Hi, all The subject of position hold mode in GPS receivers pops up every now and then. Here is a plot that may be of interest to some. Nothing new, but I thought it a nice visualisation of the difference between position hold and "not position hold". I was measuring EFOS 3 against the PPS of a U-blox LEA-6T to get a coarse indication of the frequency. I have not got around to mounting permanent antennas in my new lab, so this was a bare board with a patch-antenna on my desk - no great precision needed nor expected. I fired up the receiver and made the measurements while it was still surveying - about half way through it switched to position hold mode. The position is reported with a standard deviation of 15 meters, so not a great fix. However, I thought the phase plot was interesting. Thinking about a GPSDO, it is easy to see the difference between using the first half of the plot to discipline an oscillator versus the second half. In case the attachment does not make it though, it is also here: http://www.efos3.com/images/AHM%20v%20PPS%20pos%20hold.PNG Ole [image: Inline image 1]

		Attila Kinali

On Tue, 24 Jan 2017 07:48:10 +0100 Ole Petter Ronningen <opronningen@gmail.com> wrote: > Thinking about a GPSDO, it is easy to see the difference between using the > first half of the plot to discipline an oscillator versus the second half. > > In case the attachment does not make it though, it is also here: > http://www.efos3.com/images/AHM%20v%20PPS%20pos%20hold.PNG Said Jackson reported a similar outcome a couple of years ago: https://www.febo.com/pipermail/time-nuts/2012-December/073373.html https://www.febo.com/pipermail/time-nuts/2012-December/073416.html https://www.febo.com/pipermail/time-nuts/2013-March/074979.html Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson