[IGS-DCWG-131] Re: Problematic GLONASS navigation files ...

Tue Nov 3 00:13:25 PST 2015

Hi Oskar,

The command I suggested would not work since you have to exclude the 
entire block of data not just that line!!  sorry. you can see the entire 
block that has to be excluded with a simple:

 > grep -A 3 "  1.0" brdc2200.15g

but I must admit I cannot think off the top of my head how to exclude 
the blocks in a simple command, maybe someone else can think how!  
Thanks. A very simple script would do the job of course.

regards,

Nacho

On 03/11/2015 07:57, Nacho Romero wrote:
> Dear Oskar,
>
> It is not correct to post to this list as it is only for members of 
> the Data Center Working group, and only for data center questions and 
> not for data questions!  please use the IGSMail email list for general 
> questions as it also benefits the community at large.  Thanks.
>
> The issue you note is indeed correct, a certain version of the RINEX 
> generation software was generating glonass navigation files with a 1 
> sec epoch issue as you have found due to the introduction of a leap 
> second during last summer.  It took some time to correct the problem 
> at all the stations affected so it also affected the general "brdc" 
> navigation file.
>
> I would suggest that you simply filter the file before using it and 
> you should be fine with a command of the sort;
> > grep -v "  1.0" brdc220.15g > brdc220.15g_clean
>
> let me know privately if you can proceed with the '_clean' file
>
> I will bring this issue up within the IGS data centers to see how we 
> address it for the older stored brdc files.
>
> regards,
>
> Dr Nacho Romero
> IGS Infrastructure Committee Chair
>
>
>
> On 02/11/2015 07:53, Oskar Sterle wrote:
>> Dear Mr., Ms.,
>>
>> I was doing some processing of GPS / GLONASS data on a basis of 
>> broadcast  ephemeris and I got extremely bad results for GLONASS 
>> data. After some analysis I found that the GLONASS navigation files 
>> are, in my opinion, incorrect. I found out that the problem is 
>> evident after leap second 17 introduction, where some of the 
>> broadcast navigation data, stored in brdcDDD0.YYg files, contain an 
>> additional 1 second in an epoch. As an example, in a file 
>> brdc2200.15g 
>> (ftp://cddis.gsfc.nasa.gov/gnss/data/daily/2015/220/15g/brdc2200.15g.Z) 
>> there is:
>>
>>  1 15  8  8  0 45  0.0-0.151447951794D-03 0.000000000000D+00 
>> 0.180000000000D+04
>>    -0.112675112305D+05-0.160253047943D+01 0.931322574616D-09 
>> 0.000000000000D+00
>> 0.256164208984D+04-0.266967201233D+01-0.931322574616D-09 
>> 0.100000000000D+01
>>    -0.227310625000D+05 0.494499206543D+00 0.186264514923D-08 
>> 0.000000000000D+00
>> ...
>>  1 15  8  8  1 15  0.0-0.151447951794D-03 0.000000000000D+00 
>> 0.360000000000D+04
>>    -0.143798266602D+05-0.181855010986D+01 0.000000000000D+00 
>> 0.000000000000D+00
>> -0.187464013672D+04-0.222508335113D+01-0.186264514923D-08 
>> 0.100000000000D+01
>>    -0.209729423828D+05 0.144630336761D+01 0.186264514923D-08 
>> 0.000000000000D+00
>> ...
>>  1 *15  8  8  1 15 1.0*-0.151447951794D-03 0.000000000000D+00 
>> 0.360000000000D+04
>>    -0.143798266602D+05-0.181855010986D+01 0.000000000000D+00 
>> 0.000000000000D+00
>> -0.187464013672D+04-0.222508335113D+01-0.186264514923D-08 
>> 0.100000000000D+01
>>    -0.209729423828D+05 0.144630336761D+01 0.186264514923D-08 
>> 0.000000000000D+00
>>
>> It can be seen that the red epoch has an increment of 1 second. Is 
>> this normal? Probably not, since any position of satellite R01 after 
>> 1:15:01 is wrong for approximately 4km (1s of travel time).
>>
>> Did anybody else also encountered this problem?
>>
>> Oskar Sterle
>> University of Ljubljana, Slovenia
>>
>>
>> _______________________________________________
>> IGS-DCWG mailing list
>> IGS-DCWG at igscb.jpl.nasa.gov
>> https://igscb.jpl.nasa.gov/mailman/listinfo/igs-dcwg
>
> -- 
> Best regards,
> Nacho
> _______________________________________________________________
>
> Ignacio (Nacho) Romero
> Aerospace Engineer, PhD
> SAC @ ESA/ESOC/HSO-GN
> IGS Infrastructure Committee
> www.canaryadvancedsolutions.com
> _______________________________________________________________
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-- 
Best regards,
Nacho
_______________________________________________________________

Ignacio (Nacho) Romero
Aerospace Engineer, PhD
SAC @ ESA/ESOC/HSO-GN
IGS Infrastructure Committee
www.canaryadvancedsolutions.com
_______________________________________________________________
Este mensaje, y en su caso, cualquier fichero anexo al mismo,
  puede contener informacion clasificada por su emisor como confidencial
  en el marco de su Sistema de Gestion de Seguridad de la
Informacion siendo para uso exclusivo del destinatario, quedando
prohibida su divulgacion copia o distribucion a terceros sin la
autorizacion expresa del remitente. Si Vd. ha recibido este mensaje
  erroneamente, se ruega lo notifique al remitente y proceda a su borrado.
Gracias por su colaboracion.
_______________________________________________________________
This message including any attachments may contain confidential
information, according to our Information Security Management System,
  and intended solely for a specific individual to whom they are addressed.
  Any unauthorised copy, disclosure or distribution of this message
  is strictly forbidden. If you have received this transmission in error,
  please notify the sender immediately and delete it.

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