[time-nuts] New tide gauge uses GPS signals to measure sea level change

Bob Stewart bob at evoria.net
Wed May 28 22:08:31 UTC 2014

Hal, you bring up an interesting point:  Is the receiver in a Z3801 inherently more accurate in position reporting than the receiver in an Adafruit?  Somehow I doubt it, if for no other reason than the improvements in technology.  (Excluding any programming errors that may or may not exist in the MT3339.)  What the Z3801 has that the 3339 doesn't have is code to accurately calculate the PPS timing error based on a fixed position.  So, if my reasoning is correct, wouldn't you do better running the Adafruit "X" number of days and doing an average of the position over that period?


 From: Hal Murray <hmurray at megapathdsl.net>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
Cc: hmurray at megapathdsl.net 
Sent: Wednesday, May 28, 2014 4:32 PM
Subject: Re: [time-nuts] New tide gauge uses GPS signals to measure sea level change

tholmes at woh.rr.com said:
> I'm not sure my Z3801 or any of my navigation receivers have the necessary
> resolution to see even 10 mm.

In normal operation (post survey), a Z3801A "knows" the location and uses 
that to work out a better time and/or the time with fewer satellites.  So you 
won't be getting any new location data.

It might be interesting to set one up in a loop to do a survey, grab the 
location, then repeat.  After a day or week, you could average the locations 
and/or compute std dev and such.

More information about the Time-nuts_lists.febo.com mailing list