A New Technique Makes GPS Accurate To An Inch (gizmodo.com)

A team from the University of California, Riverside, has developed a technique that augments regular GPS data with on-board inertial measurements from a sensor. Actually, that's been tried before, but in the past it's required large computers to combine the two data streams, rendering it ineffective for use in cars or mobile devices. Instead what the University of California team has done is create a set of new algorithms which, it claims, reduce the complexity of the calculation by several orders of magnitude. In turn, that allows GPS systems in a mobile device to calculate position with an accuracy of just an inch.

Comments

This could be really useful for docks and ferries

[mikael]

One of the most time consuming parts of a short journey is getting the passenger doors aligned with the port-side gangways. Unlike airports, it's not the gangways that move to the plane, it's the vessel that must align with the portside. Sometimes the portside gangway can move up or down, but many times, the crew have to tie down these mini gangways with ropes when the tides and ballast tanks aren't enough. It takes several minutes of maneuvering to get the ship aligned with the dockside, sometimes even having to reverse and try again, especially in heavy swells. If they could get GPS down to several inches, combined with the sideways movement that many catamarans have, docking could be done automatically.

Encrypted

[Anonymous Coward]

Given that we can now use GPS to great accuracy. Does this mean that the US military no longer needs to encrypt the end of the GPS signal? After all, the military has always been able to use GPS for very precise location, whereas civilians had to put up with very coarse location.

Re:Encrypted

[Anonymous Coward]

This is incorrect. President Clinton removed selective availability from GPS. That is why we have the location boom today. We are at as accurate a position as we can be with the GPS reception. This happened in 2000. There are other forms of signal degradation that are available. SA is not an issue anymore. I am a professional land surveyor. Multi-pathing is currently your greatest hurdle to overcoming highly accurate positioning. That unfortunately, requires fairly complex calculations to remove it properly. Even with my highly accurate receivers, I have to remove multi-pathing manually sometimes. Reflection is a harsh mistress.

Re:Encrypted

[nunokjpg]

Like others have said, there is no Civilian degradation on purpose anymore. That was the SA system, that is off for several years and is not coming back at least because it is no longer a effective defense against foreign military parties. The only thing the Encrypted GPS code provides is AS (anti-spoofing). If used this avoids things like Iran taking control of your baby drone.

Re:Encrypted

[russotto]

The P(Y) code offers a couple of advantages besides anti-spoof

1) Faster code rate for more precise positioning, also offered by the newer civilian signals (L1C, L2C, and L5)

2) It exists on both L1 and L2, allowing the receiver to more accurately model the atmospheric delay terms, reducing that source of error. This is also provided by the L2C and L5 signals, but not all satellites yet transmit them.

Re:Encrypted

[DerekLyons]

I am a professional land surveyor.

You're a moron with no clue what you're talking about.
 

President Clinton removed selective availability from GPS. That is why we have the location boom today. We are at as accurate a position as we can be with the GPS reception.

President Clinton turned off Selective Availability on the C/A (coarse acquisition) signal. The more accurate P(Y) (precision location) signal used by the military is still encrypted.

Re:This could be really useful for docks and ferri

[Calydor]

Couldn't the same level of 'automatic' be achieved with image recognition cameras at the doors, or other sensors to achieve the same result?

Re:Meanwhile

[mykepredko]

No it's not; for the rest of the world it's accurate to 2.54cm.

Re:This could be really useful for docks and ferri

[zm]

Couldn't the same level of 'automatic' be achieved with image recognition cameras at the doors, or other sensors to achieve the same result?

Why would you want to do it in a simple way?

Re: Meanwhile

[Anonymous Coward]

In fact, the paper's abstract says "centimeter-level positioning estimation accuracy can be achieved"...

Re:Meanwhile

[alexhs]

Last year we had 2-cm accuracy. Now it's been improved to 1-in accuracy.
Don't forget to thank Big Brother for raising the chocolate ration to twenty grammes a week !

Re:Signal

[Saeed al-Sahaf]

Yes, I know what you mean. I left my home in upstate NY to buy a chalupa at the Taco Bell down the street and ended up in Nova Scotia...

In related news...

[fahrbot-bot]

In turn, that allows GPS systems in a mobile device to calculate position with an accuracy of just an inch.

Dick measuring goes high-tech.

Is it really as good as they say?

[Garion911]

I used to work at a precision GPS company, on differential GPS. What they would do is have a 'base station' that would stay in a single spot, and average the position from the GPS signal for a period of time. This is because, due to atmospheric interference, the position 'wobbles'.. Once we have an average position, we use that position to come up with correctors to send to the mobile units (via radio modem usually, though other means are possible). This got us to be on par with what this article is claiming.

I wonder if they account for the 'position wobble' of atmospheric interference. I suspect its possible, as they just pick one position they've received, and use the inertial adjust for the correctors. Not much more work than we were doing.

(I didnt write any of the algorithms or anything, just shuffled data around to different devices and libraries.)