Suunto Smart Heart Rate Belt 2
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@Inge-Nallsson damn, kudos! now, if insulating the module’s outer surface eliminates the noise, the coupling path would be via that surface (specs mention a stainless steel cover plate) and not via the skin.Therefore, the stated “shielding” would not protect against it, and this makes me think of a possible hw-level ESD immunity weakness or issue, hard to fix via firmware alone although Inge’s test cannot distinguish insulation from reduced shirt-module friction
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@Inge-Nallsson Great work, but honestly I don’t like to run with a rubber tube on my breast. I hope Suunto will reuse your analysis to correct the algorithm on SW side (if possible) or provides a replacement or a cap or something.
I don’t understand that a big company couldn’t do what you could do alone in a few days -
@Inge-Nallsson I’ve been spritzing the front of my shirt right in front of the module, and while it’s reduced starting noise, I’m still seeing it in the run. So I’m curious about insulators that I can use to cover the module, like perhaps electric tape or heat-shrink rubber.
The noise at the end of this run is while I was in a headwind. I’m guessing the shirt dried enough that ESD started becoming a problem again.
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All <-- Thank you for the thumbs up asf, but I was just following a logical path. Regretfully my education has been mainly within the Humanities so I have almost nothing to contribute when it comes to electrical engineering. Asking Google about alternatives to the rubber tube they listed some materials but also pointed out that static electricity has a tendency to find paths and discharge into a highly conductive steel cover plate (although measuring I find no conductivity anywhere on the pod, probably due to the coating). And looking at the construction with the push-button area I would consider that an easy path inside for discharges. For peace of mind I will continue with a rubber tube since (Google):
“Your rubber tube, on the other hand, acts as a permanent physical and dielectric barrier that doesn’t care about wind, drying times, or layer-to-layer friction. It completely isolates the pod mechanically”
It helps that I have so many years of running with rubber tubing beforehand
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Regretfully my education has been mainly within the Humanities
So, you didn’t know it couldn’t work - and that’s precisely why you came up with a working solution! Thanks a million for the excellent analysis and the solution!
Only one question remains - if Suunto dev team will get this information and what they do with it. Is there anybody able to pass the info to the dev team?
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@Dusan-Holub said:
Only one question remains - if Suunto dev team will get this information and what they do with it. Is there anybody able to pass the info to the dev team?Someone already shared the link to the post
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@isazi Thank you!
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Tried it today with a simple sticker as insulation and the anomalies were the same or worse. So thats not enough
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I hate beating this drum, but feel that three runs with the rubber sleeve proves the point to my own satisfaction (once is nothing, twice could be a fluke, thrice removes doubt). Also, today the temperature dropped enough for me to switch from T-shirt to a long-sleeved top - still 100% polyester - which would provide even more surface for electrostatic generation against the windbreaking jacket. The result was not as squeaky clean an R-R graph as from the previous session, but the Runalyze fault numbers are in line with the great ones from session one and two:
Anomalies: 0.0%
Artifacts: 0.2%
And, once again, the R-R zigzag at the beginning mirror a real HR drop from 108 bpm to 101 - confirmed by the OHR FR955 control watch.
This posting also gives me an opportunity for a piece of advice: Check the SHRM2 connectivity before stepping outside for an exercise!
When I stood in the middle of the village and discovered that the pod hadn’t been automatically activated by putting the (wet) strap on my chest, I didn’t feel like stripping down for pod examination. Home again it turned out that neither looking at the registered HR device listing, nor going into an activity, would wake the pod up. A quick press of the pod button did nothing (and the LED didn’t light up). A slightly longer press did nothing. Finally with a perhaps 3 seconds long press of the button both the LED lit up and the watch could make a connection.
Perhaps there is a hard shutdown timer in the SHRM2; it had been more than 48 hours since the previous exercise. Or perhaps my touching the outer shell at various points with the leads of a multimeter had triggered an emergency shutdown - I was looking for the beeping tone of a zero resistance area, and found none.
This episode also revealed a disadvantage of using a rubber tube. It prevents easy access to the pod button…
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