Altimeter: where exactly does air enter the Surge to get to the Altimeter

[spenceridge]

My Surge was counting floors when I was going downhill; in other words, elevation increased 5 floors or 50 feet as I went down a 300 foot hill. 

I talked to Fitbit Support.  The tech emailed me the reply in italics below. My problem could be due to sweat blocking the pathway to the altimeter.

Your tracker detects floors using an altimeter, which is a sensor that calculates altitude based on atmospheric pressure. Atmospheric pressure decreases with increasing elevation, so the tracker calculates elevation gain based on the reduction in atmospheric pressure. Your tracker registers a floor when it detects continuous motion combined with an elevation gain of 7 to 10 feet.

Your tracker may give you credit for extra floors for a variety of reasons. Occasionally your tracker may detect pressure changes unrelated to elevation gains, such as a gust of wind, weather change, or opening a door. Exposure to excess moisture can also result in extra floors being counted. This happens if the pathway to the altimeter on the back of your tracker becomes temporarily blocked with sweat or water. We recommend that your tracker be worn loosely during exercise.

My question:  Is the pathway to the Altimeter around the charging port, through the small oval  or around the blinking light module?  

This website shows the insides of a Fitbit Surge...no reference to the altimeter/barometer...but it could be worth a look if interested... https://www.ifixit.com/Teardown/FitBit+Surge+Teardown/42344

[spenceridge]

I found some pics of the insides of a Surge.  I drew red arrows to suspected locations of the altimeter or pathways to the insides of the Surge.

[SunsetRunner]

that's correct

http://www.te.com/usa-en/product-CAT-BLPS0015.html

[spenceridge]

Thanks DuboisP!

Your link to the picture of the altimeter/pressure sensor solves that mystery...that's the altimeter.

I wonder how air gets to it...through the blinking light module or through the small port near the on/enter button?

[SunsetRunner · Accepted solution]

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spenceridge wrote:

or through the small port near the on/enter button?

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99.9999% chance 

[spenceridge]

I wonder if the port is covered with something that let's air through but resists the entrance of water...like goretex?

[SunsetRunner]

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@spenceridge wrote:

I wonder if the port is covered with something that let's air through but resists the entrance of water...like goretex?

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nope

even with goretex sportwear, you have air flow, elsewhere.

but if the hole is blocked by dust/sweat, yes.

[spenceridge]

Wristband notch 3...or tight for heart rate accuracy

Wristband notch 4 or looser for elevation priority

Therefore, if elevation recording is important, wear the Surge loosely.

Heart rate wasn't part of this discussion...but I would say that if heart rate accuracy is more important, wear the Surge tighter.  For me, I regularly wear my Surge at watchband notch 4....I think that notch feels slightly loose as the watch feels comfortable.  When I'm interested in heart rate, I wear the Surge at notch 3, which is tighter but not uncomfortable.

None of this is complaining...I'm just trying to learn the personality of the surge.  Is there an advanced user who has done a FAQ?

[AngelaMa]

Hello @spenceridge as @SunsetRunner confirmed from your first photo that is the pathway to the altimeter, sometimes it becomes temporarily blocked with sweat or water and this can cause inaccuracy on how the floors are recorded. Please note that your tracker may detect pressure changes unrelated to elevation gains, such as a gust of wind, weather change, or opening a door and credit you some extra floors. Also we recommend that your tracker be worn loosely during exercise, since a tight band restricts blood flow, potentially affecting the heart rate signal. That being said, the tracker should also be slightly tighter (snug but not constricting) during exercise than during all-day wear. 

Tag me if you have any question I'll be happy to help!