Low power GPS/Telemetry/Datalogging... Interest?

[jimduchek]

TLDR at the end.

So after an inability to find yet another (cheap, thankfully) rocket out here on my dad's property (so much brush... might have walked right past it!), I decided to dig into my electronics box and put together a little something. With OTS stuff, I've got a proof of concept working of a relatively small avionics package w/GPS and LoRa to get telemetry (and find!) a rocket from a phone. Range is about 2-5 km, depending on the final orientation of the landing and LoS... The 'base station' that plugs into my phone is a cheap ($20 on Amazon) Heltec LoRa board, and the current 'avionics package' is, at the moment, a TTGO T-Beam + a couple sensor boards for fun (accelerometer, temp/humidity/pressure sensor). It's frankly, way too big and way too heavy for what it is (but it gets the job done).

There's some commercial stuff like this that already exists, it seems, but it's way too big/heavy and way too pricey (A single Featherweight + ground station is $350?!?? get outta here). Meant more for the G+ folks. I think something for the B/C/D crowd needs to happen.

Since I have the skills and ability to do so, and I kinda need a project, I'm thinking about spinning some boards for the rocket-side to get them small/light enough, as all the OTS stuff is too wide/heavy. Probably around 15x40mm (thin enough to fit into a 3d-printed 18mm nose cone w/1.2mm walls) + a small 100mAh battery (good for about an hour of full-power use, though generally the board powers down the sensors/GPS until commanded to go-live for launch). The chip shortage is terrible right now but I've got the schematics laid out (whether I can actually GET everything I used in any kind of quantity is up in the air) and a BOM and I'm fairly sure I could sell the rocket-side part ("motherboard" with processor, empty SD-card slot, GPS, LoRa transmitter, accelerometer + a "sensor package" daughterboard to go further up in the nose (literally just a BME280 board you can find on Amazon, though I'd buy a pile from China so they'd be cheap) for around $40-$45, if I have 100 made.

The whole thing would be entirely open-source and open-design, all code and schematics available. This would be rocket-side board only, you'd need to purchase your own ground-side transceiver (The one I'm using, as I said... $20 on Amazon, and I intend to treat that as the "canonical" base station), as well as 3D-print your own nose-cone/container (though I will provide STLs for 18mm and 24mm, because I'd be using them myself!) If there's a LOT of interest in the board from folks who want boards but don't have access to 3D printers, I might consider having one of the designs bulk-printed by a house. I sincerely doubt there's enough interest to justify a proper injection mold.

TLDR: I'm trying to gauge whether or not an affordable/light telemetry/GPS package ($45-ish, fittable into an 18mm B/C rocket) is something worth pursuing as a project past my own interests. No Kickstarter/Indiegogo BS, won't take anybody's $ until I have boards to ship in my possession. But I'm very curious if there's enough interest to make it worthwhile to pursue.

 

[lowga]

Personally, I love the idea--especially if telemetry with some additional sensors is part of the package. There is a real market for this type of stuff in science/STEM education if the price point is affordable enough.

 

[Hermes]

Yes! I've struggled to find a small, cheap tracker in the US; living in Tampa atm.

By way of a quick intro - I've done quite a bit of high altitude ballooning in the UK and designed/built/programmed boards to parse and Tx RTTY (434Mhz < 10mW) for live tracking. My current issue is wanting to track L3 flights but, all my trackers/Rxs (FT817ND + Tigertronix codec) are back in UK (although I have a SDR (SDRplay) which could decode RTTY using SDR Console. I tried searching for a small GPS 4G option to buy in the US but they all seem to be tied to subscriptions/contracts; this could just be my limited success finding the right solution though. For now, I've asked my son who is back in the UK to dig out one of my trackers and send it to me here.

So, if you are minded to build something small, cheap and effective - I'm interested.

For info - the UK High Altitude Society (high altitude ballooning community) has done some work on this. This UK HAS link may lead you somewhere interesting or helpful.

Good luck

 

[jimduchek]

Personally, I love the idea--especially if telemetry with some additional sensors is part of the package. There is a real market for this type of stuff in science/STEM education if the price point is affordable enough.

I think a 3-axis accelerometer and a BME280 (humidity, temperature, pressure) would be part of the basic package. The thing would be easily hackable though to add additional stuff, and I'd probably want to get some sort of camera setup available soon after (thus an SD-card slot -- the radio I'm using is very low bandwidth so any images would need to be picked up after the launch).

