diff options
| author | Eric S. Raymond <esr@thyrsus.com> | 2005-04-30 21:26:51 +0000 |
|---|---|---|
| committer | Eric S. Raymond <esr@thyrsus.com> | 2005-04-30 21:26:51 +0000 |
| commit | 48f088e68dbb390293960db6b4a954c8dd5cd0b6 (patch) | |
| tree | e5f2e669e2261f0379c84634c5d61f98cbfbc99b /TODO | |
| parent | 5ec7aceb321a9e6044d8e5403885a735f3271c48 (diff) | |
| download | gpsd-48f088e68dbb390293960db6b4a954c8dd5cd0b6.tar.gz | |
Another round of fixes from Rob Janssen.
Diffstat (limited to 'TODO')
| -rw-r--r-- | TODO | 8 |
1 files changed, 3 insertions, 5 deletions
@@ -85,10 +85,7 @@ general case. There are clock drift and bias fields in the SiRF binary protocol, but I don't know how to interpret these. Does anyone? -B. SiRF binary reports HDOP, SiRF and other NMEA devices report -HDOP/VDOP/PDOP. - -C. Only Garmin devices report estimated position uncertainties in meters. +B. Only Garmin devices report estimated position uncertainties in meters. They won't say what the confidence interval is, but it is generally believed to be 1-sigma. See <http://gpsinformation.net/main/epenew.txt>. @@ -101,7 +98,8 @@ Here is what I am presently doing in the new E command: What non-Garmin GPSes will return in the E command is UERE multiplied by PDOP/HDOP/VDOP. Annoyingly, SiRF binary mode only offers HDOP, -one respect in which it is functionally inferior to SiRF NMEA. +one respect in which it is functionally inferior to SiRF NMEA. We +compute VDOP and PDOP using an algorithm supplied by SiRF. I don't know, because my sources didn't give, the confidence level associated with the range uncertainties in gpsd.h. My educated guess |