Sunday, 22 March 2015

Lidl HRM test 3 - with Nexus 7 again

Lidl HRM chest belt recorded by Strava on a Nexus 7
For this third test I was going to take the LG L50 phone again, and I synched it up, then put my shoes on.
BUT ...
Anna likes her 'phone to go into "sleep" mode after just 30 seconds to save power, and ... the time I had got my shoes on, the screen had gone dark, and on "swiping" the screen again, both the GPS and the HRM had "lost" their signals, and were endlessly searching with no result.
I gave up after about 5 minutes, and switched on the Nexus 7 tablet again.
I took a few seconds to log in to Strava, and then the Nexus 7 picked up the Lidl HRM almost immediately (about 10 seconds, at most), and a few seconds later the GPS "locked on".
So I took the Nexus 7 out for the test.

While I was out, I did look at the screen of the tablet a couple of times, and found once that it had lost the HRM signal, but the trace above suggests that contact must have been re-establishe pretty quickly.
The two big dips in the trace coincide with when we were waiting to cross the road, so they probably don't reflect any signal issues.

For the "peak" reading on the trace we were carrying stuff uphill, so again this is probably realistic.
the readings are mostly in the 80 to 90 bpm range, which for me (with a MaxHR of about 175) is in the region of 50% max HR, which is probably about right for walking - told you it was Zone 1 (!).

So, to conclude, the Nexus 7 seems like a great device to sync up with the Lidl HRM chest belt.
The LG L50 (aka D213) seems to have a variety of intermittent issues with both the GPS signal AND in detecting the HRM belt.
Certainly at this point, I have no reason to doubt the accuracy of the Lidl "Medisana" Bluetooth HRM chest belt, and indeed, with the three tests I have conducted so far, all the numbers look pretty realistic.

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