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Landman
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Just submitted a 31/2 hr. observation and got this message back: The file 3867_2.19o seems to have a collection interval of 4 seconds!brThe collection interval must be 1,2,3,5,10,15 or 30 seconds to be processed by OPUS.

Any way of fixing this without reobserving?

Thanks

 

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Bill93
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I think you are stuck with re-observing, since OPUS is trying to get to 30 seconds and that is not a multiple of 4.  You dont have observations at every-other time it wants.

Posted by: Landman

Just submitted a 31/2 hr

I'm still trying to figure out if that was 3  1/2, as I would have guessed  or 31 1/2 as some responding assumed.
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Landman
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It was meant to say 3-1/2 hrs.

Thanks

 

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Loyal
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Landman,

 

Send me your RINEX file, and I'll take a look at it.

LDOGEO...at....aol.com

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Lee D
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Yep my mind saw 31 1/2 hours sorry

 

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Lee D
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Two things -

- OPUS doesn't like data sets that cross over two days (GPS time)

- What recording rate did you actually log at?

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Landman
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I thought it was set at 1 sec.  I have no idear how it got to 4

 

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Lee D
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Personally, I'd take that 31 1/2 hour session and use TEQC to split it up into three or four shorter sessions. Comparing the results of multiple sessions and calculating a set of weighted mean coordinates has more value than running a single very long session. The precision curve of an OPUS session pretty much flattens out at around six hours.

I found the attached to be informative on this subject.

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Bill93
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Breaking up a long file can give you a sense of the variation.
But an unweighted average of several short sessions loses the advantage OPUS has in weighting the data according to the varying number of satellites or DOP.  So I would expect its answer to be slightly more accurate.

 

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Mark Silver
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Sometimes the recording interval at the beginning of a file has gaps that make it look like 4 second, but may just be a single epoch followed by 3 seconds of no data and then 1-second data.

So it is worth taking a look at the data and perhaps trimming the beginning couple of minutes of the file.

If the data really is 4-second interval you could try interpo [ link ]. It has been a long time since I used it, so long that I can't remember if it worked the last time I tried. But it does still run in a DOS box.

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Landman
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Thank you Mark, that seems to have been the problem.  I used winteqc to trim it and resubmitted it and it processed fine. You made my day!

 

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A Harris
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The static sessions should be kept withing the parameters of the unit.

Mostly, limit the range between the receivers to not exceed your having to have over extended occupation times for new locations and most importantly, work within a box. 

I set control points about 4mi apart and use a network of equilateral triangular locations when possible.

When I expand my network I use the same technique to set new control points and they are always set from two adjacent exiting control points.

An obtuse triangle situation can look good on paper and yield really messed up physical location.

These numbers work good with me and allow for minimum setup time on a project inside my control network.

When the box is too small, the geometry is not there for the satellite information to help the static method.

Today's results are much better than 15yrs ago as the ever expanding accuracy of the overall GPS dynamic has improved and allows for smaller boxes.

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