William J. Drago

The switch to be tested has four inputs, one output and a sample port. Since the switch is also a combiner the four inputs can be activated in any combination. The sample port is coupled to the output port and is always "on." Two models are manufactured, one for AMPS band and one for PCS band.

The primary design goals of this ATE system were speed and operational simplicity without sacrificing accuracy. An Agilent PNA is used for RF measurements and is connected to the UUT through a matrix of mechanical switches thus eliminating connection changes during the test. All test instruments are controlled via GPIB and the mechanical switch matrix is controlled with Agilent's 34970A Data Acquisition unit and 34903A relay module. The ATE software was written in Agilent VEE Pro (formerly HP VEE) and runs under Windows 2000 on a generic PC. Since this system was designed to operate at a remote location, WinVNC was installed for remote control and a freeware FTP server was installed for file transfer.

The ATE software prompts the operator for name, unit serial and model number. Because there are different models for each frequency band, the software automatically sets all test parameters in accordance with model number. All operator instructions and setup diagrams are conveniently displayed on screen. At the beginning of each shift the ATE software guides the operator through a full 2-port calibration of every switch matrix path. Every combination of UUT switch input/output is tested for Insertion Loss, Return Loss and Isolation. The coupled port is tested for Coupling and Return loss. The mechanical switch matrix used in this high volume system is expected to degrade over time so all switch cycles are counted and a warning displayed when the predetermined wear level has been reached.

Upon test completion all UUT test data is permanently stored on disk and a data sheet automatically printed. Microsoft Excel generates the data sheet with data transferred from VEE via ActiveX. This process is completely transparent and requires no operator action. Using WinVNC local technicians can activate the FTP server and transfer test data files back to New York. The ATE software includes features for graphing various historical data for statistical process control.