h/t walterbell (<a href="https://news.ycombinator.com/item?id=41149870">https://news.ycombinator.com/item?id=41149870</a>):<p>> For all spy cameras.. raw image.. encoding and compression.. takes place in an inbuilt read-write memory whose operations cause electromagnetic radiation (EMR).. Whenever the visual scene changes, bursts of video data processing.. aggravate the memory workload, bringing responsive EMR patterns. ESauron can detect spy cameras by intentionally stimulating scene changes and then sensing the surge of EMRs.. Experiments with 50 camera products show that ESauron can detect all spy cameras with an accuracy of 100% after only 4 stimuli, the detection range can exceed 20 meters even in the presence of blockages, and all spy cameras can be accurately located.