Homebrew GPS Tracker

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jqavins

TRF Supporter
Given: GPS trackers are expensive. Discussion of the prices of various models is a different thread. (Not that I wou;dn't appreciate the information, but I can look it up elsewhere.)

Suppose: I have the ability to design, assemble, and test a GPS tracker of my own. OK, I don't really, but I have the bulk of it, and let's suppose I'll successfully learn the rest.

Question: Can a functional, durable homebrew tracker be made for substantially less money than it can be purchased?

Bat-mite

Rocketeer in MD
Without doing any research -- yes. When you buy a commercial product, you are buying design, parts and labor. If you do the design and labor yourself, you are only buying parts.

I believe the Eggfinder is cheaper than most, and you do the soldering yourself. A good compromise.

jqavins

TRF Supporter
You're re-buying parts at retail that a manufacturer bought in bulk. You're buying an amortized share of design effort. I know darned well that I can't build a car for less than I can buy one. That's why I think research is needed.

I'm doing research. The first step in research is to ask around among people who might already know.

Bat-mite

Rocketeer in MD
You're re-buying parts at retail that a manufacturer bought in bulk. You're buying an amortized share of design effort. I know darned well that I can't build a car for less than I can buy one. That's why I think research is needed.

I'm doing research. The first step in research is to ask around among people who might already know.
Fair enough! Good luck.

manixFan

The cheapest Eggfinder system is about $100. So if you got everything for free the most you can save is$100. That's how I tend to look at things - what's the most I can save? Your main question is: "Can a functional, durable homebrew tracker be made for substantially less money than it can be purchased?" Based on my criteria, I would say no - saving $100 to try and duplicate something that is readily available from a vendor with known excellent support is not worth the effort, if saving money is the main goal. But in the end it's a decision only you can make, based on your goals for such a system. Tony PayLoad I don't do spirals TRF Supporter I think the most important question to ask prior to seeing "if you can build for a reasonable cost" is to see if you can provide a product that people want. ALL of the trackers out there have shortcomings. Build one that automatically connects to iPhone, Galaxy, tablet or laptop, make it simply idiot proof, and the cost will be moot. gtg738w FlightSketch - flightsketch.com Sure, you can plug a GPS module into a serial radio for pretty cheap and with almost no effort. Does that count as a tracker? If you try to match the value of some of the rocketry specific products then definitely not. The cost to develop a system on par with what's currently available would be MANY times more than buying one off the shelf. jqavins Helpful Smartass TRF Supporter I think the most important question to ask prior to seeing "if you can build for a reasonable cost" is to see if you can provide a product that people want. Nope. For me that's a completely irrelevant question. I have no interest in entrepreneurship; I just want a GPS tracker and I'm scared off by the prices. (I had not found the$100 Eggfinder system.) As I said above, I know I can't build a car for less than I can buy one. On the other hand, I know I can cook a damn good steak for less than I can buy it at a restaurant. I'm not trying to open a steakhouse.

The cost to develop a system on par with what's currently available...
is the time that I put into it ($0) plus any parts I may burn up in the process. Update: I checked out the Eggfinder system. For what I have in mind I'd have to buy the basic transmitter ($70), the LCD handheld receiver kit ($55) and LCD GPS module add-on ($40). So $165. That's not unaffordable, but I'm a cheapskate. If I can do it myself for$65 and save a hundred bucks, that's probably worth it. If I can do it myself for $140 and save twenty-five, that's not. Last edited: curtisheisey Well-Known Member TRF Supporter If you think that you can get to a usable device on one or two design iterations, you are probably fooling yourself. Expect 3 or 4 design iterations, unless you have substantial electronics design experience under your belt (circuit design, PCB layout and fabrication, SMD solder AND circuit debugging) and access to good electronics tools. If you want a tracker or two for yourself, you will probably not save money designing it yourself vs Eggtimering it (that should be a verb). Now, if you want 10, that's a different story. Just my 0.02. jqavins Helpful Smartass TRF Supporter If you think that you can get to a usable device on one or two design iterations, you are probably fooling yourself. Expect 3 or 4 design iterations, unless you have substantial electronics design experience under your belt (circuit design, PCB layout and fabrication, SMD solder AND circuit debugging) and access to good electronics tools. I have some of that, but not all of it. What's more than one of two, but less than three or four? I guess two or three iterations? And iterations cost me only parts and time I would otherwise have spent goofing off. Do I sound argumentative? I don't mean to. I'm just trying to be sure I'm clear. Has anyone here done this? I'm happy to have opinions; I'd be happier to have data. MidOH Well-Known Member Pardon me, I'm a newb. But why does it have to be a GPS tracker? Why not just a simple radio ping-er like what a naturalist put on lions and such. Head phones, radio, and a directional antennae should be cheap and easy to fab. Has anyone tried a dog tracker? Rip the electronics out of the case and I'd guess they'd fit an E bay ok-ish. ETA: Nevermind, the non-web based versions cost as much as current rocket GPS. Last edited: curtisheisey Well-Known Member TRF Supporter Yeah, maybe two or three. And yes the design process can certainly be a lot of fun. I just think a lot of people are fooling themselves: BOM is$60, retail is $300. I can save money. Maybe so, but it will often take a lot of time and money and several tries. If you are in it for the learning and fun and engineering process, they hey, go for it. (And feature evolution/creep and drive additional iterations of things you didn't think of the 1st time around). I made a camera trigger board. Moderly complex. I'm don't have a lot of electronics experience. These were basic ardunio I/o circuits off the web. Optoisolators, basic transitor switching, digital I/O. 95 % working 1st iteration. 2nd and 3rd iterations were evoloving features as much as fixing things. 3rd iteration I was really happy with it, and built 4 or 5 units. Then I decided to do an SMD version and an arduino shield iterations, and those are both bombs. gtg738w FlightSketch - flightsketch.com Has anyone here done this? I'm personally on rev 17 . If you think it would be a fun project you should absolutely give it a try. It can be very rewarding but there is a 99% chance you will spend more than just buying an Eggfinder. Or build the Eggfinder first and then try your own. See how they compare first hand. cerving Owner, Eggtimer Rocketry TRF Sponsor TRF Supporter Nope. For me that's a completely irrelevant question. I have no interest in entrepreneurship; I just want a GPS tracker and I'm scared off by the prices. (I had not found the$100 Eggfinder system.) As I said above, I know I can't build a car for less than I can buy one. On the other hand, I know I can cook a damn good steak for less than I can buy it at a restaurant. I'm not trying to open a steakhouse.

