<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe said:
"JD" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe wrote: > "JD" <[email hidden]> wrote in message > news:[email hidden]... > > > > Ride-A-Lot wrote: > >> This is an out and back trail, so I would think that the tracks > >> should > >> overlap. Can the GPS be that off? > > > > > > Even without Selective Availability anymore, it's really only > > accurate > > to within three meters if you have a 3-dimensional reading from > > getting > > at least four satellites in the constellation of 26 (2 spares in > > case > > one malfunctions beyond tele-repair). If you don't get a > > 3-dimensional > > reading, it can be off up to 30 meters +. > > > > Now go buy a map and become a true cartographer. > > > > JD > > > > More like 5 m if your lucky
I was just relaying the party line on it. I wouldn't count on even 5m on a typically good mountain bike trail because of the terrain and trees.
JD
You are exactly right. And as you know, trails if mapped, are not mapped to that precision.
Road and trail systems with in the DoA and DoI are often mapped to sub meter (centerline) accuracy, although printed maps are never produced with this accuracy.
Both the BLM and NPS have been mapping trails with submeter accuracy for years. Even with SA Trimble units allowed for submeter precision, and with post processing of the data, submeter accuracy. The standard unit for the NPS for Fire, R/T and L.E. duty is a Trimble WAAS DGPS unit. The dataloggers are set up for multipath rejection, and post processing takes care of signal delay errors, ambiguity problems, doppler shift ...
Given that R/T generally uses GPS and GIS as management tools and not as Navigational tools, data collection generally takes place only when a low DOP values are given, so it is not uncommon to have a sub 1m 2drms even before post processing. Of course, given that the NMAS for a map at 1:24,000 is + or - 40.00 feet ... the data collected is most often left in a GIS rather than printing it on to some USGS base map (and DEM's only make it worse).
R ATONR/squint 1994-2000.
And you should see what we have been doing with Kinematic Positioning and Centroids.
<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe said:
"JD" <[email hidden]> wrote in message news:[email hidden]... > > Frugal Joe wrote: >> "JD" <[email hidden]> wrote in message >> news:[email hidden]... >> > >> > Ride-A-Lot wrote: >> >> This is an out and back trail, so I would think that the tracks >> >> should >> >> overlap. Can the GPS be that off? >> > >> > >> > Even without Selective Availability anymore, it's really only >> > accurate >> > to within three meters if you have a 3-dimensional reading from >> > getting >> > at least four satellites in the constellation of 26 (2 spares in >> > case >> > one malfunctions beyond tele-repair). If you don't get a >> > 3-dimensional >> > reading, it can be off up to 30 meters +. >> > >> > Now go buy a map and become a true cartographer. >> > >> > JD >> > >> >> More like 5 m if your lucky > > > I was just relaying the party line on it. I wouldn't count on even 5m > on a typically good mountain bike trail because of the terrain and > trees. > > JD > You are exactly right. And as you know, trails if mapped, are not mapped to that precision.
Road and trail systems with in the DoA and DoI are often mapped to sub meter (centerline) accuracy, although printed maps are never produced with this accuracy.
Both the BLM and NPS have been mapping trails with submeter accuracy for years. Even with SA Trimble units allowed for submeter precision, and with post processing of the data, submeter accuracy. The standard unit for the NPS for Fire, R/T and L.E. duty is a Trimble WAAS DGPS unit. The dataloggers are set up for multipath rejection, and post processing takes care of signal delay errors, ambiguity problems, doppler shift ...
Given that R/T generally uses GPS and GIS as management tools and not as Navigational tools, data collection generally takes place only when a low DOP values are given, so it is not uncommon to have a sub 1m 2drms even before post processing. Of course, given that the NMAS for a map at 1:24,000 is + or - 40.00 feet ... the data collected is most often left in a GIS rather than printing it on to some USGS base map (and DEM's only make it worse).
R ATONR/squint 1994-2000.
