[time-nuts] Looking for GPSDO for home use

David J Taylor david-taylor at blueyonder.co.uk
Thu Apr 17 02:11:26 EDT 2014


From: Chris Albertson

If you are going to buy and set up a GPS receiver. The hardest part is the
antenna.  It is best if it can see the entire sky, horizon to horizon and
if it is not near any reflecting surfaces.  It is best if the antenna is
mounted on a mast on the tallest building but a modern GPS will work if the
antenna is playing on the desk near a window.  You can connect a computer
and get software to plot data from inside the GPS but really all you need
to go is apply power and get the PPS.

The old Motorola "Oncore" series of GPS is reliable and low cost.   The
"UT" has a PPS one sigma error of about 50 nanoseconds which is "good
enough"  they sell for under $20.   The current new state of the art
version is about $60 or $35 used.
Here is an example
Motorola-UT-Plus-Oncore-Timing-GPS-Module<http://www.ebay.com/itm/ONLY-1PSC-Motorola-UT-Plus-Oncore-Timing-GPS-Module-1pps-NTP-/301132856857?pt=US_Ham_Radio_Transmitters&hash=item461ceabe19>
Be SURE to buy the "timing" version.  There are non-timing or navigation
versions.  Make sure it says "timing" in the description.

GPS receivers spew out tons of data but you can ignore it all.  All you
need is the PPS signal.

Chris Albertson
===============================================

Chris,

Thanks for your comments and advice - I agree based on my years of 
experience with using GPS modules for NTP!  The comments on antennas is 
particularly relevant as I have just placed an antenna outdoors for use with 
my Rapco GPSDO, and it has made a stunning difference to this unit from the 
last century.  All the units purchased this century (except the GPS 18 LVC, 
not the 18x) are much more sensitive and work well enough indoors - at least 
at this location on the second floor of a two-storey building.

The Arduino version piqued my interest, so the information on that is 
appreciated as well.

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 




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