketability of your device may be harmed by spurious emissions, which can degrade the performance of other devices. You can identify technical or regulatory concerns and prevent production delays or excessive production expenses by identifying RSE.

Final thoughts

OTA antenna testing is an essential part of practical wireless projects. It can decrease network clearance costs, shorten the time for a product to reach the customer, and detect performance problems, in addition to helping a device function better by:

  • identifying potentially costly design mistakes
  • enabling comparison of product versions
  • ensuring adherence to strict deadlines for product development
  • protecting the value of the client and the brand

Any phone, tablet, or connected device must undergo extensive OTA antenna testing because any attachment or product could impair OTA functionality. Additionally, companies carry out these tests to certify specific products as meeting the required standards.

OTA testing certificates indicate the well-functionality of the device in a wireless environment. It helps companies to understand the device doesn’t have any poor signal sensitivity and that its radiation power is enough to pair successfully with other nearby devices.

Most IoT and M2M device makers also need OTA-certified products because they simplify OTA compliance, they do not suffer from potentially expensive design flaws, and adhere to strict worldwide go-to-market timelines. If you are looking for a testing provider for OTA testing, the free testxchange platform can be a good first step to find a solution with little effort.