And you should see what we have been doing with Kinematic Positioning and Centroids.
I was referring to USGS, USFS maps.
Reads: "You'll never be right."
He was referring to everything and anything you don't have what he sees as the correct information on.
<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe said:
"JD" <[email hidden]> wrote in message news:[email hidden]... > > Frugal Joe wrote: >> "JD" <[email hidden]> wrote in message >> news:[email hidden]... >> > >> > Ride-A-Lot wrote: >> >> This is an out and back trail, so I would think that the tracks >> >> should >> >> overlap. Can the GPS be that off? >> > >> > >> > Even without Selective Availability anymore, it's really only >> > accurate >> > to within three meters if you have a 3-dimensional reading from >> > getting >> > at least four satellites in the constellation of 26 (2 spares in >> > case >> > one malfunctions beyond tele-repair). If you don't get a >> > 3-dimensional >> > reading, it can be off up to 30 meters +. >> > >> > Now go buy a map and become a true cartographer. >> > >> > JD >> > >> >> More like 5 m if your lucky > > > I was just relaying the party line on it. I wouldn't count on even 5m > on a typically good mountain bike trail because of the terrain and > trees. > > JD > You are exactly right. And as you know, trails if mapped, are not mapped to that precision.
Road and trail systems with in the DoA and DoI are often mapped to sub meter (centerline) accuracy, although printed maps are never produced with this accuracy.
Both the BLM and NPS have been mapping trails with submeter accuracy for years. Even with SA Trimble units allowed for submeter precision, and with post processing of the data, submeter accuracy. The standard unit for the NPS for Fire, R/T and L.E. duty is a Trimble WAAS DGPS unit. The dataloggers are set up for multipath rejection, and post processing takes care of signal delay errors, ambiguity problems, doppler shift ...
Given that R/T generally uses GPS and GIS as management tools and not as Navigational tools, data collection generally takes place only when a low DOP values are given, so it is not uncommon to have a sub 1m 2drms even before post processing. Of course, given that the NMAS for a map at 1:24,000 is + or - 40.00 feet ... the data collected is most often left in a GIS rather than printing it on to some USGS base map (and DEM's only make it worse).
R ATONR/squint 1994-2000.
And you should see what we have been doing with Kinematic Positioning and Centroids.
I was referring to USGS, USFS maps.
1) That is not what you said. In fact neither USGS nor USFS maps were mentioned until I presented Information on the NMAS. The discussion was on the accuracy of comercially available GPS dataloggers.
2) USGS and USFS maps at what scale? At what scale is "5 m if your lucky" a break point value?
3) USGS paper maps? or are you including DOQQ's, DRG's, or other digital format "maps."
<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe said:
"JD" <[email hidden]> wrote in message news:[email hidden]... > > Frugal Joe wrote: >> "JD" <[email hidden]> wrote in message >> news:[email hidden]... >> > >> > Ride-A-Lot wrote: >> >> This is an out and back trail, so I would think that the tracks >> >> should >> >> overlap. Can the GPS be that off? >> > >> > >> > Even without Selective Availability anymore, it's really only >> > accurate >> > to within three meters if you have a 3-dimensional reading from >> > getting >> > at least four satellites in the constellation of 26 (2 spares in >> > case >> > one malfunctions beyond tele-repair). If you don't get a >> > 3-dimensional >> > reading, it can be off up to 30 meters +. >> > >> > Now go buy a map and become a true cartographer. >> > >> > JD >> > >> >> More like 5 m if your lucky > > > I was just relaying the party line on it. I wouldn't count on even 5m > on a typically good mountain bike trail because of the terrain and > trees. > > JD > You are exactly right. And as you know, trails if mapped, are not mapped to that precision.
Road and trail systems with in the DoA and DoI are often mapped to sub meter (centerline) accuracy, although printed maps are never produced with this accuracy.
