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29 May 2022

BLE and Polar H10

by Stuart Lynne


Currently the fitness_ecg program only supports the Polar H10 via BLE to get ECG and Heart Rate data.

There are several issues with this. When it works properly it is great. But when it fails not so much.

Common Issues

Windows 11

There have been some issues with Windows 11:

These are due to a problem in the underlying BLE libraries in use and their interaction with the Windows 11 Bluetooth support.

At this point (2022-06) it is a case of YMMV. Both the library and Windows support are moving targets and we’ll continue to monitor developments.

Windows 10 is more stable.

Polar H10 Multiple Connections

The Polar H10 supports a maximum of two BLE connections.

The factory default is to only allow a single connection, use the Polar App (e.g. iOS Polar Beat) to configure it to support two.

N.B. The Polar H10 may reset to a single connection when the battery is changed.

Single ECG connection

The Polar H10 only supports a single BLE connection sending PPD (aka ECG) data.

The Polar H10 supports two BLE connections, it only supports sending PMD (aka ECG) data via a single ECG connection.

If you can connect to the Polar H10, but only see PPI data (aka heart rate and RR) then it is likely that another app is connected and opened the PMD service.

N.B. the Polar H10 will not automatically disconnect if the app that it is connected to stops requesting data, e.g. it crashed or exited with and error and did not correctly disconnect. This can be a problem with other applications running in Windows, IOS and Android.

In this case ensure that every app on every device is closed. If that does not work, remove the battery for a short period of time from the Polar H10 and try again.

Sensitivity to movement

The Polar H10 is very sensitive to body movement. You will see violent changes in the PMD (ECG) data if the sensor moves. It can take 4-8 seconds to re-stabilize.

Less obvious but the RR data will also show more artifacts for the same reason.


There are occasional hiccups with Windows Bluetooth support.

Sometimes there is a failure to reconnect. The BLE Status continues to show Scanning, then finds the Polar, but fails to connect and restarts quickly (less than 5-8 seconds.)

If you have verified that no other app of device has an active connection to the Polar H10, you might try the following, the Fitness_ECG program can remain running, so you can see if anything helps:

Known Good BLE Adaptors

I have tried various BLE USB Dongles.

The one that works best for me in Windows (and Linux) is:

These are about $10US on Amazon.