Smartphone GPS Tracker Version 1.0

Derek said:

Including the newer 250 mw ones? I got about a 1/4 mile range with my radios in a pretty unfavorable environment.

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I haven't tried the new ones yet, but I was surprised at how poor the range was with the 100 mw ones with even minimal topography. As you say the key is to go to the last position reported in the air, it's nearly always very close to the landing point.

mikec said:

Sure, but on modern tablets and phones it can be pretty painful to use a wired USB connection and using Bluetooth is programmatically simpler; I haven't had any issues with interference so far; it's all spread-spectrum and on different frequencies.

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+1. with android, bt just works and is built into the os. the same can't be said for usb to serial converters.

mikec said:

I haven't tried the new ones yet, but I was surprised at how poor the range was with the 100 mw ones with even minimal topography. As you say the key is to go to the last position reported in the air, it's nearly always very close to the landing point.

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ok, so same power levels. I have the 250 mw ones on order. I'm just waiting on a xbee shield to arrive from china so I can test them.

I am using Arduino for other projects, too. It is amazing what folks are doing with them and other micro-controllers.

I know!

I'm actually trying to get away from using an arduino in the base station. I think I may have found a solution, but I don't have the correct cable to plug my usb serial adapter into my phone. I've ordered a few, but they won't be here until next week.

IT WORKS!

I used the tracker on my L1 certification flight today and it worked perfectly! I'm not sure if it lost gps lock during ascent, but it definately had lock while coming down under the parachute. You could see it moving on the map on the all way down. Altitude was only about 800', but the gusty winds we had today pushed it quite a ways under the chute.

After it landed, I noticed it had started moving again. It turns out another club member found it and was bringing it back.

Now that I've proven the concept, it is time to improve it. I already know what I want to change and have almost all of the parts on hand, For this version I'll probably make a pcb for it. On to version 1.5!

Congrats on the L1 and successful test.

Congrats Derek

Great job, Derek!
Successful project test and L1 certification at the same time.....NICE!
Please keep us posted on the further testing and modifications.

Subscribed, and very interested in using this with my Samsung Galaxy Tablet.

Derek
Great job on the Level 1 and test of the GPS!
It was nice to meet you and your daughter yesterday.
I can't wait to get my Level 1 done. Maybe next month in Brunell.
I hope to see you again at a meet.
I an interested in your GPS project and will be following it.
I wish it worked with an iPhone. Maybe in the future.

The GPS was extremely accurate and work flawlessly if anyone else was interested in trying it.

It was great meeting you, too!

I looked quickly for equivalent ios apps, but nothing jumped out at me. It is possible that they natively support bt gps, but I can't get my wife's iphone to connect to the bluetooth module in the base station. I think this is because ios doesn't support the bt spp profile. I'm kind of stuck without being able to connect the base station to the phone and I don't like messing with her phone.

Again, it was great meeting you and welcome to the forum!

Derek, I am following with great interest. I had been looking at the 3DR radio modules for a similar experiment. Yours is a bit more versatile than what I had planned. I was going to take a GPS module and the 3DR air module to transmit position data to a 3DR with USB connected to a netbook computer on the flight line. I like the portability of your solution even more.

I have not gotten as far as purchasing the 3DR radios yet, so I will be very curious to see what you finally settle on for suitable performance (3DR vs Xbee).

Jim Z

JimZNJ said:

I have not gotten as far as purchasing the 3DR radios yet, so I will be very curious to see what you finally settle on for suitable performance (3DR vs Xbee).

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I'm not super happy with the 3dr radios. when they work, they work pretty well. However I've had a few times where it took multiple attempts (i.e. power cycles) for them to lock up. The lights would go solid, then flash a few seconds later. power cycling one or both doesn't always fix it. Eventually I have always gotten them to lock up, though.

I got the xbee modules last week and played with them a bit this weekend. I'm still waiting on a xbee shield to come in from hong kong before I can put together a system to experiment with. I'm debating on buying another gps module so I don't have to pull it off this one. We'll see.

oh, about the laptop thing, this system would work just fine. in fact, you could skip the whole bt link and just plug it into a usb port. or you could pick up a $200 nexus 7 and use that. it would be a lot more portable.

True, but you probably need a laptop anyway for your altimeter's software. Might as well buckle down and bring it with you to the field; in that case, bt just becomes another annoying link in the datacomm chain between your transmitter and your datalogger software.

P.S. +1 on the Nexus 7, it's a terrific buy for the price... assuming that you software will work with it.

Derek said:

oh, about the laptop thing, this system would work just fine. in fact, you could skip the whole bt link and just plug it into a usb port. or you could pick up a $200 nexus 7 and use that. it would be a lot more portable.

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Derek, congrats on L1. i'm doing mine in 2 weeks. you had posted that you might go on to v2.0 before. because of success of almost complete flight tracking are you going down another path. you had also mentioned making your own pcb. if you go that way would you make that available? i am ready to build mine. but will wait until you tweek it a little more so i don't miss something special.

accpool said:

you had also mentioned making your own pcb. if you go that way would you make that available?

