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External Tempe Sensor Question

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  • External Tempe Sensor Question

    I have a Garmin Tempe sensor connected on one of my running shoes. I've noticed whenever I start an activity the sensor is always reading 20-30 degrees Fahrenheit warmer then the actual temperature. This will last for about 2-3 minutes and then start recording the correct temperature for the remainder of the activity. When the temperature does change, it corrects itself immediately. There is no gradual or sloping change on my temperature graph. This morning's run started and stayed at 75 degrees for the first 2:30 mins then dropped to 50 degrees for the remainder. The actual temperature reported for my location was 49 degrees. The battery is new and I keep my running shoes in the garage where the temperature is slightly higher than the outside temperature, but not nearly by 20-30 degrees. It's really not a big issue. I'm just curious if anyone else's acts the same?

  • #2
    not really...I wait until the icon appears
    could it be your watches temperature for those first minutes ?
    the tempe sensor has a rather slow data transmission interval, saving power because it is on all the time

    but I know jim_m_58 could fill a book with all the info he ever wrote explaining it's workings

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    • #3
      Originally posted by OnlyTwo View Post
      could it be your watches temperature for those first minutes ?
      I considered this at first, but I wait for the tempe sensor to connect while waiting for the GPS green circle to ensure a good GPS fix before starting an activity. I don't recall ever getting a notification that my tempe sensor is connected around that 2-3 min mark, but I'll pay closer attention the next time to see if that's the case.
      Last edited by TMK17; 10-13-2018, 11:31 AM.

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      • #4
        What's happening here is when you start an activity, the DF will show the data from the internal sensor as it tries to connect to the Tempe. And connecting to the Tempe can take a couple minutes.

        When you first start and see internal temp, you'll notice it can change quite often (multiple times a minute). When the Tempe gets connected, it changes at most every minute as that's as often as the tempe takes a reading.

        You don't see a slope as the data switches from the internal sensor to the tempe when it connects. So watch temp for 2:30, tempe connects, and drops rights to garage/ambient temperature.
        Last edited by jim_m_58; 10-13-2018, 11:35 AM.
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        • #5
          I understand that Jim, but what I'm seeing is my watch display that my external tempe (with it's assigned number) is connected before I start the activity. I wait for any sensor I'm using to connect before starting an activity. I don't even use a data field with a temperature display outside your Hike2 app. I'm seeing this in the temperature graph in GC after the activity is completed.

          I have a routine I use prior to every activity. I calibrate my altimeter and barometer. I select the activity app I'm going to use. I'll wait until all sensors I'm using shows that they are connected while obtaining a good GPS fix with the green circle. This usually last about two minutes to ensure a good 3D fix. After all these are completed, I then start the activity. I guess it's possible during this procedure the external tempe drops and it's going back to the internal sensor, but I'm absolutely positive the external sensor was showing as connected.
          Last edited by TMK17; 10-13-2018, 11:50 AM. Reason: Additional info

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          • #6
            jim_m_58 After looking at all my previous runs and bike rides, what you're saying makes perfect sense as far as the internal sensor providing the initial reading and then the external sensor taking over. I'm just puzzled by why my watch is showing the external sensor as being connected prior to starting my activity if it actual isn't. Perhaps the next time you do an activity with an external tempe sensor you could wait until it shows that sensor connected before starting the activity to see if you get the same results? Curiosity is getting the best of me.
            Last edited by TMK17; 10-13-2018, 12:26 PM.

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            • #7
              this is how it shows in my latest activities

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              • #8

                Temperature




                Created with Highcharts 6.1.1























                Avg: 54.0 °F0:001:403:205:006:408:2010:0011:4013:2015:0016:4018:2020:0040.060.080.0



                8:39

                This is what I got this morning starting the activity after the watch said the external tempe was connected. It seems as Jim is correct and that the first couple of mins was from the internal sensor. Now I'm wondering why the watch is displaying the external as connected when it doesn't appear to be so?

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                • #9
                  Lol. It appears I'm not attaching a copy of my graph correctly.

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                  • #10
                    I hope this one worked.

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                    • #11
                      welcome to the terrible, horrible, annoying forum workings...

                      geuss the watch connects to the ANT channel from the tempe, but did not get the full data stream coming from the tempe
                      afterwards it captures a full data stream from the tempe
                      perhaps someone like aweatherall could explain this ANT data stream workings
                      Last edited by OnlyTwo; 10-13-2018, 01:12 PM.

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                      • #12
                        Originally posted by TMK17 View Post
                        jim_m_58 After looking at all my previous runs and bike rides, what you're saying makes perfect sense as far as the internal sensor providing the initial reading and then the external sensor taking over. I'm just puzzled by why my watch is showing the external sensor as being connected prior to starting my activity if it actual isn't. Perhaps the next time you do an activity with an external tempe sensor you could wait until it shows that sensor connected before starting the activity to see if you get the same results? Curiosity is getting the best of me.
                        From my recollection, the Tempe has quite a slow update frequency - something like once every 30 seconds. This contrasts with most other external sensors, which send information evey second (or even more often than that).

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                        • #13
                          The Tempe takes a new reading once a minute, and some of that is that the tempe does the same thing 24/7/365, so it needs to conserve battery. Other sensors like footpods/HRMs have a ultra low power mode when they aren't in use.
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                          • #14
                            Originally posted by jim_m_58 View Post
                            The Tempe takes a new reading once a minute, and some of that is that the tempe does the same thing 24/7/365, so it needs to conserve battery. Other sensors like footpods/HRMs have a ultra low power mode when they aren't in use.
                            This is the issue.

                            Check this post:

                            https://forums.garmin.com/forum/into...114#post456114

                            From a Garmin support response:

                            While Tempe can sense changes in temperature as often as once a second, it is not typical for it to send updates this frequently to the device.
                            The process through which temperature changes are detected, filtered for irregularities and sent to the device will typically take longer than one second. An exact time for this process is not available as it is dependent on many variables. Often changes are seen within 15-30 seconds.
                            Noting the probability of variable update rates will allow for proper expectations when using the Tempe sensor.

                            Kind Regards,
                            Emma S
                            European Customer Care Associate
                            Garmin (Europe) Ltd | PO Box 392 | Southampton | SO40 0FW | UK
                            I often see a minute+ delay before the Tempe sensed ambient temperature replaces the temperature sensed by my 935. The trade-off here seems to be battery life over sampling rate: I've heard a Tempe can run for *years* on the same battery.
                            Last edited by CJOttawa; 10-14-2018, 07:01 AM.

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                            • #15
                              Originally posted by CJOttawa View Post

                              I've heard a Tempe can run for *years* on the same battery.
                              29 months and counting here with my Tempe, still on the original battery

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