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GPS Toolkit (GPSTk) 1.0 Released
rmach writes "Based on many years of work performed at ARL:UT, we have release GPSTk under the GNU LGPL. GPSTk is a cross platform library and set of applications that provides both fundamental and advanced GPS processing algorithms to the GPS and open source community. A wide array of functions are provided by the GPSTk library, including: RINEX I/O, ephemeris calculation, P-code generation, atmospheric refraction models, and positioning algorithms. GPSTk applications provided more concrete benefits to the user, including: cycle slip detection and removal, calculation of the Total Electron Content (TEC) of the ionosphere, position residual computation, and RINEX file manipulation. The library is about 41,000 SLOC with a COCOMO estimated cost to develop of about $1.3 million. You can also read more about it in the current issue (September '04) of Linux Journal."
No, it means you can do precise calculations with cheap equipment. Most of these functions cost thousand of dollars if done in hardware.
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When I bought my Garmin Etrex, I wanted to use it to store mountain bike rides and overlay them with maps. Easy, right? Bah! I spent two weeks trying to find a way to do this on my Linux box before giving up. I ended up paying out of my rear end to buy expensive Garmin maps and closed source software. Even then, I couldn't mix and match tracks, let alone cut and paste sections of them together to make trail maps.
The other featuer I've always wanted is to do profile slices of my rides to see climbing and descending rates, especially during races.
All in all this toolkit sounds hugely promising, as the last time I looked at SF.net/Freshmeat the capabilities were nearly nil. All I want is a simple import module, track overlay over free downloadable maps, and a track editor...
I'm going to be spending the evening trying to get this stuff working, hopefully it will provide a replacement to my current Garmin/Microsoft solution!
Please correct me if I'm wrong, but this software is very important. This is the software that normally runs inside the GPS, not for drawing maps, but interpreting the GPS radio signals and calculating the lat/long numbers. Why would this be useful? Well, say, you take a project like GnuRadio and make your own GPS receiver. GnuRadio can demodulate the signals and convert it to data. This software would allow you to take the data you receive with GnuRadio and do something with it.
It seems to me that this is first time that code like this has ever been published under an open license.
What you get from YOUR GPS is an autonomous position estimate.
What I get from my array of GPS receivers is a set of observables, including the pseudorange from the code phase measurements, and carrier phase information. When I get done processing, I have a set of baselines, a set of potential delays in the troposphere and ionosphere, doppler shifts for the satellites in view, timing deltas, and information on signal multipath propagation.
When I report something out, I can give horizontal positions with respect to a known coordinate system to about 1 cm (2sigma RMS) and vertical estimates (referenced to the WGS84 ellipsoid) on the order of 2 cm (2sigma RMS). Given a good gravity model, I can estimate geoid height differences to about 3 cm.
Given code phase observables from a satellite-borne receiver, I can make reasonable estimates of the satellite's ephemerides and state vector, provided 3 sets with a temporal spread of about 20 minutes. Given code and carrier data I can derive the state vector in less time and with better accuracy.
I can estimate the amount of precipitable water in a vertical column of atmosphere above a GPS receiver site.
I can make estimates of the ionosphere's total electron count.
There's more.
For the record, I've been doing all of the above, for several years.
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