Bluetooth connection

I am currently using the MetaMotion R board with the Metawear app in order to see movements.

The data I am extracting is or:

The Accelerometer BMI160 (Scale -2/+2, HZ 50)
Gyro BMI160 (Scale: 1000º/s, HZ 50)
Sensor fusion (Mode IMUPlus, Output Gravity)
The way I proceed: (Using the Metawear app)

Or, 1) I 'Start logging' from a sensor 2) I do the movement 3) I 'Stop logging' 4) Then, send data to my computer
Or, 1) I 'Start streaming' from 1 sensor 2) I do the movement 3) I 'Stop streaming'
(Always keeping the mobile at a distance of maximum a meter away from the MMR board)
And my issue is that in many occasions, the tracker disconnects.
It disconnects when I do a movement (Logging or streaming), when I download data, when there is 'clearing log', when I send data, etc...
It even disconnects when I don't use the board and just keeps it connected.
( I have used the board in many devices from IOS to android, old to new versions)

And I would like to know how I can have the bluetooth connection reliable.
I want to have it as constant as possible.
The way I see it, for example, if I take a bluetooth device like a beats by dre headphone. The music never stops, it never disconnects. Even if i run, move etc.
This is how I would like to have the Metamotion R board to work (but sending data to a mobile)

Could you tell me how this could be possible. To make the connection between a mobile and the board constant with no disconnections.

Best regards

Comments

  • You can't stream that much data all at once. Either stream the raw IMU data by itself or the sensor fusion data.

  • Yes, for that I know.
    I am talking about extracting the data of one of the output at a time.
    Meaning, or, from the gyro, or the Sensor Fusion, or from the accelerometer.

    My mistake, I thought I was clear about it.

    And I would like to extract that data with a perfect bluetooth connection. As even using your Metawear app and the tracker, it disconnects a lot. (Explained in the previous message.)

    What bluetooth parameter should I put?
    Even if I have to consume more energy, I need a GOOD bluetooth connection.

  • Ok, in that case, the behavior you are describing does not sound normal. Ttry increasing the tx power to 4db.
    https://mbientlab.com/androiddocs/3/settings.html#ble-advertising

    Do you have other boards to test with?

  • Yes, I have increased the tx power to 4db. But the board is still disconnecting.
    I have four Metamotion R board. Same problem each time.

    When, in my work environment, I connect the Metamotion R board to the Iphone, The connection is good(no to almost no disconnection)

    However, when I go to another environment (Like a gym club), this is when the tracker starts to disconnects.
    And, when in the same environment I connect to beats by dre headphone or even other cheaper headphones, the connection is perfect (and never disconnects).

    This is why I am asking if there could be a better way to take advantage of the bluetooth. As in other devices, the bluetooth work, I just want to know how to make that happen with this Board.

  • @Esclozas1,

    If your device is still under warranty, we are happy to look at it. You can fill out an RMA here: https://mbientlab.com/troubleshooting/

  • Yes, we can but I am convinced it is not a problem of the board. I have four MetaMotion R board that I have bought from Mbientlab. And they all face the same problem.

    I think it is en environment problem. In which the Board connects perfectly except in specific places.
    This is why I would like a solution to have the bluetooth configured to face that problem.

    Again, another device in bluetooth does not face that environment problem.

  • The boards are Bluetooth Low Energy, not classic Bluetooth. Aren't Beats by Dre a classic Bluetooth headset?

  • @Esclozas1,

    As per Eric's comment, note that Bluetooth Low Energy is quite different from Bluetooth Classic; you have only about 15m of range or so. Maybe you are operating the BLE out of spec?

  • edited December 5

    Hello,

    @Esclozas1

    Laura is right, I do think that we are operating out of the spec of BLE 4.

    I have the same issues with my App running with three Metawear-R streaming together and I do think that only BLE 5 will be able to help us for these kind of stability issues in "overcrowded" 2.4 GHz environnement.

    Indeed, as human body absorb 2.4 GHz signals, keeping a strong and constant transmission in overcrowded environnement is quite impossible with BLE 4 (i.e. poor transmission level even with TX power set to +4dB)...

    And if moreover, all this people have a smartphone in there pocket scanning WIFI network and BLE devices, it is quite "normal" to get stability issues as BLE 4 algorithm used to select a 2.4GHz channel is far from being optimized for so many devices without interferences.

    BLE 5 comes with
    1. 2Mbs for higher throughput (i.e. much better for streaming data)
    2. 500/125kbs modes for considerably increased range (x4) (but only available with code PHY of the new nRF52840)
    3. Advertising extensions for increased broadcast capacity (x8) (which means much more stability for the BLE signal).

    cf. https://devzone.nordicsemi.com/b/blog/posts/taking-a-deeper-dive-into-bluetooth-5
    cf. https://devzone.nordicsemi.com/f/nordic-q-a/38069/bluetooth-5-range-through-human-body-particularly-outdoors-when-signal-can-t-reflect-off-something-as-wall-or-floor

    @Laura @Andrew

    Am I always the only one to ask for firmware upgrade regarding that the Nordic nRF52832 used on Metawear-R is already BLE 5 ready for best throughput and stability.

  • Thanks all of you for your answers.

    Maybe I am running out of spec of the BLE.
    In this case, would there be a solution? As to use the Metamotion R Board in a crowded environment. (With the Iphone being 1meter from the person)

    As for the Bluetooth Low energy and classic bluetooth I now understand the difference. Then, is it possible to have classic bluetooth with your MetamotionR board. As maybe to use the button in order to turn on/off the Board. And maybe get a bigger battery.

    BLE 5 is great, the problem is it's compatibility with other devices. As most phones like 'older' devices running on IOS and Android does not have BLE 5 yet. But are BLE 4 compatible. (Also, the Nordic Semiconductor nRF52832 in the MMR is already a BLE 5 component)

    In the end, I know there are many problem. My only request is to find a solution in order to use your board and have it not disconnected.

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