garmin foretrex 401 track log storage capacity

[starshippe]

. . i'm getting a 401 to use with adis missions. i am having a little trouble interpreting the track log storage capacity. it says that the current track log can hold 10000 points. at once a second, this is two point seven hours, which doesnt seem like much time.
. . can anyone verify just how long of a track log this unit will hold? can the intervals be extended to less often than once a second in order to cover a longer time overall?
. . the unit has a built in altimeter and apparently a flux gate compass, which i understand should not be relied on for an accurate reading. the compass can be turned off to conserve battery power. i understand a good charge will power the unit for 15+ hours. 

thanks,
bill

[starshippe]

. . ok i am refining the question. i looked at the gpx file from a sarex we had last weekend, and there were only a few track log points that were at one second intervals. there were a few at two, but most of the points were 3 to 10 seconds apart.
. . obviously, with ten thousand points available, storage at any interval of three or more seconds should not be a problem, having long since been overshadowed by bladder and fuel constraints.
. . i'm left with the one question of what determines this interval? why are some points two seconds apart, and others six?
. . i used gpsbabel to generate a delorme streetmap log file, and played it. i noticed that the density of track log points is highest in the turns, and lowest during straight and level flight. is there an algorithm that generates track log points more frequently in turns?


bill

[starshippe]

. . heres a link to the foretrex 401 write up at soldier systems. looks like it might be useful for gts. i believe it does do mgrs. if u dont need the compass and altimeter, the 301 will work.
. . btw if u race sailboats, it has a timed alarming start sequence function too.

http://soldiersystems.net/2010/04/19/garmin-gps/

bill

[starshippe]

. . the 401 got here today. for those of u interested in details i offer the following.

. . the track points can be saved automatically, which apparently saves points frequently in the turns, and not so frequently while travelling in one direction. the auto selection has four resolutions. they can also be saved as a function of distance or time. the distance resolution is to the tenth of a foot, if ur travelling really really slow. the time resolution is from one sec to about 100 minutes. i have the track log saving as a function of time, at 2 second intervals. i'm going to verify that this gives me about five hours of recorded track log.

. . the position formats include d.d, d m.m, d m s.s, loran td, maidenhead, mgrs, rt90, sweref 99 tm, us national, utm/ups, about 30 foreign systems,and one utm-looking system that u can apparently define urself.

. . the gps plugs into a post xp computer and appears as an additional drive. the gpx files are directly accessible by robo geo, or they can be copied into the computer like any other file.

. . the flux gate (i think) compass works better than expected, as long as its held level. for those flat earth folks out there, and i know ur there, "north" is about 30 degrees from straight down at our 31 deg latitude, so the compass must be held level to keep the vertical component in check. tilting about the north south axis tears it up, just like any other magnetic compass.

. . i have two nimh triple a's installed, and will be checking the claimed 15+ hour battery life. the batteries can charge from the usb cable but the life is slightly reduced.

regards,
bill

[starshippe]

. . correction, the usb connection will work with windows xp.

bill