Rocket Track - Open Source GPS Tracker for Smartphones

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Derek

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This thread is the follow on to my original DIY Smartphone GPS Tracker:

https://www.rocketryforum.com/showthread.php?46676-Smartphone-GPS-Tracker-Version-1-0

I've been working on an open source GPS tracker that uses a smartphone as the display. The system consists of three components:

1. GPS transmitter
2. Receiver with Bluetooth interface
3. Android smartphone with the correct app

Complete System:

rocket track system small.jpg

(Sorry for the lousy pic. When I build another rx I'll take some better shots!)

Finished transmitter and the bare PCB:

Rocket_Track_Tx_v10.JPG

The idea is to use a simple, inexpensive, unlicensed radio link between the rocket and a base station. The GPS receiver in the rocket sends the current position over the radio link to the base station, which in turn relays the data to a smartphone for display. The simplest, most universal interface for external devices available on smartphones is Bluetooth. Therefore the base station actually consists of two transceivers, one for the air link to the rocket and a Bluetooth slave that connects to the smartphone. By disabling the GPS in the phone and using the GPS data from the rocket, apps like Google maps display the rocket's position on the map, not the smartphone's! Both the transmitter and the base station run off a single cell Lipo battery. The base station includes a Lipo charger powered from a micro USB connector so you can easily charge the batteries in the field using your cell phone charger.

Only Android is supported because iOS devices have stupid rules prohibiting connecting to "unsigned" Bluetooth devices.

System Components

GPS transmitter:

Rocket_Track_Txs_v10_small.jpg

Base station receiver with Bluetooth interface:

Pic coming soon!

Motivation:

I don't really need a tracker where I fly, but I like gadgets and a GPS tracker definitely qualifies as a neat gadget. However I have no desire to get a ham license and the $400+ radio and equiptment to use a licensed tracker, especially since I already own a vastly more capable device. The goal is to make this small, simple and most importantly, cheap!

The system is based on the XBee Pro 900HP radio modules. In the US, It operates on the unlicensed 915 MHz ISM band. The maximum output power of the transceiver is 250 mW.

Questions:

1. Does it work?

Yes. It works great!

2. What is the range?

Miles in the air. Realisticaly less than a mile on the ground. The radio modules have the ability to connect to each other in a mesh network so the range can be extended quite far.

3. Does it work with my iPhone?

No. Apple doesn't allow your iPhone to connect any old Bluetooth device. Manufacturers must comply with their rules and pay a fee to get a key to allow the device to connect. I'm not doing that. If you really want to use this but don't want to give up your iPhone, buy a Nexus 7.

4. Do I need cell coverage at the field?

No. This tracker will work with phones or tablets without cellular coverage or plans. However, if you want to actually see where your rocket is on a map, you need to save an offline version of the map beforehand.

5. Are the any restrictions on its use?

In the US, not that I'm aware of. The radio operates in the unlicensed 915 MHz ISM band and is under the power limits for this band. It does not use cell phones or the cellular network to transmit the position. If you don't reside in the US, you need to purchase the XBee modules licensed for use in your country.

6. Are you going to make it better?

Yep, that is the plan. Future versions may include features like an altimeter, accelerometer and logging.

7. Are you going to sell the tracker?

Assembled systems, no. However I do have PCBs available for sale. Transmitter is $10, receiver is $20, set is $27, shipping to CONUS included. PM me if you are interested.

Transmitter PCB:

Rocket Track TX 1.0.JPG

Receiver PCB:

Rocket Track RX 1.1.jpg

8. $27 for a couple of PCBs! What a ripoff! Why so much?

No one is forcing you to buy from me. Grab the files and send them to your favorite PCB board shop. Although I'd be surprised if you ended up spending less than $27. Please let me know if you find a cheaper board shop!

9. Are you going to release the plans?

Yes! Everything you need to reproduce this tracker for yourself is included in this thread, including the PCB fab files.

10. The Bluetooth base station seems like a stupid hack. Why not just use Bluetooth (or Wifi) in the rocket?

Bluetooth doesn't have the range that these radios have, and Wifi requires more complex electronics in the rocket. Additionally, Android already has the ability to use an external Bluetooth GPS so all the existing map apps just work.

