Agilent Measurement Journal - Issue 5 - 2008 - (Page 8)

Identifying the major issues A cursory glance at this methodology shows potential problems ranging from unknown pedigree of the shareware authors, extreme human intervention in the test process, an unknown ability to vary test parameters, lack of repeatability, no ﬁrm audit trail to test results, and no traceability to a ﬁxed test methodology. Further complicating matters, the actual DUT must be conﬁgured through Port 1 to send bi-directional trafﬁc from Port 1 to and from Port A. It must then be reconﬁgured to send trafﬁc from Port 1 to and from Port B. Before implementing the N2X system into the test strategy, it was ﬁrst necessary to determine what was needed to conﬁgure the DUT ports. Data from a standard test cycle was captured using the free Wireshark software package. A trafﬁc pattern emerged which could be duplicated using the N2X PDU builder functionality (Figure 2). A test PDU was built on the N2X system and transmitted to a separate N2X port where the data was captured, decoded and veriﬁed as correct. The test PDU was then sent to the DUT where physical inspection veriﬁed that it had caused the desired response. Crucial to this test was the N2X system’s ability to send a single unique PDU followed by another unique PDU, creating the necessary command string for DUT conﬁguration. This iterative process was used to build, test and verify the three speciﬁc control signals needed to conﬁgure the DUT. Creating a better solution Improving this test strategy required a method for sending control data over the trafﬁc link so that the ports could be reconﬁgured programmatically. Agilent’s N2X system, a comprehensive multi-services test solution for converging network infrastructures, proved to be ideal for this task because of its ability to create proprietary or custom payload data units (PDUs), and capture and decode Ethernet trafﬁc. Figure 2. Working clockwise from the left, the N2X system walks the user through the process of building, testing and verifying a speciﬁc PDU to be sent to a DUT. 8 Agilent Measurement Journal

Table of Contents Feed for the Digital Edition of Agilent Measurement Journal - Issue 5 - 2008

Agilent Measurement Journal Issue 5 Finding a New Path when Assumptions Break Down Contents Testing MIPI D-PHY Protocols Oscilloscope Firmware Update DNA Replication Joining the LTE/SAE Trial Initiative Testing Proteins Praise for DC Power Analyzer Scripting Features for AMDS Testing Hybrid PCBA Systems Improving the Gene Expression System Workflow Turning a “Good Enough” Test Strategy into One That’s Reliable, Repeatable and Traceable Understanding the Effects of Limited-Bandwidth Channels on Digital Data Signals Introducing the 3GPP LTE Downlink Validating the 26 Validating the Physical and Protocol Layers in DDR Memory Interfaces Understanding Total Jitter Measurements of Low Probabilities Using Behavioral-Model Simulation to Accurately Predict First-Order PLL Performance Creating Synchronous High-Frequency Sampling across Multiple Digitizers Overcoming the Challenges of Testing FlexRay Networks Understanding Operating Life and Repeatability of Electromechanical Switches and their Effect on Total Cost of Ownership Implementing Micro and Nano LC/MS Techniques for High Sensitivity Lipidomics Analysis

Agilent Measurement Journal - Issue 5 - 2008

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