Mark - I think you need to find the NMEA 0183 specification for $GPxxx strings. They are a lot easier to write a simple program to read than bit-banging to extract a DST bit from a binary stream.
How did knowing the DST bit help anybody who lived in Indiana before the law change last weekend? At best, it was a warning to apply local knowledge. Read the other threads about the variation in the iono layer height impacting WWVB timing, and you'll have to agree that WWVB clocks are at least good to a minute, while GPS is good to better than a microsecond. The earth radius is about 6380 kilo-KM, so if you can get GPS synched up, you have time to about 20 ms - add a position solution, and you have time to about 0.1 microsecond. There must be a reason why the military uses GPS for time dissemination. http://tycho.usno.navy.mil/gpstt.html N7WY ---- Mark Bayern <[EMAIL PROTECTED]> wrote: > Thanks for the reference. However, the idea that this system is > 'superior' would depend upon why one is looking for a time reference. > If all you want is a relatively high accuracy clock the WWV signal is > superior IMO. It certainly is easier to decode! As an added benefit it > includes the DST bit -- you never know when the govt will decide to > change the DST rules. > > If you need to know where you are and have a clear view of the sky > your system works well. (As long as I don't have to code the > algorithms.) > > Mark > > On 4/3/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > Mark - you are correct... I am just to used to working with the superior > > system described at > > > > http://www.navcen.uscg.gov/pubs/gps/sigspec/gpssps1.pdf > > > > that is only good to about 100 nanoseconds anywhere on the planet, but it > > has no clue about DST. The starting and ending dates for DST are easy to > > determine if you can figure out which day of the month it is, and what day > > of the week it is. > > > > N7WY > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
