GBPPR Non-Linear Junction Detector

One of the great stories of using &quot;Non-Linear Junction&quot; devices occurred circa 1985, during the Cold War between the US and the Soviet Union.<p>The US was building a new embassy in Moscow. Naively, they allowed the Soviets to do most of the work. The result was a building impossible to secure. Eventually the top 4 stories needed to be completely replaced.[1]<p>The relevant part to this discussion is that the Soviets mixed thousands of discrete diodes[2] into the precast concrete. What is a diode? A nonlinear junction. What does it cost? A few pennies. What does it do? It creates false positives, so it keeps you from using a device such as the one discussed in this article to detect actual bugs.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Embassy_of_the_United_States,_Moscow#Building" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Embassy_of_the_United_States,_...</a> [2]<a href="https:&#x2F;&#x2F;www.washingtonpost.com&#x2F;archive&#x2F;politics&#x2F;1990&#x2F;06&#x2F;18&#x2F;unbeatable-bugs-the-moscow-embassy-fiasco&#x2F;5bb6dcbf-0a61-4948-a953-e2d81085ed05&#x2F;?noredirect=on" rel="nofollow">https:&#x2F;&#x2F;www.washingtonpost.com&#x2F;archive&#x2F;politics&#x2F;1990&#x2F;06&#x2F;18&#x2F;u...</a>

Any theory on why PN junctions emit even harmonics and natural nonlinear junctions emit odd harmonics?

I wonder how much easier&#x2F;cheaper this would be with modern technology&#x2F;parts (archive.org shows that the link to this project on the overview page already existed in 2008, which is their first capture, and the PCB style looks quite old).

It should be noted that this is for US use-only, since it transmits on the 900 MHz band (FCC part 15).<p>In Europe this frequency falls into the GSM band and will get authorities to your doorstep in a hurry.

Kind of a bummer, doesn&#x27;t look like we ever find out if his project worked or not.

I read this as “GDPR non-linear function detector” for neural network regulation