Magnetocardiography is a thing. The NRO has some insane capabilities, so I wouldn’t immediately discredit the idea that a magnetocardiographic scan of a large area is possible.
It’s important to note that the individual was isolated by miles. And that they knew the time and location of the crash to determine the search radius.
It’s also one of the many tools they can use. So they may have used some combination of methods to reduce the search area and to pinpoint the target’s location. To say that they only used magnetocardiography is probably false.
Earth’s geomagnetic noise fluctuations are on the order of nanoteslas (10^-9 T), which is 18 orders of magnitude above the signal they claim to have pulled out.
It’s below the thermal noise floor of any physical measurement system that obeys thermodynamics. You can’t engineer around it because it’s not an instrumentation problem. The signal is smaller than quantum noise limits at that scale. “AI” filtering doesn’t help when there’s no signal to filter. You can’t computationally recover energy that isn’t there.
This is certainly bullshit of the finest, most grassy and odorous caliber.
It is. One of the first magnetocardiographs was of my heart, because I happened to be in the basement when my fellow graduate students were looking for a subject (I’m a theorist and wouldn’t be allowed to actually touch anything). They used a SQUID that cancelled out the Earth’s field and its gradient; the sensor was close to my skin but not touching it.