High School Robotics Course using the Particle.io Mesh Devices Blog


#61

Got my cell hotspot working.

Found a line of sight location. Left my Antenna Xenon with battery pack on a pole Antenna Vertical and started walking with my Hotspot enabled Argon with both Antenna and of course carrying my cell phone. Got a whopping 520 m with good signal. At 550 m I lost the signal. Had to walk back to within about 150 m to reconnect. This was a beautiful, crisp cold sunny morning. Probably very different results on different days.

line-of-sight03


#62

the experience of not reconnecting until within ~150 meters is interesting.


#63

I would like to see this with a node in between the Argon and the Xenon to see how the range is then and how quickly the 2nd Xenon reconnects after you get out past the middle Xenon’s range.


#64

For my tests I have found the disconcerting issue that a repeater can not reconnect an Endpoint that has been fully rebooted (powered off) The xenon has to go back to the gateway. This is a bug, that should eventually get fixed.

Google Group openThread-users

As long as the Xenon is not reset or powered down it would be interesting to see if the distances can be doubled each time.


#65

Yea, it better be a bug :wink:

Looking forward to more of your range testing.

In the future, I’m going to test the XBee3 Modules the same as you also just to see how they compare range wise.


#66

This video series has some really good comparisons between the types of Mesh protocols.

Interesting that it is labelled Silicon Labs Thread and not OpenThread.


#67

Found a good Mesh article also. I’m using Digimesh.

XBee does have some Thread 🧵 based radios but they have removed just about all Google indexed links to Thread links they used to have on their website.

They have been working with Thread for 2-3 years so not sure why they have removed everything related to Thread on their website.

https://www.mouser.com/new/digi-international/digi-xbee-s2d-modules/


#68

Trying to organize distance measurements. Found this old link that is relevant

I would really like a thread just about mesh distances, however the one that seems relevant

at Mesh distance between devices

was closed by @will in Feb, 2018

Any chance we can re-open this or should I just start a new one.


#69

This image says it all, for me. Outside, Line of Sight distances are dramatically better than anything I get inside the home of School for an Argon connecting to a Xenon.


#70

thing is if it will not reconnect until you are within ~150 meter then getting transmission at any distant above that is somewhat hollow achievement even though interesting. i’m wondering if the reconnect sequence requires more current than those batteries could provide to either device or both. hopefully though it was just a fluke they would not reconnect at distance over ~150 meters.


#71

Reconnecting is going to take time, it’s cold outside and I am quickly walking back to the Argon Gateway. Most likely the results are skewed in favor of the shorter distance. I really should walk back 20 meters then wait 2 minutes, then walk another 20 meters etc, until it connects, but as I said its cold.

If you see the maximum range as 100% and you consistently lose the connection at 120%, for an installation you are not going to put your Xenons at 100% probably more like at 75%. Note that I had reconnection at about 50% of the range, but a better number is probably 75% if I was willing to wait.

Unfortunately all these distances depend on your situation. Even in the same building the results may vary a fair bit. This might be a career for someone. A company that sets up-time as the highest priority may choose a 50% distance whereas someone who could fly a Boron equipped drone around the business once a day might go with a cheaper arrangement of the 100% distance. (You could also walk around the business with an Argon and a cell phone hotspot.)

So if a business that had a 100% distance at 33.3 m and had a lot that was 100 m x 100 m using the poor connection approach the lot could be covered with 4 Mesh devices as in the diagram. However it might need some method to reconnect devices that become unconnected.

Note: Diagram updated after @peekay123 suggestion

At 75 % max distance would need 9 devices.

but if that same business wanted great up-time with the devices maybe they used the 50% distance then they need 25 devices to cover the entire lot as in the following diagram.

The coverage decisions has a huge effect on the number of devices to purchase. And I am only researching a single connection between a Xenon and an Argon. The entire situation becomes much more complex with a true mesh.

Will be interesting to see what coverage is needed with actual businesses.


#72

I started a new thread called

Which has my summary chart

Using the ideas of Business-Home-LineOfSight here are my results averaged over several days. Using this concept:

Business/School: concrete floors, lots of metal framing/school lockers, Busy Wifi
Home: wood, a few walls, private Wifi, windows
LineOfSight: Outside, both devices can directly see each other


#73

@rocksetta, see my post here:


#74

@peekay123 I pasted your image here on my blog because I really like it.

image


#75

by mesh antenna i infer you mean a bt antenna, but where do you get those?
btw, here in toronto i would like to teach tech (iot, tensor flow, etc) to disadvantaged youth (and not only youth) populations. can i use your materials?
fraser value looks gorgeous this time of the year :slight_smile:


#76

@exquisitus, Particle Mesh does NOT use BT. It uses 6LowPan atop of 802.15.4 running the OpenThread protocol. As such, the mesh antenna is more akin to WiFi or Zigbee antennas. An Argon WiFi antenna can be used as a Mesh antenna as well (ie extra antenna).


#77

To be fair, though, the external antenna u.FL connector is marked BT. :slight_smile:

I think that’s been sparking a lot of confusion. But in the end, aren’t WiFi, 802.15.4, and Bluetooth all working at 2.4GHz (though perhaps in different bandwidth ranges? haven’t checked that)? So the same type of antenna should work well for all of them?


#78

@dougal, I think it is marked BT because MESH/BT was too large! The antenna is actual shared between the mesh and BT (managed by the nRF52840) so you are correct. I always want to make sure folks don’t think the mesh is done over BLE.


#79

Very welcome to share all my stuff. Nice to have someone else teaching this to students.

There are lots of much easier approaches to Robotics (Lego Mindstroms, Vex and First) but I think the Javascript approach is the least expensive, best and most flexible. Note: Particle devices are not Javascript based but I interact with them using web pages or web sockets.

My Particle Robotics Github Not yet updated for Mesh Devices.
My Machine Learning Github
My Phonegap/Javascript Github (Old now)
My Independent Directed Studies Site

The Fraser Valley is always gorgeous (Something to do with much to much rain.) :slight_smile:


#80

Hmmm… So, @ScruffR, If I use my Etherwing to update all of my Xenons (and turn on the Etherwing switch), but use them later as stand-alone nodes (not in an Etherwing), do they still think they are a Gateway, or do they only become a gateway when they detect they are in an Etherwing? Is there a way to detect/report that status from an app, or the dashboard?