is the time that I put into it ($0) plus any parts I may burn up in the process. Update: I checked out the Eggfinder system. For what I have in mind I'd have to buy the basic transmitter ($70), the LCD handheld receiver kit ($55) and LCD GPS module add-on ($40). So $165. That's not unaffordable, but I'm a cheapskate. If I can do it myself for$65 and save a hundred bucks, that's probably worth it. If I can do it myself for $140 and save twenty-five, that's not. For your$165, you're getting a system that's self-contained, no other devices needed, and gives you the coordinates, distance to your rocket, compass direction of your rocket, and an arrow/bearing that you can follow right to your rocket. It also acts as an altimeter telemetry receiver. The software has been developed over the course of 7 years and is well vetted. Just sayin'... you CAN make something cheaper if you try, but how much is your time worth? Considering the amount of development time, flight time, and money required to shake these things down (we test with our own rockets and motors, no volunteer "beta testers" shelling out their time and money), you probably will find that from an economic point of view it's not worth it. Now if you're doing it for fun or education, that's an entirely different matter... those don't need to be cost-justified.

boatgeek

Well-Known Member
Just sayin'... you CAN make something cheaper if you try, but how much is your time worth?
...
Now if you're doing it for fun or education, that's an entirely different matter... those don't need to be cost-justified.
I think that's the real key for this--what value do you put on your time? If it's $0 as mentioned above, then lots of things become more "affordable". jqavins Helpful Smartass TRF Supporter If I would otherwise spend the time watching TV, and wondering now and then if maybe I could be doing something, the yes, that time is worth zero. The old saying, "Time is money" is total BS. Pardon me, I'm a newb. But why does it have to be a GPS tracker? Why not just a simple radio ping-er like what a naturalist put on lions and such. Head phones, radio, and a directional antennae should be cheap and easy to fab. Many people do. Playing Marko Polo with a directional antenna is not as easy as it sounds. When the target calls out "Marko - here are my latitude and longitude - Polo" then life is a whole lot easier. cerving, I'm not knocking your products or your prices, nor questioning your quality or value. My thinking is only that that if I can make a bare bones device that works so I stop losing rockets then, well, as I said, I'm a cheapskate. Last edited: MidOH Well-Known Member I was just about to post that they should make a GPS and altimeter on one board............and derp, they do: billdz Well-Known Member My thinking is only that that if I can make a bare bones device that works so I stop losing rockets then, well, as I said, I'm a cheapskate. There are other threads on this forum about homebrew GPS trackers, one guy claims he made his for$25. See, for example:

These are all point to point GPS trackers. My personal project has been cellular GPS, which is cheap but only works if your field has good cell service. In a larger rocket, you can simply wrap up an old Android phone and stick it in your rocket, see https://www.rocketryforum.com/threads/cheap-cellular-trackers-update-and-where-are-the-3gs.151170/.

I don't do spirals
TRF Supporter
OK, So, your time is worth nothing to you.
You've been made aware of cheap kits out there.

So the answer to your original question is "No".

GrouchoDuke

Well-Known Member
I was going to write something similar to Cris. If you value your time at all, you can't make one for cheaper than you can buy one. Not even close. Yes, the BOM plus manufacturing costs per unit can be quite a bit less than the prices you see, but you'd need dozens, if not hundreds, for yourself to really break even. If it's for fun & that's how you want to spend your time, then that changes the calculations.

