1. Tuning AUTCLN for editing

2. Autcln basics Controlled by the autcln.cmd file
The defaults in the program are set for data from modern receivers
These default values need not be included in the command file
Post-fit cleaning is primary exception
Can be "tuned" extensively
Very useful for data from older receivers
13-Nov-18
GAMIT/GLOBK Tutorial 5

3. Basic aims and operation
Generate a set of one-way phase time series in which all cycle slips are either
corrected (with integer step functions)
flagged (to introduce real-valued offset)
“Bias flags” are used for cycle slips that cannot be resolved to integer values
Generate one-way phase residuals that can be used for data weighting
13-Nov-18
GAMIT/GLOBK Tutorial 5

4. How autcln works (1) Generate models for receiver and satellite clocks
Measure clock offset epoch-by-epoch using pseudorange data
Align offsets with the polynomial estimated from the K- and J-files.
(2) Identify and flag possible jumps in phase data
using wide-lane (WL) when available
and/or ionospheric-delay (LG) phase
13-Nov-18
GAMIT/GLOBK Tutorial 5

5. How autcln works (II)
(3) Align the phase data with the range clock solution
look for large slips in the phase data
look for jumps in the ionospheric delay
(4) Scan selectively double differenced phase
Look for jumps
Attribute each DD jump to 1 sat and 1 station
(5) Iterate steps 1-4 to improve estimates
Phase data set now bias flags at each possible slip and after gaps
13-Nov-18
GAMIT/GLOBK Tutorial 5

6. How autcln works (III) (6) Remove short segments
(Actually, they are assigned a flag to “unweight” them.)
(7) Estimate the number of cycles missing (jumped) at each bias flag
by polynomial fits to surrounding data
use good data from other stations and satellites.
determine integer values and their reliability
13-Nov-18
GAMIT/GLOBK Tutorial 5

7. How autcln works (IV) (7) Iterate step 7 using previously-cleaned data
(8) Estimate receiver and satellite clock offsets again
use the phase data in an iterative process
generate new one-way phase residuals
(sum for each station and satellite is zero)
(9) Write clean C-files
preserve input C-files, OR
over-write intermediate C-files
13-Nov-18
GAMIT/GLOBK Tutorial 5

8. autcln command file
Go to your computer to examine the distributed autcln.cmd file
Note the use of the POST option
Which options would you change for older code-less data?
Using sh_gamit makes 2 summaries:
autcln.cmd.prefit AND
autcln.cmd.posfit
13-Nov-18
GAMIT/GLOBK Tutorial 5

9. Checking autcln.sum files
Postfit scatter
Usually RMS < 10 mm
Discarded data
Usually < 10% data discarded
More than 20% discarded indicates problem
Missed cycle slips are now very rare
Most problematic slip is
1 cycle in L1 AND 1 cycle in L2
does not change WL
13-Nov-18
GAMIT/GLOBK Tutorial 5

10. Why are ALL the data from my favorite station deleted?
This question is number 1 FAQ
Bias flags too close together
Post-fit phase RMS too large
Check editing reports in autcln.sum
Bad apriori coordinates
Example /dell3/tah/swis/gps00/1999_149/autcln.post.sum
13-Nov-18
GAMIT/GLOBK Tutorial 5

11. Autcln commands Read the $HELP_DIR/autcln.hlp file
Also output by just typing autcln
13-Nov-18
GAMIT/GLOBK Tutorial 5

12. Tuning autcln dd_fit_tol ion_jump trim_oneway
sets the sizes of jumps to be flagged as
ratio to rms
min size
max size
ion_jump
similar parameters for ionspheric jumps
trim_oneway
sets minimum sizes for segments of data as
time
number of epochs
ratio to good length
min at end
13-Nov-18
GAMIT/GLOBK Tutorial 5

13. Summary Default autcln.cmd usually works fine Tuning is useful for
anomalous data
some old data
If you need to tune
delete the link in the day dir -> tables dir
copy the autcln.cmd file to the day dir
modify the autcln.cmd file in the day dir
re-run sh_gamit (or bexpt?.bat) for that day
13-Nov-18
GAMIT/GLOBK Tutorial 5