[OSM-talk] Conflating Tracks - getting error margin from Garmin devices

[Ed Avis]

Karl Newman <siliconfiend <at> gmail.com> writes:

>>Are any of you aware of a conflation algorithm that "snaps" GPS tracks
>>to the street grid?  This could be a useful way to verify existing
>>road networks and fill in any gaps.

>To do that you'd ideally want to know the margin of error for the GPS readings.
>My GPS unit (Garmin eTrex Vista HCx) shows an error circle on its screen

>I have a Vista HCx, too. Bafflingly, Garmin does not store the DOP with the
>tracklog and there is no way to extract it after the fact (or even realtime, I
>don't think).

Oh, that is disappointing.

>If you can get an NMEA stream, you can get the HDOP (which is what you care
>about for this application). The USB-only Garmin units (like the Vista HCx)
>cannot emit a NMEA stream like the serial-enabled units could.

Apparently the Windows program GpsGate can convert the output from the USB
Garmin devies to NMEA format.  I wonder if there is a free equivalent to get it
working with gpsd or similar on Linux?

-- 
Ed Avis <eda at waniasset.com>