HR Data and RR Intervals

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10 February 2020 12:19 AM

Greyfox Newbie

Total Posts: 4

Joined 2020-02-05

Hello.
I used sample code in my app.
On the screen and my HR data log I see that HR data updating is more frequently than real heart beats.
On one real heart beat HeartBeatCounter is increased by 4-5. CalculatedRRInterval receives more frequently too.
Data on the screen and log file writes direct from parameters of CalculatedRrIntervalReceiver() and HeartRateDataReceiver().
But ComputedHeartrate in HeartRateDataReceiver() is correct.
What's wrong?

10 February 2020 01:37 PM #1

haighi Administrator

Total Posts: 370

Joined 2012-06-27

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How are you arriving at the following statement: "On the screen and my HR data log I see that HR data updating is more frequently than real heart beats. On one real heart beat HeartBeatCounter is increased by 4-5."

The profile specifies that this counter increments once per beat.

Note that the computed heart rate may remain constant across consecutive beats.

Ian

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Ian Haigh

10 February 2020 05:37 PM #2

Greyfox Newbie

Total Posts: 4

Joined 2020-02-05

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It seems that the problem is in the HR chest belt. It transmits incomprehensible data. HR is 74-75, but HR belt transmits increment BeatCount in every page. I don't understand it... HR belt build on nRF51422 (ANT+ and BLE).
Data from SimulAnt:

945801734 : Rx: [04][55][17][BE][55][C1][A8][4A]
945801968 : Rx: [04][55][55][C1][93][C4][A9][4A]
945802218 : Rx: [04][55][93][C4][BB][C7][AA][4B]
945802468 : Rx: [04][55][BB][C7][EE][CA][AB][4B]
945802718 : Rx: [84][55][EE][CA][21][CE][AC][4B]
945802953 : Rx: [84][55][21][CE][54][D1][AD][4B]
945803203 : Rx: [84][55][54][D1][87][D4][AE][4B]
945803453 : Rx: [84][55][87][D4][BA][D7][AF][4B]
945803703 : Rx: [04][55][BA][D7][ED][DA][B0][4B]
945803937 : Rx fail
945804187 : Rx: [04][55][2B][DE][69][E1][B2][4A]
945804421 : Rx: [04][55][69][E1][A7][E4][B3][4A] 

10 February 2020 05:52 PM #3

haighi Administrator

Total Posts: 370

Joined 2012-06-27

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Yes that looks to be an incorrect transmission by the sensor. The beat to beat time seems to be fixed at 333 * (1/1024 sec) = 0.325 sec

I recommend that you report this to the sensor manufacturer. Does the sensor appear in our directory?

Ian

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Ian Haigh

10 February 2020 09:04 PM #4

Greyfox Newbie

Total Posts: 4

Joined 2020-02-05

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I can't find sensor in compatible devices list.
I will try get data from BLE and compare with ANT.

16 February 2020 04:10 AM #5

ifor Sr. Member

Total Posts: 122

Joined 2010-10-25

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Some of the cheaper devices coming out of China are not following the spec correctly with regard to this. The Coospo ones were the first dodgy ones I saw. There have been others since. There are similar sorts of issues with speed and cadence sensors not counting pedal revs or wheel revs correctly. The data to display the instantaneous main value is correct so to look reasonable to start with. If your head unit / app is using the counts though for things like averages then that data will be wrong.

I actually had contact with one of the companies spamming me a sales pitch for a customized version of a sensor. I normally don't respond to this stuff but in this case they got a detailed explanation of how they were breaking the spec and along with the response that I would only be interested in a device that had passed the certification tests.

18 February 2020 11:45 AM #6

haighi Administrator

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Greyfox: Can you share what sensor you are running into issues with?

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Ian Haigh

05 March 2020 09:55 PM #7

Greyfox Newbie

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Joined 2020-02-05

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haighi - 18 February 2020 11:45 AM
Greyfox: Can you share what sensor you are running into issues with?

haighi, yes, this is Kyto Fitness KYTO2809 ANT+ and Bluetooth heart rate sensor.
Manufacturer did not help, they convince me that everything is fine.

But I solved this problem by making my custom firmware using nRF5 SDK. Now sensor works fine.
This sensor maked on nRF51422-AA chip.

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