[HN Gopher] Mapping the Ionosphere with Phones
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Mapping the Ionosphere with Phones
Author : gnabgib
Score : 91 points
Date : 2024-11-13 18:59 UTC (5 days ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| acidburnNSA wrote:
| Interesting use by Google of everyone's android phone data to
| compute space weather info.
|
| Do users who unknowingly contributed sensor data get a sticker or
| badge or anything? Reminds me of seti@home.
|
| What else could you do with full control of a global botnet of
| high powered sensor packs like android phones?
| BobbyTables2 wrote:
| Imagine if they all transmitted simultaneously in a manner that
| was phase synchronized at a particular destination...
| lxgr wrote:
| What would you expect to happen?
| RF_Savage wrote:
| Most current day cellphone antennas don't have phasing for
| any tuned directionality. There are hard limits to array size
| due to physics and phones are just very small compared to yhe
| wavelengths they use.
|
| And then there is the general challenge of synchronizing the
| transmitter phase. There is only so much that can be done via
| GNSS.
|
| If cellphone frequencies were not filled with cellphones, it
| could make for a neat radiotelescope on receive.
| cozzyd wrote:
| This would be more practical with cell towers I think, but
| again they have the same GNSS based timing
| itishappy wrote:
| Ignoring phase synchronization concerns, a cell phone can
| transmit about 3W of power, so a million of them would be
| about equivalent to the 3MW of the HAARP transmitter.
| Frequencies are different, HAARP is in the MHz range, cell
| phones are GHz, so while I bet your cell phone array would
| have less effect on the ionosphere, I also bet it it would
| cook a mean hot pocket.
|
| https://en.wikipedia.org/wiki/High-
| frequency_Active_Auroral_...
| caf wrote:
| The existing ground-station ionosphere data mentioned has been
| used to detect missile launches:
| https://www.armscontrolwonk.com/archive/1216884/detecting-mi...
|
| I imagine you could do the same thing with much better coverage
| using this distributed ionosphere monitoring method.
| secretsatan wrote:
| We're doing much more work now with RTK devices in our
| application and this was recently an issue for us.
|
| A customer had been complaining that the RTK devices we were
| supporting were not working correctly and I got sent out there to
| have a look. After some back on forth and getting tests done on
| site, they revealed they often didn't get good fixes with any
| equipment between late morning and late afternoon, and that's how
| I found out about ionospheric interference and the the correction
| service's ionospheric warning page which consistently reported
| high interference around these times
| mkesper wrote:
| What is RTK in this context?
| admash wrote:
| https://en.wikipedia.org/wiki/Real-
| time_kinematic_positionin...
| ramses0 wrote:
| This is super interesting! For data quality nerdery:
| "there's no such thing as a string (without an encoding)",
| "there's no such thing as a timestamp (without a
| timezone)", and apparently for geo-data:
|
| There's no such thing as a location (without a relative,
| timestamped, chain of reference points).
|
| eg: 38deg53'52''N 77deg02'11''W (the white house), but
| needs a timestamp (eg: continental drift, san andreas
| fault: https://geotripper.blogspot.com/2023/10/why-did-
| road-cross-s...)
|
| ..and if you're doing this RTK-stuff, you kindof need to
| know that "chain of custody": Here => There => GPS@time
|
| With GPS, we've kindof lost a lot of surveying / map-
| reading / orienteering in the general population, but
| looking at the guy trying to map out where the lines in the
| parking lot are to sub-millimeter accuracy really points
| out that it's inherently a relative (and time-fixed)
| process where the local _relative_ positions might not
| change really appreciably at all, but relative to GPS, over
| decades there'd probably be some skew (which could be
| "corrected", but only if you kept that original "chain of
| custody" of your measurements).
| mannykannot wrote:
| This is rather tangential, but I see from the map of Europe that
| monitoring stations are clustered in three nations - Italy,
| Portugal and Sweden (at least the southern part of the last,
| which is as far as the map covers.)
| xnx wrote:
| From https://research.google/blog/mapping-the-ionosphere-with-
| the...:
|
| > Knowing the current ionospheric conditions allows a GPS
| receiver to reduce location error by several meters.
|
| This is amazing
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(page generated 2024-11-18 23:02 UTC)