$25 GPS Solution

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I was using a 100mw 433Mhz module, and that was with the phantom about 400 feet up and the ground module literally on the ground since I haven't made any kind of pole or anything to get it up in the air a bit. I would say range is pretty significant given the cost of this setup.
 
Dan, By connecting the B/T module in the manner you show are you able to program the radio over Bluetooth also? I think in reality one only would need to take the received data out of the Hope module
as that would be the position strings of the rocket. I like your setup better. Think an HC-06 would work? I have a couple of those around.

Also is there a reasonable way to get the plastic cases apart without damaging what's underneath? Kurt
 
I have not tried programming the radio over bluetooth, but I can't see why not, since it is just another COM port. It really shouldn't matter I wouldn't think. An HC-06 should work just fine. My intention was to use one of those but they didn't get here today so I just grabbed an HC-05 that I already had. I just split the cases with an Xacto knife. Mine were just held together by 6 tapered pins that slipped right apart.
 
Quick rundown on the Android OTG:

Fantastic mobile program for Android:

https://play.google.com/store/apps/details?id=de.pilablu.gnsscommander&hl=en

I'm sure there are others out there, but so far, this is the only one I have used.

With proper OTG cables and a compatible mobile device, this system seems to work quite well. Some setup and program configuration is necessary but it was pretty intuitive.

Screenshots using my trusty Samsung Galaxy S4 with 4.4.4 KitKat Android:

Screenshot_2017-08-12-19-00-52.jpgScreenshot_2017-08-12-19-00-58.jpgScreenshot_2017-08-12-19-01-03.jpgScreenshot_2017-08-12-19-01-18.jpgScreenshot_2017-08-12-19-01-33.jpgScreenshot_2017-08-12-19-01-55.jpg

The system as I would use it in the field:

DSCF0017.jpgDSCF0018.jpg

My prefect launch site has fantastic network coverage, so my options are open as to how I can use the data. All I need are coordinates and a map (mobile Google Maps for me). I'll eventually make a little case or use the stock covers and some way to velcro/fasten the radio to the phone when using it as a tracker in the field.

I'll be at the desk with a soldering iron Monday to figure out the Bluetooth connections and I think that about wraps this up. I intend to use the OTG method (until I eventually figure out Bluetooth is more convenient), so my Bluetooth efforts are merely for informational purposes and as a guide for a BT solution for those who may end up with the integrated radios like mine (rather than radios with Hope modules) as dan_olson kindly gave us the lowdown on Bluetooth with Hope modules in his recent entry.

After I figure out Bluetooth, I will do some significant field and range testing.

Stay tuned!
 
I've been following this thread with great interest. I hope when you guys get everything worked out you can do a "Dummies Guide to the $25 GPS Tracker". It's not that I don't like fiddling with stuff to make it work, I just don't have the funds to replace the magic smoke that escapes when wires are crossed. Gotta do it in 1.
 
I also concur, waiting to see if a "buy these specific items and then do these specific steps" guide comes from this.
 
Have you done a run time with a 1S lipo on this setup yet? I'd be jittery if the radio calls for 5V and you try to run it with something less even though you say there is a 3.3V regulator on the 3DR board. Is your GPS 3.3V?
Guy tried a 1S cell on an EggFinder and the thing choked by the time it was launched. Yeah, I know that's a different device but powering something differently than what's marked can lead to an unpleasant surprise.
Ahhh, I see with the program, OTG or B/T.

Other problem I see is you won't be able to track with this as the enabling Mock GPS location means your local GPS is subverted and the incoming stream is presumed your local position. Yes you will be able to see where it went, you can
take the lat/long and apply it to another application but won't be able to live track/navigate all in one app.

Shoot, the only way to live track then with the "GPS Rocket Locator" program would be to convert the receiver with a USB board like described above so the incoming strings could be used as the "rocket". I don't know if
GPS Rocket Locator can use an OTG connected source. Anyone know an answer that that? Kurt
 
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I can confirm that adding a Bluetooth module to the ground module works very well with rocket locator. It is a fairly simple and inexpensive mod to do as well. I hope I explained the steps clearly enough but if anyone would like any help let me know.
 