Each of the components are detailed in following posts. Please feel free to post any questions, comments, improvements, etc. in this thread.

Enjoy!

Derek

Update 1 (4-25-13): Added prices and system picture
 
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Rocket_Track_Txs_v10_small.jpg

The GPS transmitter is designed to be as small and light as possible. The wire antenna version is 2.5" x 1.0" and weighs < 1 oz. without the battery. It is powered from a single cell Lipo battery. XBee radios have two antenna options, either a small wire whip antenna or a RP-SMA connector for a larger, higher gain antenna.

The GPS tracker that gets mounted in the rocket consists of three components:

1. GPS receiver module with integrated antenna
2. Radio module with external antenna
3. Battery

Components

1. GPS receiver module

The GPS receiver chosen is the u-Blox (formerly Fastrax) UP501 GPS receiver with a built in antenna:

inhouse_up501_t.jpg


All of the documentation can be found here:

https://www.u-blox.com/en/download/documents-a-resources/fastrax-gpsgnss-modules.html

It was chosen because it is small, cheap and readily available. Currently the module is only available from ebay.

https://www.ebay.com/itm/High-perfo...074?pt=LH_DefaultDomain_0&hash=item27cf28c8b2

Note: As of 5-15-14, the ebay vendor above is out of stock. See here for other sources:

https://www.rocketryforum.com/showt...S-Tracker-for-Smartphones&p=708459#post708459

This thing is tiny! It is also extremely sensitive. It will lock on to 5 - 6 satellites and provide a fix in an all metal building. Other very expensive GPSes I've used in the same building with large external antennas can't get a fix. It is amazing. The pins are also large enough so that it can be easily soldered on the PCB.

The antenna is integrated into the module. The picture above is actually of the bottom of the module. The antenna is on the other side (the top) of the module. All you need to do is apply power and it will start outputting NMEA strings. That's it!

2. Radio module

The radio module chosen is the XBee Pro 900HP module from Digi. It is available in a couple of different versions depending on where you plan on using it and which antenna you want to use. They cost $39 from vendors like Mouser or Digikey.

xbee-xsc-s3b-rpsma_lg.jpg


Digi supplies a Windows program to configure and test the modules, however this program cannot yet configure the remote 900HP radios over the air. Therefore if you need to change the configuration or upgrade the firmware, you need to do it before you solder the module to the board. These radios are very difficult to remove once all the pins are soldered!

I left the transmitter radio at the default configuration. You can experiment with setting the destination address to your base station's address. If you are operating multiple transmitters in the same area, you will need to do this otherwise the basestation will receive GPS coordinates for all the transmitters. These modules also have the ability to build mesh networks to greatly increase the range. The original thread has some info from another member that has played around with this feature.

If you buy the module with the RP-SMA connector then you'll need an antenna for it. The antenna I currently use is a 2 dBi antenna sold by DIY Drones for $7.95:

WI-W1063-900mhz-2dbi-2.jpg

https://store.3drobotics.com/products/antenna-900mhz-rp-sma-2dbi

The antenna measures 4.25" in length and can be rotated and bent 90 degrees.

I have noticed a difference between the performance of the wire antenna and the 2 dBi antenna. With the wire antenna I noticed more dropped packets, however it still works just fine. In all of the launches I've used the trackers in I've never completely lost the signal from either antenna.

3. Battery

The transmitter is designed to operate only on a singe cell Lipo battery. Powering the transmitter from a 9 V battery will destroy the power circuitry!

The on-board voltage regulator generates 3.2 V for the radio and GPS. There is a voltage supervisor that shuts the voltage regulator off when the battery voltage falls to ~3.08 V. This prevents the transmitter from discharging the battery below the recommended 3.0 V minimum level.

I suggest using a battery with a minimum capacity of 300 mAh. 300 mAh will run the transmitter for about 1.25 hours. I'm experimenting with different settings on the GPS to increase this time. Currently I use this 500 mAh battery for my transmitters:

SKU037929-001.JPG

https://www.banggood.com/Wholesale-5-X-Tigers-1S-3_7V-600mAh-2_1Wh-15C-LiPo-Battery-EFLB5001S-p-47835.html

You'll need to supply a mating battery connector for the battery you choose. If you go with the battery above, you'll need a JST female connector. You can find these on ebay, Hobby King, rc-connectors.com, etc. I usually make the lead about 2 to 2.5" long.