GPS is really the price sticking point. Getting ahold of the cheapest GPS chip right now is ~$10 even in quantity, and that's not counting the supporting electronics. Seeing _exactly_ where my rocket is on a map on my phone is the coolest thing, though, and I'd kinda hate to separate it out to an optional daughterboard. But it'd cut the price almost in half for those who didn't want/need it, not to mention the size/weight. So that may be the way to go.

 

[Kelly]

You're proposing a system that's smaller than, and cheaper than, anything else on the market and wondering if there would be interest?

 

[waltr]

There is interest but there are also big technical challenges.
Check the Electronics sub-forum topic for discussions on GPS, telemetry, sensors and code.

 

[jimduchek]

There is interest but there are also big technical challenges.
Check the Electronics sub-forum topic for discussions on GPS, telemetry, sensors and code.

The electronics sub-forum has like, 3 posts from this year, and seems mostly geared towards the "big boys", which is why I posted here. Frankly, the challenges aren't terribly great for <=D motor rockets -- not like they would have been 30 years ago when I got my first Alpha for Christmas. I put together a working package from OTS stuff in a week, and half that was waiting for Amazon to get an OTG cable for an old phone It gets _much_ harder, yes, when you start launching several miles high, but this isn't for that. The big thing is that there isn't really any thing off-the-shelf designed A> with weight in mind and B> a footprint that will fit in an 18mm tube.

 

[mikec]

Have at it, but it won't be the first. What you're talking about is admittedly smaller than https://www.rocketryforum.com/threads/rocket-track-open-source-gps-tracker-for-smartphones.53120/ but I'm not sure you can get great performance with the size of GPS antenna you'll need -- but maybe.

 

[jimduchek]

You're proposing a system that's smaller than, and cheaper than, anything else on the market and wondering if there would be interest?

Well, I'm trying to gather some information on what kind of price point + features would be necessary for _enough_ interest to bother with making this a commercial venture of some kind. I mean I'll probably have 5 or 10 boards spun up for me and my dad and a couple buddies either way, and release all the code+schematics+design. Just trying to decide whether it's worth going much further with it.

 

[jimduchek]

Have at it, but it won't be the first. What you're talking about is admittedly smaller than https://www.rocketryforum.com/threads/rocket-track-open-source-gps-tracker-for-smartphones.53120/ but I'm not sure you can get great performance with the size of GPS antenna you'll need -- but maybe.

The antenna I'm using now is a ~16x6x5mm chip antenna and the performance has been excellent in any orientation. Would probably go smaller. GPS receiver ICs are much better than they were in 2013, too, cell phones have really been a boon for this kinda stuff.

 

[bad_idea]

Anything that's smaller and lighter than the Eggfinder Mini is of interest to me, and given my current plans I would buy at least two devices if they were available today and came in under $100 apiece. What I'd buy in the future if/when it actually was available, I can't say for sure since my plans may change, but as long as it's the smallest/lightest device out there, I bet I'd still be interested.

I don't yet know much about radio, so I don't know if Eggfinder is using LoRa too; if it is, then making your tracker compatible with the Eggfinder receivers would be a big plus.

 

[Kelly]

Let me come at this from another angle... you say that a featherweight system is $350... The eggfinder mini (which is almost as small as your proposed system) runs $100 for a complete system (which you need to solder together yourself)... What does your system lack that these others have? It sounds as though your range is not great, at 2-5km, but it's still more than many users of these systems need. Because if your system has the same features/performance (or even just 'enough') as the existing solutions, is as small or smaller, and is a fraction of the cost (even if we have to put it together ourselves) then there would probably be huge interest in it.

 

[allensmith]

I am certainly interested

 

[jimduchek]

Let me come at this from another angle... you say that a featherweight system is $350... The eggfinder mini (which is almost as small as your proposed system) runs $100 for a complete system (which you need to solder together yourself)... What does your system lack that these others have? It sounds as though your range is not great, at 2-5km, but it's still more than many users of these systems need. Because if your system has the same features/performance (or even just 'enough') as the existing solutions, is as small or smaller, and is a fraction of the cost (even if we have to put it together ourselves) then there would probably be huge interest in it.

