Fast analysis instrument expected to speed up 3G mobile phone testing

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In the mobile phone market where technology is becoming increasingly complex and profits are becoming increasingly thin, testing must be fast, flexible and effective to ensure that the production line reaches a batch size that maintains profits. By using test instruments with advanced software and hardware and different test modes, various mobile phones can be measured quickly and accurately, thereby ensuring the quality required for 3G products.

Today's wireless phones require more precise and rigorous testing than ever before, and engineers responsible for ensuring the quality of wireless phones on the production line need more than precision. In today's mobile phone market, where new technologies are becoming more complex and profits are becoming thinner, testing must be fast, flexible and effective to ensure that the production line can reach the large volumes that can meet market demand and maintain profits.

Test instruments that use advanced hardware and software and have different test modes can quickly and accurately measure various mobile phones. In particular, the new generation of test equipment can make testing faster and easier while providing more detailed analysis, thereby further improving the throughput and cost-effectiveness associated with manufacturing mobile phones.

In fact, advanced test instrumentation hardware and software can enable engineers to perform some traditional R&D tests in a manufacturing environment. The ability to perform deeper tests on the production line is important because these tests can reveal potential problems or the need to make minor adjustments to address component tolerances.

In short, to ensure the quality required for third-generation products, simple pass/fail measurements are not enough unless you want to risk losing customers. Mobile phone manufacturers must carefully detect any errors in the manufacturing process that could affect a small number of components.

In order to detect very small changes in wireless signals, test instruments must be able to perform fast analysis. Today's latest test platforms integrate ASICs, unique DSP technology and CPUs to achieve faster and more detailed measurements. In fact, most test instruments currently used to test wireless devices have at least three digital signal processors (DSPs), one DSP is used to measure signals and average, a second DSP performs debugging processing (allowing the test instrument to be used as a base station simulator), and a third controls the display, front panel, computer interface and the other two DSPs.

DSP speed and power consumption are the two main factors that determine the test speed of the test instrument. Other factors include the internal bus speed connecting the three processors and the architecture and efficiency of the software.

Average advantage

Because these new platforms enable test instruments to make faster measurements, they enable averaging during the manufacturing process. Averaging requires taking and analyzing multiple samples, which takes more time, but it is worth it because it improves repeatability. In turn, higher repeatability means tighter specifications, which can bring more advantages to manufacturers. For example, higher repeatability allows the use of lower-cost parts, effectively reducing the cost of mobile phones for consumers. In addition, higher repeatability can also improve yield and profits.

The averaging requirements depend on the specific measurement, the device under test (DUT), and the stability of the results of the test and DUT, as well as the waiting time for the phone to reach a stable state after changing the input or output power of the phone. In some cases, as many as 20 averages will be necessary to achieve a stable, repeatable test. Each measurement is an average of multiple measurements made on a single pulse, so each of the 20 averages will be an average of 20 pulses.

In the test example with 20 averages, the wideband CDMA phone in the test instrument was in test loopback mode 2 (Figure 1). The power control bit pattern was set to all 1s, and the maximum output power of the phone was just below 24dBm. This is a power class 3 phone, and the specification requires a maximum output power of 24dBm with a tolerance range of +1dBm to -3dBm.

The objects of the twenty averages are the transmitted power, frequency error and occupied bandwidth. The filtered power measurement is realized by a root raised cosine filter, which is configured on the receiver of the user equipment and Utran (UMTS terrestrial radio access network).

Test two phones at a time

In addition to time and money, space is also an important factor that needs to be considered on the production line. If a measuring instrument can achieve more functions with the same size specifications, it has a higher value. It is precisely because of this that test manufacturers have added some optional functions to improve production test efficiency.

One option that can save time, space and money is parallel phone testing. With this feature, one tester can test two phones at the same time, even if they use different wireless standards. This type of configuration can save up to 30% by reducing power consumption, cabling requirements and the number of instruments required, thereby increasing throughput and saving space on the production line.

In Figure 1, the test instrument has a wideband CDMA phone in test loopback mode 2. In addition, the power control bit pattern is set to all 1s, and the maximum output power of the phone is just below 24dBm. A total of twenty averages are taken of transmit power, frequency error, and occupied bandwidth.

By: Craig Hendricks
Senior Technical Support Engineer
craig.hendricks@anritsu.com
Anritsu Corporation