Guest Column | September 8, 2008

Time Matters — How Power Meters Measure Fast Signals

Time Matters — How Power Meters Measure Fast Signals

This article is part of a series of quarterly guest columns by Wolfgang Damm, International Product Management Director, Wireless Telecom Group.

Power Measurements

Modern wireless and cable transmission technologies, as well as radar systems, present demanding challenges for device and system developers. Manufacturers of test and measurement equipment are driven to offer products that fully support today's needs, while anticipating the requirements of future technologies. Accuracy has always been a critical requirement in the test and measurement world, but modern technologies demand another must-have — highest data acquisition and processing speeds to allow accurate measurements of complex signal waveforms. This article describes the different techniques RF peak power meters employ to meet these challenges.

Signal Triggering

Modern peak power meters can measure virtually all types of pulsed or repeating signals. To achieve this, these instruments are equipped with sophisticated trigger capabilities. Prerequisite to any fast measurement is the synchronization of the instrument's measurement cycle to the actual event. Simply put, the input signal of interest has first to be "found." Specific trigger settings prepare the instrument for this synchronization and, once the desired event occurs, provide stable signal representations, allowing detailed signal analysis and accurate measurements. To be able to "look ahead," digital instruments often use special techniques such as circular acquisition buffers to facilitate display and measurement of pre-trigger events. Most RF peak power meters provide internal and external trigger capabilities. Internal triggering utilizes the envelope of the actual incoming RF signal, while external triggering utilizes a baseband trigger signal that is in some way synchronized with the RF input signal.

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