[time-nuts] Is my Acutime broken ?

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sun Dec 20 07:58:57 UTC 2009


Adam Feigin wrote:
> I recently picked up an Acutime off of Ebay. I'm wondering if
>
> 1) The acutime is broken
> 2) There's something wrong with the cheapo USBtoRS422 convertor
> 3) My wiring
>
> It appears to function, but exhibits strange behavior. Here are 3 URLs
> with pngs of screenshots from the (they're 20K each, but I figured I'd
> save the bandwidth here)
>
> 1) http://www.iis.ee.ethz.ch/~feigin/acutime/allespaletti.png
>
> This would appear to be in normal operation
>
> 2) http://www.iis.ee.ethz.ch/~feigin/acutime/doingfixesnosvdata.png
>
> Here's an instance where the acutime indicates its in OD mode, but shows
> no SV signal data
>
> 3) http://www.iis.ee.ethz.ch/~feigin/acutime/only2usablesv.png
>
> Here's where its about 1/2 way done its site-survey, indicating that it
> only has 2 SVs available, and yet the SV data shows 7 satellites, 6
> with>  50 dbc/hz values
>    
SV geometry is also important so a plot of the SV positions would help.
If they are too low they wont be used even though the signal level is high.
Unfavourable relative positions in the sky will increase the position 
error significantly.
Ideally one or more SV directly overhead together with several uniformly 
scattered around the sky at lower altitudes  (but above a minimum) allow 
more accurate position calculations.
>
> Other strange behavior includes TR_Mon giving me "Floating point
> Overflow" errors, the product info window being sometimes completely
> empty, and other generally "weird" happenings. It does, however, on a
> Power Cycle, "do the right thing", gets the time from the first SV, and
> then going to OD mode when enough SVs are visible. I can even factory
> default it, and it will then do a site survey, and then go to OD mode....
>
> If its broke, thats (not really) fine, as I didn't pay all that much for
> it, and before I invest the time and effort making a cable for it (man,
> those Deutsch connectors are expensive!), I'd like to know for sure. Or
> perhaps its something else I missed.
>
> Thanks for any pointers
>
>
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>    
Bruce




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