[time-nuts] Dual GPSDO - any advantage?

CORNACCHIA corcsal at yahoo.ca
Tue Apr 10 18:35:39 UTC 2018


 Bert may I ask how you created the charts (what software are you using).Thank You
    On Tuesday, April 10, 2018, 9:04:58 a.m. EDT, ewkehren via time-nuts <time-nuts at febo.com> wrote:  
 
 Looking at the pictures it is the same unit I bought. It is not dual oven bit trimble works with LH right now shows tracking 10 satelites.Attached  is data that made  me buy a second one for Jürg for $ 129  and one more for me for $9.50.What you see is highly filtered data to see long time changes to better understand if analog filtering os possible. Planning on using Wenzel 600 sec. Filter maybe up to 2000 seconds. Board is ready for order.Top plot is my data against my Cs 5061B bottom is original Tbolt against his FTS  Cs. We use 53132 counters.I think  the new one lends it self better for filtering looking at both  with my Tracor, Trimble uses a  much shorter time constant and no short 1E-10 changes you see on our standard units.Will keep you posted         Bert Kehren

Sent from my Galaxy Tab® A
-------- Original message --------From: Tim Shoppa <tshoppa at gmail.com> Date: 4/10/18  6:46 AM  (GMT-05:00) To: Discussion of precise time and frequency measurement <time-nuts at febo.com> Subject: Re: [time-nuts] Dual GPSDO - any advantage? 
Most of the Chinese cheapo units have been frequency, not phase locked.

It would be great if you could put the GPSDO outputs into a 2 Channel scope and eyeball them for a while to see if they appear in phase (say plus-minus 20ns) over a few hours.

Tim N3QE

> On Apr 10, 2018, at 1:43 AM, donald collie <donaldbcollie at gmail.com> wrote:
> 
> I`ve just bought two GPSDO`s from China @ US$9-50 each [This is not an
> error!] They are stated as being new, and use a Trimball dual oven OCXO. I
> plan to run these in parallel [2 antennas, 2 feedlines, and 2 GPSDO`s] It`s
> been said that a man with two watches is never happy - unless, of course,
> they agree with each other ;-). Being identical the outputs should be
> coherent, unless one becomes faulty [one advantage of having two - any
> discrepancy and you know something must be wrong]], but is there some
> crafty way I can squeeze a little more "accuracy" out of two than if I only
> used one?
> TIA for your comments............................................Donald
> Brett Collie ZL4GX
> 
> PS : I have no connection to the eBay seller. The US$9-50 seems to include
> a basic puck antenna, long downlead, and 4 interseries adaptors
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