GPS Date and Time from dc or TGO

Hi Chris

I played around with the creation of custom queries and exports from TGO by manipulating the MDB schema a number of years ago. It worked - sort of - but it was a long learning curve. One important lesson learned was that changes to the schema in TGO version 1.50 were not supported in TGO version 1.63. When I tried to upgrade a project containing a custom query from 1.50 to 1.63 it crashed the program. I had to restore the old database from a backup.

Extracting data from a DC format file downloaded from the data collector was easier. Information about the records contained in a version 10.70 (and other) DC format files can be found at:
Trimble Survey Controller ver 10.x documentation

Personally, I've turned my attention to working with the JXL (XML) file format instead since it offers much for flexibility particularly with writing custom stylesheets that can be run directly on the data collector. The Date and Time records are readily available.

Scott

Scott,
I have been googling the GPS-time format and will find a way to convert it.
I'll hope to make some time to take a closer look at the xml style sheets, what would you recommend as a guide to start, I did browse the Trimble papers some moths ago ... it's a complete different approach compared to traditional windows programming (I've been working with Delphi - Turbo Pascal for almost 15 yrs I think). I modified a report to sort our field notes but ran into memory troubles on the TSC2, so I left this path.

thanks for the advice,
chr.

Hi Chris

The only documentation I've been working with to date for style sheets is the stuff on the Trimble support site:

Style Sheet Documentation

I've simply opened up a number of the custom export style sheets available via that link and looked to see how they work. There are a number of good ideas to be 'borrowed'.

This site has a good primer on working with XML:

Introduction to XML

Trimble has migrated to XML file formats for data exchange - the JXL files can be directly imported into TBC and utilities written to extract custom reports, ie for RTK redundancy checks.

I recommend the XML style sheet development as it will provide the best opportunities for the future.

FYI you might have a look at the GPS Toolbox compiled by Michael Craymer (GSC/NRCan) and Steve Hilla (NGS/NOAA) for algorithms and source code for converting GPS date/times along with some other goodies:

http://www.ngs.noaa.gov/gps-toolbox /">GPS Toolbox

Scott

This may or may not help, but the way I convert week and time-of-week data to a date using VB is to use the dateadd function. First I add the week number to 1/6/1980. That gives the date of the start of the week (midnight Sunday). Then I add the seconds to that date. Code is as follows:

startofweek = DateAdd("ww", weeknum, "1/6/1980")
UTCstart=DateAdd("s", sow, startofweek)

For Trimble DC data, I use the info stored in the QC1 record:

startofweek = DateAdd("ww", Val(Mid$(QC1Rec$, 108, 4)), "1/6/1980")
UTCstart= DateAdd("s", Val(Mid$(QC1Rec$, 112, 16)), startofweek)