[time-nuts] New GPSDO on EBAY From China

Charles Steinmetz csteinmetz at yandex.com
Mon Dec 29 00:50:31 EST 2014


Li Ang wrote:

>This unit is done by BG7TBL. In his store on taobao.com,
>there is a adev chart. Please refrer to this link

That ADEV chart (see below) raises more questions than it 
answers.  At least the time constant is not too short (a very common 
problem with DIY GPSDOs).  But when the GPS takes over above the 
crossover (tau ~ 5000 seconds), the ADEV is ~2e-11.  GPS should be 
significantly better than this at 5000 seconds.  It appears that 
something is wrong with the design.

Best regards,

Charles

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