Bluetooth Range and number of data points

RE: Bluetooth Range and number of data points

vkadal — Fri, 22 Jan 2021 14:52:51 GMT

nRF52840 DK - 3 No, Need to be purchased? This not very expensive too, Thanks for the suggestion

RE: Bluetooth Range and number of data points

Edvin — Fri, 22 Jan 2021 14:46:34 GMT

What part numbers do you refer to?

There is an nRF52840 Dongle, but please note that it is not intended for debugging, and hence not that good for development.

If you intend to have 3 devices to test, I suggest that you use DKs. Once you have a FW that you have tested with 3, and you wish to expand, you can use dongle's for this, because you don't need to debug your code. You will probably need to debug on all 3 devices (one network leader and one server and one client, for example).

What sort of part number are you looking for? Can you give me an example?

BR,

Edvin

RE: Bluetooth Range and number of data points

vkadal — Fri, 22 Jan 2021 13:59:56 GMT

Thanks for the recommendation. Kindly give me the part number of the development kit. I think there are some BLE dongles also which can be configured as mesh . Please give me that part number too

RE: Bluetooth Range and number of data points

Edvin — Fri, 22 Jan 2021 13:23:51 GMT

nRF52840 DK:

https://www.nordicsemi.com/Products/Low-power-short-range-wireless/nRF52840

Best regards,

Edvin

RE: Bluetooth Range and number of data points

vkadal — Fri, 22 Jan 2021 12:17:50 GMT

I want to try blue tooth mesh with 3 nodes. Kindly give me the part numbers for DK and BLE nodes so that I can purchase

RE: Bluetooth Range and number of data points

vkadal — Fri, 22 Jan 2021 12:12:14 GMT

Thanks for the recommendations

RE: Bluetooth Range and number of data points

Edvin — Wed, 20 Jan 2021 13:14:01 GMT

The nRF9160 is a cellular chip. Of course, it could be used, but that would be cellular data connected to a cell tower using a SIM card and all that.

The nRF9160 DK does in fact have an nRF52840 chip as well as the nRF9160 chip, but the pin routing on that DK works a bit different, so I would recommend that you get hold of either an nRF52840 DK or an nRF52833 DK. You could use the nRF52832 chip (and DK) as well, but if you are starting development now, I believe the nRF52833 is the better choise. But I only work with technical stuff, and not pricing, so you can of course look it up.

So you probably could use the 9160 DK, but it is not straight forward, and I am not familiar with that DK. I suggest that you get hold of one of the nRF52 DKs.

Best regards,

Edvin

RE: Bluetooth Range and number of data points

vkadal — Wed, 20 Jan 2021 08:03:07 GMT

Al ready have nrF 9610 DK. Can that be used ?

RE: Bluetooth Range and number of data points

vkadal — Wed, 20 Jan 2021 08:02:25 GMT

Thanks for the reply

RE: Bluetooth Range and number of data points

Edvin — Tue, 19 Jan 2021 10:35:45 GMT

For Bluetooth Mesh I would recommend the nRF52833 or the nRF52840, depending on your application size. It is easy to port the application between the two, so you should start with either of those DKs.

When you have an application that is working, you can port it to the nRF52840 Dongle if you like (less expensive and smaller, which can be used for a larger scale of testing).

Best regards,

Edvin

RE: Bluetooth Range and number of data points

vkadal — Mon, 18 Jan 2021 16:08:39 GMT

Thanks for the detailed reply. As you suggest, I can use a rigid plastic enclosure and avoid moisture. So the range should be as required. The data rate is very slow. May be, one or two data per hour per device. And I can reduce the number of data points to reduce the congestion. That will not be an issue.

Can you suggest me the right part number to do a POC? I have nRF 9160 DK with me

RE: Bluetooth Range and number of data points

Edvin — Mon, 18 Jan 2021 14:53:45 GMT

Hello,

I believe you need to test these conditions with your equipment. There are two concerns. Range and throughput.

1 - Range:

My intuition says that Rigid PVC is your best option. At least if this encapsulates the entire nRF (with antenna).

5 meters in itself is not an issue, but the 50CM below the soil worries me. It depends on the soil. Remember that water absorbs RF, so if the soil is moist, this may be an issue.

2 - throughput:

You say you want to collect data from 20 000 points. Does that mean 20 000 unique devices, which will report in the same network? If that is the case, how often will they report? Bluetooth Mesh is not a great protocol for high throughput. And the overall throughput goes down when the number of nodes in the network increases.

Bluetooth mesh works well with a lot of "passive" devices, such as light bulbs that listen for a message that is intended for many devices. The reason for this is that all nodes will repeat all messages several times, so the message is flooded with that message, to make sure that the message covers the entire network. This is not great if you have many (!) devices that report their own custom message. It means that the message from all devices will be relayed (repeated) at least once by all other nodes. Comparing these scenarios, a light switch message will be repeated typically 3 times by all nodes. If you have 10 000 devices, that means 30 000 messages going through the network. If all 10 000 nodes send out their own message, each of these will be repeated 30 000 times. 10 000 * 30 000 messages = 300 000 000 messages.

Of course, you can limit the number of retransmissions, and turn off the relay functionality in some nodes, but that also impacts the coverage of the network.

Perhaps you can elaborate the throughput that you need. Will 20 000 devices send their own messages? How often?

BR,

Edvin

RE: Bluetooth Range and number of data points

vkadal — Mon, 18 Jan 2021 08:44:29 GMT

Antenna can be placed at the top of the chamber , in other words, closer to the earth surface. Then it may need travel through 5-10 cm of soil or chamber top wall. Next Bluetooth device will be within 5-7 meters

RE: Bluetooth Range and number of data points

Daniel Chisholm — Sun, 17 Jan 2021 16:59:52 GMT

Interesting question. We need to figure out if the nodes can talk to each other, and if so, can a BLE mesh network can handle the load?

To the first part: Is it fair to say that the bluetooth chip (more importantly, its antenna) has to be with the sensor, in which case this problem statement begins with "can the bluetooth signal of a device buried up to 50cm deep travel up to 5m through the soil?" Or can the problem be solved by having the antenna closer to the surface, ideally at or above grade level?