Both the BLM and NPS have been mapping trails with submeter accuracy for years. Even with SA Trimble units allowed for submeter precision, and with post processing of the data, submeter accuracy. The standard unit for the NPS for Fire, R/T and L.E. duty is a Trimble WAAS DGPS unit. The dataloggers are set up for multipath rejection, and post processing takes care of signal delay errors, ambiguity problems, doppler shift ...
Given that R/T generally uses GPS and GIS as management tools and not as Navigational tools, data collection generally takes place only when a low DOP values are given, so it is not uncommon to have a sub 1m 2drms even before post processing. Of course, given that the NMAS for a map at 1:24,000 is + or - 40.00 feet ... the data collected is most often left in a GIS rather than printing it on to some USGS base map (and DEM's only make it worse).
R ATONR/squint 1994-2000.
And you should see what we have been doing with Kinematic Positioning and Centroids.
I was referring to USGS, USFS maps.
1) That is not what you said. In fact neither USGS nor USFS maps were mentioned until I presented Information on the NMAS. The discussion was on the accuracy of comercially available GPS dataloggers.
2) USGS and USFS maps at what scale? At what scale is "5 m if your lucky" a break point value?
3) USGS paper maps? or are you including DOQQ's, DRG's, or other digital format "maps."
<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe said:
<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Frugal Joe wrote: > "JD" <[email hidden]> wrote in message > news:[email hidden]... > > > > Frugal Joe wrote: > >> "JD" <[email hidden]> wrote in message > >> news:[email hidden]... > >> > > >> > Ride-A-Lot wrote: > >> >> This is an out and back trail, so I would think that the tracks > >> >> should > >> >> overlap. Can the GPS be that off? > >> > > >> > > >> > Even without Selective Availability anymore, it's really only > >> > accurate > >> > to within three meters if you have a 3-dimensional reading from > >> > getting > >> > at least four satellites in the constellation of 26 (2 spares in > >> > case > >> > one malfunctions beyond tele-repair). If you don't get a > >> > 3-dimensional > >> > reading, it can be off up to 30 meters +. > >> > > >> > Now go buy a map and become a true cartographer. > >> > > >> > JD > >> > > >> > >> More like 5 m if your lucky > > > > > > I was just relaying the party line on it. I wouldn't count on even > > 5m > > on a typically good mountain bike trail because of the terrain and > > trees. > > > > JD > > > You are exactly right. And as you know, trails if mapped, are not > mapped > to > that precision.
Road and trail systems with in the DoA and DoI are often mapped to sub meter (centerline) accuracy, although printed maps are never produced with this accuracy.
Both the BLM and NPS have been mapping trails with submeter accuracy for years. Even with SA Trimble units allowed for submeter precision, and with post processing of the data, submeter accuracy. The standard unit for the NPS for Fire, R/T and L.E. duty is a Trimble WAAS DGPS unit. The dataloggers are set up for multipath rejection, and post processing takes care of signal delay errors, ambiguity problems, doppler shift ...
Given that R/T generally uses GPS and GIS as management tools and not as Navigational tools, data collection generally takes place only when a low DOP values are given, so it is not uncommon to have a sub 1m 2drms even before post processing. Of course, given that the NMAS for a map at 1:24,000 is + or - 40.00 feet ... the data collected is most often left in a GIS rather than printing it on to some USGS base map (and DEM's only make it worse).
R ATONR/squint 1994-2000.
And you should see what we have been doing with Kinematic Positioning and Centroids.
I was referring to USGS, USFS maps.
1) That is not what you said. In fact neither USGS nor USFS maps were mentioned until I presented Information on the NMAS. The discussion was on the accuracy of comercially available GPS dataloggers.
2) USGS and USFS maps at what scale? At what scale is "5 m if your lucky" a break point value?
3) USGS paper maps? or are you including DOQQ's, DRG's, or other digital format "maps."
R
Now you've done it. You asked concise, well thought out questions....he won't be back.....
