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Use GPS longitude/latitude to calculate speed
lewkahkang
5 Points
I am currently assessing the validity and reliability of a GPS (VXSport) device. I am trying to work with the raw data export which only provides speed and longitude/latitude (less altitude) data. VXSport has mentioned that the speed data that they obtained in independent of the longitude/latitude coordinates, mentioning that it is recorded directly from the GPS chip.
One of my tasks is to calculate speed using the longitude/latitude coordinates so that I can compare this value to that of the speed value recorded directly from the GPS chip. What I have done is that I have referred to this research paper specifically obtaining the section on user velocity http://d1.amobbs.com/bbs_upload782111/files_33/ourdev_584835O21W59.pdf but it seems that there is a lot more information required that I am unsure how I can obtain them, for example, XYZ coordinates of each satellite connected, frequency correction determined from navigation message updates.
Aside from branching to other topics such as Kalman filtering, I also understand that these iterative calculations may be done via computing programs instead of solving it in a mathematical. I would like to hear anyone's honest opinion regarding my project and especially if anyone could recommend me to any resources as to how GPS calculate speed using the longitude/latitude coordinates ideally with numerical examples.
I deeply appreciate anyone who has taken time to go through my thread and sincerely apologize if I had stated any information incorrectly. Please feel free to let me know if there are any issues.
Thank You!
One of my tasks is to calculate speed using the longitude/latitude coordinates so that I can compare this value to that of the speed value recorded directly from the GPS chip. What I have done is that I have referred to this research paper specifically obtaining the section on user velocity http://d1.amobbs.com/bbs_upload782111/files_33/ourdev_584835O21W59.pdf but it seems that there is a lot more information required that I am unsure how I can obtain them, for example, XYZ coordinates of each satellite connected, frequency correction determined from navigation message updates.
Aside from branching to other topics such as Kalman filtering, I also understand that these iterative calculations may be done via computing programs instead of solving it in a mathematical. I would like to hear anyone's honest opinion regarding my project and especially if anyone could recommend me to any resources as to how GPS calculate speed using the longitude/latitude coordinates ideally with numerical examples.
I deeply appreciate anyone who has taken time to go through my thread and sincerely apologize if I had stated any information incorrectly. Please feel free to let me know if there are any issues.
Thank You!
Comments
And before you ask... no, I have no idea where you would find a site to discuss this kind of thing, sorry.
That question is above my pay grade as well, although one thing stuck out to me in your post. While a GPS chip may provide speed data, I suspect they are only calculating it based on the time and position data the chip calculates. Afterall, the only thing a GPS chip does is fetch the current time from the satellites, nearly everything else is calculated on-chip.
So any speed calculation you do might not be any better than the speed calculation the chip is performing.