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college project PDA with GPS

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SHoCK2xTc

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college projects on gps

Hello, my name is Brian Warner and I am an Electrical Engineering student. I am working on a group project that concludes in 4-5 months. My group is working on a PDA with GPS car locator. After a long day of classes/work you may have forgotten where you parked your car. I know this post is long so I appreciate your attention and replies/responses. Please let me know if you have any concerns/interest with what we are TRYING to accomplish.

Right now our project is somewhat crude and is designed to provide a distance and direction to our parked car. We have a RF transmitter hooked up to our car's ignition cables thru some relays and we will tell our PDA when our car is turned on or off (using some code which WILL BE written in C), thus marking the car's GPS position when we turn off the engine and walk to class/work.

To make the project much more robust we wanted to get turn by turn directions to our car using the software that comes pre-installed on PDAs that have built in GPS capabilities. This leads to my questions...

1) Is there any software available that allows you to create your own custom map/scenario? For example: our school's campus.

I have not yet purchased any PDA with GPS but I did contact Garmin and they said their software is not programmable.

2) Is there a way to write a program from scratch and run it on the PDA to interface the GPS? (taking into account that my group only has 5 more months to work on this and none of us are very proficient at programming)

One crude method my group was considering to address question 2 is to create a program where every building/parking lot on our campus is represented by a node. We would then have to run some type of software loop that finds the closest/nearest node and then output to the user which way to go to get to the next node. The PDA has to recognize when it is at a node (interaction with the GPS will be necessary here). We were thinking about making each entrance to a building and each "corner of the building's primary boundary" a node just to get a little bit more accurate. This method requires MASSIVE amounts of time in order to create the nodes, measure the distance between them, store the data, then write the loop which processes the data, but we are willing to work hard these last 5 months if this approach is even possible. If there is a better way of doing this PLEASE ADVISE.
(PLEASE input your comments here PLEASE!!)

3) Does anyone have any suggestions how we can approach the issue of parking garages and the issue of Height/Depth? This may be something that we avoid altogether and put in our "if we had more time" section. :D

I invite responses both critical and helpful. I am a student and I am learning, your feedback is appreciated. I will check back to this post daily for the next few months but I can also be reached at brianiw@hotmail.com
 

Cluricaun

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Re: college project PDA with GPS (long post)

Hi

Cool project.
I only park at small garages so I have no problem with memory :)
but I know many that having hard time finding their car...

I moved the post here, if you or a moderaor finds it better to move it elsewere please PM me.

Cl
 

    SHoCK2xTc

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ee_expert2000

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Re: college project PDA with GPS (long post)

Hi!
you have to use programmable GPS modules form different wendors.
there you can write your own operating system to do perform anything you need.
but you have to design PCBs to interconnect the module to perihperal devices.
 

pisoiu

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college project PDA with GPS (long post)

The idea is nice. However, here is my 2 cents: The precision of the GPS system is not good enough for such an approach. You can do an experiment: leave a GPS receiver at one place (preferably a GPS module, not a complete receiver), without moving it, and take all the raw position data (ex. $GPGGA sentence) along several days. Place them on a map, and study the dispersion of the position. You will have a circle with several meters of diameter. The reason for this are the sattelites, they are constantly moving above you. Sometime you have fewer sattelites in view , perhaps 3 or 4 and then the precision (DOP) is worsen, and sometimes you can have 10 or more, and then the precision is more accurate. If you are making this experiment in the urban jungle with tall buildings, some sattelites will be inevitably obstructed. The second big problem are the maps. If you will use an already made map, the navigation will drastically depend on the accuracy of the maps. If the maps are raster, then it will be a nightmare to work with them, but if the maps are vector, then it will be easier. However, the vectorial maps are very expensive, can go to several tens of thousands of dollars for the resollution you need (1:5000 or even less), depending on coverage. On the vectorial maps, it is crucially important to have all the layers very well defined and to have the reality well represented on the map. For example, if two pedestrian roads are crossing on the map, you will guide the user from one to another, to reach the destination. But what if one road is in fact a foot bridge passing above the other one and they are not actually connected, but the map representation is wrong?
On the other hand, if you plan to make your own maps, then you will have to find a way to get rid of the positioning errors I've talked previously.
I do not want to discourage you, I just want to warn you about the possible problems. Of course, you may not face some of them, depending on what you really want to achieve.

/pisoiu
 

    SHoCK2xTc

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SHoCK2xTc

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Re: college project PDA with GPS (long post)

if each node is no closer (to each other) than the max deviation of the inherent GPS error, then is my problem slightly resolved? maybe some type of averaging function can be designed...
 

Cluricaun

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Re: college project PDA with GPS (long post)

Hi

It is a good point by pisoiu, since the problem is the deviation in sattellite orbit I do not think it make any difference if you use older GPS or more modern ones with greater accuracy.
You could use an averaging function and likely get a smaller area but perhaps you do not need it in demo version?
For demo version I think it is good enough with a few meters in deviation, when you arrive to the spot where you parked your car you most likely will see the car or atleast remember you been there before...

In some GPS you can get the height, since a parking garage will limit the received signal from the sattellites you must use an altimeter. Once again, if I were you I would wait, it can always be added later. In some this sensor is built in but I do not know about demo boards, since your project mostly belong to SW it is better to solve that part first then improve.
I do not know about you but I prefer success before failure, so finish the design in steps.

Sorry for an non technical answer...


Cl
 

rag_perfect

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i am also working on GPS reciever.can anyone plz tell me where to find 'c' codes related to gps software.
and friends,plz send me any idea abt project oreantation.




rag_perfect
 

bluecube

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There are a few companies out there that assemble a Sirf star-3 chipset and RF into a module,
and all you need to do is interface that to your cpu serial port,
and hook the antenna to the otherside. instant gps


I think Sirf even sell something like that
 

bluecube

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From what I read, the Sirf chipset can lock into satellite signal under tree or indoor. They can pick up a signal at -170dbm
 

SHoCK2xTc

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thought you guys might like an update to my group's project...

we bought the pharos gps (compact flash) to run with our dell axim x5
one of my partners hacked one of the buttons on the pda that we wont be using to a circuit that receives an RF signal from our automobile when the engine turns off. this opens the gps software that came with the pharos gps receiver and stores the initial gps position, which becomes our gps destination when we actually need to return to our automobile.

one problem remains

the idea of this project is that everything is automated, as opposed to taking out a pencil and paper and writing down where you parked. but our pda isnt always ON so how is the program supposed to run in the first place. WELL we could turn on our pda (and once the pda is on the circuit does its job and we get the gps position).. but the conscious act of turning on the pda ruins the automated aspect...

how can i turn on the pda without pressing the on button?
infrared? rf?

suggestions PLEASE
 

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