Thought I'd top post as well as answering my own posts! It seems that the 'linux drivers' that are downloadable from DS are raw c code. That's taken the fun out of it!
Still not sure how to check, other than to run it against one of the internet stratum 2 servers. Cheers, Steve On Tue, 24 Feb 2004 19:39:49 +1300, you wrote: >On Tue, 24 Feb 2004 18:52:33 +1300, you wrote: > >>> >> I note that Dick Smith are offering a GPS receiver that is M$ >>> >> compliant, and is around the NZD250 mark. Is there any support for it >>> >> under linux >> >>These things always have a serial port -> trivial. The protocol they speak >>is NMEA-0183, http://www.nmea.org/pub/0183/ unfortunately an expensive >>standard. It's based on the exchange of ASCII lines of 15 - 80 characters >>(usually). If you get a manual which describes which control messages and >>info messages are supported by this receiver (should be possible), you're >>home and hosed. >> >>The serial port will give you a time accuracy of around 1 second and a >>resolution of 1 second. >> >>> >I've been looking at these as well. I'd be curious to see what the >>> >clock accuracy is like on one of these devices. >>> >>> Allegedly 0.1sec according to the label. I might nip in next time the >>> boss isn't around (: >> >>Ooouuuuuuch, man that's bad. That's 100ms. Not a good NTP source. NTP can >>synchronise the time over the internet between Europe and America to within >>5-20ms, and this box is hanging straight off the back of your computer. >>Cheap though, and you never have to set your watch. (I had this in 1985 in >>Germany for less money than you mentioned - nahnahnahnahnah... ;))) ) >> >>Note the accuracy below 1s comes from a pulse signal which the receiver >>should also supply. You can expect 1ms accuracy here. Good receivers should >>manage <1us. >> >>Some other trivia: GPS runs on neither TAI (international atomic time) nor >>UTC (which one could call civil time) (no comment). You'll have to >>compensate yourself. NTP is probably supposed to use UTC, but leap seconds >>are not implemented. Whenever there is a leap second in UTC, (in the words >>of David Mills, inventor of NTP) "the behaviour of NTP can be described in >>terms of a pinball machine". No comment either. >> >>Volker > >Thanks for the info Volker. According to the blurb on the outside of >the box ( contents removed! ) it was purely an USB interface, and I've >not programmed that. Come to think of it, it's the best part of 20 >years since I used ioctl on a serial device (: > >Off to google nmea and usb! > >Steve > > >