I can confirm that adding a Bluetooth module to the ground module works very well with rocket locator. It is a fairly simple and inexpensive mod to do as well. I hope I explained the steps clearly enough but if anyone would like any help let me know.

That's the direction I'm going with it once I get a GPS module for the transmitter. I confirmed with Francois that GPS Rocket Locator (in another thread) only accepts a B/T stream. I'll vouch for the fact it's nice to track on a single app that
shows your position and your rocket's and not have to doing anything such as manually inputting data from one device to another. Plus once you get within the tracker's ground footprint your receiver will display an updated position. Kurt
 
Have you done a run time with a 1S lipo on this setup yet? I'd be jittery if the radio calls for 5V and you try to run it with something less even though you say there is a 3.3V regulator on the 3DR board. Is your GPS 3.3V?
Guy tried a 1S cell on an EggFinder and the thing choked by the time it was launched. Yeah, I know that's a different device but powering something differently than what's marked can lead to an unpleasant surprise.
Ahhh, I see with the program, OTG or B/T.

Other problem I see is you won't be able to track with this as the enabling Mock GPS location means your local GPS is subverted and the incoming stream is presumed your local position. Yes you will be able to see where it went, you can
take the lat/long and apply it to another application but won't be able to live track/navigate all in one app.

Shoot, the only way to live track then with the "GPS Rocket Locator" program would be to convert the receiver with a USB board like described above so the incoming strings could be used as the "rocket". I don't know if
GPS Rocket Locator can use an OTG connected source. Anyone know an answer that that? Kurt

To respond to your first point: It is my understanding that said "Guy" was in a bit of a hurry to push his L3, and either failed to calculate or miscalculated his tracker power requirements and used an insufficient battery capacity,therefore consuming what power was available while waiting on the pad. Correct me if I am wrong.

This type of error, however, could have been avoided with a little bit of math and an understanding of device power consumption. I have provided the data sheets for the two power-hungry transmitter components in a previous entry. Power requirements can be directly calculated with the information contained within the data sheets. This error is relatively simple to avoid as long as you do the math and ensure you supply the components with sufficient power (voltage and amp draw) to run the duration of your estimated pad, flight, and recovery times.

Personally, tracking is tantamount to proper flight computing/events execution, as I spend far too much time building them. My projects are not expendable. I take time and pay attention to detail on every one of them and want them back regardless of their condition, hence my motivation to piece together a low-cost, reliable, small form-factor, commercially available system with off the shelf crap (not smart enough to design my own stuff like Eggtimer).

As for your second point: I'm not sure what "this" is when you refer to mock locations. GNSS Commander does not require mock location. I know you value "live tracking", but I'm not sure how you define that. All GPS systems are live tracking. If what you mean is an application that plots a path from your position to the rocket (which I presume is the case), then I guess some just aren't happy without luxury in life.

To me, I could care less about a plot because I know how to read maps and orient myself using them. Realistically, how often would one follow the exact path anyway? In fact, I would posit that an application that simply plots a path from "A" to "B" without displaying coordinates or some other means of data logging would be dangerous to the cause. What if your receiver/phone/tablet/whatever failed? What if the battery died and you lost connection and were unable to regain a signal while replacing the battery, or any number of other failures were to occur?

Having and displaying a log of coordinates removes this dilemma, as I can apply them to any number of means to process them and eventually find my vehicle.

Finally, to your third point, I was unable to use OTG with "Rocket Locator".
 
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Correct on the first point but he didn't read the instructions that suggested a 2S pack. I don't care how much math you do, once your 1s voltage starts to drop feeding a 3.3V regulator, funny things can happen. Sure, use a larger capacity pack and you may be fine. I'd say don't let it sit on the pad that long if you're aren't going to test it first.

If you have to go the the developer setup and allow mock GPS location you will feed the rocket location to a map and that's it. The internal GPS is ignored. A bluetooth module on the receive side can pipe it to a program that will display both points at once. Ok, you want to stand there and dink with a log and feed your position to something else to get you there, suit yourself. Many have done it, just be certain you get your data input correctly.

Personally, with the NMEA trackers I don't consider it a luxury to track and navigate on a single application. It's relatively easy to setup, to refer to one device, one screen, track, navigate, go get the rocket, come back and fly the next one.

