Re: reading Skytraq: part of exported tracklog is repeated

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Re: reading Skytraq: part of exported tracklog is repeated

by Robert Lipe-4 :: Rate this Message:

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I use a Canmore USB thumbdrive data logger (GT-730FL-S) with GPS
Babel. I wrote the python script below for extraction:
(the main thing to notice is the switches)

It works fine except that the tracklogs always have a section that is
repeated. For example, in a particular gpx file, the vertices from
1530 ~ 2038 are exactly the same as the vertices from ~ 1020 ~ 1529.

It's likely that you have corruption in the flash on the device. These low-end devices tend to behave badly. Things like running out of battery often corrupts the memory in them in weird ways. Manually clean up the tracks the best you can and erase the memory seems to be the norm.

RJL

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Re: reading Skytraq: part of exported tracklog is repeated

by Robert Lipe-4 :: Rate this Message:

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On Fri, Dec 16, 2011 at 12:04 PM, Evan Thoms <ethoms@...> wrote:

Thanks RJL,
are you suggesting that the memory might be corrupted for good or that erasing it might fix the problem (for awhile)? In either case, is there a parameter I should use in the command line besides 'erase' that would more completely re-format the memory?

Most likely the latter is the case. While it's possible that you have a bad sector in a flash chip, it's far more likely that the software controlling the internal "file system" was merely developed by programmers that didn't understand transactional integrity in light of losing battery, dropping it and losing power for a few zilliseconds, etc. (Sorry, guys...)

Perhaps other owners of Canmore or Skytraq can pipe in with their experiences.

RJL

Evan Thoms U.S. Geological Survey, Alaska Science Center 4210 University Drive, Anchorage, AK 99508 voice: 907-786-7409 fax: 907-786-7401 ethoms@...

On 12/15/2011 5:48 PM, Robert Lipe wrote:

I use a Canmore USB thumbdrive data logger (GT-730FL-S) with GPS
Babel. I wrote the python script below for extraction:
(the main thing to notice is the switches)

It works fine except that the tracklogs always have a section that is
repeated. For example, in a particular gpx file, the vertices from
1530 ~ 2038 are exactly the same as the vertices from ~ 1020 ~ 1529.

It's likely that you have corruption in the flash on the device. These low-end devices tend to behave badly. Things like running out of battery often corrupts the memory in them in weird ways. Manually clean up the tracks the best you can and erase the memory seems to be the norm.

RJL