Assembly Tips

All of the components were chosen with an eye towards relatively easy assembly. The board can be assembled with just a fine tip soldering iron, some tweezers, a magnifing glass and a little patience in about 30 minutes.

Solder the voltage regulator and supervisor on the board first followed by the passive components (resistors, capacitors and LEDs). At this point, use a multimeter to check for shorts on the battery connections and between pins 1 and 10 on the XBee socket.

If you don't have any shorts, then power up the board and measure the voltage at pins 1 and 10 on the XBee socket. Even if you had a short, the voltage regulator's output is protected against shorts and won't destroy it. However the battery input is not protected against shorts.

You should read 3.2 V and the green power LED should be on. At this point it is safe to finish the assembly with the XBee and GPS modules. If you ever plan on removing the XBee module, then only solder pins 1 - 3, 10 and 15. If you solder all 20 pins, you will have an extremely difficult time removing the module, even with the right tools.

Version 1.1 of the transmitter adds a 6-pin header that allows a FTDI USB to serial cable to be used to configure the XBee radio. In normal operation, there are two solder jumpers that need to be closed so that the serial data lines between the GPS and the radio are connected. In order to use the USB serial cable, you will need to remove the solder from the jumpers and insert the header. The black ground wire (pin 1) on the USB serial cable is identified by the "BLK" silk screen on the board. The USB serial cable will not power the board - you will need to connect the battery to power the board. You must make sure that you only use the 3.3 V version of the USB serial cable otherwise you may damage the XBee radio.

I covered the transmitter with some clear 1" heat shrink tubing to protect the tracker. It is probably a good idea to wrap it with something to prevent accidental shorts.

Update 1 (6-5-13): Added version 1.1 info
Update 2 (11-27-13): Changed link for UP501 to ebay
Update 3 (12-27-13): Added info about battery connector
Update 4 (5-15-14): Added link to alternate UP501 vendors
 
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Rocket Track RX 1.1 Assembled.jpg

The tracker communicates with the smartphone through the Bluetooth base station (I use the term base station and receiver interchangably). The base station has two radios: a XBee Pro 900HP radio for communtication with the transmitter in the rocket and a Bluetooth radio to communicate with the phone. Bluetooth was chosen because it is very easy to configure Android devices to use an external Bluetooth GPS.

Like the transmitter, the base station is powered only by a single cell Lipo battery. Additionally it includes a built-in Lipo battery charger so that you can charge the system's Lipo batteries without having to buy a Lipo battery charger. The base station has a micro USB connector for power for the battery charger. Everything is housed in a nice little case with a battery compartment for convenience.

1553_hands.jpg


Version 1.1 of the receiver board adds a loud buzzer that sounds when communication with the smartphone is interrupted and headers that allow you to program the XBee and Bluetooth modules after they have been installed on the board. There are two 6-pin headers that allow connection to a $20 FTDI 3.3V USB to serial cable:

RX Jumpers.jpg

ttl-232r.jpg

https://www.mouser.com/ProductDetail/FTDI/TTL-232R-3V3/?qs=sGAEpiMZZMvYU0Oh5y3R5sMdbLgwj41z

Make sure you only use the 3.3V version of this cable! The modules are not 5V tolerant. Connecting a 5V FTDI cable could damage them. In normal operation, two jumpers must be installed on the headers to connect the serial data lines between the modules. The location of the jumpers is outlined on the board. If you don't want to use the jumpers, there are two solder jumpers you can close that accomplish the same thing.