Well, first, I will say that this will _not_ be a solder-it-yourself system. Parts are too small. I think this will definitely be a lower-range solution than what's out there in some cases, but those are also years-old designs... parts get smaller and smaller, microcontrollers get faster/better/cheaper, and very small/light is the plan here. Plus I'm not really interested in necessarily turning this into a 'business'... This is something _I_ want for _me_ and I'm going to do it anyway, though if I can justify having a couple hundred boards spun up I would certainly be selling them at some profit.

I'm off to do a range test today here in a little bit (Just walking... too windy to fly anyway, I think) with a couple antenna options and playing with some power settings, so may have some more reality-based numbers on that front. If I can get a pretty consistent 4-5km in various orientations (out here, in the desert, conditions are _perfect_ so it's best-case numbers) I think that covers 99% of what B-D engine hobbyists will need. Even if you can't get signal from your launch site, it's not like you have _no_ idea where your rocket ended up and you can probably get close enough to get signal. I'm also curious if, without GPS, signal strength alone can be used to find a rocket. GPS is cool, but pricey, and the goal is really just to make sure you can find the thing

 

[Kelly]

So then if you're just talking RDF without GPS, that's a different story. I'm not sure what else is in this space currently since most people, I think, have moved on to GPS as prices have come down, and due to the much greater simplicity of GPS (at least to the searcher!). I think the market is smaller, without GPS. Note too that most GPS users expect to lose signal when the rocket hits the ground, so that's not a show stopper - if you have a location from when the rocket was 100' high that's good enough to get you to where you can reacquire signal.

I wouldn't limit yourself to 'B-D engines', though. There are D rockets flying over 1km high, and J or higher impulse flights going less than that, so I think any device that has several km line of sight range will have appeal to a broad range of flyers.

 

[cls]

Most of us can direction find a radio beacon pretty well. Maybe this doesn't need GPS, how about a tiny 10mW beacon? Kinda like the old Walstons or Big Red Bee trackers.

 

[bad_idea]

So then if you're just talking RDF without GPS, that's a different story. I'm not sure what else is in this space currently since most people, I think, have moved on to GPS as prices have come down, and due to the much greater simplicity of GPS (at least to the searcher!). I think the market is smaller, without GPS.

Agreed. Unless there is a super-simple direction finder that makes using a beacon as easy as using GPS, I'm less interested, though "less" <> "at all." Sooner or later I will get into beacons, but with the ease of GPS solutions for modest altitudes, that may be a long time.

Most of us can direction find a radio beacon pretty well.

I don't know that's true of most low power flyers. Certainly not true of me yet (well, I was taught to use a direction finder to locate a beacon back in CAP, but that was nearly 35 years ago, and I've not used one since).

 

[OzHybrid]

There is a T-Beam with an onboard ublox6? gps on the same board. check banggood. just needs someone to put the software together to make it all talk for us rocketry folks.

 

[jimduchek]

There is a T-Beam with an onboard ublox6? gps on the same board. check banggood. just needs someone to put the software together to make it all talk for us rocketry folks.

This is precisely what I'm using for my proof of concept. It's much too big though -- 35mm across and 100mm long, and heavier than I'd like to boot. But it flies If you've got one handy, I'm happy to share my code and everything. You'd need a second somethin' for a base station too.

So then if you're just talking RDF without GPS, that's a different story.

Well, my current thinking (it's evolving as this conversation goes -- I appreciate all the feedback!) is to split the GPS off into a separate board. GPS dang near doubles the price, and there are folks who won't need/want it, especially if they're doing STEM stuff with fairly small rockets and just want some datalogging/telemetry and experiment capacity. I think it's possible to bring a LoRA-only MCU/transmitter board down to maybe $20, $25, with another $20-ish for a GPS add-on. Getting the basic 'package' with some sensors and telemetry, minus GPS, below $25, would really make it fairly widely accessible and not too scary to lose it on a roof or a pond or whatever. I need to play with some layouts -- if I can get the boards below 14mm in width I think they could 'stack' together inside an 18mm 3d-printed nose cone w/1.2mm walls.
[/QUOTE]

 

[Kelly]

Sounds good. IMHO, the combination of (low cost, data logging, telemetry) targets a very small market - which of course is fine if you're making something YOU want to use and just thinking about making a few extra. The combination of (low cost, GPS, telemetry) targets a market which is orders of magnitude larger, depending on cost and range.

