What's The Point of the Temperature Sensor?

Of course.

Garmin never say anything.

But advertise as such.

In fact Garmin never stated that the hour will be exact on their watches. Their gadgets are for fun and not for real time display.

What a silly discussion.

P.S.

Garmin think that we are retards.

Of course that if you advertise as thermometer on a watch you expect to get the ambient temperature.

If you use some watch faces which have a temperature option (I suggest GearMin) you can add a temperature offset in settings to be able to adjust for body heat and still get an accurate (approximate) ambient temperature. I find it fairly acurate.

I guess that will not be a great idea. Use a Tempe.

gaijin said:

The internal temperature sensor is to determine the temperature AT THE PRESSURE SENSOR.  This temp is required to accurately determine Elevation based on Absolute Pressure. Examples here: Altitude from atmospheric pressure Calculator

Did Garmin state somewhere that the temperature sensor is used to fine adjust the altitude/baro setting, and if so, could you provide a link to that statement, thanks. 

If they stated that, then its possible that the barometric pressure sensor has a calibration algorithm for the pressure value it reports, based on the temperature of the sensor.  Hard to say without knowing the exact sensor being used, and reading the spec sheet for the device.  Has Garmin ever published info on which pressure sensor it uses?  

FWIW, the link you provided requires the temperature value for an entirely different reason.  It calculates altitude based on the user providing the known sea level pressure and the air temperature, using a theoretical air density profile based on the temperature provided. In real world usage, the air density profile will not match what that calculator assumes, so that calculation would not provide the correct altitude value most of the time.  Also, the user may not know the exact sea level pressure at their location, so the calculator would be useless.

Since you've mentioned before that you live at around 4500ft, try an experiment.  Read the altitude from your watch at room temperature, then put it in the refrigerator for 15-30 minutes and watch the altitude reading as the temperature drops.  Most likely you'll see a slight change in altitude as the temperature drops, less than 10 feet, which is due to the pressure sensor value not being 100% stable over temperature (and why it may have a fine adjustment calibration curve based on temperature).  Now enter the two temperature values into the calculator from the link and you'll see that the reported elevation will change by hundreds of feet based on the temperature value.  That should prove that the formula in the link is not used by the watch.

5693709 said:

Did Garmin state somewhere that the temperature sensor is used to fine adjust the altitude/baro

No need. It has nothing to do with Garmin. It's physics, and affects other instruments as well.

interesting responses. so i see there's some purpose for it, but for practical purposes i wonder if it can actually take skin temperature like the new fitbits

www.theverge.com/.../fitbit-sense-versa-3-smartwatch-inspire-2-fitness-tracker-ecg-eda-stress

No, the sensor would need to be right against the skin to get an accurate reading. The sensor is contained in a metal watch body, so (like others have said above) the reading is always somewhere in-between skin temp and ambient temp. It does not accurately measure ambient temp, nor skin temp. It does accurately measure the temperature of the watch itself, which is important for reasons already stated by others above. Garmin lets us see the internal temperature for two reasons, because some people might find it useful for swimming (when it will be much more accurate) and for taking the temperature by removing the watch from your wrist for a few minutes. If you want to measure the temperature in any other way, you'll need an off-body temperature sensor - the Tempe.

Some future version of Fenix might include a secondary skin-temperature sensor on the back of the watch, but as of now, it doesn't have that, and the internal watch temperature cannot be re-purposed for that use with any useful degree of accuracy.

I don't know if the fitbit has a dedicated skin-temperature sensor, or if they're using algorithms to offset the internal watch temperature - if it's the former then that's kind of neat, but if it's the latter then that's not going to be accurate at all, for the same reason it wouldn't be accurate if garmin did it. I do know that fitbits aren't usually regarded as an accurate devices though, so maybe they don't care.

Edit: Just read the article you posted a link for - it seems that it uses the watch's internal sensor (not a dedicated skin-temperature sensor) but they increase the accuracy by telling the user to cover the face of their watch with the palm of their hand. So it's purely just a UI thing, it's not because they have some state-of-the-art sensor. Garmin could just as easily tell someone to cover their watch with their hand for a couple minutes and take a temp reading too. But how useful would that be? Not very, IMO. Part of the beauty of Garmin's stress-analysis algorithms is that it's all passive, you don't ever have to open any apps or take any manual readings. With fitbit's versions you have to remember to periodically go into the Stress app and follow the directions to take stress readings.

bluefish said:

No need. It has nothing to do with Garmin. It's physics, and affects other instruments as well.

not sure what you're trying to say, this statement is pretty vague.

some pressure sensors have elaborate temperature compensation algorithms that are applied to the readout pressure value.  Like this one that appears to give compensation coefficients to the user and asks them to run the algorithm they provide in the appendix:

https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP388-DS001.pdf

others, like this one, have an internal temperature sensor that performs pressure compensation automatically, with the added benefit of being able to provide temperature information to the user.

www.st.com/.../lps25hb.pdf

So if they have a combo pressure/temperature sensor device inside the watch, then the temperature just happens to be available for convenience because its provided by the sensor.  If they have a pressure only device, then they may use a temperature sensor to compensate the pressure readings. 

But, that part is mostly splitting hairs, my main point is an altimeter doesn't need a temperature reference to compute altitude from pressure.  The standard atmosphere formula defines the pressure/altitude relationship with a pre-defined temperature curve built into the formula, and all altimeters are calibrated to that formula.  Mechanical altimeters existed for years with no temperature measuring capability.

People who are complaining about the temperature sensor should go back in time to 5-6 years ago when other people were saying "we know Garmin has an internal temperature sensor because it MUST due to the nature of GPS clocks, barometric sensors, et al, therefore why is Garmin so stingy and won't expose this temperature to us. GIVE US THE INTERNAL TEMPERATURE YOU CREEPS."

Ironic