Components

1. XBee Pro 900HP radio

This is the same radio used in the transmitter. I suggest installing the version with the RP-SMA connector and using the biggest antenna you can find. I use this 3.5 dBi antenna:

$(KGrHqN,!rcE-ZED)ZLJBPtHEC)6Dg~~60_35.JPG

https://www.ebay.com/itm/900MHz-3-5dBi-RP-SMA-GSM-Antenna-wireless-router-/290362347165?pt=US_Networking_Boosters_Extenders_Antennas&hash=item439af1ce9d

The only change I suggest to the configuration of this radio is to change the baud rate to 115200 bps. You can download the software to configure the XBee radio here:

https://www.digi.com/support/productdetail?pid=3352&osvid=57&type=utilities

View attachment 131366

Screen shot courtesy of farsidius.

2. Roving Networks RN42XV Bluetooth module

rn42p.jpg

https://www.mouser.com/ProductDetail/Roving-Networks/RN42XVP-I-RM/?qs=sGAEpiMZZMsGelYiB%252bjhZkM9O5Hj9Wmg8j5TbHRD3BE%3d

I chose this Bluetooth module primarily because the through hole pins make it very easy to solder onto a board. There are other less expensive modules available, but I didn't think the possible added frustration was worth it.

You will need to make a couple of configuration changes to the Bluetooth module before you can use it. I suggest first resetting it to the factory defaults first. The default baud rate is 115200 bps, which is why I suggested changing the XBee to this rate.

The following five commands put the RN42XV module into command mode, reset it to the factory defaults, change the name of the device to "RocketTrack", configure the device for SPP use in Android and reset it.

Code:
$$$
SF,1
S-,RocketTrack
SE,0000110100001000800000805F9B34FB
R,1

3. Battery

I use this 750 mAh battery which fits perfectly in the battery compartment:

34531-main(3).jpg

https://hobbyking.com/hobbyking/store/__34531__Turnigy_nano_tech_750mAh_1S_35_70C_Lipo_Pack_Walkera_V120D02S_QR_Infra_X_.html

This battery should power the base station all day.

You'll need to supply a mating battery connector for the battery you choose. If you go with the battery above, you'll need a JST female connector. You can find these on ebay, Hobby King, rc-connectors.com, etc. I usually make the lead about 2.5 to 3" long. Using the same connector on the receiver and transmitter allows you to charge the transmitter battery with the receiver.

4. Enclosure

The base station PCB is designed to fit into the 1553 enclosure by Hammond Manufacturing:

1553BBKBK_s.jpg


They are available in a few different colors. For the first base station I built I bought the black one. This turned out to be a mistake because as it turns out, black isn't the easiest color to find when you drop the base station in the woods or thick under brush. Oops!

You can see all the colors here:

https://www.hammondmfg.com/1553colors.htm

For future base stations I'll be building I will use the red case. Hopefully that will stand out more making it easier to find if it gets dropped.

1553BRD_s.jpg


You'll need to supply four #4 x 1/4" self tapping screws to mount the PCB to the enclosure. Hammond also offers a belt clip option for this case. It makes it convenient to carry the base station with you - just make sure you clip it to your belt and not your pocket!

I designed a face plate that you can print with a 3d printer. Here you go:

View attachment Face Plate.stl

Assembly Tips:

Install the micro USB connector first and the power switch last. As with the transmitter, it is a good idea to check for shorts and the verify that the 3.2 V supply is working correctly before installing the two radio modules.

The battery charge rate is controlled by a solder jumper (SJ1 for rev 1.0 boards, SJ3 for the rev 1.1 boards). If the solder jumper is left open, the charge rate is set to 100 mA. Closing the solder jumper increases the charge rate to 280 mA. I use the 280 mA rate. Even though this is above the USB spec, I haven't come across a computer where the higher rate has caused a problem.

Monitor the battery the first time you use the charger to make sure it doesn't get too hot. When the red charging LED goes out, the battery is charged. You should measure the battery voltage after the first charge to make sure the charger is working properly. The battery voltage should be about 4.2 V.

Once you have built and tested it, your Android phone should be able to connect to it.

Update 1 (4-27-13): Added enclosure info
Update 2 (5-20-13): Added version 1.1 info
Update 3 (5-28-13): Added link to Digi X-CTU software
Update 4 (5-31-13): Added info about charger
Update 5 (12-27-13): Added info about battery connector
Update 6 (10-24-16): Added faceplate stl
 
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New software

Kevin has written the "official" software for the Rocket Track system. Some of the really neat features of this app are:

  • Tweaks to the GPS to improve accuracy and increase transmitter battery life by 50%
  • Map view
  • Compass view
  • Console view to see incoming data
  • Saving data for further analysis
  • Units in feet or meters
  • System status indicators
  • Lots more to come!

