I'm currently working on a project that tracks an airplane using GPS.

The GPS receiver is on the plane - what I am supposed to do is the trasmit the position of the plane back to earth and feed it into my laptop.

So the general idea is to take the GPS data output - use a microcontroller to format the data into a way that I can output using a RS232 cable (this is because my transmitter takes in data using RS232)

Then back on earth, there is a receiver that feeds the data into my laptop.

I have already chosen my transmitter and receivers (both are really transceivers which use RS232)

I would like to know your guys suggestions as to what microcontroller I should use?
Questions that are just passing through my head is that it is that the GPS output data rate is so high, and I need to microcontroller that is suitable. I am not very clear on how to choose a suitable microcontroller.

Your help is very much appreciated.

 

Are you talking about model aircraft, i.e., low speed and low altitude, or commercial aircraft?

As I recall, there are safeguards built into publically available GPS with limits for altitude and speed to prevent what it seems like you are trying to do. That excludes, of course, on-board systems and air traffic control.

John

 

Does the DHS know about this "plan"?

I am sure you are not a potential terrorist, but come on, asking about tracking planes does set off some alarms. Beyond that your request seems a little lite on info. What model gps unit? What interface does it use? That kinda thing.

Best whishes to you and your future fellow detainees in Guantanamo,

Michael

 

Oh, its more for rescue missions where a mini plane is sent to scout out a certain area and either capture some pictures or stream some video etc...

but it is supposed to be able to go quite far like...hundreds of kilometres...
But I shall check that up and come back here.

I actually have the liberty to choose any GPS receiver and a suitable microcontroller (to output the GPS data into a transceiver which uses RS 232 ports as I/O).

I'm really not thinking about any fancy solution, but a simple compatible combination that would have a lot of simplicity in design.

Thanks.

 

I will be using a cessna or something like that.

I know for perhaps certain transceivers I don't even need to have the microcontroller interfacing the GPS - but the microcontroller would still be preferable, just so i can manipulate the data in some way, and maybe add stuff for future development.

the transceiver will be operating at the amateur band around 433MHz
As for the baud rate

Within the visible range, when the height of antenna is higher than 2m and The Bit Error
Rate (BER) is 10-3, the reliable transmission distances respectively is 4500m @1200bps, and
>2000m@9600bps.

I have found some people using PIC16F87X series for this purpose. I'm not quite sure if there are better alternatives though

 

but it is supposed to be able to go quite far like...hundreds of kilometres...

I will be using a cessna or something like that.

the transceiver will be operating at the amateur band around 433MHz

I don't think it is a good idea to be piloting a Cessna remotely from a distance of 100's of kilometers using amateur-designed equipment on the 433 ISM band.

Somethings just don't add up here. In the USA and, I suspect, most civilized nations, that would be illegal.

Maybe you can explain more accurately what you are really trying to do.

John

 

I didn't see that he wants to control the plane remotely, just track its location.

Some GPS sensors already emit an RS232 ASCII data stream - why can't you just feed that directly into an RS232-ready radio and send it with no microcontroller between them?

Just send the NMEA data sets as they come out of the GPS sensor, like this:

$GPGGA,052305,3755.7870,N,12202.8196,W,1,04,2.6,184.3,M,-27.4,M,,*7A
$GPRMC,052306,A,3755.7871,N,12202.8186,W,000.0,211.7,050309,015.4,E*65

For an example of one such sensor, my Garmin 35-LVC can be configured to send from a selection of a dozen or so NMEA messages like the GPGGA and GPRMC examples above, at one of half a dozen available baud rates from 300 to 19200. All you might need is a level translation, as the sensor sends more of a CMOS-level of signal rather than true RS232 levels.

 

I didn't see that he wants to control the plane remotely, just track its location.

Sorry, my error.

John

 

I didn't see that he wants to control the plane remotely, just track its location.

Some GPS sensors already emit an RS232 ASCII data stream - why can't you just feed that directly into an RS232-ready radio and send it with no microcontroller between them?

Thanks for that. The same thing crossed my mind too, I was thinking of the microcontroller interface for the sake of future development, and also to reduce the bits that are sent to the minimal level.

Are there any microcontrollers that you would recommend?

Thanks,
Joel

 

If you use amateur band transmissions, you're supposed to transmit your call sign every so often, so you might need a controller to periodically inject your callsign into the serial data stream.

Here's a link to a device that already does this - it retransmits GPS information, with periodic call sign transmissions to comply with the rules. Maybe this will give you some ideas.

http://www.byonics.com/tinytrak/

There are regular discussions about the pros and cons of different microcontrollers in the microcontroller forum; here's an example -

http://forum.allaboutcircuits.com/showthread.php?t=16715

I think that just about any microcontroller could do this job; the best one for you might depend on whether you already are familiar with some particular controller, or if not, whether you prefer C, or Basic, or assembly, or have a limited budget, or want a controller with an active user community willing to help you get started.

 

Thanks davebee, the TinyTrak website was pretty helpful to learn about other similar available products.

As I am building one (95% similar to the tinytraks), i would have to build it right down to the chip level. Tinytrak kits offer up to 18km altitude (I would follow up with them on that to see if they have higher ranges)

But as I was checking out the GPS chips... one thing I realized is that the chips are really small - and it is impossible for an amateur like me to wok with it. It comes in dimensions like 1cmx 1cm - when I am planning to solder it to a PCB board that I would make on my own.

I am currently contacting Sirf .... to buy 1 chip from them. Not sure if they would ignore me!

I tried to search on ebay - but normally they sell the whole GPS navigation system. But what I am looking for is a GPS Chip that comes in a way that is big enough for me to work with.

Any suggestions?

Thanks,
Joel

 

That's pretty good.

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If you need to work with small chips like SMD PLCC packages, get a compatible DIP socket adapter and do it your way.