GPS "Demo" mode vs the barometer

[WallyGator]

I've found vast inconsistencies between the barometer plots on the eTrex Touch 2 and both a GPSMAP 60CS and an eTrex 32x.
Normally, all unit's barometer plots matched very closely to each other (in the same place, over long periods of time & not moving at all). All unit's barometer settings were set exactly the same...until I did something on the Touch 2 that altered it's barometric plotting behavior. That something eluded me for quite awhile until I finally figured out what it was. That setting was putting the Touch 2 into GPS "Demo" mode. While this shuts off the GPS receiver (as expected), it also seems to shut off the barometer and it's barometric readings over time. I experienced very odd deviations with spikes and dips in the barometer plot compared to the other two units and could not figure out why...until I finally did by flipping settings, observing and trying to remember what I did. The spikes, dips and irregularities ended up coinciding with me toggling GPS "Demo" mode off and on depending on what I was doing with the unit.

One would think that putting the unit into GPS "Demo" mode would not be affecting the barometer since it supposedly just turns the GPS receiver off. It never once crossed my mind that this would also be turning the barometer off as well. Why would one even want the barometer disabled when GPS is in "Demo" mode is beyond me.

Add one more oddity to the list...maybe it's set up to work this way "by design". I really don't know at this point.

[GPSrChive]

Firmware version?

Any screen captures to show what you were seeing?

[WallyGator]

Screenshots are in the "spoiler" below.

eTrex Touch (Gen 2) Firmware v10.13 (blue barometer plots in screenshots)
eTrex 32x Firmware v2.90 (green barometer plots in screenshots)
I don't know if this was an issue with firmware prior to v10.13 but I recall this irregularity from quite awhile back and always wondered why the plots on the Touch 2 were so off compared to the 32x. They would start off fine and stay the same until I did that "something" (turning on GPS Demo mode) on it that started causing the deviations.

All barometer settings were the same between both units:
1. Barometer Mode: Variable Elevation
2. Pressure Trending: Save Always
3. Plot Type: Ambient Pressure

The units were not moved from their locations
All X & Y axis settings are also set the same between the two units when viewing the plotted graph

You can see the perfectly straight line plots that indicate jumps in the plot when the barometer was off, then was enabled again. Since there is no actual user setting on the unit that lets you disable the barometer, the system is apparently doing it when GPS Demo mode is enabled. Is it supposed to be doing this? I would assume not.

If you use the barometer to monitor weather systems while stationary and you put the unit into GPS Demo mode to save the battery, your barometric plots/readings are going to be pretty skewed. Without a comparison to what is actually correct, you'll be scratching your head (as I was) why the readings are jumping around and have perfectly straight line segments in the plot.

I've reported this to Garmin support with screenshots and info a few days ago via direct email but they have not responded, not even with a "we'll look into it" reply. They usually reply within a day at the most but not this time.

Spoiler

Initial plot Total plot time: ~4-1/2 hours

initial.png

~12 hours later. Total plot time: ~36 hours

plus 12 hours.png

[WallyGator]

Somewhat related and may be helpful if you encounter the above-mentioned issue...

I was trying to put the Touch 2 into "Forced USB Mass Storage mode" but never got it to do so (that puny button deos not make attempts very). In the process of trying quite a few times and giving up, I noticed the barometer plot was wiped out. So it appears there is a way to wipe out the barometer without hard-resetting the unit. None of my other settings nor data were touched. AFAIK, only the barometer was wiped.

[GPSrChive]

Thank you for all the additional information, now I can do my own testing... Stay Tuned!

[WallyGator]

Garmin have replied this morning that they are "looking into this".

[WallyGator]

Here is the most recent email exchange (note that I sent ALL data to them as in my original posts here...maybe it's too much data for them to comprehend):

Me

Additional info:

I have since found that enabling the “GPS Demo” setting (which is supposed to only turn off the unit’s GPS receiver) seems to be causing the strange barometer readings that I have shown. It seems as if the “GPS Demo” setting is somehow interfering with or possibly disabling the barometer for the time that it is enabled.

If I run the unit with the “GPS Demo” setting off and actually tracking the GPS satellites, the barometer readings are normal.

One would expect that the barometer would NOT be affected when enabling the “GPS Demo” setting.

Garmin

Hello,

Demo Mode (or Simulator) - The handheld will not acquire a satellite fix, however will simulate as if it is receiving a satellite signal.
NOTE: This mode is not recommended for navigation.

You don't want to use demo mode as that is normally what is set up in a store display to show what would happen if the device actually had an actual satellite fix.

Me

I know this. I’m am running Demo Mode INDOORS to only monitor the barometer and am NOT navigating. I enable Demo Mode specifically to prevent GPS from tracking satellites to save battery life and so I can monitor the barometer ONLY. Under this situation, the barometer plots deviate from other known & verified barometer reading & plots.

Garmin

So you're only experiencing this issue while in demo mode? Or is it when you're out using the device?

Me

ONLY in Demo Mode and using the device INDOORS

Garmin

Just out of curiosity, if you take both devices outside is there a difference?

I feel like I'm talking to styrofoam.
Anyways, I won't be posting any more of this silliness here unless there is some response like "working as intended" or "it's been logged as a bug". All I want is for them to research & log it as a possible bug/issue. I don't need help "resolving it" since there is no resolution except for NOT enabling "GPS Demo" mode.

[WallyGator]

Update:

Garmin have "created a case" to further investigate this issue.

[WallyGator]

Additional more revealing screenshots & info sent to Garmin

The first screen shot is the plot with GPS Demo turned OFF (GPS is active). The plot is normal.

The second screen shot is when I enabled GPS Demo (GPS is inactive). I enabled GPS Demo mode at ~5:30pm and the spike started occurring within a few minutes. It continued until I disabled GPS Demo mode at 12:30am the following day. Notice the extreme spike. But also note that the upper graph is normal between the two screenshots. This spike seems to only affect the lower section of the graph. This spike lasted for 7 hours with no change in the barometer plot...all I saw was this erroneous plot in the lower graph. Zooming in/out in either the X or Y axis did nothing. The spike was still present and did not change. Note also that the upper graph on both screenshots is the same; the barometer was not plotting for those 7 hours that the spike was showing and GPS Demo mode was enabled. After I disabled GPS Demo mode, this spike went away in a few minutes on the lower section of the graph & it resumed plotting correctly.

This looks pretty clear to me that the barometer is being disabled when GPS Demo mode is enabled.

Spoiler

Touch 2 barometer issue.png

[/spoiler}