Comments

You must log in or register to comment.

TWiesengrund t1_j5qhu5q wrote

Consumer grade GPS devices have such a broad accuracy, military and engineering GPS receivers have always had much better accuracy down to centimeters or even below for long-term measurements.

95

apeowl OP t1_j5qj86h wrote

Yeah, but to achieve (sub-)millimeter accuracy with Galileo you need much less complex technology than for GPS, also Galileo only needs a few minutes for that, while with GPS, such accuracy can only be achieved with long-term measurements.

Also, Galileo's high accuracy service which provides said 20 cm was just released to public today

36

Volcan_R t1_j5qlbgq wrote

The technology for accurate GPS measurement isn't particularly complex or expensive. You just need a GPS receiver in a fixed location to log the fluctuations against the GPS you are determining the location of. You would use the same strategy for Gallileo I assume but there isn't the intentional addition of innacuracy for non military use.

28

MrWrock t1_j5rcfvg wrote

In another thread I read that that intentional accuracy drop was removed 20 years ago but there still is a second frequency in the military can use for higher accuracy than consumer grade

18

Volcan_R t1_j5rmigc wrote

Looks like you're right. I guess the 10-15 foot distortions I was getting 10 years ago when I was working with it were atmospheric distortions from the single frequency.

4

bdesign7 t1_j5u60bl wrote

Yep. When I was in the Army in the late 90’s/early 00’s we would hold our military gps and a consumer gps (probably a garmin, I would guess) and you could see instantly how much more accurate the military one was.

3

Shillforbigusername t1_j5rjl7x wrote

Isn’t that additional inaccuracy a thing of the past? I googled it because I was unfamiliar with the concept and came across this:

> Doesn't the government degrade civilian GPS accuracy?

>No. During the 1990s, GPS employed a feature called Selective Availability that intentionally degraded civilian accuracy on a global basis.

>In May 2000, at the direction of President Bill Clinton, the U.S. government ended its use of Selective Availability in order to make GPS more responsive to civil and commercial users worldwide.

>The United States has no intent to ever use Selective Availability again.

https://www.gps.gov/systems/gps/performance/accuracy/

12

bellendhunter t1_j5sng78 wrote

There is indeed a more precise GPS signal for military use. It requires crypto keys to use it. Can’t remember the specifics but I think GPS has a completely separate signal for it.

−1

SupFellar t1_j5qp7hm wrote

"but there isn't the intentional addition of innacuracy for non military use." there is, it's at 20cm

4

ggrieves t1_j5qqi4n wrote

GPS, as I understand it, was intentionally throttled because of concern it could be used to guide a weapon. But technology has improved so much since then that GPS isn't the limitation any more.

7

seamustheseagull t1_j5txdsg wrote

Nevertheless, I believe GPS devices sold in the US are still required to shut off above a certain speed/altitude, much to the annoyance of amateur rocket/balloon people.

1

Apeshaft t1_j5vm9eg wrote

And these two systems are compatible with each other so the accuracy gotta be pretty great? Oh, and modern phones even use the Russian GLOSNASS system. It consists of almost three satellites and have an accuracy of 200 potatoes.

1

Electricpants t1_j5qu0qm wrote

GPS design started in the '70s.

I would hope 30 years would lead to some advancements.

33

WillTFB t1_j5qyysm wrote

Mate it's been 50 years.

44

apeowl OP t1_j5ub6nn wrote

Yeah ofc, but 16 of the 31 GPS satellites that are currently operational have actually been launched after the start of Galileo in October 2011, and the oldest of the other 15 was launched in 1997. Also, they get software updates from time to time.

0

DBDude t1_j5uxkuh wrote

There may be a limit to how much you can increase accuracy on a system while maintaining compatibility with an old standard.

1

StrikeZone1000 t1_j5r7qbv wrote

GPS launched 1978, Galileo 2011

30

Commotion t1_j5rspdl wrote

True, but the oldest GPS satellite that is still operational was launched in 1997.

