Next generation GPS:

[+Star*Hopper]

While reading the below linked article, I wondered what if any changes would come to GPS as a result of Block III deployment, and more specifically, if it would affect and/or obsolete gear now in our hands. I'm shopping for a GPS unit, & long story short, don't want to get stuck with another BetaMax!

 

Anyone 'up' on the technology, & can say what the future holds?

TIA!

 

+++

Related article:

http://www.spaceref.com/news/viewpr.rss.sp....html?pid=24600

 

***

[yogazoo]

IMHO it's like the whole metric VS english argument. Yeah, the US should probably change over to the metric system but think of the costs to do so. I'm guessing that would be the attitude toward designing a global positioning system that would not be backward compatible. Think of the cost to the military, airlines, consumers, etc. if we switch to something brand new and incompatible with all the navigation systems out there. Just my thoughts. If they convene in 2008 (this year) we're probably not going to see anything in the air for at least 5 years or more. Even the Colorado's, Triton's, PN-20's will be outdated by then.

[Phoenix2001]

While reading the below linked article, I wondered what if any changes would come to GPS as a result of Block III deployment, and more specifically, if it would affect and/or obsolete gear now in our hands. I'm shopping for a GPS unit, & long story short, don't want to get stuck with another BetaMax!

 

Anyone 'up' on the technology, & can say what the future holds?

An old GPS receiver that still runs would work with the newest satellites. They just won't use the newer features. The future holds better performance.

[snakyjake]

What will the actual improvements be for us civilians?

 

I can see a need for a new system/signal for military and aviation. Something that is difficult to jam, less susceptible to interference, and something that will be reliable for aviation.

 

For my use, I just want to see improved performance and reliability in mountains and valleys, tree cover, in and between buildings. Having accuracy that is better than 3 meters would be great for caching, and perhaps provide the ability for a GPS to tell you exactly what lane you're driving in. But I haven't heard anything that explicitly says those areas will be improved.

 

Jake

[anethema]

It would be nice if they just released the codes for (or just transmitted in the clear) the P(Y) codes so that normal civilian GPSr's could compare L1 and L2 without it taking forever (surveying gps's etc). I dont think they ever plan on doing this though. I read somewhere they might transmit additional codes on L2 and L5 to increase accuracy.

 

Maybe we should just eliminate the ionosphere! dadgum unpredictable bugger!

 

What will the actual improvements be for us civilians?

 

I can see a need for a new system/signal for military and aviation. Something that is difficult to jam, less susceptible to interference, and something that will be reliable for aviation.

 

For my use, I just want to see improved performance and reliability in mountains and valleys, tree cover, in and between buildings. Having accuracy that is better than 3 meters would be great for caching, and perhaps provide the ability for a GPS to tell you exactly what lane you're driving in. But I haven't heard anything that explicitly says those areas will be improved.

 

Jake

[Phoenix2001]

What will the actual improvements be for us civilians?

 

I can see a need for a new system/signal for military and aviation. Something that is difficult to jam, less susceptible to interference, and something that will be reliable for aviation.

 

For my use, I just want to see improved performance and reliability in mountains and valleys, tree cover, in and between buildings. Having accuracy that is better than 3 meters would be great for caching, and perhaps provide the ability for a GPS to tell you exactly what lane you're driving in. But I haven't heard anything that explicitly says those areas will be improved.

The old GPS had one civilian frequency, L1. The future GPS will have two more civilian frequencies, L2 and L5. L5 is considered a "safety of life" civilian use signal (especially for aviation) and has a higher transmission power than L1 and a longer spreading code than the C/A code on L1. Block III satellites generally have increased signal transmission power.

 

I believe there are currently four block IIR-M satellites, which support the new L2C signals. This gives us civilians a second frequency to reduce the error from the ionosphere. Different frequencies travel at different speeds through the atmosphere so the ionosphere can be better modeled (note that if you can receive WAAS signals - these also help correct ionosphere caused errors). L2C has a CM (moderate length code) and a CL (civilian long length code). They are not as long as the current military P code but better than the C/A code we have now. All of this will help us a little when consumer receivers start supporting the additional signals.

 

The biggest cause to poor accuracy is a poor view of the sky caused by mountains or buildings, etc. and few satellites in view because they aren't distributed in the parts of the sky that you (your receiver) can see. The EU Galileo system is designed to be compatible with GPS (NAVSTAR) so that manufacturers can also receive its signals with a minimum of additional work. A dual system receiver would be more likely to have a set of satellites in view with a "good" geometry (A slot canyon will never have good geometry) in mountainous/urban canyon situations. This would provide the "best" improvement.

 

Unfortunately the EU member countries are squabbling resulting in delays for Galileo and even possible cancelation. The Russian GLONASS is another possibility for additional satellites and is currently being "upgraded" but it was not designed to be compatible with GPS so it's more difficult to incorporate. Some dual system receivers using GPS and GLONASS exist but are expensive survey grade receivers. A GPS/Galileo receiver would be many years in the future but would provide you with the most noticeable improvement in poor sky view situations.

[+Egnix]

I would think GPS III is far enough into the future that you don't need to worry about it yet. We won't even see the launch of the first Block IIF satellite until next year.

 

I would guess the next major upgrade to civilian receivers would be the ability to utilize the new civilian signal on L2. As of this morning, there are only 6 SVs that can transmit the L2C signal, so there still isn't much use for a receiver that can use the new signal.

 

So I think you are safe to buy whatever you want right now.