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<tt>Dear Oskar,<br>
<br>
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.<br>
<br>
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.<br>
<br>
I would suggest that you simply filter the file before using it
and you should be fine with a command of the sort;<br>
> grep -v " 1.0" brdc220.15g > brdc220.15g_clean<br>
<br>
let me know privately if you can proceed with the '_clean' file <br>
<br>
I will bring this issue up within the IGS data centers to see how
we address it for the older stored brdc files.<br>
<br>
regards,<br>
<br>
Dr Nacho Romero<br>
IGS Infrastructure Committee Chair<br>
<br>
<br>
</tt><br>
<div class="moz-cite-prefix">On 02/11/2015 07:53, Oskar Sterle
wrote:<br>
</div>
<blockquote cite="mid:5637166B.9020700@fgg.uni-lj.si" type="cite">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
Dear Mr., Ms.,<br>
<br>
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 (<a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="ftp://cddis.gsfc.nasa.gov/gnss/data/daily/2015/220/15g/brdc2200.15g.Z">ftp://cddis.gsfc.nasa.gov/gnss/data/daily/2015/220/15g/brdc2200.15g.Z</a>)
there is:<br>
<br>
<tt> 1 15 8 8 0 45 0.0-0.151447951794D-03 0.000000000000D+00
0.180000000000D+04</tt><tt><br>
</tt><tt> -0.112675112305D+05-0.160253047943D+01
0.931322574616D-09 0.000000000000D+00</tt><tt><br>
</tt><tt>
0.256164208984D+04-0.266967201233D+01-0.931322574616D-09
0.100000000000D+01</tt><tt><br>
</tt><tt> -0.227310625000D+05 0.494499206543D+00
0.186264514923D-08 0.000000000000D+00</tt><tt><br>
</tt><tt>...</tt><tt><br>
</tt><tt> 1 15 8 8 1 15 0.0-0.151447951794D-03
0.000000000000D+00 0.360000000000D+04</tt><tt><br>
</tt><tt> -0.143798266602D+05-0.181855010986D+01
0.000000000000D+00 0.000000000000D+00</tt><tt><br>
</tt><tt>
-0.187464013672D+04-0.222508335113D+01-0.186264514923D-08
0.100000000000D+01</tt><tt><br>
</tt><tt> -0.209729423828D+05 0.144630336761D+01
0.186264514923D-08 0.000000000000D+00</tt><tt><br>
</tt><tt>...</tt><tt><br>
</tt><tt> 1 </tt><tt><font color="#cc0000"><b>15 8 8 1 15 1.0</b></font></tt><tt>-0.151447951794D-03
0.000000000000D+00 0.360000000000D+04</tt><tt><br>
</tt><tt> -0.143798266602D+05-0.181855010986D+01
0.000000000000D+00 0.000000000000D+00</tt><tt><br>
</tt><tt>
-0.187464013672D+04-0.222508335113D+01-0.186264514923D-08
0.100000000000D+01</tt><tt><br>
</tt><tt> -0.209729423828D+05 0.144630336761D+01
0.186264514923D-08 0.000000000000D+00</tt><br>
<br>
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).<br>
<br>
Did anybody else also encountered this problem?<br>
<br>
Oskar Sterle<br>
University of Ljubljana, Slovenia<br>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
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</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Best regards,
Nacho
_______________________________________________________________
Ignacio (Nacho) Romero
Aerospace Engineer, PhD
SAC @ ESA/ESOC/HSO-GN
IGS Infrastructure Committee
<a class="moz-txt-link-abbreviated" href="http://www.canaryadvancedsolutions.com">www.canaryadvancedsolutions.com</a>
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