Mike, Comments below... > I have to learn more about how you do your measurements. A 53132A is > way out of my price range at the moment. But I do have a 53310A > which should give comparable results.
Yes, if you can get a clean series of 1PPS sub-ns time interval measurements over GPIB from your 53310A then you're all set. What time/frequency reference do you have available against which to compare your GPS receiver? > I am interested in learning more about these errors. Is there a list > somewhere that describes the sources of error, and what can be done > to reduce it? I keep coming across hints of doing this in software, > but it would seem that has to be done in the signal processing part > of the receiver. But we don't have access to that. Is there anything > else we can do to help remove some of these errors? This is a large topic. Google for words: gps error budget and you'll begin your long journey. Also look for topics like ionosphere multipath troposphere ephemeris. A typical OEM GPS receiver board will get you within 100 ns of UTC without much effort. Here's a couple of pages to get you started: http://edu-observatory.org/gps/gps_accuracy.html http://www.trimble.com/gps/howgps-error2.shtml http://www.cmtinc.com/gpsbook/chap6.html http://www.ias.ac.in/currsci/oct102007/927.pdf http://www.usace.army.mil/publications/eng-manuals/em1110-1-1003/c-4.pdf http://seismo.berkeley.edu/~battag/GAMITwrkshp/lecturenotes/unit1/unit1.html > That is very interesting. What do you mean by granularity? I have a > file somewhere that talks about the algorithm to select the next > 1PPS pulse. It added 500ps to the rounding, so the result would be > on 1 ns boundaries. Is that what you meant? Your GPS receiver outputs a correction value in fixed integer units of ns; no less. Other words loosely used on this context are resolution or quantum or precision. > That is getting very subtle. How much effect does it have, and where > on earth do you learn all this stuff? When you write your software to correct sawtooth errors you'll see where GPS or TIC sign errors and off-by-one sample errors can bite you. Not all receivers do it the same way, either, so make sure to study the manual(s). /tvb _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
