[time-nuts] GPRS zero azimuth and elevation, most PRN displayed as not O/K,

Mark C. Stephens marks at non-stop.com.au
Wed Jun 26 23:02:18 EDT 2013


I miss-advertently restarted the GPSR-A due to the after effects of a liquid lunch.. 

and about 30 minutes later:

E-113>:syst:stat?
[ Active ] -------------------- GPSR 2 Status --------------------------------
SYNCHRONIZATION ........................... [ Outputs Valid/Reduced Accuracy ]
SmartClock Mode _________________________    Reference OutPuts _______________
>> Locked to GPS                             TFOM     3          FFOM        0
   Recovery                                  1PPS TI  +400 ns
   Holdover                                  HOLD THR
   Power-up                                  Holdover Uncertainty_____________
                                             Predict

ACQUISITION ............................................... [ GPS 1PPS Valid ]
Tracking: 8       Not Tracking: 4            Time ____________________________
PRN  El  Az  C/N   PRN  El  Az               GPS      02:56:29     27 Jun 2013
  3   25 228   50   15  Not OK               GPS 1PPS  Synchronized to GPS
  6   42 239   49   16  Not OK               ANT DLY       0 ns
 14   21 349   51   24  Not OK               Position ________________________
 18   70 181   46   29  Not OK               MODE     Survey:  45.0% complete
 19    0   0   48
 21   62 109   52                            AVG LAT  S  33:45:49.292
 22   54 268   50                            AVG LON  E 151:05:31.486
 27   34 229   52                            AVG HGT          +112.91 m  (MSL)
ELEV MASK 10 deg
HEALTH MONITOR ........................................................ [ OK ]
Self Test: OK   Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK
Alarms:    (none)


Now, Compared to a Z3805A for the same time, same place:

         HEWLETT-PACKARD,Z3805A,3502A00508,3543B-A. Life count: 33099
SYNCHRONIZATION ............................................. [ Outputs Valid ]
SmartClock Mode ___________________________   Reference Outputs _______________
>> Locked to GPS                              TFOM     3             FFOM     0
   Recovery                                   1PPS TI +3.0 ns relative to GPS
   Holdover                                   HOLD THR 1.000 us
   Power-up                                   Holdover Uncertainty ____________
                                              Predict  1.3 us/initial 24 hrs
                                                
ACQUISITION ............................................ [ GPS 1PPS CLK Valid ]
Satellite Status __________________________   Time ____________________________
Tracking: 6        Not Tracking: 4            LOCAL    12:55:57     27 Jun 2013
PRN  El  Az   SS   PRN  El  Az                1PPS CLK Synchronized to UTC
  6  49 276   94     3  36 252                ANT DLY  28 ns
 14  47 347   86    15  13 137                Position ________________________
 18  52 139  167    19  25 227                MODE     Hold
 21  46  71  130    24  18 103                
 22  65 218  184                              LAT      S  33:45:49.225
 27  47 258  114                              LON      E 151:05:31.528
ELEV MASK 10 deg                              HGT               +80.11 m  (MSL)
HEALTH MONITOR ......................................................... [ OK ]
Self Test: OK    Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK 

Actually, A Z3815A might be better as it uses c/n

  HEWLETT-PACKARD,Z3815A,KR73503191,U-4010.0-A. Life count: 39166
[ Active ] --------------------- GPSR 2 Status --------------------------------
SYNCHRONIZATION ............................................. [ Outputs Valid ]
SmartClock Mode ___________________________   Reference Outputs _______________
>> Locked to GPS                              TFOM     3             FFOM     0
   Recovery                                   1PPS TI +12.0 ns relative to GPS
   Holdover                                   HOLD THR 1.000 us
   Power-up                                   Holdover Uncertainty ____________
                                              Predict: 1.5 us/initial 24 hrs
                                                
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 8 ____   Not Tracking: 2 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                LOCAL    12:57:40     27 Jun 2013
  3  36 252   50    19  25 227                GPS 1PPS Synchronized to UTC
  6  48 277   49    24  18 103                ANT DLY  28 ns
 14  48 347   47                              Position ________________________
 15  12 138   44                              MODE     Hold
 18  52 139   47                              
 21  46  71   47                              LAT      S  33:45:49.500
 22  65 217   47                              LON      E 151:05:31.734
 27  47 258   50                              HGT               +95.40 m  (MSL)
ELEV MASK 10 deg                              
HEALTH MONITOR ......................................................... [ OK ]
Self Test: OK    Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK 
Alarms:    (none)

Hmm, the Z3815A Holdover predicted uncertainty is usually down around 100-400ns but it's particularly rainy, cloudy and stormy today, here.
But the c/n are roughly the same so I guess the front end of the GPS module is o/k.

All the Receivers are fed off the same splitter so it's not an antenna issue.