 

[OzHybrid]

This is precisely what I'm using for my proof of concept. It's much too big though -- 35mm across and 100mm long, and heavier than I'd like to boot. But it flies If you've got one handy, I'm happy to share my code and everything. You'd need a second somethin' for a base station too.


Well, my current thinking (it's evolving as this conversation goes -- I appreciate all the feedback!) is to split the GPS off into a separate board. GPS dang near doubles the price, and there are folks who won't need/want it, especially if they're doing STEM stuff with fairly small rockets and just want some datalogging/telemetry and experiment capacity. I think it's possible to bring a LoRA-only MCU/transmitter board down to maybe $20, $25, with another $20-ish for a GPS add-on. Getting the basic 'package' with some sensors and telemetry, minus GPS, below $25, would really make it fairly widely accessible and not too scary to lose it on a roof or a pond or whatever. I need to play with some layouts -- if I can get the boards below 14mm in width I think they could 'stack' together inside an 18mm 3d-printed nose cone w/1.2mm walls.

[/QUOTE]
I've got 4 handy. Bought them a while and and have been waiting for this moment. I'll PM you.

 

[lowga]

I really think the telemetry and RDF option could be attractive to STEM buffs, especially if GPS was an affordable add on.

 

[GalantVR41062]

With the proposed size, option list and price I will buy 4. Let me know when they are ready to ship.

 

[jgavlik]

Most of us can direction find a radio beacon pretty well. Maybe this doesn't need GPS, how about a tiny 10mW beacon? Kinda like the old Walstons or Big Red Bee trackers.

Agreed! This project is full of "feature creep"...and if you want to make it a business, consider raising the price so you can stay in business.

 

[Jimmyfun]

TLDR at the end.

So after an inability to find yet another (cheap, thankfully) rocket out here on my dad's property (so much brush... might have walked right past it!), I decided to dig into my electronics box and put together a little something. With OTS stuff, I've got a proof of concept working of a relatively small avionics package w/GPS and LoRa to get telemetry (and find!) a rocket from a phone. Range is about 2-5 km, depending on the final orientation of the landing and LoS... The 'base station' that plugs into my phone is a cheap ($20 on Amazon) Heltec LoRa board, and the current 'avionics package' is, at the moment, a TTGO T-Beam + a couple sensor boards for fun (accelerometer, temp/humidity/pressure sensor). It's frankly, way too big and way too heavy for what it is (but it gets the job done).

There's some commercial stuff like this that already exists, it seems, but it's way too big/heavy and way too pricey (A single Featherweight + ground station is $350?!?? get outta here). Meant more for the G+ folks. I think something for the B/C/D crowd needs to happen.

Since I have the skills and ability to do so, and I kinda need a project, I'm thinking about spinning some boards for the rocket-side to get them small/light enough, as all the OTS stuff is too wide/heavy. Probably around 15x40mm (thin enough to fit into a 3d-printed 18mm nose cone w/1.2mm walls) + a small 100mAh battery (good for about an hour of full-power use, though generally the board powers down the sensors/GPS until commanded to go-live for launch). The chip shortage is terrible right now but I've got the schematics laid out (whether I can actually GET everything I used in any kind of quantity is up in the air) and a BOM and I'm fairly sure I could sell the rocket-side part ("motherboard" with processor, empty SD-card slot, GPS, LoRa transmitter, accelerometer + a "sensor package" daughterboard to go further up in the nose (literally just a BME280 board you can find on Amazon, though I'd buy a pile from China so they'd be cheap) for around $40-$45, if I have 100 made.

The whole thing would be entirely open-source and open-design, all code and schematics available. This would be rocket-side board only, you'd need to purchase your own ground-side transceiver (The one I'm using, as I said... $20 on Amazon, and I intend to treat that as the "canonical" base station), as well as 3D-print your own nose-cone/container (though I will provide STLs for 18mm and 24mm, because I'd be using them myself!) If there's a LOT of interest in the board from folks who want boards but don't have access to 3D printers, I might consider having one of the designs bulk-printed by a house. I sincerely doubt there's enough interest to justify a proper injection mold.