Download the Rocket Track app for Android here:

View attachment RocketTrack.zip

Unfortunately this forum doesn't allow uploading files with .apk extensions so you'll need to download this zip file. The easiest method of installing it is to unzip the app and email it to your gmail account. You can install it from the gmail app. You'll need to temporarily enable installation of apps from unknown sources to install it.

The software is located in the repository here:

https://github.com/kruland2607/RocketTrack

If you don't feel up to building the software, then there is a simpler app called GPS Rocket Locator that has been released that also works with this hardware. You can read about it here:

https://www.rocketryforum.com/showthread.php?55650-GPS-Rocket-Locator-for-android-(Now-released-!)

This app is available in the Google Play store:

https://play.google.com/store/apps/details?id=com.frankdev.rocketlocator

With either of these two software options you do not need the software described below!

Older version of the software for historical purposes

In order to use the built in mapping apps, you need to trick your phone into using an external Bluetooth GPS. This is easily accomplished by disabling the phone's GPS and installing a Bluetooth GPS provider app. To disable the phone's GPS, use the power control widget and turn off the location function (the dot with compass-like icon).

The app I used for the external GPS is a free app called "Bluetooth GPS Provider" by mobile-je.de. You need to pair the Bluetooth shield with the phone before starting this app. You will also need to enable the developer options on the phone and enable the mock GPS locations setting. The Bluetooth GPS provider app will tell you this when you first launch it.

Here is the startup procedure I use:

1. Power up the tracker.
2. Power up the Bluetooth base station. The link light should be solid green when the link is established.
3. Open the Bluetooth GPS app. Press the big "Start" button.

The key is to have the radio link up and running before you start the Bluetooth GPS app otherwise it fails and you need to kill the app and start over. The GPS doesn't need a fix when you start the app, but the data must be coming into the phone. Once the GPS locks up, you will see the position status in the the Bluetooth GPS app.

Now you can open Google Maps or My Tracks and track your rocket!

I've used this successfully on a Nexus 4, Nexus 7, Motorola Droid 4 and a Nexus S 4G.

Have fun!

Update 1 (4-8-14): Added Rocket Track app
 
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Every thing you need to build this system is included here. There are two zip files, one containing the files for the transmitter and one for the base station. In each you'll find the Eagle schematics and board files, a BOM (Bill of Materials, or parts list), a PDF version of the schematics and a PDF with the locations of the components for easier assembly.

These files are released under the Creative Commons Attribution Share-Alike 3.0 License.

As of 6-5-13, the latest transmitter version is 1.1

View attachment Rocket_Track_Tx_v11.zip

You can order three transmitter PCBs directly from OSHPark with this link:

https://oshpark.com/shared_projects/zd45QFcL

As of 5-21-13, the latest receiver version is 1.1

View attachment Rocket_Track_Rx_v11.zip

You can order three receiver PCBs directly from OSHPark with this link:

https://oshpark.com/shared_projects/BqpOMOVp

Mini Transmitter version 1.0:

NOTE: THE MINI TRANSMITTER AND THE REGULAR TRANSMITTER ARE NOT THE SAME! ALL OF THE INFO IN POST #2 IS FOR THE REGULAR TRANSMITTER (I.E. NOT THE MINI)!

As of 4-7-13, the latest mini transmitter version is 1.0

View attachment Rocket_Track_Mini_Tx_v10.zip

I don't sell the mini tx PCB but you can order three for yourself from oshpark.com (my PCB vendor) for $7.50 including shipping. It takes about two weeks for your order to be delivered. Buy them here:

https://oshpark.com/shared_projects/L0ku57fF

Older versions:

View attachment Rocket_Track_Tx_v10.zip

View attachment Rocket_Track_Rx_v10.zip

Update 1 (5-21-13): Added receiver version 1.1 files
Update 2 (6-5-13): Added transmitter version 1.1 files
Update 3 (4-7-14): Added mini transmitter version 1.0 files
Update 4 (9-11-14): Added links to purchase tx and rx PCBs
 
