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[Reply #15 on:]

Maybe you can get together with a couple of lab accomplices and pick up some free
STM32F4-Discovery boards to plan ahead for when you need faster hardware

http://www.st.com/internet/mcu/class/1734.jsp

[Reply #16 on:]

Hi,

for free? I don't think so! But I will ask tomorrow. At least they have more MHz!

I checked http://www.sparkfun.com and would like to ask for a good combination of an Arduino mega 2560, gps module (that can also provide gps-time to the arduino) and a communication link that uses 2.4ghz and has it's own antenna AND where I can plug in an external antenna, perhaps yagi. and it would be great to have it ready so that I don't have to build and solder them on my own.

greets,

Andreas

[Reply #17 on:]

..and the direct answer to your question: European Union is trying that (Galileo) and Russia as well (Glonass). Not sure it works today, however..

[Reply #18 on:]

Hi pito,

an answer to what question?

And Galileo has only 2 test satellites up there and 2 real satellites that had been launched last friday. So at LEAST they have to have 4 real satellites up there to be working in any way, AND you have to have them all covering one region, and that's very very unlikely. So it's not working unless they have 18 out of 27 satellites up there, that will be in 2015 (I think).
Glonass is not fully working, yet.

But anyway, I want to have it the other way round. That's why I don't understand your answer.

[Reply #19 on:]

-horn-
Free, for real. Try the link, you'll see.

[Reply #20 on:]

Free, for real.

U.S. and Canada only  

But only £9.72 in the UK (in 12 days time) 
http://uk.farnell.com/stmicroelectronics/stm32f4discovery/board-eval-stm32f4-discovery/dp/2009276?Ntt=STM32F4DISCOVERY

[Reply #21 on:]

@-horn-
>Hi pito,
>an answer to what question?
Has anyone ever tried to build own GPS-System?
 

[Reply #22 on:]

I did once consider building a GPS, but the launch costs were simply prohibitive.

[Reply #23 on:]

@awol: you may try harder:
http://www.kickstarter.com/projects/251588730/kicksat-your-personal-spacecraft-in-space
24x$300 
p.

[Reply #24 on:]

If you can use bursts of ultrasound instead, it would be a lot easier to do with slow hardware. Use a frequency just above 20kHz and common tweeters should quite well. Or get a whole bunch of old smoke detectors from a fire alarm company and drive the buzzers in them at the first ultrasonic harmonic.

[Reply #25 on:]

There are two methods in use for enhancing the accuracy of GPS, Differential GPS and Real Time Kinemetrics.  The simplest is differential GPS. 
We were doing differential GPS back in 1986 with some pretty slow processors, so the Arduino would probably work fine for the differential calculations. 
A differential system uses a fixed base station to collect psudeo-range information.  The location of base station is well known, perhaps on a high precision survey point.  The data collected by the base staion is transmitted to the users (WiFi would work well) (data = position + errors).  The user is able to calculate his position very precisly because he can subtract out the errors in his measurements by using the measurements made at the base station.  The Ardunio processors would not be doing the actual reception of GPS signals, just the data processing.  Amateur Radio enthusists have been doing this for some time.  The trick is to find a good GPS receiver for the base station.  The old Motorola Oncore receivers could be used as I recall.