Difference between revisions of "Short-hand"

Latest revision as of 23:56, 17 September 2007

The short_hand script is used to aid with cleaning GPS data. To run, you should be in the flt directory. Type:

  short_hand {solution-name}

{solution name} is all the text before the period in the filenames in the flt directory, e.g. 03jan 15alaska-nf.
The short-hand script runs a plotting program to show the postfit residuals for all the bad data in order from worst offender to least. Here are some examples of how situations might look like.

Furthermore, the program will first deal with the P-code problems and you may be asked to approve the deletion of a list of P-code outliers (I usually just say yes, so in answer to 'select points to be deleted?' I type . (no), then for 'delete points?' I type 0 (yes)).

Next, the program looks at the phase problems. It will order the outliers (problem points) from the biggest outlier (worst problem) to smalled outlier. For the first go-through, you may not need to go through the whole list, but just deal with the worst problems and then re-run the solution.
For each outlier, the program will create a plot of residuals for the station-satellite pair that contains the outlier. You then judge whether to

• delete the point (type 1),
  
• add an ambiguity (type 2),
  
• do nothing (type 3) or
  
• stop going through the list of points and just deal with what you've done so far (type 4).
  

Once you are done (either by going through the whole list of problem points or by typing 4), you will be asked whether you want to add more points to be deleted (a chance to add or delete points from the list opf points that will be deleted) and then whether you want to delete the points. Next you'll be asked the same questions but for adding ambiguities. Note that ambiguities should be added to the point AFTER the cycle-slip and so the point that has the largest residual may not be the point where you add the ambiguity.

At the end you are asked whether you want to delete the files. If you have had to delete points or add ambiguities, then type O (yes), otherwise type . to compress the files and keep them in the flt directory.