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I have used your system twice and both times it worked great. As a point of reference here is the way I use the system. The rocket side is standard but with the RX side I use a USB - XBee board. This inputs the NEMA data stream directly into my Netbook. I run a program called GPS Diagnostics V1.05 by CommLinx Solutions. This displays the NEMA data in a user friendly way, giving the Lat/Lon and much more. You can also log the data to the disk for later use. After the flight we read the Lan/Lon and type in the data to a free GPS app for the iPhone. We use that data as the waypoint so the phone knows where we are and the way point is where the rocket is located and it gives us an arrow to follow along with distance to target. This has worked fairly well but the iPhone GPS is flaky sometimes as it may not be a true GPS. In addition to the tracking function the log file can be used to display your flight on Google earth. Just rename the log file from .txt to .log and import into GE and see the track. I would guess that if there was a street view you may see a 3d view. None of my flights have been close to any road in street view.

Dick
 
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Dick makes a good point about only needing the transmitter if you want to display the rocket's position on a computer. I believe there is another member of this forum that does the same thing with just a transmitter.
 
I've been getting a bunch of questions about how easy these board are to assembly by people with little or no experience soldering surface mount parts. The truth is this is not a great project to learn how to solder small surface mount components on. Could it be done? Sure, but it may take a few parts (and possibly boards) before a beginner assembled one. Removing and installing parts multiple times can damage the pads and/or parts. The LEDs are particularly fragile. You only get one chance to solder those.

The components I chose are a trade off between size and ease of assembly. I could have chosen smaller parts, but then assembly gets a lot more difficult. It also wouldn't have made the tx much smaller as the xbee and the gps aren't getting smaller. Bigger parts would have made the board bigger. The size of the rx is dictated by the case and there is plenty or space in the case I chose.

So, I've been thinking about making a new, larger version that used all through hole components if there is enough interest.

Does this sound like a worthwhile trade off?

There will be some compromises other than the increased tx size. The tx will most likely lose the lipo low voltage protection (I can't find a through hole version of this part) and the cost of the pcb will increase a bit. The rx will lose the lipo protection and the usb lipo charger (same issue). The up side is both boards could run off a 9 - 12v battery and will probably be cheaper to build due to fewer components.

Does this appeal to anyone?

If I get enough positive comments I'd consider doing this. I don't personally have a need for these changes, but I'd be willing to help out those who want a cheap, more easily assembled gps tracking system.

Derek
 
I ordered some PCBs from Derek and thought I would post my experience building this transmitter and receiver. I'm not an electronics guru, so this will be the layman's build. I played around with electronics when I was teen, but that was 25 years ago. I have a couple of soldering irons but I had to order some finer solder for this project. The soldering iron I preferred was a little 20w hobby iron from radio shack (cat no 64-093 on the handle). I have a fine-tip Weller, but found it too pointy. I ordered 0.6mm solder, it worked ok but I think i could have used something a little smaller still. This will also be my first real attempt to do surface mount components. I found a few good videos on YouTube showing how to solder surface mount parts. They were very helpful and made that part a breeze.

WP_000577.jpg
Since I ordered last month, I received the version 1.0 transmitter and receiver boards.

I ordered all the components as specified in Derek's BOM and in his build post #2 and #3 above.

WP_000599.jpg
No fancy workspace; just used my helping hands magnifier, some tweezers and other various items
 
First part: the transmitter.

The helping hands magnifier did a fine job of magnifying the board for me. As per the instructions I started with the supervisor and regulator. Here you can see the small bead of solder on one of the pads for the supervisor.
WP_000600.jpg

I used the tweezers to hold the part on the board at that location and then touched the iron to it to secure it. Now that it's held in place, I can apply solder to the other pads.
WP_000601.jpg
And those parts are done. The blue pad underneath the board is just jiffy-grip. Keeps it from sliding around while I'm working on it. You don't need to worry about it melting - you never heat up the board enough.
 
