How to monitor several beacons in an open area with one Hub.

[Vikindio]

Hi.

We are a Norwegian company trying to create a prototype to monitoring people. We are already waiting our BLE 5 with ANT capabilities to start creating the prototype. But we are right now having a hard time to find the right and best device to monitor all the beacons. Do you have any idea or suggestion of what we could use as a hub, reader/receiver for all those beacons we want to deploy in a open space area? The Hub/reader need to be able to handle 50 to 100 beacons at a time, ant this reader/hub is the only device connected to the main PC by ethernet. We plan to extend and improve the options, like 2 way comunication and other type of sensors. But for now only we could get the beacons send a small amount of date to position them (triangulate) in an area that will have several Hubs/readers so we can triangulate them, but each hub/reader needs to be able to handle from 50 to 100 beacons at on time.

[Roger Clark]

If you didn't want ANT, I'd suggest a Raspberry PI (or the new RPi Zero W if you can use Wifi instead of Ethernet) but I don't think any of the RPi board have ANT (though you should check)

Apart from that, I suspect your next best option is to attach a nRF52 to a RPi as a SPI slave, and have the nRF52 handle the monitoring, and use the RPi for transmission via Ethernet to wherever the data is needed.

If you are willing to write the drivers, you could directly connect an Ethernet module to the nRF52. But I suspect for a prototype it would probably be easier to use the RPi for the Ethernet connection.

Edit.

BTW. Triangulation via RSSI is extremely inaccurate. There are multiple posts on this forum about using RSSI for distance measurement and triangulation and I have never seen one where anyone got it to work well.

[endnode]

Hi Roger, to be fair you can make it work but there is some non-trivial effort needed. There are commercial solutions using BLE for real-time location service with <2m accuracy but these are just few on the planet and teams were working on them for 3+ years. There is also load of patents around that so you might have problem if you reinvent something and want to make money on it...

[Vikindio]

Thanks Roger. ANT is a must for our system, the new nRF52840 BLE 5 comes with mesh networking and its a key factor for our system. We will get these chips by the end of the month, and we will start putting the beacons together. But we are still trying to look for the right hub/reader that can handle a mesh network and a bunch of beacons at the same time. We got as an example the new sensoro that looks and by the specs. works fantastic. Then also we have the "pixie point" that triangulats the beacons by inches, and thats impresive and thats what we are aiming for. Do you have any suggestion on how we should triangulate the BLE 5 beacons? any hub/reader you know of that could help us to start with this?

[endnode]

Hi Vikindio, all what I've found about Pixie seems to work with >5m accuracy (e.g. here they claim 10-45m which seems to be perfectly in-line with BLE RSSI experience from such basic solutions). Do you have more details explaining how ANT mesh, BT5.0 mesh, nRF52840 and location tracking relates to each other in your solution? So far it doesn't make much sense and it prevents us to give you more specific answers. Also as far as I know nRF52840 is just preview (= pre-production) version with pretty extensive anomaly list and poor SW support. Full production versions should come in the end of 2017, I'm wondering if this influences your project...

[Roger Clark]

The information Pixie was vague.

The only statement I can find on location accuracy is "within inches", which is open to a lot of interpretation e.g. 6 inches, 12 inches, 18 inches.

Their youtube video was uploaded in 2015 and the last comment was a year ago.

The implication was that they use a mesh network, but they may simply be scanning and then rebroadcasting the RSSI and MAC address of every device they can hear.

I couldn't see any data on the battery life. They are a very small product, so the battery capacity is only likely to be 500mAH at the most, (probably less)

Mesh networks are power hungry, so I wonder how long each tag lasts. BTW. I noticed a comment on YouTube that the batteries were not replaceable.

Edit. Thinking about the mesh networking, perhaps full mesh functionality is only needed when the user wants to locate a beacon. So perhaps they normally just adveritse