From the trade magazines: Impedance matching, AM flutter, DIY AI

Back to Basics: Impedance Matching By Lou Frenzel, W5LEF

The term “impedance matching” is rather straightforward. It’s simply defined as the process of making one impedance look like another. Frequently, it becomes necessary to match a load impedance to the source or internal impedance of a driving source. A wide variety of components and circuits can be used for impedance matching. This series summarizes the most common impedance-matching techniques.

• Impedance Matching: Essential Design Knowledge
• Back to Basics: Impedance Matching – Part 1
• Back to Basics: Impedance Matching – Part 2
• Back to Basics: Impedance Matching – Part 3
• Automatic Impedance Matching in RF Design
• Impedance Matching Basics: Smith Charts

The entire series is available as a downloadable ebook.

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While I’m not sure, I’d guess that something similar happens on 160 meters or even the HF bands….Dan

AM Radio ‘Flutter’

Sometimes I like to listen to a couple of AM radio stations that transmit from southern New Jersey, which is rather far from here on Long Island. Their signals are pretty strong during the daytime but now and then there is a rapid in-and-out fading effect, which sounds very much like a flutter.

I’ve sometimes heard that same effect when listening to shortwave radio and I initially assumed it was an ionosphericphenomenon but now I don’t think so. There seems to be an alternative explanation.

…read the complete article

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I haven’t tried these yet, but they look like fun….Dan

Google’s AIY kits offer do-it-yourself artificial intelligence

There’s plenty of low-cost hardware out there feasible for implementing deep learning training and (especially, along with being your likely implementation focus) inference, as well as plenty of open source (translation: free) and low-priced software, some tied to specific silicon and other more generic. Tying the two (hardware and software) together in a glitch-free and otherwise robust manner is the trick; select unwisely and you’ll waste an inordinate amount of time and effort wading through arcane settings and incomplete (and worse: incorrect) documentation, trying to figure out why puzzle pieces that shouldfit together perfectly aren’t.

That’s where Google’s AIY (which stands for “Artificial-Intelligence-Yourself,” a play on DIY, i.e., “Do-It-Yourself) Project Kits come in. They’re targeted at hobbyists and professionals alike: in Google’s own words, “With our maker kits, build intelligent systems that see, speak, and understand.

…read complete article