A Cost-effective Way to Test Bluetooth® Modules on Smart Devices

Interconnection of Smart Devices

Most smart devices use Bluetooth as the wireless protocol to interconnect with other devices or networks. As one of the major technologies for personal area network (PAN), Bluetooth has evolved in the past years and the latest Bluetooth low-energy technology enables long operational life with minimal power consumption for smart devices. Table 1 lists the key attributes of Bluetooth.

Table 1

Testing Bluetooth on Smart Devices

Most manufacturers develop smart devices with Bluetooth-certified chipsets and modules. Although the chipset vendors and module vendors provide reference designs that guarantee the RF performance, smart device manufacturers usually cannot leverage 100 percent of the reference design due to various requirements of the smart devices. For example, the small footprint of a device may require a different antenna design, or the design of a printed circuit board may cause the Bluetooth circuit to get crosstalk from the device’s other digital and RF circuits. Therefore, smart device manufacturers need to test the Bluetooth RF performance in both R&D and manufacturing phases, in order to make sure their products meet the Bluetooth RF specifications. For companies with the need for high test throughput and richer test functions, one test solution is the Keysight Technologies, Inc. E6640A EXM wireless test set and X-Series signal analyzer and generators. Table 2 lists typical Bluetooth transmitter test items that can be completed with the Keysight Technologies, Inc. N9000A CXA signal analyzer and N9081A Bluetooth measurement application.

A Cost-effective Bluetooth Test Solution

Many of the smart device manufacturers are small to medium size, and some are even start-ups. Since Bluetooth is a mature technology, these types of manufacturers often elect to use a general-purpose test solution rather than a Bluetooth-specific test set. One cost-effective Bluetooth test solution, shown in Figure 1, uses the Keysight Technologies, Inc N9320B and N9322C basic spectrum analyzers (BSAs).

To use this test solution, the device under test (DUT) is set to test mode to disable frequency hopping. Keysight recommends measuring the three advertising channels shown in Table 2.

Table 2

Pro and Cons of the Cost-Effective Bluetooth Test Solution

There are pros and cons for this cost-effective test solution. When selecting a test solution, these attributes should be assessed along with the alternative test techniques. The small to medium size companies may find this cost-effective solution appealing for the following reasons:

1. Bluetooth is a mature technology so complete Bluetooth RF test may not be necessary, especially for production test.

2. The N9320B/N9322C basic spectrum analyzers costs only a fraction of a

Bluetooth test set.

3. In test mode, Bluetooth devices do not hop over frequencies, so it is easier to make stable power measurement.

4. This solution measures only three advertising channels to save test time.

The major limitations of this cost-effective solution are:

1. It cannot measure modulation characteristics.

2. The N9320B/N9322C do not provide an automatic Bluetooth test application.

An external computer and custom-developed software are required for an automated test solution. However, since the N9320B and N9322C support USB, LAN, and GPIB ports, as well as SCPI programming, it is possible for customers to develop their own test software.

More Information About the N9320B/N9322C BSA

These basic spectrum analyzers focus on general-purpose spectrum analysis, addressing primary frequency domain measurement needs. They are Ideal for consumer electronics, R&D, manufacturing, bench repair, universities and polytechnic education, and general purpose spectrum monitoring.

They cover frequencies up to 7 GHz, offer the one-button power measurement, and provide analog/digital demodulation and SCPI command compatibility with the Keysight ESA Series spectrum analyzers.

Built to perform on the test bench and priced to compete in the market place, the BSAs provide reliable RF performance and a robust feature set at an affordable price.