[time-nuts] Simple GPSDO

Murray Greenman denwood at orcon.net.nz
Fri Dec 30 14:59:09 EST 2011

Two thoughts re Simple GPSDOs:

1. For a conventional 1pps approach, see 'A Simple GPS Disciplined 
Reference" http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm, by yours 
truly. It uses a high performance 10MHz OCXO and gently disciplines it. 
Despite not having a Kalmann filter, the holdover is excellent and the Adev 
is almost as good as the OCXO allows.

2. The excellent 10kHz design by James G3RUH 
http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm requires a 10kHz 
GPS source, and folk on this group asked where you can get a modern GPS 
module with 10kHz output. One suitable answer is any of the u-BLOX modules, 
such as the LEA5-P. These have completely programmable pulse outputs in 1us 
steps (width and duration). I use an older u-BLOX Antaris 4 development kit 
which is Atmel based, and it also has a programmable pulse output.

Murray ZL1BPU

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