I have a Mio Link – a sports wristband that can measure heart rate at the wrist and transfer it to a mobile phone or sports watch – and I got a heart rate monitor (HRM) belt that came with my Ambit3R watch. I would like to know if it is possible to use both heart rate sensors at the same time to record them with the Ambit3R watch and verify that they measure similar heart rates? I did a test run with the watch, and according to the results I viewed in the movescount app it appears to measure only with a single HRM.
While it surely is possible to pair the watch with several HR monitoring devices, I don't think it's possible to use more than one at the same time. I cannot tell for sure since I don't have an Ambit3 (which uses the Bluetooth Low Energy protocol to connect external sensors, as far as I remember) but only an Ambit2 (which communicates via ANT+) but in the case of my watch it stops searching for a certain type of external sensor as soon as it has detected one it was paired with.
Technically, it would surely be possible to use more than one sensor of the same type at a time, however that imposes a lot of extra stuff to handle:
The watch needs a logic to handle two data sources of the same type that quite surely will deliver slightly different signals. That means, if you ask it to show "heart rate", what should it display? The signal from source 1 or source 2? The average of both? Should all the measurements that are derived from the heart rate (average heart rate, times in certain zones etc.) also be handled for both sources? Should both of them be recorded in full? All this on a device that has limited battery and storage capacity and computation power.
These thoughts make it quite improbable that such a functionality has been (or will be) implemented by Suunto, since its use case is very limited and the possible issues coming with it are rather significant.