I must mention I took your advice and did a syst:pres last night which seems to have made it behave slightly better.
But look at the PPS offset. 400ns is not good.
I think the GPS module is possibly a bit wacky (I mean off frequency or something, dunno).
That could also explain why it has difficulties in calculating the position of the satellites.
It's looks like a standard Motorola UT RX but with the battery add on.
I checked the battery and its 3v.

I think I'll let the survey complete and if it's still wonky I'll drop another Moto receiver in and see what happens,
I mean what's the worst thing that could happen, the GPSDO could change the firmware on the module to 3.2 or something ;)

But anyway, Let's see what happens at the end of survey.


-marki

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Azelio Boriani
Sent: Thursday, 27 June 2013 2:37 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPRS zero azimuth and elevation, most PRN displayed as not O/K, 

12 minutes are enough to receive the data... another strange thing is that you have the 1PPS TI always 0. Have you already given the :SYST:PRES command to preset the receiver to the factory settings?

On Wed, Jun 26, 2013 at 6:13 PM, Mark C. Stephens <marks at non-stop.com.au> wrote:
> Hi Azelio, err...
>
>
> E-113>:syst:stat?
> [ Unlocked ] ------------------ GPSR 2 Status 
> -------------------------------- SYNCHRONIZATION ........................... [ Outputs Valid/Reduced Accuracy ]
> SmartClock Mode _________________________    Reference OutPuts _______________
>    Locked to GPS                             TFOM     3          FFOM        3
>    Recovery                                  1PPS TI  +0 ns
>    Holdover                                  HOLD THR
>>> Power-up: OCXO Warm-up                    Holdover Uncertainty_____________
>                                              Predict
>
> ACQUISITION ............................................... [ GPS 1PPS Valid ]
> Tracking: 6       Not Tracking: 0            Time ____________________________
> PRN  El  Az  C/N   PRN  El  Az               LOCL GPS 02:10:05     27 Jun 2013
>   7    0   0   39                            GPS 1PPS  Synchronized to GPS
>   8    0   0   50                            ANT DLY      28 ns
>   9    0   0   52                            Position ________________________
>  15    0   0   44                            MODE     Survey:   1.3% complete
>  17    0   0   49
>  24    0   0   39                            AVG LAT  S  33:45:49.689
>                                              AVG LON  E 151:05:31.705
>                                              AVG HGT          +131.66 m  (MSL)
> ELEV MASK 10 deg
> HEALTH MONITOR ........................................................ [ OK ]
> Self Test: OK   Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK
> Alarms:    (none)
>
>
>
>
> They are all zero now!
> I have just changed eman to 10 and rebooted.
> I guess it must be something to do with almanac, perhaps being patient 
> and waiting a day or 3 may yield a change.
> Hopefully for the better.
>
>
> marki
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] 
> On Behalf Of Azelio Boriani
> Sent: Wednesday, 26 June 2013 7:09 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] GPRS zero azimuth and elevation, most PRN 
> displayed as not O/K,
>
> Try to put the elevation mask to 10degrees, not 25 :GPS:SAT:TRAC:EMAN 
> 10
>
> On Tue, Jun 25, 2013 at 8:41 AM, Mark C. Stephens <marks at non-stop.com.au> wrote:
>> I have a GPSR2 with unusual; GPS behaviour.
>>
>> E-113>:syst:stat?
>> [ Active ] -------------------- GPSR 2 Status
>> -------------------------------- SYNCHRONIZATION ........................... [ Outputs Valid/Reduced Accuracy ]
>> SmartClock Mode _________________________    Reference OutPuts _______________
>>>> Locked to GPS                             TFOM     3          FFOM        0
>>    Recovery                                  1PPS TI  +0 ns
>>    Holdover                                  HOLD THR
>>    Power-up                                  Holdover Uncertainty_____________
>>                                              Predict
>>
>> ACQUISITION ............................................... [ GPS 1PPS Valid ]
>> Tracking: 5       Not Tracking: 7            Time ____________________________
>> PRN  El  Az  C/N   PRN  El  Az               GPS      06:37:39     25 Jun 2013
>>   1    0   0   49    3  Not OK               GPS 1PPS  Synchronized to GPS
>> 11    0   0   47    6  Not OK               ANT DLY      28 ns
>> 14   25 349   43   15  Not OK               Position ________________________
>> 31    0   0   49   18  Not OK               MODE     Hold
>> 32    0   0   47   21  Not OK
>>                     22  Not OK               LAT      S  33:45:49.374
>>                     27  Not OK               LOG      E 151:05:31.495
>>                                              HGT              +118.61 m  (MSL)
>> ELEV MASK 25 deg
>> HEALTH MONITOR ........................................................ [ OK ]
>> Self Test: OK   Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK
>> Alarms:    (none)
>>
>>
>> As you can see the Azimuth and elevation are zero.
>>
>> Group opinion please, bad antenna connector or bad GPS module?
>>
>>
>> -marki
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