There are several of us here who are working on rocket electronics projects of various types. I have a couple rocket electronics projects I'm working on. Even cheap electronics take a lot of money & time to develop. That said, it's really fun to use your own creations.

One thing that I did a while ago was cobble together electronics purposed for other things to use as a tracker. A quadcopter flight control board running free software plus a $10-20 GPS breakout board can talk through an r/c controller to give you tracking - if you have some of that stuff already. All that said, what's a bare bones device worth to you?$75 for a built tracker module? $50? What about the ground station/receiver? What do you consider bare bones? MidOH Well-Known Member Well, I'm glad you guys mentioned them, at least. I haven't done digital electronics since high school (class of 1862), and I hate IT. But I can solder beyond pro level. (RC car racing). Might be worth a shot. jderimig Sponsor TRF Sponsor You can make a gadget that sends raw gps packets to your computer with about$30 in parts, (cheap GPS chinese module from ebay, 10% chance you will get a dud, ~$10, and 2 wireless serial port radios for about$10 each or less). You will need a 3 or 5v power supply, battery and wiring. The ground setup can be an FTDI cable ($10) to your wireless serial port module running a GPS program on your PC. It will be crude but it will work. If you like to tinker and play it could be a rewarding and fun project. Fun is personal. jqavins Helpful Smartass TRF Supporter What do you consider bare bones? The conversation has got me leaning away from the project. I haven't ruled it out. For the record, to me "bare bones" means an on board and hand held pair that can tell me "Hey, dummy, your rocket's over there!" GrouchoDuke Well-Known Member For the record, to me "bare bones" means an on board and hand held pair that can tell me "Hey, dummy, your rocket's over there!" Makes sense, thanks. mikec Well-Known Member I built my own GPS system with 900 MHz XBee radios, a GPS module, and an Arduino with a 16x2 LCD display. It cost me roughly$160 in parts and probably 20-30 hours of labor, much in writing the code to interpret and display NMEA strings. I've subsequently laid out my own transmitter boards but even then the parts cost is around \$70 per transmitter. I could use cheaper radios than the XBees, but they're reliable and I know how to use them.

I enjoyed doing this and certainly didn't do it to save money.

manixFan

Not a rocket scientist
I have some of that, but not all of it. What's more than one of two, but less than three or four? I guess two or three iterations? And iterations cost me only parts and time I would otherwise have spent goofing off.

Do I sound argumentative? I don't mean to. I'm just trying to be sure I'm clear.

Has anyone here done this? I'm happy to have opinions; I'd be happier to have data.
You say iterations only cost you the time and parts. But if the ultimate goal is saving money, each iteration takes you farther away from that goal. I guess based on my experience with similar projects, I find it hard to believe that unless you already have extensive experience with GPS systems, the idea you’ll be able to design a system from scratch that will cost substantially less than a readily available system is very unlikely.

I’d say the data you are looking for is found in the lack of responses from folks who think it can be done.

Tony

cerving

Owner, Eggtimer Rocketry
TRF Supporter
Iterations are part of the development process. Most things that I sell went through four or five prototypes before the first marketable unit, and over time some of them have changed two or three times. Again, if you're doing it for fun or education, the cost is irrelevant. (Especially if your significant other doesn't ask about it...)

Michael L

Random Pixel Generator
TRF Supporter
I get the DIY thing. I even have a background in electronics. However, I haven't figured out a good way to keep a 6L6 in it's socket at launch.

RF electronics, data logging, and inter-chip communication are more than I care to tackle. I'm working on some non-tracker / non-deployment related things at the moment.

I have zero desire to enter the commercial market for anything I make. The commercial market has people in it I did that with photography for about 5 years and it dang near killed off my desire to photograph (I got over that). I recently made a simple little board power board that makes it easy to hook up 2 batteries, a tracker / dual deploy board, and a switch (magnetic or Schurter) using JST connectors. Boards can't be bought in ones... so I gave some of the extras to a few members of the club and kept some for future use. That said, designing my little board wasn't "R o c k e t Science" (I've been wanting to type that for over a year )

"Boards can't be bought in ones" so if you take Chris's post - 4 or 5 prototypes plus 3 design changes - that's 8 iterations x 3 board minimum at Osh Park (I don't know of anyone that does single board runs. Osh Park isn't "per board cheap" but it's better than ordering 10 cheap boards only to find out you screwed up a via or the trace wasn't fully connected, or wired to the wrong pin. I suppose that there is cheaper electronic software out there but I've used what used to be called CadSoft Eagle for a very long time. It's now owned by Autodesk and it's a subscription based software. I'm not a fan of what they did to the software but It "talks to" Fusion 360 which isn't a bad thing.

All of that said, I agree with Chris, it's a great way to learn a new skill. I choose to think if it as - "cost? what cost? Oh... that Weller WX-2??? pfft... that was free, I'm sure it was free... so were those tips. Oscilloscope? yeah... they give those away. RF Sig gen... pfft. pennies". I'm still working on making that believable...

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