Wireless service providers incur unnecessary expense by replacing fully functional phones that their owners believe to be defective. Testing the phones before replacement would prevent this financial loss. But since phones often are returned to retailers who lack test equipment or the technicians to operate it, the problem continues.
A new, simplified test system allows retail salespeople to evaluate phones and identify those that are operational. Agilent Technologies, a subsidiary of Hewlett-Packard, developed the system in conjunction with EMC Test Systems (ETS), and several hundred systems now are used in retail stores nationwide.
Testing Challenges
Before the development of the test system, excellent product reliability had not reduced the high costs associated with frequent, and often unnecessary, phone replacement for wireless service providers. If customers had problems with their phones, they returned them to the retail outlet. Then store personnel typically swapped out the phone for a new one—an action that cost the service provider from $100 to $400 depending on the type of phone.
Often, product quality isn’t the culprit. Approximately 70% of the time, the phone is in perfect working condition. In these cases, the customer simply isn’t using the phone properly or has been trying to use it in an area with poor network coverage. Either way, those customers get new phones at the wireless provider’s expense.
The solution to this problem is to place test capabilities at retail centers where the phones are returned. But service providers face two major obstacles with this strategy:
Wireless test sets are designed to be operated by engineers and technicians who understand the test process, not retail salespeople.
To perform the tests, the phones must be placed inside an RF isolation box where a cable is manually connected to the data port. Not only does every brand of phone require a different RF connector, but the connectors also are prone to breaking from mishandling.
As a result, it was easier for salespeople to just give the customer a new phone—a costly decision for the service provider.
Developing a New Solution
Engineers at Agilent Technologies set out to resolve this problem by developing a user-friendly interface for operating the company’s sophisticated wireless test sets. The result was point-of-service test software (PoST) which uses the Windows operating system.
The software has two modes of operation: one designed for nontechnical users and one for developers, engineers, and technicians. Now nontechnical users such as retail salespeople can follow a series of screen prompts and quickly determine whether or not a customer’s phone is faulty.
To improve on the isolation box, Agilent Technologies contracted ETS to combine all of these elements in a compact, easy-to-use unit. As a result, ETS developed a self-contained, portable enclosure that can check cell-phone transmit and receive functionality with or without direct cable connection to the RF test port. This was accomplished by incorporating a stripline antenna in the enclosure that couples with the phone’s antenna.
The coupling coefficient was determined using a small, fixed-element dipole. Measurements showed an essentially flat coupling response over the frequency range of 700 MHz to 2 GHz.
With the common air interface (CAI) provided by the stripline, a salesperson performs the test faster and simulates a real-world environment. In contrast, the direct-connection method bypasses the antenna and can inadvertently pass a failing unit. The CAI method provides a shorter signal path and readily detects a faulty antenna.
The enclosure includes one external Type-N connector that links the antenna coupler to the test set, one Type-N connector feedthrough for traditional direct connection testing, and a nine-pin filtered D-sub miniature connector for more advanced test procedures. To eliminate nulls and hot spots, each enclosure is lined with RF absorber material. Compressible RF gasketing seals the lid on closure. Nominal shielding effectiveness is 60 dB, although higher values are possible.
Consistent orientation of the phone in the enclosure is important for test repeatability. To help the salesperson position the phone correctly, a sliding clamp with markings is built into the bottom of the enclosure.
The enclosure has overall dimensions of 19.5″ × 14″ × 9.5″. It accommodates wireless phones up to 7.5″ long with antennas extended to 7″ in length.
Examining the Applications
Agilent Technologies now is marketing a complete testing solution by combining its test set, the PoST software package, and the ETS isolation enclosure. Integrating these technologies has created a simple and cost-effective way to handle in-store wireless phone testing from start to finish. With minimal training, sales clerks and other nontechnical personnel can make fast, accurate measurements of wireless phones. That means they can identify no-trouble-found phones quickly and reduce the quantity of products returned to manufacturers.
A major telecommunications service provider already has purchased several hundred of these test enclosures for use by its retail salespeople. Based on the feedback received so far, the store personnel have been extremely pleased with the new technology. The percentage of phones being tested on-site has increased, returns have decreased, and the service provider has seen positive financial results.
Exploring the Potential
In terms of future applications, this technology makes a very compelling business case. As society continues to demand more advanced two-way communications, manufacturers will have an increasing need for fast, accurate RF testing at their points of service. Whether that means testing highly sophisticated pagers or wireless personal digital assistants (PDAs), this technology could be adapted to serve a wide variety of additional markets.
About the Author
Glen Watkins is director of marketing at EMS Test Systems where he has been employed for 12 years. He is a member of the IEEE EMC and Communication Societies and a graduate of James Madison University in Virginia. EMC Test Systems, 2205 Kramer Lane, Austin, TX 78758, (512) 835-4684, e-mail: [email protected].
Copyright 2000 Nelson Publishing Inc.
February 2000
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