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

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.

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.

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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.

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.

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

@rocksetta, see my post here:

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

image

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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:

@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).

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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?

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@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.

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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:

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?

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Not sure, that would be something to try out, but I’d expect that this should lock the gateway flag, otherwise this would be an easy way to mimik a micro network which could otherwise easily be converted into a HA mesh.

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2 Problems. First using the featherwing does not guarantee it is a gateway. This bit of code at the top of your program

STARTUP(System.enableFeature(FEATURE_ETHERNET_DETECTION));

makes the featherwing plug and play, gives the Xenon internet but does not on it's own setup a gateway.

If you use the App to make a gateway using the Feathering and a xenon, you still have the problem of not being able to join to any other mesh network. So by taking the featherwing off of your xenon it becomes useless because it can't be part of any other network except the network that is was setup to be a part of.

Hopefully at some point Particle is going to allow us to join multiple gateways to a mesh network..

So I went out to test if glass hurt the RF signal. Xenon and Argon in jam jars. When I got to the location I wanted to set a base line and didn't want to walk too far so I used a Xenon and Argon without Mesh Antenna. Should get about 300 m.

But today Thinking about Antennas tend to be about 1/4 the wavelength. I did some math. Velocity = Wavelength x frequency.

or Wavelength = Velocity (Light) /Fequency = 3.00e+8 m/s / 2.4 1e+9 1/s = 0.125 m about 13 cm or 5 inches So the perfect antenna should be about 3 cm or about an inch.

Looking at the Mesh/Wifi antennas they have a wire but the antenna part is about an inch, well so is the Argon and Xenon about an inch long. So to get my base line I set them up both vertically and started walking. HOLLY SMOKE at 600 m I came to a slight curve, so I never did find the full distance.

MOUNT YOUR MESH DEVICES VERTICALLY to get the most of the internal antenna!

I finally had to position the devices for the worst range to just be able to test the glass, which seemed to have no effect on the distance.

I think this is worth it's own topic.

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Spurred on by the above discovery I spent the afternoon researching how to make a parabolic reflector.

but they both seemed like a lot of work

I did design a parabolic shape to 3D Print tomorrow, but then I would have to cover it with some kind of metal paint.

so I dug a bit deeper and found this image

image

which reminded me that radio waves can be reflected by a metal mesh (Some website mentioned the mesh should be at least 1/10 the wavelength) for 2.4 GHz the mesh would be like the mesh in a microwave.

So I found a Summer Salad insect protector. Was super excited to try it out, but it did not seem to help at all :disappointed:.

You might be oversimplifying a directional antenna a bit. But, the metal mesh doesn’t do a anything by itself. Rather, the metal mesh is supposed to create an artificial ground plane. Try attaching the metal mesh to ground. It might work…

The shape of the parabola doesn’t look right either.

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Nice... also I was not testing line of sight, so I will do that when I get a chance. So just a wire that attaches to the ground would be enough. I might just place the thing on the ground. Finding the correct focal point might take a bit of testing,

Those companies that make salad protectors should really concentrate more on making correct parabola shapes.

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So today my thinking was: Since a metallic mesh stops or reflects RF signals, what about the breadboard the Mesh Devices are attached to. If you take apart a breadboard it is a mesh of wires (however they are not interconnected). If I hang a mesh device vertically but reverse the direction so the breadboard is facing my Xenon. I should get a very reduced max distance.

Made no difference. Got the same max distance.