Re^6: Converting GPS seconds to readable time&date


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Re^6: Converting GPS seconds to readable time&date

by n3toy (Hermit)

on Jan 11, 2009 at 23:45 UTC ( [id://735580]=note: print w/replies, xml )

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in reply to Re^5: Converting GPS seconds to readable time&date
in thread Converting GPS seconds to readable time&date

If you have a good GPS device that's meant to do time-transfer

I do, and their (I have two, and neither have a display) PPS accuracy is within 20 nanoseconds of UTC (assuming you have accounted for the cable length from the antenna to the device). But the time displayed on a typical handheld consumer GPS for LBS (location based servies) are not "accurate" to that level. (Although some quality handheld GPSs have a PPS (Pulse Per Second) that probably meet the specs you quote.) It is good enough to check against a known source to see if it is outputting UTC or GPS, as per the node I was commenting on.

The time displayed on a handheld GPS is derived from the processing of C/A code and is "old" by the time the display is updated.

But you are correct in that time-transfer is the whole foundation behind GPS, and LBS is only an application of the system.