GPS Timing at Brunters... accurate?
17-08-2005, 10:55 AM
#1
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GPS Timing at Brunters... accurate?
Got thinking earlier... ive got tomtom for my car, and the speed readout on that doesnt take into account up/down movement (ie hills) so it will underread up n down slopes...
now, does the Datron gear take into account the Z azis also? if it doesnt, then surely the timings at brunters are not 100% accurate (as brunters is up at the top, down at the bottom, on a mini-hill)
anyone?
now, does the Datron gear take into account the Z azis also? if it doesnt, then surely the timings at brunters are not 100% accurate (as brunters is up at the top, down at the bottom, on a mini-hill)
anyone?
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17-08-2005, 11:48 AM
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let me translate Porkster:
Oh fook! Of course all GPS use XY and Z, my cheapo ebay one does I cannot see why Tomtom does not.
Jim, you're being dim....my TomTom certainly works in 3D. How many satellite locks have you got?
Oh fook! Of course all GPS use XY and Z, my cheapo ebay one does I cannot see why Tomtom does not.
Jim, you're being dim....my TomTom certainly works in 3D. How many satellite locks have you got?
17-08-2005, 12:26 PM
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does it actually work in XY and Z though?
there is nothing but lat and long on the positioning...
the 3D could be done with position on a map against a contour... i.e. if you are sitting on a road and X,Y position and its so many metres above sea level then you must be at 'so many' metres above sea level??
my tom tom frequently gets confused if I ignore it carry on the same road when should come off slip road at a different level... so not sure it does actually get the height position too?
there is nothing but lat and long on the positioning...
the 3D could be done with position on a map against a contour... i.e. if you are sitting on a road and X,Y position and its so many metres above sea level then you must be at 'so many' metres above sea level??
my tom tom frequently gets confused if I ignore it carry on the same road when should come off slip road at a different level... so not sure it does actually get the height position too?
17-08-2005, 12:55 PM
#20
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i cant see the hill being more than 2 degrees. So, at 150 mph, ur doing 150 x cos 2 = 149.909 mph in the horizontal axis, and 5.235 mph on the vertical axis, ie straight up.
17-08-2005, 01:33 PM
#22
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im not saying it would be far out, im just saying it wouldnt be 100%
bill, tomtom does NOT take the Z axis into account, the software is 100% 2D (the GPS is getting a 3d position, but tomtom only understands the X and Y) its even stated on tomtom's website that the speed readout is not based on the Z axis.
porkie, do you know for 100% that datron uses XYZ (it probabyl does, it costs enuf
) or are you assuming?
porkie, tomtom is satnav for PDAs and Phones... v. v. good www.tomtom.com
bill, tomtom does NOT take the Z axis into account, the software is 100% 2D (the GPS is getting a 3d position, but tomtom only understands the X and Y) its even stated on tomtom's website that the speed readout is not based on the Z axis.
porkie, do you know for 100% that datron uses XYZ (it probabyl does, it costs enuf
) or are you assuming?porkie, tomtom is satnav for PDAs and Phones... v. v. good www.tomtom.com
17-08-2005, 03:23 PM
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My apologies Jimbo, I think I was thinking of the GPS data screen, not TomTom itself..... doh!
As for the hills etc. it doesn't matter - 100mph is 100mph wether uphill or down. I suppose the distance covered vs time would vary uphill as opposed to flat, but don't forget it's like anything else - compare runs at Brunters with runs at Brunters, it's not like anyone has a special advantage if they all use the same venue.
As for the hills etc. it doesn't matter - 100mph is 100mph wether uphill or down. I suppose the distance covered vs time would vary uphill as opposed to flat, but don't forget it's like anything else - compare runs at Brunters with runs at Brunters, it's not like anyone has a special advantage if they all use the same venue.
17-08-2005, 03:29 PM
#24
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bill, 100mph might be 100mph uphill, but if th GPS only reports is as 98...
its all about if its measuring speed or velocity, as velocity would NOT work on a non-flat surface
its all about if its measuring speed or velocity, as velocity would NOT work on a non-flat surface
17-08-2005, 03:36 PM
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Quote from Datron:
It's worth bearing in mind that the Datron equipment samples at a faster rate then most cheapo GPS receivers, so I wouldn't go comparing your speed readings from a consumer GPS unit to the Datron gear.....and it's certainly more accurate than the old optical setups. Not saying it's flawless, but i reckon it's probably the most accurate gear non-military peeps will get near....
MicroSAT is the
reliable new way to measure:
_ vehicle speed
_ distance travelled
_ elapsed time
_ lap times
_ braking distance and time
_ acceleration
_ lateral acceleration
_ longitudinal acceleration
_ absolute position
_ height
_ heading
VELOCITY
Accuracy 0.1 kph
Units kph or mph
Update rate 20 Hz
Maximum velocity 1,850 kph
Minimum velocity 0.1 kph
Resolution 0.01 kph
DISTANCE
Accuracy 0.05% (<50cm per Km)
Units Meters/Feet
Update rate 20 Hz
Resolution 1 cm
ABSOLUTE POSITION
Accuracy 1.8 m CEP*
Accuracy with DGPS <1 m CEP*
Update rate 20 Hz
Resolution 1 cm
TIME
Resolution 0.01 s
Accuracy 1 part in 100,000
ACCELERATION
Accuracy 0.5%
Maximum 20 G
Resolution 0.01 G
Update rate 20 Hz
reliable new way to measure:
_ vehicle speed
_ distance travelled
_ elapsed time
_ lap times
_ braking distance and time
_ acceleration
_ lateral acceleration
_ longitudinal acceleration
_ absolute position
_ height
_ heading
VELOCITY
Accuracy 0.1 kph
Units kph or mph
Update rate 20 Hz
Maximum velocity 1,850 kph
Minimum velocity 0.1 kph
Resolution 0.01 kph
DISTANCE
Accuracy 0.05% (<50cm per Km)
Units Meters/Feet
Update rate 20 Hz
Resolution 1 cm
ABSOLUTE POSITION
Accuracy 1.8 m CEP*
Accuracy with DGPS <1 m CEP*
Update rate 20 Hz
Resolution 1 cm
TIME
Resolution 0.01 s
Accuracy 1 part in 100,000
ACCELERATION
Accuracy 0.5%
Maximum 20 G
Resolution 0.01 G
Update rate 20 Hz
17-08-2005, 03:41 PM
#26
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Bruntingthorpe height changes, Start of the straight then raises by 14 feet by the middle and then drops 13 feet at the end,
This was checked today by V Box
Mark
This was checked today by V Box
Mark
17-08-2005, 03:41 PM
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The moral of this entire thread is that Jim should just STOP thinking about shit like this and realise that the people at Datron are not Stooooopid!!!!
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