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Issue #231 October 2009
Signal Significance
by C. J. Abate
Readers and writers know we typically run about one or two “theme-related” articles per issue. We do this because we have a wide readership with diverse interests. We try to please as many people as possible. And we’ve been doing that well since 1988. What’s always interesting about the Signal Processing issue is that almost every article we run (as well as many of those considered for publication) has something to do with signal theory, processing, or control in one way or another. You don’t need a PhD with a focus on signal processing to be an embedded design engineer. But you definitely need a good grounding in signal theory to be a successful one, whether your end goal is a marketable embedded wireless product or simply a handy design for your workbench.
This Signal Processing issue is true to form. As you’ll see, the topics of signal processing and control figure prominently in most of the subjects covered.
In “IR Signal Control,” Naubert Aparicio presents a design for offsite control of an electrical system (p. 12). He uses the IR signal controller design to remotely operate his home’s AC system from his cell phone. You can use the techniques Naubert covers to customize an IR signal control project of your own.
Frequency monitoring is the topic presented in Arnold Stadlin’s article, “Frequency Sensing Made Simple” (p. 22). In this article, he describes a microcontroller-based power frequency monitor design that can indicate the relative stability of a power grid. The design measures power grid frequency via a standard electrical outlet. The acquired data is transferred to a PC, which displays the information and relays it to a web server for real-time analysis.
As you probably know, many instruments don’t measure equivalent series resistance (ESR). Enter Ed Nisley. After studying the design of a classic pure-analog ESR meter, he built an analog front end for an MCU that measures ESR. In “Capacitor ESR Measurement,” he covers the project’s design and math (p. 28).
Starting on page 38, George Anderson presents a dsPIC30F2023-controlled, high-end vacuum tube stereo amplifier with distortion control, power output, and more. He describes unique circuitry and specialized processing software.
Turn to page 50 for information about multirate techniques and cascaded integrator-comb (CIC) filters. Robert Lacoste explains how you can use these moving average filters to tackle difficult signal-processing issues. When a FIR filter won’t do the trick, this might be the perfect solution.
In “Airflow Analysis,” Jeff Bachiochi describes an effective way to measure airflow in an air duct (p. 60). He explains how he took apart a small CPU fan, calculated RPMs, and implemented a circuit to output data to an LCD.
Remember when Acorn Computers introduced its RISC CPU? Tom Cantrell has been following the story for nearly two decades. In “Thumbs Up: The ARM Saga Continues,” he brings you up to speed with a review of the ARM Cortex-M0 core (p. 66). The story continues.
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