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Learning from Turing’s silver hoard (2016)

reuters.com

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Re: Learning from Turing’s silver hoard (2016)

#11

Post by jofer »

saalweachter wrote: post #8
jofer wrote: post #7

Earlier quoted context omitted.

That's not as accurate as you think unless you've got a full geodetic antenna. (i.e. $200k worth of equipment + a lot of permits to be allowed to have/use it) Getting to within +/- 30m doesn't help a ton when you're digging a hole to find a small box. With geocaching, you've got something to look for. You get close-ish and then do an easter egg hunt. When it's beneath the ground, it's really hard to "look". Finding e…

Doesn't modern GPS claim +/- 3 meters, with a clear enough signal? (Which is still a heckuva lot of dirt to shift.)

Given nearby local ground-based correction stations (e.g. WAAS) it can use and flat terrain, yeah, you can certainly get that kind of accuracy.

In practice, though, I've spent a fair bit of time trying to re-occupy sites taken with handheld GPS receivers. (I'm a geologist -- it comes up a lot) 30m is a better representation of typical repeatability for a consumer-grade handheld unit or a phone.

You're often on the side of a hill, so you can't see the full constellation. If you don't have line-of-sight to more than a few satellites, you risk an inaccurate location. You're often in highly remote areas, so WAAS doesn't always help (it's based on proximity to a ground station). If you don't have WAAS, you're at the risk of atmospheric effects significantly affecting your accuracy.

There's also the user error side: You might have the handheld set to display in NAD27 one time and WGS84 another, which can easily offset the same lat/long by several hundred meters.

+/- 3m with consumer GPS is definitely possible, but that's for ideal conditions. You're rarely working with ideal conditions in the field.

Re: Learning from Turing’s silver hoard (2016)

#12

Post by BurningFrog »

jofer wrote: post #3

Number one lesson: Don't bury stuff and expect to find it later. Seriously, folks. I grew up around a bunch of preppers and general outside-the-law folks. Burying things in ammo cans was kind of a pastime of a lot of people I knew. It's _really_ hard to find something like that a year or two later, even if you think you know exactly where it is. I've been the person wielding the shovel to dig up a box of important st…

An alternate theory is that someone else dug it up first.

Doesn't seem too farfetched among "outside-the-law folks".

Re: Learning from Turing’s silver hoard (2016)

#13

Post by downerending »

miked85 wrote: post #5

> like so many very successful and brilliant people Turing was wildly over-confident in his own analysis This is so common, yet most individuals that fall into this trap will never recognize it.

I'd probably be over-confident, too, if I was a key figure in both a major new branch of mathematics and a global war.

Re: Learning from Turing’s silver hoard (2016)

#14

Post by CamperBob2 »

jofer wrote: post #7
Cpoll wrote: post #6

Earlier quoted context omitted.

The story asserts the landmarks changed, but can't you pick landmarks that won't change? Better yet, use GPS and grab the Lat/Long.

That's not as accurate as you think unless you've got a full geodetic antenna. (i.e. $200k worth of equipment + a lot of permits to be allowed to have/use it) Getting to within +/- 30m doesn't help a ton when you're digging a hole to find a small box. With geocaching, you've got something to look for. You get close-ish and then do an easter egg hunt. When it's beneath the ground, it's really hard to "look". Finding e…

An extreme exaggeration. Geodetic antennas are neither regulated nor necessary. Any decent GPS receiver -- meaning less than US $100 -- will get you to within a couple of meters, even without WAAS.

Of course, in a SHTF scenario, GPS accuracy will start to degrade fairly rapidly as soon as the control stations are gone. So your point about not being able to return to the same spot is certainly valid.

Re: Learning from Turing’s silver hoard (2016)

#15

Post by ChrisLomont »

jofer wrote: post #7
Cpoll wrote: post #6

Earlier quoted context omitted.

The story asserts the landmarks changed, but can't you pick landmarks that won't change? Better yet, use GPS and grab the Lat/Long.

That's not as accurate as you think unless you've got a full geodetic antenna. (i.e. $200k worth of equipment + a lot of permits to be allowed to have/use it) Getting to within +/- 30m doesn't help a ton when you're digging a hole to find a small box. With geocaching, you've got something to look for. You get close-ish and then do an easter egg hunt. When it's beneath the ground, it's really hard to "look". Finding e…

Real-time Kinematic GPS (RTK-GPS) [1], available from Sparkfun for $200 [2] (and cheaper elsewhere), gets you centimeter accurate positioning in the US and most other countries.

[1] https://en.wikipedia.org/wiki/Real-time_kinematic

[2] https://learn.sparkfun.com/tutorials/what-is-gps-rtk/all

Re: Learning from Turing’s silver hoard (2016)

#16

Post by jackfoxy »

I worked on a farm in the former West Germany (BRD), before the re-unification, not far over the border from East Germany (DDR). The proprietor's family was leasing the historic farmstead. His family's original farm had been just over the border in the DDR, and of course appropriated by the government. At the point they learned the American occupiers were withdrawing and they would be in the Russian occupation zone, they high-tailed it into the American occupation zone.

They visited me in America a couple years after The Wall fell, and he told me the rest of the story. Apparently his father's initial plan was to stick it out and see how things unfolded, but first they buried the family silver in the forest. He was in his early teens and supplied the teenage labor.

When they could return after the wall fell, he remembered roughly where the hoard should be. It took him a couple days with a metal detector, but they found it. He was very lucky because it was very near where the DDR had done trenching for the boarder hazards employed all along the east/west border. Some of the pieces were in very bad shape after 45 years underground, but most of it could be restored.

Re: Learning from Turing’s silver hoard (2016)

#18

Post by grawprog »

jofer wrote: post #11
saalweachter wrote: post #8

Earlier quoted context omitted.

Doesn't modern GPS claim +/- 3 meters, with a clear enough signal? (Which is still a heckuva lot of dirt to shift.)

Given nearby local ground-based correction stations (e.g. WAAS) it can use and flat terrain, yeah, you can certainly get that kind of accuracy. In practice, though, I've spent a fair bit of time trying to re-occupy sites taken with handheld GPS receivers. (I'm a geologist -- it comes up a lot) 30m is a better representation of typical repeatability for a consumer-grade handheld unit or a phone. You're often on the si…

The best i've ever personally got with a handheld GPS under actual work conditions was +/- 15m. I've gotten +/- 5m in large open areas lacking trees, mountains or large rock formations but areas without any of those things are rare.

Weather conditions can make a big difference. In stormy or rainy weather I was lucky if I could get +/-20m

Re: Learning from Turing’s silver hoard (2016)

#20

Post by jannotti »

miked85 wrote: post #5

> like so many very successful and brilliant people Turing was wildly over-confident in his own analysis This is so common, yet most individuals that fall into this trap will never recognize it.

I thought that was a strange takeaway for the article to take. His analysis was correct. He was undone by a factor he didn't even contemplate. His confidence in his "analysis" was spot on.

There's definitely a lesson here, but I would not call it over-confidence. If the bank had gone under, would that have been called over-confidence on the part of his friend? At some point, every mistake of any kind whatsoever is called "over-confidence".

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