GPS actual readings

[SpockThePain]

I once saw an application for the pocket pc (long ago) which showed the last 50 or so points plotted on a map as calculated from GPS.

With the GPS unit still, the points plotted moved in a trail due to imprecision. The application would plot an X at what was the average of the last points in the buffer. This X would move around slightly within a circle which was the minimum radius of accuracy.

At some times during the day the accuracy could visually be seen as much better than usual. The trail would move in a tighter pattern.

Most GPS applications try to lock into something so the location doesn't move around on the map like this. But as described above, the application would be used when the phone was placed in a stationary location for a time to try to get a more accurate position.

Is there an application on the Droid that does this?

[dylanthecat]

I think that may have been used when the US was degrading the GPS accuracy using selective availability. I think they stopped doing this in 2000 or so. With the high accuracy now I don't see a need.

[SpockThePain]

I was interested in this because I recently saw a demo of surveying equipment. They said that most of it was obsolete and that now GPS was most often used. But the GPS equipment they use is very expensive.

Most GPS apps on the Droid will give a error radius. Today, on GPS Test I found the best I was getting was 25 to 40 feet. And it appears common that most apps give the "convenience" of averaging the GPS readings quickly enough to give what looks like a stable point. However, I can start GPS Test once, then the second time I can get a location different than the first one that can vary by several feet. Most app displays give a radius on the map for which the phone is somewhere inside.

The number of apps that claim to read and display the raw GPS data are very few. I would expect an app I am looking for would be in the GPS Tracking genre. There is one called Ultra GPS Logger. I am curious if it can plot the raw GPS data of a phone in a fixed location as track data.

There are two other factors. One is how closely the app can zoom in on the map. If it is too far away a track within a 25 foot radius won't be much use. The other is how fast the phone can do the GPS reads. I have heard that some phones can't read very fast. I have the Droid X which appears to update frequently in GPS Test so my hope is that it can do at least one second reads if not better.

Roger

[takeshi]

Keep in mind that GPS isn't the only method of determining your location. If you're using GPS you should easily get accuracy within 3m. Anything more and you're probably not actually using GPS. If you want to see the GPS locating info then try an app like GPS Status which will give you plenty of info regarding what's going on with your GPS receiver. AFAIK it doesn't log.

Edit: Noticed that you mentioned GPS Test already. Don't forget the forced inaccuracy on consumer GPS devices. Several feet may fall within the margin of error.

The number of apps that claim to read and display the raw GPS data are very few. I would expect an app I am looking for would be in the GPS Tracking genre. There is one called Ultra GPS Logger. I am curious if it can plot the raw GPS data of a phone in a fixed location as track data.

Sure you can. The tracking apps don't care if you're moving or stationary. They'll continue to log your location at the set intervals.

[SpockThePain]

The number of apps that claim to read and display the raw GPS data are very few. I would expect an app I am looking for would be in the GPS Tracking genre. There is one called Ultra GPS Logger. I am curious if it can plot the raw GPS data of a phone in a fixed location as track data.

Sure you can. The tracking apps don't care if you're moving or stationary. They'll continue to log your location at the set intervals.

That depends on the app. For example, My Tracks has a setting to allow a track record every two seconds. But it also has a minimum of 6 feet to record to the track file. Even at these settings, if the unit is left out on the patio, it still ends up with only one point in the track file after several minutes. There is filtering going on to take the noise out of the track.

I know why tracking apps do this. It is to keep the size of the tracking file reasonable. One way around this would be to make the track file a rolling file with only so many e.g. 1000 records, and allow the user to change the size limit.

I need to face it. The kind of ability I am looking for is kind of geeky. But I am sure there is something out there that can do it however obscure.

Roger