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Golgotha Occasional Visitor
Joined: Dec 31, 2008 Posts: 9
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Posted: Wed Jan 14, 2009 1:37 pm Post subject: Trail Resolution |
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Hi,
My first post to the Satmap forum.
I've had my Active 10 for a week now and very nice it is too. I went out for a bike ride on Sunday. When I reviewed my trail I noticed that there seems to be largish gaps between readings that resulted in the trail not accurately following the path - effectivley cutting corners.
How often does the Active 10 record its position?
Do these readings become waypoints?
TIA,
Andrew. |
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Westlothian Occasional Visitor
Joined: Dec 07, 2008 Posts: 56
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Posted: Wed Jan 14, 2009 1:59 pm Post subject: |
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Hi Andrew,
Welcome!
Updates are every second, every four in Power Saving Mode.
Were these high speed sections and corners?
I could be signal loss causing jumps but I find the reception to be flawless when outdoors (so far).
Alistair |
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Golgotha Occasional Visitor
Joined: Dec 31, 2008 Posts: 9
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Posted: Wed Jan 14, 2009 2:29 pm Post subject: |
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Hi,
Thanks for the reply.
My top speed on the day was about 20mph, which works out at about 8 meters per second. So that would account for the corner cutting in the trail. I noticed that the update was a second from the waypoint list, but just wanted to confirm.
I wonder if it is possible to increase the update rate or is it limit by the hardware? 4 times per second would be nice, but I reckon battery life would decrease proportionally.
Andrew. |
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Physicist Occasional Visitor
Joined: Nov 08, 2007 Posts: 57 Location: Cambridge
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Posted: Wed Jan 14, 2009 10:25 pm Post subject: |
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US Dept of Defense only allow updating of coordinates once per second on the civilian GPS system (otherwise sets could be used to guide missiles). The military version has higher update rates. |
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ed_crouch Occasional Visitor
Joined: Jan 05, 2009 Posts: 6
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Posted: Wed Jan 14, 2009 11:30 pm Post subject: |
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'S interesting... I guess you'd have to use INS to interpolate positions between GPS fixes... |
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jonesbach Regular Visitor
Joined: Jun 07, 2008 Posts: 185
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Posted: Sat Jan 24, 2009 8:14 pm Post subject: |
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Westlothian wrote: |
.....Updates are every second, every four in Power Saving Mode......
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I was of the same opinion until today. In the search to stretch my battery further I tried 'power saving mode'. On inspection of raw internal gpx file(prior to it being 'condensed' for export) I find that points are still stored at anything between 1 and 3 second intervals.
When I read the manual with my eyes open it says that the SCREEN is updated every four seconds. Does anyone know of any reference where it says that points can be logged at four second intervals. I'm using these internal files as they contain data not in the exported file and I am having to delete points to make the files manageable. It would save me work if I could force points to be saved every four seconds. |
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mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
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Posted: Sat Jan 24, 2009 8:39 pm Post subject: |
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Go to Settings/ Advanced Power Control and use the cursor control to toggle between Advanced (which gives you a 4 second update) or Normal where you get an update once per second, the Normal selection also allows you to select the trail up map display rather than being stuck with North up all the time - Mike |
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jonesbach Regular Visitor
Joined: Jun 07, 2008 Posts: 185
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Posted: Sat Jan 24, 2009 8:52 pm Post subject: |
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mikealder wrote: | Go to Settings/ Advanced Power Control and use the cursor control to toggle between Advanced (which gives you a 4 second update) or Normal where you get an update once per second, the Normal selection also allows you to select the trail up map display rather than being stuck with North up all the time - Mike |
Mike, sorry if I've been unclear. That's what I have been doing, but I have found that track points are logged at about the same rate, i.e. anything between 1 and 3 seconds and certainly not 4 seconds. Is there any other setting required? |
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mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
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Posted: Sat Jan 24, 2009 8:59 pm Post subject: |
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I will have to have a look at what the device is doing by taking it for a walk, are you refering to the trail points it records on screen or when you are viewing the actual recorded data on the PC? - Mike |
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jonesbach Regular Visitor
Joined: Jun 07, 2008 Posts: 185
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Posted: Sat Jan 24, 2009 9:26 pm Post subject: |
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I'm viewing the actual recorded data on the PC. I'm copying the raw file out and reading the data by opening the xml file in the web browser. This is prior to the size reduction that occurs when the file is exported.
When set to 1 second update the files always displayed a 'band' in the sample rate(1-3) and were never consistently at 1 second intervals but I assumed this was due to processing constraints. I always assumed that there was a 4 second sample rate but never tested it.
I have now created files at both 1 second and 4 seconds sample rates and find that within reason the actual sample rate is the same.
Incidentally, I do get the impression that since v1.3 the number of samples that actually hit 1 second have increased though this could be due to wishful thinking. |
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CheeseMeister Occasional Visitor
Joined: Jun 02, 2005 Posts: 8
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Posted: Sat Jan 24, 2009 10:46 pm Post subject: |
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Does the 4 sec rate not refer to the screen update rate? I don't really see a great power saving in slowing down the rate data is obtained from the GPS rx, it should be possible to achieve 1 update/sec even with the processor clock scaled right back.
Kev. |
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jonesbach Regular Visitor
Joined: Jun 07, 2008 Posts: 185
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Posted: Sun Jan 25, 2009 12:30 am Post subject: |
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CheeseMeister wrote: | Does the 4 sec rate not refer to the screen update rate? .... |
Exactly CheeseMeister! If someone can find me a 4 second log update I will be well pleased but I don't think there is one. |
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