TLDR: I'm trying to gauge whether or not an affordable/light telemetry/GPS package ($45-ish, fittable into an 18mm B/C rocket) is something worth pursuing as a project past my own interests. No Kickstarter/Indiegogo BS, won't take anybody's $ until I have boards to ship in my possession. But I'm very curious if there's enough interest to make it worthwhile to pursue.

My friend, I really think there is a market for this! I would def. be a customer!!

 

[jimduchek]

Agreed! This project is full of "feature creep"...and if you want to make it a business, consider raising the price so you can stay in business.

Honestly, have no intention of making this a "real business", though I do intend to pick up a few bucks. I'd need to sell, so, so, so very many to pay for my time working on this at my professional rates, though. This is for fun. And if I lose interest and quit, literally everything will be reproducible by anybody who wants to -- all schematics, layouts, code, etc will be open and available. Though of course, quantity is the key to getting prices to an affordable level. This will be a $150 board if you get a fab house to make _one_. At qty 10, probably around $70. Qty 100+ is where it starts being what I expect.

 

[jimduchek]

Agreed! This project is full of "feature creep"...and if you want to make it a business, consider raising the price so you can stay in business.

And honestly, I think I will try hard to avoid feature creep.... my plans are starting to solidify with the feedback here. There will be a 'base board' with an MCU w/LoRa transciever (probably an STM32WLE), SD card slot, USB-C port, and probably an accelerometer and magnetometer. It will have an onboard chip LoRa antenna, as well as an IPEX/U.FL connector for a LoRA antenna if you want more range. It will have a battery connector and a power management chip that can charge the battery via the USB-C port. It will have headers to access i2c, and what GPIO I can expose, and a dedicated header to mount a GPS daughterboard. It will NOT have WiFi, Bluetooth, etc. Gotta jam this guy into maybe 14mm wide and 30, 40mm long?

I will also produce the GPS daughterboard, and like the 'base board', it will have a chip antenna as well as a U.FL connector for a better antenna if you really want to. The GPS daughterboard and base board will be designed to fit together tightly as the feedback I'm getting here indicates that GPS is either "meh" or an utter "MUST HAVE", so I want to keep the baseboard+GPS board option real tight.

For both the LoRa antenna and GPS antenna, you will be required to de-solder a part (I'll try to make it easy) to disconnect the on-board chip antenna to use the U.FL connector. Likely there will be little reason to use a different GPS antenna, but a stronger LoRa antenna might well be a good move for a lot of folks.

I will not make, but will provide easy instructions, to mate the main board with an off-the-shelf BME280 or BMP280 board (temp, pressure, and humidity in the case of the BME280). It's a cheap setup and a big win for "Let's Do Some Science With a Rocket".

I will _maybe_ make a camera daughterboard. Taking pics isn't really my jam, so I'm not super interested in spending any time on that, but I know a lot of people love it, and it's why I'd have an SD-card slot on the mainboard. Either way, the mainboard would have headers available to access a camera.

So with all that said. I have no intention of being some sort of a-la-carte warehouse with every option. There will likely only be two purchasable options -- Baseboard+80mAh battery, or Baseboard+80mAh battery+GPS board. Maybe an option to add a BME280 board.

I want this to be an off-the-shelf, 3rd-grade option for a lot of folks to have fun and collect data and mess with that data, etc. I also want it to be a really hackable option for people with the skills to do so. What I don't want it to be, is adminstrative work for me

 

[drgarymartinez]

Count me in for 5-10 units

 

[DaHabes]

This...https://flightsketch.com/store/catalog/flightsketch-sst_228/

I think you will find that to get something small enough to fit in an 18mm body tube it isn't going to be all that cheap. Smaller components cost more than bigger ones - newer tech vs. older. The FS Mini is $29, the FS Comp is $59 (point in case).

The SST above will fit in a BT-20. Hopefully later this year if the electronics supply chain issues improve (which they may not). It's been in the works for 3 years (due to Covid and supply chain).

I'm not saying other options won't be welcome, but it's a lot harder to make a production grade, sellable product than it is to cobble something together. The tech is the easy part. Vendor management, component supply, manufacturing, customer support. Product design is also critical - components change (form factor) and often go away. Having a design that can withstand product evolution is hard.

All that said, I'll buy if the price is right.

 

[dvdsnyd]

I'd absolutely be in! I like the idea of being hackable and open source.