Hi Dieter,
Interesting device, I wasn't aware of it (I know about the book). Is the Source Code of the book available ? So far I have only seen some material for download at the following site, not sure if there is the whole content of the DVD:
The (blue) receiver is the old dongle sold by SparkFun during the last years. I only remember from visiting their website, but don't own one. I don't know if the DVD contains more than the matlab code that can be downloaded.
There's actually quite a lot of information out there, but there also seem to be quite a lot of half-abandoned projects (and a few seem to have vanished since the last time I had an interest in it around 2005).
This site (from 2003)... http://home.earthlink.net/~cwkelley/ ...explains the calculation in the "Operations" section, it's a rather concise summary of the basic math involved.
I had a short look at some but always had the impression that it is not exactly what I am looking for. I guess I should try to get a GPS receiver which provides the required data, thats probably the easiest approach.
http://home.tiscali.nl/samsvl/oemtable.htm has a table comparing various chipsets, some are quite ancient.
Chris