The Helium mapping journey continues…
I’ve written a few other posts about putting the Helium network to use by deploying a GPS-enabled, Helium-compatible LoRaWAN mapper and testing and mapping coverage around Canberra. I’ve done several trips to see how well it performs, and to see just how good the coverage actually is for a typical sensor using the Helium network.
My Mapper and it’s sub-standard antennae
The Heltec CubeCell GPS ASR-6502 sensor/mapper I have depends on external antennas for both LoRaWAN and GPS signals. The stick LoRaWAN antenna is next to useless, as is the onboard GPS antenna which always struggled to get a lock.
The code for the Heltec CubeCell GPS sensor is written in such a way that it first seeks out a LoRa signal from a hotspot and attempts to join the network (which can take a while), and only then does it attempt to get a GPS lock. Finally it sends some mapping data. This initial join/lock process can take forever while out and about.
Note: Once the GPS lock is established, subsequent attempts to send data happen much quicker. The GPS lock though is a killer, and especially when moving at speed, this needs to happen very quickly. I needed something MUCH faster and with a little more Tx/Rx power.
I tested various different combinations of antennas/wires/etc including donations (thanks for the freebie GPS antenna @plainsimple!).
I finally bit the bullet and ordered this Molex telemetry antenna for the LoRaWAN side and this new antenna for the GPS. Delivery from RS-Online was effectively overnight. VERY happy with the freight and delivery times.
Note: Free shipping from RS-Online for orders over $70.
I went for a spin with the mapper *cough* 3M-taped to the roof of the car.
Do not be alarmed, this is just while I test. The final install will be far more discrete and permanent, I assure you.
The results
The results are significantly better as you can see. Previously I’d been able to map maybe 11 hexes? Now, a whopping 36!
The GPS lock happens MUCH faster now with the new antenna, and the gain of the telemetry antenna seems to have improved the range SOMEWHAT.
Some learnings
- Modern GPS antennas work, and investing in something new is probably gonna save some headaches and frustrations with slow
- The telemetry antenna is pretty good, but I’m keen to see what kind of range it will get when fixed to the windscreen (I’m sure the ‘plane’ at which the antenna sits makes a difference)
- I’m keen to test a 3dbi hotspot antenna with the mapper next
- Elevation makes an enormous difference – as evidence by the near perfect coverage all along Dryandra St
- Generous Wooden Loris accounts for almost ALL of this mapping. It is mounted high (23m) and facing west (I’m guessing) and running the stock antenna (I think)
- Northbourne Ave seems like some kind of impenetrable barrier that the signals are unable to cross