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Next I added the resistors and capacitors to the board. Sheesh...these things are tiny
WP_000602.jpg
Sorry for the fuzzy pic. Two resistors on the board, one pad pre-soldered for each so I could tack each one down, then I came back and applied solder to the opposite end.

WP_000603.jpg
Finished with the capacitors and resistors.

Next I attached the LEDs and battery cable. LED's must be attached quickly or they will melt (thankfully I didn't melt any). Next I checked for shorts as directed: on the battery connections and between pins 1 and 10 on the XBee socket. I didn't have any shorts - Yeah!

BTW, the part number for the battery connectors listed in the BOM are not the correct ones. I ended up just using some JST leads that I had already. I use them in my AV bays a lot. You can find bulk packs on ebay fairly cheaply. (https://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=280865460134&ssPageName=ADME:L:OC:US:3160) usually about $5 for 10 pair or $10 for 50 pair. They take about 2 weeks to ship from Hong Kong

I next applied power to check voltage (connected the battery). If I did it right I should measure 3.2V at pins 1 and 10 on the XBee socket and my green LED should come on. Well, I had 3.2 V, but no LED - figured I must have done something wrong. A quick PM to Derek and it was suggested that I might have the LED on backwards. I didn't want to ruin the LED taking it off, so I used two soldering irons on both ends at once and quickly slid it off the pads. I connected the battery to the board and placed the LED back on the pads in the opposite orientation and it lit up. I resoldered it to the board. I had to correct the orientation of the red LED also.

WP_000604.jpg
Yeah - green light!
 
Now the easy parts. I put on the XBee module and soldered it in place.
WP_000605.jpg

Next I added 6 pins header to the board so I could attach the GPS module. The header comes as a 100 pin strip and you just snap 6 pins off. This got soldered to the board then I snipped the long pins off from underneath the board
WP_000606.jpg

Next I placed the GPS module onto the header pins and soldered it in place
WP_000607.jpg


And I'm done with the transmitter.
WP_000608.jpg

Powered up I have a steady green LED and a flashing red LED
WP_000610.jpg

I hope to get going on the receiver later this week. I'll need to get some more help on that part. It's not exactly clear to me how I make the configuration changes to the Bluetooth module.
 
farsidius,

nice work! If you haven't already done so, I suggest soldering the two mounting tabs on the sides of the gps module. that will help keep it in place.

About configuring the radios, you can use a usb to xbee adapter. I happen to use this one:

XBEE-USB_3.jpg

https://gravitech.us/xbtousbad.html

a little cheaper than the sparkfun one. I think I got them on ebay.

you can also find different ones at places like sparkfun or ebay.

https://www.sparkfun.com/products/8687
https://www.ebay.com/sch/i.html?_tr...313.TR9.TRC1&_nkw=xbee+usb&_sacat=0&_from=R40

what was the issue with the battery part number? I just checked it and it was correct. I've bought bag of them but haven't needed to use them as I prefer the jst like you used.

Thanks for posting your experiences!

Derek
 
To configure the Bluetooth radio, I use Hyperterminal. The default baud rate settings are 115200 baud rate, 8N1, no flow control. just paste the settings above into hyperterminal.

To configure the xbee radio, you need to use digi's software, x-ctu.

https://www.digi.com/support/productdetail?pid=3352&osvid=57&type=utilities

the xbee radios should have a default rate of 9600 baud, 8N1 and no flow control.
 
Thanks for the additional info on programming the XBee radio and Bluetooth modules. This will be my first time using these - I'm such a noob (or is that newb). I already have this adapter (https://www.sparkfun.com/products/9819) as it was suggested by someone in your original thread and I was toying with just receiving the signal directly to my netbook. Guess I have what I need after all. I'll look at getting those programmed tonight at home.

With regards to the battery connectors; I was expecting something that the batteries could plug into. I received small, white connectors that are too small for either battery to plug into. Maybe Digikey sent me the wrong part? Regardless, I like the JST leads that I used.

Again, thanks for your help and for this fun project.

-brant
 
With regards to the battery connectors; I was expecting something that the batteries could plug into. I received small, white connectors that are too small for either battery to plug into. Maybe Digikey sent me the wrong part? Regardless, I like the JST leads that I used.

that is the right part number. the original boards can accommodate those battery connectors so you could buy a battery from sparkfun with the mating connector on them. I just never used them as all the batteries I had use jst connectors or something similar. sorry for the confusion!