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If you're going to use the XBee I'd definitely be interested in a PCB. If possible it would be nice if the package could be powered by a 1S lipo; if you use the right voltage regulator this should be easy.

my roadmap is roughly as follows:

version 1.0

uses the 3dr radios. this was primarily a proof of concept version. it works, but I'm sure it can be improved.

version 1.5

will use xbee pro radios. the initial version will be built with perf board like version 1.0, but I have already started working on a pcb. it will use a 1s lipo or 9v battery, your choice. I've already got the schematics done, I'm just waiting for a new gps module to show up (should be here this morning). I'm experimenting with two different layouts to try to make it smaller.

the initial base station will be built with a xbee shield and the bt shield using the arduino for power. I'm still waiting for the xbee shield to come from hong kong. I should have bought another bt shield at the same time so I could have two complete systems (the 3dr and the xbee versions), but I didn't. that was a mistake. oh well.

my plan for the base station is to also create a pcb for it and put it in an enclosure. it will also run off a 1s lipo (probably the same type) or 9v and my plan is to put a lipo charger on there as well. these schematics have not been started. for now I'm sticking with the bt link to the phone as it is the most universal interface for android phones. from my research, support for usb serial adapters is limited and may require kernel drivers that aren't present in most phones. I will not root my phone in order to make this work. I'm still not super thrilled about the bt hack, but atm it is the best interface available.

version 2.0

this will be further down the road. probably xbee based depending on the performance of version 1.5. version 2.0 will be about adding sensors to the transmitter. initially I really wanted to log all this stuff, but for now I'm primarily focused on recovery. we'll see.

software development

this is the biggest issue for me as I'm not a software developer. after using the tracker in the field, it is obvious that there needs to be a bearing and range to the rocket added. right now the map shows you where the rocket is. however if you don't know where that is in relation to your position, you could still end up wandering around looking for it. you can always mark the location on the map where the rocket is and switch back to the phone's gps, but I'd like this to be more automatic.

so, if anyone out here is an android developer and would like to help, please contact me via pm. I'll provide you with the hardware for your effort.

as far as selling stuff goes, my thoughts right now would be that I would sell pcbs for you to assemble. I may expand that some and install the surface mount components, but you will still need to buy and install the radios and gps (all through hole parts). this approach would keep the cost to you to a minimum. however, this could change.

that's it for now. I'll start a new thread when the version 1.5 is up and running. that could be as soon as today. I may also start a few polls to see what others want in terms of size, power source, etc.

thanks for all the interest!

Someone mentioned use where cell coverage is poor. I wonder if precaching the maps would work to eliminate this problem.

UncleVanya said:

Someone mentioned use where cell coverage is poor. I wonder if precaching the maps would work to eliminate this problem.

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it will. I've already done this. I have a development phone that doesn't have a sim card in it. I have used it for all my tests prior to the launch.

however I could only get it to save the regular map, not the satellite image. I'm not sure if I didn't check the right option or if that isn't possible. I need to look into that some more.

Version 1.5!

Hi Derek, I saw this thread last week and my cousin did a quick eBay search and came up with a guy selling 2ea XBee pro 900 mhz modules w/programmer and 2 antennas for 80. Jumped on that and also picked up the GPS module you speced. I found a USB devise from XBee that has a socket for the XBee pro for 12.50 but is coming from China. I need to find a clean spot to sort out the parts and get the soldering iron fired up. Cant wait to start transmitting..... Thanks for sharing your projest.

Dick Moran
Tri 14074 L1
NAR 6306 L1

that looks like an ok deal. those look to be the older versions, but I can't tell for sure. if they are, then they have a lower power output than the newer xsc s3b versions so your range potential won't be as great.

I found a carrier board for the xbee modules that looked to be a great fit, but it turns out that the regulator doesn't supply enough current to power the xbee and the gps. I have and idea on how to fix that, but it will have to wait until monday before I can try it out.

please keep us posted with your progress!

Derek said:

I found a carrier board for the xbee modules that looked to be a great fit, but it turns out that the regulator doesn't supply enough current to power the xbee and the gps.

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I use the Sparkfun XBee regulated board https://www.sparkfun.com/products/9132 . There should be sufficient current -- 500 mA.

dickmoran said:

a guy selling 2ea XBee pro 900 mhz modules

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Make sure they're Pro 900 XSC and not standard Pro 900s (can't tell from the photo) -- the latter only has a range of about a mile with an omni antenna IIRC.

mikec said:

I use the Sparkfun XBee regulated board https://www.sparkfun.com/products/9132 . There should be sufficient current -- 500 mA.

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that sparkfun board does look better. the one I bought claimed about 140 ma of spare current which is more than enough for the gps, but it doesn't seem to have enough power.

this is the one I bought:


https://www.droids.it/cmsvb4/content.php?143-990.001-XBee-Simple-Board

also, the xbee pro xsc s3b modules behave slightly differently than the older ones. if your adapter board has a led on the rssi pin, it will cause the xbee to go into config mode. you need to remove either the rssi led or the resistor in order for the board to work.

mikec said:

Make sure they're Pro 900 XSC and not standard Pro 900s (can't tell from the photo) -- the latter only has a range of about a mile with an omni antenna IIRC.

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I checked the partnumber and it says XBEEXSC.

I have included a picture and 2 pics of the USB adapter. I have GPS SW on my netbook and it also has sat photos so I can use that to find my rocket, The GPS SW is already looking to the USB port for a GPS signal from the external GPS receivers I use.

Dick

it looks like you have two different modules?