Standards & Regulations
connector to the PCB with hot melt adhesive or to use a small tie wrap connector to provide added protection.
The special test modes that radio compliance requires can be power intensive. If your DUT is a battery-powered device, it is important to provide a suitable number of spare batteries and/or a means to charge them. Alternatively, should the standard permit, a battery eliminator may be provided, which allows the DUT to be powered by a bench power supply. Many radio standards have tests whereby tests are repeated under extreme test conditions (variations of DUT input voltage and temperature). The laboratory will need a means to set the voltage to the maximum and minimum voltages.
Test laboratories use a range of wireless communications test sets that can be used to emulate a mobile network for test purposes, such as those supporting LTE Cat M1, NBIoT and 5G, REDCAP. The UE (user equipment) must not be locked to a particular mobile operator. The laboratory will need access to the SIM card slot on the DUT in order to insert a 3GPP test SIM. Many IoT devices now use an embedded UICC, a MFF2 form factor that is soldered
directly onto the circuit boards during manufacturer. The laboratory will need the MFF2 UICC to be replaced with a test SIM as mobile network operators will not share the security algorithms required by the test set to connect to the DUT. To enable a test SIM profile, a remote SIM provisioning tool is required.
Many internet-enabled devices may be looking to connect to a specific server (or IP address). The test sets are not normally connected to provide an end-to-end connection to the internet, and so a DUT firmware may need to be changed so that the DUT remains connected to the test network if a specific IP address or server cannot be reached.
Test modes
Efficient testing normally requires the DUT to be configured to perform differently to how it would in normal use, also special test modes enable the radio to be controlled by the RF engineer so that they can take the measurements required by the standard.
Whilst the test modes are standard specific, they will generally enable the test engineer to configure the DUT to:
Continuously transmit Change the channel Enable/change/disable modulation Disable the transmitter for receiver testing The ability to vary the output power can also be useful, should a device need to be modified.
Most RF chipset manufacturers build the necessary test modes into their devices and provide support tools to enable them. Some products have a convenient interface to enable the test modes to be activated. For example, a computer can be connected to a USB port, presuming that the end product manufacturer has made provision to enable the USB to communicate with the RF chipset. Other equipment will not have such a convenient interface, so a different means of triggering the test mode must be established, such as pressing a button to cycle through the various modes.
Receiver testing
Some standards require evaluation of the receiver’s performance, so the manufacturer must provide the test laboratory with the means for this to be achieved. Ideally, the DUT should present its frame error
rate (FER) or packet error rate (PER) data but other means to indicate the successful reception of a packet may also be acceptable, such as the fl ash of an LED.
Support equipment
A support device, such as a laptop, is usually used to configure the sample and control the test modes. To avoid issues with incompatible drivers, I would highly recommend you provide the test laboratory with support devices. Of course, if your product features a display, then this can be used to configure the test mode. However, this is not recommended for products undergoing climatic testing, as opening the chamber door to configure the device between tests will alter the internal temperature and may cause condensation to form on the DUT.
To help you expedite time to market for your products, effective preparation ensures effi cient and timely testing in the laboratory. It is therefore paramount that the supplied application form is completed, samples can be easily confi gured to facilitate testing, and instructions are provided with the samples.
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www.cieonline.co.uk Components in Electronics June 2025 39
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