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ISO offers API for car navigation systems

The International Organization for Standardization (ISO) is offering a solution to improve compatibility of car navigation systems with the databases they access. The ISO, last Wednesday, introduced a new inter... Read More...
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Comcast net neutrality case goes to court

U.S. Internet service provider Comcast said the Federal Communications Commission lacks the authority to admonish the company over how it manages traffic on its network. Comcast representatives delivered oral a... Read More...

EMC Test Site Qualifications: Site Voltage Standing Wave Ratio versus Time Domain Reflectometry

Everyone in the EMC business is familiar with the traditional Normalized Site Attenuation test (NSA). However, in February of 2007 CISPR 16-1-4 was published complete with the new Site Voltage Standing Wave Ratio (SVSWR) test. At the time, the American National Standards Institute (ANSI) Accredited Standards Committee (ASC) C63® had developed a draft proposal for C63.4 (Draft 1 - May 20, 2005) called the Time Domain Reflectivity (TDR) measurement. The critical question addressed by this article is which method – SVSWR or TDR - more accurately provides an assessment of the test site. Given the investments companies make in test sites for EMC compatibility, this is key assessment question.


S-parameter Data Correction Using Time Domain Gating for PCB and Cable Applications

This paper describes how to remove the measurement artifacts caused by discontinuities in high frequency S-parameter data caused by the test connectors on the Printed Circuit Boards (PCBs) and cables. The frequency domain S-parameters are converted to the time domain to get the impulse response. Time domain gating is then used on this impulse response to remove reflections due to end connectors and/or other discontinuities. The gated impulse response is then transformed back to the frequency domain. The final result is a much improved S-parameter data set with unwanted resonance removed, allowing the PCB trace or cable loss to be determined.