8

apeowl OP t1_j5ub954 wrote

Also, 16 of the 31 GPS satellites that are currently operational have actually been launched after the start of Galileo in October 2011. Also, they get software updates from time to time.

−1

GingerScourge t1_j5s3l82 wrote

Did you also just learn that a 2011 Ford truck gets better gas mileage than a 1978 Ford truck? Crazy what 30 years will do!

8

apeowl OP t1_j5ub2a9 wrote

Yeah ofc thats true, but 16 of the 31 GPS satellites that are currently operational have actually been launched after the start of Galileo in October 2011, and the oldest of the other 15 was launched in 1997. Also, they get software updates from time to time.

−1

Supersnazz t1_j5sdkpp wrote

Most phones today will access it too.

iPhone 14 for example can use

  • GPS - US
  • Galileo - European
  • GLONASS - Russian
  • BDS - Chinese
  • QZSS - Japanese
8

RuaidhriM t1_j5r96h4 wrote

…. Which can provide “precision”. Precision and accuracy are different. The time now is “today” is accurate but not precise. The time now is 12:03:24.1724544444 is precise but not accurate (probably).

2

apeowl OP t1_j5u9l8g wrote

Yeah ur right, thanks! I'm still learning english, didn't know that

2

dvdmaven t1_j5rybqd wrote

Apparently this is better than the Gen III GPS system which will have "Unbelievable Accuracy" (per Lockheed) of 1-3 meters. Snort.

1

MinimumPsychology916 t1_j5sj60m wrote

This is by design so that foreign militaries can't use the USA's GPS satellites to guide weapons, and the air force knows the programmed lag time of each satellite and military GPS units compensates for that

1

apeowl OP t1_j5u8ybz wrote

No, with GPS you can reach a maximum precision of about 20-30 cm (this signal is encrypted and almost only used by the US government), while Galileo's encrypted signal provides about 1 cm. Note that these are the values that are possible to get almost instantly, and by only using a single signal band (with long-term measurements, and by using several signals, you can get a sub-millimeter precision with both GPS and Galileo)

2

crazyhadron t1_j5sl25f wrote

We have equipment at work that requires accuracy down to mere millimeters, and that takes hours to calibrate using conventional GPS.

1

RuaidhriM t1_j5r9o3e wrote

Good TIL but accuracy is not the same as precision. Eg. The time is “today” is accurate but not precise. The time is “12:03:17.1234556” is more precise but probably not accurate. The article has it right.

0

apeowl OP t1_j5u9kl8 wrote

Yeah ur right, thanks! I'm still learning english, didn't know that

1

TommyTuttle t1_j5roxpm wrote

Precision of GPS is intentionally limited. It was created by the defense industry after all.

Edit: this info is out of date.

−2

42gauge t1_j5rrh9p wrote

Not since May 2000

7

NedIsakoff t1_j5sd0zp wrote

It still is. GPS satellites broadcast many codes for positioning. Civilians do not have access to military P(Y) or M codes which are far more accurate then the civilian C/A or L2C codes.

Your thinking of when they turned off Selective Availability, which is an intentional degradation of the C/A code to reduce accuracy.

11

john22544 t1_j5rxtfx wrote

If you have your own base station within a few miles of your job you can get repeatable sub 2 centimeter vertical accuracy.

Selective availability that intentionally limited the accuracy was turned off May 1, 2000.

6

apeowl OP t1_j5u8p7c wrote

Yeah, but with GPS you can reach a maximum precision of about 20-30 cm (this signal is encrypted), while Galileo's encrypted signal provides about 1 cm. Note that these are the values that are possible to get almost instantly, and by only using a single signal band (with long-term measurements, and by using several signals, you can get a sub-millimeter precision with both GPS and Galileo)

1

Silly_But128iq_ t1_j5qmhka wrote

Not me thinking about the Bohemian Rhapsody song😮‍💨

−11