Let’s Talk NanoTags on Helium

One of the core ben­e­fits of a glob­al LoRaWAN net­work like Heli­um is the abil­i­ty to track assets across a large area. Now, track­ing isn’t mag­ic, it’s engi­neer­ing, and it always comes down to fun­da­men­tals: How are you get­ting your loca­tion? How long do you need your track­er to run? How often should it ping? 

As the Heli­um ecosys­tem matures and we dive deep­er and deep­er into what we can do with the net­work we’ve now built, it’s worth div­ing into a spe­cif­ic prod­uct to explore how they approached, solved, and con­tin­ue to the improve the solu­tion for a track­ing problem.

Let’s talk a look at the Nan­o­Tag prod­uct from Nan­oTh­ings to see how one com­pa­ny went about solv­ing for a spe­cif­ic problem. 

We’ll start with the gen­er­al offer­ing: A low cost ($25) track­er with tem­per­a­ture mon­i­tor­ing, about the size of a McDon­ald’s nap­kin, and it’ll last a few years if you set it to ping at 1 day inter­vals. Peel ‘n stick adhe­sive on one side makes it easy to just slap on damn near any­where. Pret­ty cool.

Joey Hiller, Tech­ni­cal Direc­tor at the Heli­um Foun­da­tion, sent me a few to check out. Now, I’ve got an alter ego I don’t often talk about, but in my pre-Heli­um life (and still to this day) my wife Lee and I run a lit­tle dessert shop called Paleo Treats that ships per­ish­able desserts all over the world. We’ve been doing that since 2009. Back in 2015 FedEx rec­og­nized us as one of the top ten small busi­ness­es in Amer­i­ca. Out of that came the oppor­tu­ni­ty to work with FedEx on mak­ing per­ish­able ship­ping eas­i­er for small busi­ness­es to nav­i­gate, and I got to run a cou­ple time/temperature exper­i­ments with their mil­lion-dol­lar ship­ping lab, which was, pun intend­ed, very cool.

I learned every­thing you need to know about how to ship small per­ish­able goods pack­ages (and a lot you don’t). Now that’s not to say I learned every­thing there IS to know, just that I fig­ured out a way to reli­ably keep a small box cold as it shipped from San Diego to any­where else in the country.

As part of that learn­ing curve, I scoured the inter­we­bz for some kind of tem­per­a­ture track­er I could use to assess my ship­ments. They weren’t cheap (still aren’t)* and the ones I found just logged temps, they did­n’t trans­mit ’em over any distance. 

It meant that I could only real­ly send pack­ages to folks who would send the log­ger back, or, the “rapid feed­back ver­sion”, were will­ing to add an app to their phone, down­load the data off the log­ger, and email it to me.

Of course, you only need to send a few pack­ages in the sum­mer to fig­ure out that you’ve got about 48 hours before a box gets to choco­late melt­ing temps, but…that also assumes you’re using the same “pack out”, or method of pack­ing (insu­la­tion, dry ice, gel packs, etc) every time. We use dif­fer­ent pack­outs all the time depend­ing on how much we’re send­ing, what insu­la­tion is avail­able, and where it’s going.

So right off the bat, it makes sense for Paleo Treats or any small busi­ness ship­ping per­ish­able goods to buy a cou­ple Nan­o­tags and just use ’em for in-house test­ing. Here’s a pack­age I sent from San Diego Mem­p­is, then on down to Louisiana. I used Meteo Sci­en­tific’s Uplink Engine dash­board to keep an eye on it as it trav­eled. At the begin­ning it was 34F or so, with the tem­per­a­ture grad­u­al­ly ris­ing to what­ev­er the local envi­ron­ment was over the course of a few days.

If you want to keep track­ing tag 789 as it moves around the coun­try, use this link to see what’s going on. You may see that it’s offline, or appar­ent­ly mov­ing around a bunch at some spe­cif­ic loca­tion. Both of those demon­strate the lim­i­ta­tions to Nan­o­tags. This goes back to the open­ing piece about track­ing not being mag­ic, but an engi­neer­ing problem.

First, Nan­o­tags don’t use GPS. They just send out a pack­et say­ing “This is me, I’m Nan­o­tag 789. Please report that you heard me along with the sig­nal strength received”. Any Hotspot that receives that sig­nal then for­wards it on to the Heli­um Router, which checks to see if any­one wants to buy that pack­et, and how many Hotspots they want to buy it from.

From there, the Nan­o­tag decoder pulls the strongest sig­nal received, and shows you the loca­tion of that Hotspot. It’s not the loca­tion of the tag, which can be a lit­tle con­fus­ing. Here’s what that can look like as a pack­age trav­els from San Diego to LAX. It’s *most­ly* accu­rate, but a few high hotspots with high gain anten­nas on tel­co tow­ers can dis­tort the path a bit.