Yes, I confirmed with the developer that "GPS Rocket Locator" won't work with OTG but the instructions were posted how to effect that fix very easily by attaching a B/T module up above on the receiver. The picture is quite clear and looks simple to do. Simpler than the transmitter if you ask me. Not that much work to achieve the ability to track and navigate from one application. Kurt
 
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The developer also posted the source code on github. Modification could be easily added for OTG function.

Start writing, Kurt!

Throw in NMEA display and log while you're at it :)
 
I use a 1s 600mAh batteryhttps://hobbyking.com/en_us/turnigy...-solo-pro-328-eflite-mqx-120sr.html?wrh_pdp=3 and have left it on for up to 8 hours with it still sending a strong signal. I accidentally left one running for about 20 hours and it was dead enough that I have marked that battery for testing only as I don't trust them to fully recharge after they are taken below 3v. At $3 a battery it's not worth risking a rocket.
 
I use a 1s 600mAh batteryhttps://hobbyking.com/en_us/turnigy...-solo-pro-328-eflite-mqx-120sr.html?wrh_pdp=3 and have left it on for up to 8 hours with it still sending a strong signal. I accidentally left one running for about 20 hours and it was dead enough that I have marked that battery for testing only as I don't trust them to fully recharge after they are taken below 3v. At $3 a battery it's not worth risking a rocket.

Great! I may have to rethink my strategy of using a 5-volt regulator. A 600mah pack is not that large. You're right about dorking a battery. Sometimes you do that and they won't take a charge at all. Thanks for the report. Kurt
 
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I've done some cursory study on the UBLOX 7 message protocols and such. I got very curious, as to a method to inject my HAM call-sign into the NMEA strings being output from the GPS unit.

On page 63 of the UBLOX 7 receiver documentation, there is a function "TXT" which would appear as $GPTXT in the NMEA strings. Field number 4 says any ASCII text can be transmitted. Field number 3 describes the message type, and "02" is a notice. I am thinking this could be easily the call sign of the radio operator, when using the 433 MHz band in the United States.

Further reading into just how to reprogram the UBLOX module indicates that a GPS to FTDI cable would be needed. I have a general FTDI cable on order, and if I get a certain level of confidence, I'll take a look at the coding inside the module. I may order another module just in case, given the probability of me bricking it with ineptitude.
 
My set of 500mW Tx/Rx just turned up. Looks great. Can someone just confirm for me the input voltage required is 5V please?

Just about to start installing the required software etc. I will need to wait for a GPS module to turn up before I get to test it properly.

Thanks for starting the thread on this Corzero :)
 
My set of 500mW Tx/Rx just turned up. Looks great. Can someone just confirm for me the input voltage required is 5V please?

Just about to start installing the required software etc. I will need to wait for a GPS module to turn up before I get to test it properly.

Thanks for starting the thread on this Corzero :)

Si1000 3DR

Voltage range is 0.9 to 4.0

See pages 1, 29 and 40:

https://www.silabs.com/documents/public/data-sheets/Si1000.pdf

85mA consumption

Neo7 Ublox GPS antenna:

Voltage range is 1.65 to 3.6

See pages 16 and 17:

https://www.u-blox.com/sites/default/files/products/documents/NEO-7_DataSheet_(UBX-13003830).pdf

67mA consumption

Hope this clears the air on voltage. 1S lipo satisfies voltage requirements for 3DR and the GPS antenna. Correct me if I am wrong.
 
I didn't show you anything you didn't already know. So what am I missing?
 
I didn't show you anything you didn't already know. So what am I missing?

I didn't have a lot of time to read through the rest of the thread doco, so I skimmed it a bit. Thanks for distilling it down for me! Appreciated.

Just to put things in perspective, I am currently designing some electronics for work. It is a small board (8-10 square inches) and the data sheet page count is somewhere above about 4000 pages. Information overload. Since I do this for a day job I just buy electronics for rocketry. I would rather be doing something else related to rockets with my time.
 
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I figured. Alright well just don't sit too close to the TV, you'll rot your brain.
 
My set of 500mW Tx/Rx just turned up. Looks great. Can someone just confirm for me the input voltage required is 5V please?

Just about to start installing the required software etc. I will need to wait for a GPS module to turn up before I get to test it properly.

