3 ms·

Sure, sensationalist copy as well. The point is that press releases are written by people who neither know nor care about the subject, and can't be trusted to a

Sure, sensationalist copy as well. The point is that press releases are written by people who neither know nor care about the subject, and can't be trusted to accurately reflect the state of the field or the content of the papers they refer to.

defrost 4y ago
Absolutely, read the paper and not the press release. By way of example, this linked press release contains the paragraph: > While the effects are small, [ ... ], just as the slight frequency shift induced by gravity became crucial to allow GPS systems to accurately convey their positions to orbital satellites. which is a /headdesk given the reality that ground based GPS receivers compute their positions using signals from several 'visible' transmitting GPS satellites; they do not "convey their positions to orbital satellites". This doesn't detract from the source paper but it does highlight the quality of the lay press release. (Note: It's essential to correct for gravity induced shifts in timing given these exist because of relativity .. but the shifts themselves are not "crucial" to the triangulation; in a hypothetical universe where relativity didn't exist | had a minor effect in this usage case, the triangulation of GPS against moving stations would still work with either no correction for relativity or a different correction)
- dataflow 4y ago
  > crucial to allow GPS systems to accurately convey their positions to orbital satellites. I actually think they may have been referring to the ground stations here, not the GPS devices you carry as a user, since they said "GPS systems" and not "GPS receivers". Presumably the satellites need to determine their positions based on the positions of the ground stations.
  - defrost 4y ago
    > Presumably the satellites need to determine their positions based on the positions of the ground stations. The satellites broadcast a rough guide to their collective positions (an almanac) to recievers and a precise guide to their specific exact location (the ephemeris) to ground clients (phones, GPS receivers, etc). Master Ground control stations update the satellites with that information every four hours or so .. strictly speaking the satellites don't do any computation of their own position - they broadcast their weekly lapsed epoch signal and echo data frames from their last Master Ground Station update. Orbital changes can result from solar wind pressure, magnetic forces, passing objects with mass, etc. It's the GPS receivers that do the 'heavy' positional computations for individual fixes .. and the Master Stations that do the somewhat harder work of constellation updates. ( There's a wealth of accuracy processing that can be run in parallel or post - differential base station GPS, forward error correction, post aquisition corrections, et al ) [1] https://gssc.esa.int/navipedia/index.php/GPS_Ground_Segment https://gssc.esa.int/navipedia/index.php/GPS_Ground_Segment [2] https://en.wikipedia.org/wiki/GPS_signals https://en.wikipedia.org/wiki/GPS_signals
kergonath 4y ago
> The point is that press releases are written by people who neither know nor care about the subject, and can't be trusted to accurately reflect the state of the field or the content of the papers they refer to. These people should be fired at once. They have no business writing propaganda about things they do not understand. We need better ethical guard rails in research institutions, this is ridiculous.

defrost 4y ago

Absolutely, read the paper and not the press release. By way of example, this linked press release contains the paragraph: > While the effects are small, [ ... ], just as the slight frequency shift induced by gravity became crucial to allow GPS systems to accurately convey their positions to orbital satellites. which is a /headdesk given the reality that ground based GPS receivers compute their positions using signals from several 'visible' transmitting GPS satellites; they do not "convey their positions to orbital satellites". This doesn't detract from the source paper but it does highlight the quality of the lay press release. (Note: It's essential to correct for gravity induced shifts in timing given these exist because of relativity .. but the shifts themselves are not "crucial" to the triangulation; in a hypothetical universe where relativity didn't exist | had a minor effect in this usage case, the triangulation of GPS against moving stations would still work with either no correction for relativity or a different correction)

dataflow 4y ago
> crucial to allow GPS systems to accurately convey their positions to orbital satellites. I actually think they may have been referring to the ground stations here, not the GPS devices you carry as a user, since they said "GPS systems" and not "GPS receivers". Presumably the satellites need to determine their positions based on the positions of the ground stations.
- defrost 4y ago
  > Presumably the satellites need to determine their positions based on the positions of the ground stations. The satellites broadcast a rough guide to their collective positions (an almanac) to recievers and a precise guide to their specific exact location (the ephemeris) to ground clients (phones, GPS receivers, etc). Master Ground control stations update the satellites with that information every four hours or so .. strictly speaking the satellites don't do any computation of their own position - they broadcast their weekly lapsed epoch signal and echo data frames from their last Master Ground Station update. Orbital changes can result from solar wind pressure, magnetic forces, passing objects with mass, etc. It's the GPS receivers that do the 'heavy' positional computations for individual fixes .. and the Master Stations that do the somewhat harder work of constellation updates. ( There's a wealth of accuracy processing that can be run in parallel or post - differential base station GPS, forward error correction, post aquisition corrections, et al ) [1] https://gssc.esa.int/navipedia/index.php/GPS_Ground_Segment https://gssc.esa.int/navipedia/index.php/GPS_Ground_Segment [2] https://en.wikipedia.org/wiki/GPS_signals https://en.wikipedia.org/wiki/GPS_signals

kergonath 4y ago

> The point is that press releases are written by people who neither know nor care about the subject, and can't be trusted to accurately reflect the state of the field or the content of the papers they refer to. These people should be fired at once. They have no business writing propaganda about things they do not understand. We need better ethical guard rails in research institutions, this is ridiculous.