I've done away with those connectors on the version 1.1 boards and just have two holes to solder wires to.

Derek
 
One of the other changes I made to the version 1.1 rx boards is I identified pin one on the xbee/bt module footprints with a square pad and changed the orientation of the bt module so the placement is a little more obvious. Make sure you study the orientation of the bt module in this (lousy) pic of a version 1.0 rx board:

rocket track system small.jpg

the bt antenna must point up so it doesn't cover the silkscreen or interfere with the battery cable.
 
Part two: the Receiver

Last night I programmed the Bluetooth and XBee radio modules. I used PuTTy to send the commands to the Bluetooth module and x-ctu for changing the baud rate of the XBee. In PuTTy I entered each command one line at a time and it returned OK after each set except for the final command with returned "Reset" so I figured it worked. With the BT unit still plugged into my computer, I used my phone's BT setup menu and searched for devices. It found one named RocketTrack which told me I did it correctly.

The x-ctu interface looked like this:

x-ctu.jpg

After selecting the new baud rate (115200) click on write and wait for it to finish. It tells you at the bottom that it's complete. Done with that now.

On to the PCB. Following the directions I soldered on the micro USB connector first, then the charger, supervisor and regulator. Next I added the capacitors and the resistors. A couple ugly solder connections, but it's all functional. Tested for shorts. I'll test more tomorrow after the LEDs and switch are attached.
WP_000614.jpg

And that's all for tonight. Tomorrow I'll put on the LEDs and switch, BT and XBee radio.
 
Finishing up now. Connected the two red and one green LEDs. These LEDs are jumpy - lost one that jumped out of my tweezers. Good thing I ordered a few extra of all the small stuff.

Next the switch. Checked for shorts on the battery connections and between pins 1 and 10 on the modules. Connected the battery and the green LED came on - guess I'm getting better at this already. Checked voltage at pins 1 and 10 for both modules; both read 3.2 volts. Flipped the switch a few times to make sure it worked.

WP_000619.jpg

Next I attached the BT and XBee modules. Plugged it in. Looks like it's working :)

WP_000620.jpg

I opted for the red case. I'll cut out holes in the case for the antenna, usb and switch later. Tomorrow I'll get my phone set up and test it out.

One more question: I notice in the middle of the board there's a solder jumper to change the charging current from 100 mA to 280 mA. Any reason I wouldn't want the higher charging current on this?

This was fun to build and Derek was quick to respond to my every question, here and through PM. Thanks for all your help with this. I'll update the post as I test out the unit over the next few days.
 
I use 280. I haven't found a computer that this causes problems with even though it is over the 100 mah max spec. Try 280. If it works, great. If not open the jumper back up. If you use a phone charger 280 should be fine.

Watch it the first time you charge a battery. When the red light goes out, the battery is charged. You should check the battery voltage with a volt meter and it should read 4.2 volts.
 
Looks great. I'll save the congrats until you test it with a phone.

:)
 
Has anyone tested this GPS up to or above 10,000 feet yet?
 
I found a little time to test my tracker this weekend. I was hoping to make it to the club launch on Saturday and send it up in a rocket, but alas, we opted to attend my daughter's graduation instead. :p (although honestly I think she would rather have attended the launch too)

I just did a little ground testing in the neighborhood. I was able to keep a lock on the transmitter between 1/3 and 1/2 mile. Now, this is probably the worse terrain for testing this - rolling hills, tons of trees, lots of homes and probably endless sources of electrical interference with all the wireless networks in my neighborhood (Derek knows where I live). But, I know it works now. I'll try to find a more open space later and get a better idea of ground range. I probably won't have chance to test it in a rocket until the 26th of this month - lots of traveling this month.

I have a question about the receiver and battery charging. When I have a powered USB cable plugged into the receiver it appears that it will operate it without the battery plugged in. If a battery is plugged in also, will the battery charge while the unit is operating, or will it only charge if I turn the receiver off? The charging light is on, so I'm assuming it does, just want to double check.
 
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