Advancements in GPS

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talos Active Contributor Join Date: Sep 2008 Location: India,Vagabond Posts: 22	Advancements in GPS 08/28/2009 7:24 AM
	A few days ago i had devolopeda GPS based speed measuring and recording system proposed to be fitted in a locomotive of a train.The system is having the following inherent deficiencies eventhough it was working fine in a plain environment.But the required accuracy could not be obtained due to the following reason: 1.The train while passing thro curves/gradients, the distance travelled and in turn the speed was observed to be not accurate as GPS system is based on co-ordinates. 2.When the train passes thro tunnels the speed recording is absent. Is there any possibility to tide over the design locks with any advancements as of date.Please note proposed speedometer of GPS base is for high sensitivity application where accuracy is important.. __________________ True strength comes from the loss of ignorance,even in martial arts.
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: Advancements in GPS 08/28/2009 7:27 AM
	<...speedometer of GPS base is for high sensitivity application where accuracy is important...> Given that, historically, railways operate to time-driven sequences, and not to speed criteria, the proposed application is of great interest as a technical curiosity. Please explain more. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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Steve S. Guru Join Date: Aug 2007 Posts: 1790 Good Answers: 87	#2 Re: Advancements in GPS 08/28/2009 7:29 AM
	Buy a Garmin dude...work brilliantly even on curves and gradients, and even seems to be able to extrapolate through tunnels (at least those it knows about).
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talos Active Contributor Join Date: Sep 2008 Location: India,Vagabond Posts: 22	#3 Re: Advancements in GPS 08/28/2009 7:34 AM
	Well it is just an idea which i had for a conactless speedometer which can work indipendent of speed sensors which are susciptible to wear and tear and can act as a plug andplay meter to any moving objects. Well what are technical details i need to furnish.Willbe more than gadtoshare what i know to improve upon what i have. __________________ True strength comes from the loss of ignorance,even in martial arts.
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TVP45 Guru Join Date: Jul 2007 Posts: 4448 Good Answers: 143	#4 Re: Advancements in GPS 08/28/2009 7:39 AM
	Yes. What PW said. The first time I stood on a BART platform in San Francisco (in the day when many watches were not yet electronic), I was astonished to see people reset their watches as the train pulled in. Time at location is extremely important. Nonetheless, in a high throughput system, you must also know the speed. Have you no wheels on these trains? As to accuracy on curves and gradients, speak to a surveyor. They have been handling this many years. My cheap GPS tells me elevation. It also goes bonkers when I go under large trees. Surely this is the wrong technology for tunnels. Speak to a coal mine engineer to learn how to deal with this. __________________ "Well, I've wrestled with reality for 35 years, Doctor, and I'm happy to state I finally won out over it." Elwood P. Dowd
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#5 Re: Advancements in GPS 08/28/2009 8:15 AM
	The other thing that many GPS-based systems do is to extrapolate the speed and position assuming no acceleration while there is no position signal available. All it takes is software...... __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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cwarner7_11 Guru Join Date: Dec 2006 Location: Panama Posts: 4273 Good Answers: 213	#6 Re: Advancements in GPS 08/29/2009 1:00 AM
	Look at a set of accelerometers to integrate with the basic GPS signal...
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U V Guru Join Date: Jun 2007 Location: East of Seattle, Washington state Republic of the 50 states of America Posts: 2045 Good Answers: 36	#7 In reply to #6 Re: Advancements in GPS 08/29/2009 7:59 PM
	Beat me to it. A little more complicated but use accelerometers to refine the GPS data and fill in any gaps. __________________ (Larrabee's Law) Half of everything you hear in a classroom is crap. Education is figuring out which half is which.
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rickwil Power-User Join Date: Mar 2009 Posts: 162 Good Answers: 5	#8 Re: Advancements in GPS 08/30/2009 10:07 PM
	Locomotives that I have worked on use radar focused at the ground to read out the speed. No need for anything as exotic as GPS. This radar also checks for wheel slip between the wheel motors based on the diameter of the wheels and the current that the motors turning the wheels draw. The GPS would not be of much use because it is too course of a measurement.
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cwarner7_11 (1); PWSlack (2); rickwil (1); Steve S. (1); talos (1); TVP45 (1); U V (1)

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