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Old October 12th 16, 11:14 AM posted to sci.geo.satellite-nav
Terje Mathisen[_3_]
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Posts: 26
Default Why are a few timestamps missing?

Terry Pinnell wrote:
I've been examining the GPS recordings of walks made on my iPhone. The
GPX files should of course contain one text line for each position
recorded, containing position, altitude and a timestamp. But
occasionally (less than 1%) the timestamp is obviously missing. The
4th line of this small extract shows an example:

trkpt lat="50.5573525932"

trkpt lat="50.5573393079" lon="-4.9283319153"ele22/ele/trkpt

trkpt lat="50.5573267350"

How does that flaw arise please? I can understand that for various
reasons, recorded trackpoints may be missing completely, or wildly
inaccurate. But how can some be without a timestamp?

Note that the two surrounding track points have just one second between
them: I'm guessing your logging app skips the timestamp when it is
identical to the previous one.

A very simple parser that ust picks up fields as it finds them will
remember the previosu timestamp and repeat it.

- Terje.Mathisen at
"almost all programming can be viewed as an exercise in caching"