[LEAPSECS] Leap Second and GNSS Probems

[Richard B. Langley]

The u-blox company has told me that the receiver reset was expected at  
the leap-second adjustment. "Due to limited amount of information on  
GLONASS system available our approach was to issue a cold start  
command at leap second adjustment to prevent receiver lock up, etc.   
Now we have collected real data from GLONASS system during leap second  
event and will be looking at incorporating time change without reset  
in the future versions of firmware."

-- Richard Langley

On 1-Jul-12, at 11:24 PM, Richard B. Langley wrote:


> A u-blox 6 GPS Engine did not play nice with the leap second. This  

> new engine is GPS/SBAS/QZSS/GLONASS compatible but it only runs in  

> either GPS/SBAS/QZSS mode or GLONASS mode. I was running it under  

> GLONASS mode for the leap second check and recording its NMEA  

> messages. Just before the leap second, it was tracking 9 satellites.  

> At the leap second it reset itself. I don't know if this was caused  

> by an error associated with the leap second or the receiver was  

> programmed to do this. At second 0 of 1 July, it ceased positioning  

> and did not know the time (at least no information was in the $GLZDA  

> NMEA message). At 00:00:40.48 seconds, it once again knew UTC, and  

> by 00:02:39.00, it was tracking enough GLONASS satellites (4) to  

> report position information again. Extracted $GLGGA and $GLZDA  

> messages from before and after the leap second are in the appended  

> file.

> I'll be contacting u-blox to report the behaviour.

>

> Note that when I was monitoring a previous leap second with a GPS- 

> only u-blox receiver, it sailed through the leap second with no  

> problem:

> $GPZDA,235955.00,31,12,2005,00,00*6D

> $GPZDA,235956.00,31,12,2005,00,00*6E

> $GPZDA,235957.00,31,12,2005,00,00*6F

> $GPZDA,235958.00,31,12,2005,00,00*60

> $GPZDA,235959.00,31,12,2005,00,00*61

> $GPZDA,235960.00,31,12,2005,00,00*6B

> $GPZDA,000000.00,01,01,2006,00,00*62

> $GPZDA,000001.00,01,01,2006,00,00*63

> $GPZDA,000002.00,01,01,2006,00,00*60

> $GPZDA,000003.00,01,01,2006,00,00*61

> $GPZDA,000004.00,01,01,2006,00,00*66

> $GPZDA,000005.00,01,01,2006,00,00*67

>

> We may have had trouble tracking GLONASS satellites with some of the  

> continuously operating GNSS receivers operating at UNB and the  

> Russian Space Agency may have had trouble monitoring the GLONASS  

> satellites. I'll report on these anomalies later.

>

> -- Richard

>

> -----------------------------------------------------------------------------

> | Richard B. Langley                            E-mail:  

> lang at unb.ca         |

> | Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/ 

>  |

> | Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506  

> 453-5142   |

> | University of New Brunswick                   Fax:      +1 506  

> 453-4943   |

> | Fredericton, N.B., Canada  E3B  

> 5A3                                        |

> |        Fredericton?  Where's that?  See: http:// 

> www.fredericton.ca/       |

> -----------------------------------------------------------------------------

>

> -----------------------------------------------------------------------------

> | Richard B. Langley                            E-mail:  

> lang at unb.ca         |

> | Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/ 

>  |

> | Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506  

> 453-5142   |

> | University of New Brunswick                   Fax:      +1 506  

> 453-4943   |

> | Fredericton, N.B., Canada  E3B  

> 5A3                                        |

> |        Fredericton?  Where's that?  See: http:// 

> www.fredericton.ca/       |

> -----------------------------------------------------------------------------

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| Richard B. Langley                            E-mail:  

lang at unb.ca         |

| Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/ 

  |

| Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506  

453-5142   |

| University of New Brunswick                   Fax:      +1 506  

453-4943   |

| Fredericton, N.B., Canada  E3B  

5A3                                        |

|        Fredericton?  Where's that?  See: http:// 

www.fredericton.ca/       |
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