[time-nuts] More GPS testing, KS-24361 quirk

Bob Camp kb8tq at n1k.org
Thu Aug 27 23:49:06 UTC 2015


Hi

It would be really interesting to eventually dig up a spec on just what these two 
boxes are supposed to do. There are far to many “interesting features” for them 
all to have been un-intentional.

Bob

> On Aug 27, 2015, at 5:41 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> More testing...
>  I lost everything from roughly 12:00-24:00 UTC Tue and 10:00-20:00 UTC Wed
> 
> 
> I stumbled into an interesting quirk in the KS-24361.
> 
> Short version:
>  After it has been in holdover for 5 or 6 minutes, the GPS unit switches to 
> tracking the non-GPS unit and says it isn't in holdover mode anymore.
> 
> Long story:
>  I have a program collecting statistics.  It was plugged into the unit with 
> the GPS, aka Secondary.  A graph of holdover time didn't make sense.
> 
> The response to ":ROSC:HOLD:DUR?" is something like 3.08000E+002,1  I think 
> the 1 at the end says it's in holdover mode and the 308 is the number of 
> seconds it has been in holdover.  Graphing holdover shows the ramp I expect 
> for 5 or 6 minutes. Then it drops out of holdover.  It returns to holdover 
> for a minute or two when I expect it to be recovering.
> 
> Digging deeper, the status page switches from
>>> Holdover: GPS 1PPS invalid
> to:
>>> Recovery: fine freq adj   [TI  -50.0 ns]   1PPS TI -50.0 ns relative to Ext
> and then to
>>> Locked to Ext: stabilizing frequency       TFOM     3             FFOM     
> 1
> 
> The other box,  non-GPS, aka Primary, does stay in Holdover.
> 
> --------
> 
> -------------------------- Secondary Receiver Status 
> --------------------------
> SYNCHRONIZATION ............................................. [ Outputs Valid 
> ]
> SmartClock Mode ___________________________   Reference Outputs 
> _______________
>>> Locked to Ext                              TFOM     3             FFOM     
> 0
>   Recovery                                   1PPS TI +50.0 ns relative to Ext
>   Holdover                                   HOLD THR 1.000 us
>   Power-up                                   Holdover Uncertainty 
> ____________
>                                              Predict  11.5 us/initial 24 hrs
> 
> ACQUISITION ................................................ [ Ext 1PPS Valid 
> ]
> Tracking: 0 ____   Not Tracking: 10 _______   Time 
> ____________________________
>                   PRN  El  Az  PRN  El  Az   UTC      06:40:32     27 Aug 
> 2015
>                   * 1  55 270  *31  64  90   GPS 1PPS Invalid: not tracking
>                   * 3  35 310  *32  72 352   ANT DLY  1.000 us
>                   * 4  52 216                Position 
> ________________________
>                   *11  37 243                MODE     Hold
>                   *14  23  56                
>                    22  17 114                LAT      N  37:26:04.813
>                   *23  23 260                LON      W 122:12:15.762
>                    25  10  55                HGT                +9.95 m  
> (GPS)
> ELEV MASK 10 deg   *attempting to track       
> HEALTH MONITOR ......................................................... [ OK 
> ]
> Self Test: OK    Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: 
> OK
> 
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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