Of course, you can refine the loca­tion by buy­ing from mul­ti­ple Hotspots and do some fan­cy math to get a bet­ter idea of where the tag is, which is what a few com­pa­nies are attempt­ing now.

That “amount of Hotspots to buy from” is a vari­able. In my case, I added the Nan­o­Tag to my Con­sole and set it to buy pack­ets from up to 21 Hotspots, just to see what the track­ing looks like. If you’re using the UplinkEngine inte­gra­tion that Nan­o­Tags has to help you demo your tag, it will buy mul­ti­ple packets.

If you’re using Track­pac, they built an impres­sive machine learn­ing mod­el by buy­ing every pos­si­ble pack­et (like mine). Once they had a few mil­lion data points, they could buy far less pack­ets and still get accu­ra­cy of loca­tion to the 300–500 meter accu­ra­cy lev­el! If you’d like to access that, you’ll need a Track­pac account, which you can sign up for here.

This works well for mak­ing sure your box is in the right city (and some­times the right block), but it ain’t sub-cm accu­ra­cy like GEODNET, or even reg­u­lar 5 meter (~16′) accu­ra­cy GPS, which is on your phone. 

Using tri­lat­er­a­tion to assess the sig­nals from mul­ti­ple Hotspots and nar­row down a like­ly loca­tion is reliant on a few things, and vul­ner­a­ble to the vagaries of radio. 

First, you need enough Hotspots receiv­ing the sig­nal. If the label is in a box in a pal­let with met­al walls in a met­al walled air­plane, the sig­nal may not get out. The same may hap­pen inside a build­ing; that’s the main rea­son you’ll see the “offline” mes­sage in the link to tag 789 above. 

If you only have one Hotspot that receives a pack­et, accu­ra­cy is prob­a­bly only use­ful down to the 5 km lev­el (or worse), as fig­ur­ing out dis­tance based on RSSI with just one vec­tor is damn near impossible.

Sec­ond, those Hotspots need to be spread out enough from each oth­er. A tight clus­ter of Hotspots does­n’t help nar­row down where you are, espe­cial­ly if that clus­ter is off in the dis­tance. You just can’t get a bunch of use­ful­ly inter­sect­ing lines that way. It looks like it in the first pic­ture, but that’s assum­ing a per­fect world with no build­ings and a crys­tal clear air path between tag and hotspots. That rarely happens.

The ide­al set­up is that the Nan­o­tag is sur­round­ed by Hotspots, which means we can start to get much bet­ter results. Still, as I said above, radio tri­lat­er­a­tion on Heli­um isn’t bang-on accurate. 

One of the chal­lenges with Heli­um is that the loca­tion of Hotspots has to be accu­rate. If they’re not where they say they are, and many aren’t, that can throw off loca­tion results. Whether some­one is inten­tion­al­ly mis­as­sert­ing their Hotspot to pro­tect their pri­va­cy, or they’re doing it to cheat, that dis­tort­ed loca­tion can sig­nif­i­cant­ly affect the accu­ra­cy. More impor­tant­ly, because those mis­as­ser­tions aren’t a known vari­able, unlike the first two prob­lems, with mis­as­ser­tions you won’t be able to tell if the accu­ra­cy is off.

Now, the take­away here is real­ly that we’re in the ear­ly days of this tri­lat­er­a­tion accu­ra­cy thing on a LoRaWAN like Heli­um. What you see today is not rep­re­sen­ta­tive of what it can do in the future. This is a rough ‘n ready ear­ly ver­sion, not the refined end state. We’re dri­ving cov­ered wag­ons, not pilot­ing an F‑117 to knock out two bridges in Iraq (that sto­ry is here, start­ing at 47:47 and is about a good a sea sto­ry as you’ll hear.) I expect we’ll see sig­nif­i­cant improve­ments as the ecosys­tem matures and we as a com­mu­ni­ty get to exper­i­ment, test, and improve this rad world­wide net­work we’ve all built together.

If you want to par­tic­i­pate in this improve­ment and at the same time reap the ben­e­fits of a pret­ty darn cheap and long-lived loca­tion track­er, I’d sug­gest pick­ing up a Nan­o­Tag and try­ing it out on the Nan­o­Tag pub­lic site to get started!

*For you pro Googlers, yes, you can find cheap­er ver­sions now, around $20 instead of the more expen­sive device I used. None of those cheap ones also trans­mit over long dis­tances the way LoRa does.

**Yep, you may find affil­i­ate links on this page that pay me a small com­mis­sion at no addi­tion­al cost to you.