Sunday, November 26, 2017

FastNet vs. Comsol with the Oyster LoRaWAN

Comsol is a public LoRaWAN network in South Africa. We've been testing it for a while, alongside the other public network FastNet.

Comsol have adopted Actility as their backend network server. Actility is popular around the world. A common network server is appealing to us because one integration into Telematics Guru gets us onto a number of networks around the world.

We're waiting for the DM Software Gods to work through a busy schedule and do a proper integration of TG and Actility. In the meantime, I've written a little test app to receive data from Actility and push it into TG.

A proper integration means supporting all of the uplink message types (there are 3 for the Oyster) and allowing TG to push downlinks to the Oyster. Downlinks allow reconfiguration of Oyster system parameters Over-The-Air.

For now, it's just exciting to see some data in TG from both networks. I'm impressed with their coverage so far. I live in Jo'burg, and we expect the metro to be covered well. The test below is a dog walk along the Sandspruit - next to a river in a significant valley.

This is not a great real-world setup for the Oysters. The devices are set to log very regularly. Because the GPS is on so much, you'd have a flat battery in a couple of months. Our devices are designed to last for years, but with a reasonable number of positions per day - 5 years plus at once per day.

Comsol using Actility:
Here is our afternoon dog walk, recorded by the Oyster LoRaWAN on the Comsol network:
Point History in TG for the dog walk. Lots of points. Almost all that were sent by the Oyster were received by Comsol.
Below is Actility's best guess at where the device is. This is using just the LoRaWAN network, with no knowledge of our GPS coordinates - "LoRa Locate" is the name of this geo-location feature. This probably explains why my coverage is so good. I appear to live 900m from a gateway. We'll do some more testing of this feature with the Guppy LoRaWAN tags...
Actility's best guess at location of the Oyster. 900m off. There's probably a gateway there.
Here is the same walk, with another Oyster LoRaWAN in the other pocket. Less points were heard by the network here, but it's not bad given we were walking in a valley. FastNet doesn't give a LoRaWAN based position estimate, so I can't guess at where their gateway is.
The same dog walk, as heard by FastNet's network.
So there's nothing terribly scientific about these tests. Its just exciting to see:
  1. Both Comsol and FastNet working well with the Oyster in Jo'burg.
  2. Some LoRaWAN data in TG, even if it's just a temporary test. I'm looking forward to the full integration.

Thursday, November 23, 2017

New Dart - New Networks

The Dart is a solid performer for us - our entry level wired tracking product. The end of 2017 marks the end of its 2nd year in production.

Here are prototype of the next iteration:

Existing Dart users won't notice much difference. It's the same harness, housing, and the same functionality. It uses a micro-SIM (3FF size). No reason to upgrade if you're in one the existing territories.

The exciting part is the new modem and new network options. We've moved to UBlox modems for this product. They have a range of 2G, 3G, LTE CAT M1 and NB-IoT modules, which we can place on the same footprint. In short, it opens up new territories for us. LTE CAT M1 for the US market is the goal.

The Guppy LoRaWAN

This is the first small scale Guppy production run - hot out of the oven.

The Guppy is a LoRaWAN tag. It has a LoRa radio, accelerometer, runs on 2x replaceable AAA's, and has an IP67 housing. No GPS in this product. We've made 868 and 915 MHz variants, so it should work all over the world.

Here is the Product Page.

And here is a discussion on what to do with the Guppy LoRaWAN.

Now we wait to receive the PCB's from the factory, test them, and assemble them. Sounds easy!
A partially populated PCB panel.
The best view of the pick and place machine I could get - video not working yet...
This is how solder paste is applied to the PCB. A stencil and a big scraper.

Another view. Look closely and you can see the detail in the stencil.

Tuesday, November 21, 2017

Oyster LoRaWAN on FastNet - Telkom 947 Cycle Challenge

Telkom sponsors the 94.7 Cycle Challenge in Johannesburg. Telkom also owns FastNet - a local public LoRaWAN network provider.

The cycle race is a great tour of Jo'burg. It makes for an interesting FastNet coverage test. The Oyster LoRaWAN happens to fit in a cycling jersey pocket quite conveniently.

The Oyster LoRaWAN product page is here.

TG showing all the points logged for the day. This means there's FastNet LoRaWAN coverage at each of these points.

This is a screenshot from Telematics Guru, showing all the points that were logged for the day. It includes the drive from home to the start. The outer path is the race.

The coverage is decent. There are a few stretches where no messages were received, showing some coverage gaps.

The Oyster LoRaWAN gets GPS fixes on a configurable schedule. As soon as it has the fix, it tries to
send it to the network. There is no confirmation of receipt for GPS messages, because downlinks and confirmed uplinks are generally much more expensive than uplinks. The GPS points give a good indication of coverage in the city, because there is no buffering of positions and sending them later.

It's important to stress, this is not a real world use case. Working your Oyster this hard would result in flat batteries in a month or two. It's also on the limit of the regulatory duty cycle restrictions - you can only be on air for 1% of the time. And this would violate some networks fair usage policies.

These devices are designed to intelligently use the GPS as little as possible, to maximise the battery life. You should get 5 years with one position and transmit per day. Here, I've got it set to fix and send every 2 min. Not a practical usecase!

The spreading factor on this device was set to 10-12. So it would use SF 10, 11, 12, and the LoRaWAN stack tries to spend an equal amount of air time (transmit time) on each data rate.

The FastNet to Telematic Guru integration is also a hack. The FastNet API is pull only, which means it needs to be polled a lot. I wrote a simple app to do the polling and when a new message is received, push it into TG. That is not a proper integration. We're still hoping to get a push API from FastNet before we complete the integration.

We do have full The Things Network integration, and we should have Actility integrated too soon. Actility is exciting because it is the LoRaWAN network server behind many public networks around the world - Comcast in the USA; and Comsol locally.

There's an Oyster LoRaWAN in my pocket. Seem to have lost my tandem partner though...

Monday, November 13, 2017

Flexi1 - Long Term Test

Flexi1 - Long Term Test

The Flexi1 in the flower bed outside the office has been running for about 230 days. It is using 4 x AA Lithium batteries. 

It is setup in a Typical Aquacheck configuration:
  • Take a probe reading every 30 min
  • Upload it every 3 hours
  • Get a GPS fix every 24 hours
We added an external temperature sensor, so it is also:
  • Reading the temp sensor every 30 min
The main encouraging take away is the number of uploads so far. 1832 uploads means about 230 days. Not bad for 4 x AA's. They're probably close to flat now, but they're still going, so we'll see how much more we get. Using 4 x C Cell Alkalines would give you roughly double this capacity.

I graphed the temperatures in Telematics Guru. It doesn't get that cold in Jo'burg - about 2.8 degrees C. There is some direct sun on the housing at mid-day, hence the 47 degrees C maximum. Interesting how close they are together - min on the 25th of August and max on the 13th of September. I wouldn't read too much into the max, as the directness of the sun makes a big difference. Not the clearest graph out, because of the swings from night to day, with the added heating effect of direct sun.
Telematics Guru Asset Analogue Graph - Temperature vs Time 

Here is a screen shot of Aquacheck Web. They do the agronomy magic with the telemetry we collect. Here is the data plotted from March to November. Again, you can't read too much into it because of the unknown water habits of our office park, but it's great to visualise the data. Of course, visualisations are cool, but how do you commercialise this? Ask Aquacheck about the science of Agronomy...
Aquacheck Web - Soil Moisture Content vs Time