Thanks for starting the thread on this Corzero :)

The units in the first post suggest 5V. The Ublox GPS in the first post (I believe it was the $8.56 one?) says 5V. Now yes that may mean there is a voltage
regulator in both the radio and the GPS that perhaps is 3.3V. The post above shows that a test was done with a 600mah 1S cell that had a good runtime.
I would suspect one wouldn't have anything to fear as long as a 1S cell is of adequate capacity. That would make it possible to have a minimalist tracker.
3DR remote, GPS and battery to take advantage of weight savings. For the paranoid out there, a 5V regulator would be possible: https://www.ebay.com/itm/AMS1117-5V...&sd=221363364696&_trksid=p2047675.c100623.m-1
I bought a bunch of these for a lot less some time ago without terminals for .99 each for other projects and jury rigged one to feed the 3DR remote so I
could fire up the programming app. I didn't want to risk wrecking anything and it worked fine. I now have to wire in the GPS to the remote;transmitter. Kurt
 
For reference, I have only used a 1s lipo on the 100mw radio. I believe the 500mw radios have a higher power requirement and have been told that the rfdesigns 1w radio requires a solid 5v and don't like being powered from a USB port.
 
I also concur, waiting to see if a "buy these specific items and then do these specific steps" guide comes from this.

I dunno about other people, but I would pay something reasonable ($10-$20?) for the instruction set and parts list. There's room between paying you something for your time and getting into the same price range as the Eggfinder kits.
 
Ok, a link on feeding 3.3V into a 5V to 3.3V regulator: https://electronics.stackexchange.c...you-feed-3-3v-to-a-5-to-3-3-voltage-regulator (I'm working with a 500mW radio not the 100mW)

Looks like the consensus is it's not a good idea. I think I'll go with one of those 99 cent 5V voltage regulators I posted in the link above. They're small, they can do 800ma to 1 amp out and
I think they'll provide enough juice for the 500mW radio and the GPS. Can shrink tube it to the other side of the 3DR board after laying down some insulating tape.

Well shoot, found this output curve for that little 5V regulator and it seems the higher the input V the lower the expected output mah capability: https://envistiamall.com/blogs/envi...v-module-output-current-vs-voltage-soa-curves. Hmmmm, I wonder what the 500mW 3DR draws. Will have to look again for a solution as it doesn't look like the little AMS board I show in the above link won't work with the 500mW radio current draw requirements.

Ok, found a post that said a 500mW 433Mhz 3DR radio draws 500Mah on transmit: https://hobbyking.com/en_us/hkpilot-500mw-transceiver-telemetry-radio-set-v2-433mhz.html

Ok, here is a Pololu 5V regulator that would allow a 2S battery to work: https://www.pololu.com/product/2831

Again, I'm working with a 500mW radio and not the 100Mw one. The 1s battery on the 100Mw may hold true as long as the 1S 4.2V battery is fresh and has decent capacity. A higher output set may have different current requirements.
The transceiver in the 500mW radio is not a Hope radio and is apparently a clone of some kind. Kurt
 
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Well shoot, found this output curve for that little 5V regulator and it seems the higher the input V the lower the expected output mah capability: https://envistiamall.com/blogs/envis...age-soa-curves. Hmmmm, I wonder what the 500mW 3DR draws. Will have to look again for a solution as it doesn't look like the little AMS board I show in the above link won't work with the 500mW radio current draw requirements.

That 5V regulator you mention is a linear device, essentially making a variable resistor in series with the load to regulate the load voltage. This creates lots of heat (and wastes energy) and hence the lower current ability at high input voltages. It will overheat and either switch off the output or end up dead if you exceed the safe operating area curve, especially in warmer environments.

Consider a SBEC or something like it from Hobby King. These use switchmode regulators so are generally 85% efficient or better, so they don't overheat so easily compared to the linear regulators. The other advantage is as well as making less heat, more of the energy from the battery goes to the telemetry, so you get better run time: https://hobbyking.com/en_us/sbec-ubec-regulator-1.html
 
Thanks, I think the Pololu regulator might be more acceptable and is a nice size. A BEC looks too large. I used the small 5V AMS for simply programming the set with the software to get familiar with it. I had the parts lying around already and
didn't have the GPS wired up yet. Kurt
 
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