Category Archives: Track and sensors

MyTrails records zigzag around my track

This means your GPS signal is noisy, which may be:

  • because your GPS module is not very sensitive or misconfigured
  • because of the terrain (in thick woods or canyons)
  • because it’s stored at the bottom of a backpack or pocket
  • because of jamming (intentional or power lines)

Once you’ve excluded the physical causes and have reset your GPS (and rebooted the phone for good measure), if the track is still showing zigzags, you can set up filtering in MyTrails by using the set kalman filter n hidden option, where n is the approximate nominal speed in m/s, for example 1 for walking, 8 for cycling.

How can I transfer GPX tracks to my computer?

MyTrails store the GPX files for tracks you have recorded in /sdcard/MyTrails/gpx (you can change this in MyTrails > Preferences > Other).

Here are a few methods you can use to transfer track files:

  • the most basic method for transferring files is to connect your device to the computer via USB (make sure to set the USB transfer mode to MTP, and on Mac use Google’s Android File Transfer to copy the files over). More info here.
  • another method is to use a file manager on Android to copy the files to a physical SD card (if you have one and can plug it into your device) and then read the SD card on the computer
  • MyTrails Pro has built-in support for saving tracks to Dropbox (or a track-sharing community such as GPSies); if you also use Dropbox on your computer, the file will magically appear there
  • finally, in MyTrails’ Track Manager, you can long-tap a track and use the Share menu to send the file via email or another app that is capable of sharing files

Cumulated climb or descent

Dénivelé

In order to calculate the cumulated altitude differential, MyTrails must identify parts of the altitude curve where the track switches from uphill to downhill or vice versa. Because altitude measurements are not exact (especially from the GPS), MyTrails uses a filter to attempt to differentiate measurement errors from actual changes in the track.

Different applications use different filters, which may yield very different altitude differentials.

You will get better results when using altimeter-derived altitudes, or after applying altitude normalization (when saving the track, or in the Track Manager).

In MyTrails 2.0.11 and later, you can additionally use two options in Preferences > Sensors: Altitude stabilization (which performs some filtering on GPS altitude data to reduce the noise) and Cumulative climb filter, which you can set higher to avoid MyTrails overestimating cumulative climb when the GPS data is very noisy.

New recording UI

MyTrails 2.0.9 introduces a new recording UI, which should make it easier for new users to grasp what the application is doing. The original recording UI is still available and will continue to be supported for users who prefer a greater degree of control.

How to select

You can select the type of recording UI in MyTrails > Preferences > Recording, Extended recording UI (uncheck for the new UI).

How does the new recording system work?

The new system consists of two buttons: Record/Pause and Stop.

New recording UI

Currently recording

The icon that is lit corresponds to the current recording state. Tap a button to switch to that state. For example, to pause the recording (without saving and closing the track), tap Record/Pause.

Tap the Stop button when you are done with your recording: MyTrails asks you to save the track (providing a name, etc.), and possibly upload the track to a community. The recording is then cleared, so MyTrails is ready for another recording, which you can do immediately by hitting the Record button.

You can also find the recording controls in the navigation menu, which is available on all main screens (stats, graphs, tracks, maps, etc.), not just the map view.

Streamlining the recording experience

With this new mode, MyTrails tries to make it very quick and easy to record your tracks:

  • when you launch MyTrails, recording starts right away (unless MyTrails was exited in the paused state)
  • when you get back to your starting point, MyTrails reminds you to save the recording with an unobtrusive notification (you can dismiss it by swiping it away; you can also disable this feature)
  • when you stop the recording and save the track, you can leave MyTrails any way you like:
    • just sending MyTrails to the background (using the Home button) stops using the GPS
    • actually quitting (using the Back button) is still better: when you next start it, MyTrails will know to start recording a new track

MyTrails is always looking for a GPS signal – AKA how can I stop MyTrails?

MyTrails can record your track whether it’s visible or running in the background. Even if you’re not recording a track, MyTrails may use the GPS if you have the proximity notifications option turned on.

When you want to stop using MyTrails, you should quit it like any other application (including Google Maps), by using the back key or button. When you do this, MyTrails asks you whether you want to keep recording the track in the background. Answer ‘no’ to stop MyTrails entirely.

Back button

Back button

Back key

Back key

Note that MyTrails doesn’t ask about quitting if you have already paused track recording. You can also use the Pause button in the recording notification to stop recording.

Recording notification

Recording notification

If you find this confusing, you can enable a Quit option to the navigation menu in MyTrails > Preferences > Other.

Compass calibration

MyTrails can use your phone’s built-in magnetometer and accelerometer to simulate a compass. However, unlike a physical compass, phones need to be periodically calibrated to provide an accurate reading of the magnetic north bearing.

There are two methods (both need MyTrails to be running with the screen on – MyTrails disables the compass when the screen is off):

Keep in mind that even after calibration, the compass is sensitive to interference: don’t place it next to ferrous metals.

Unlike a physical compass, MyTrails can automatically correct the magnetic declination to provide a reading of the geographic rather than magnetic north.

If the compass seems to rotate in the opposite direction of your real movement when you, please try using the toggle reverse compass hidden option.

In addition to the compass, MyTrails can use the GPS-derived heading, with the following caveats: it’s only active above 1m/s (too imprecise at slower speeds), and the GPS heading indicates the direction of your travel, not the direction the phone’s screen is pointing.

Another method, described by Google.

MyTrails incorrectly computes distance and speed

MyTrails uses built-in Android methods to compute distances (and speeds). Unfortunately a small number of phones use a version of Android where a critical element of the platform (the Dalvik JIT compiler) suffers from a bug that causes these calculations to be severely incorrect.

This issue may also cause tracks to be displayed as thick lines across the screen.

In MyTrails 2.0 and later, please try to activate the Fallback distance calculation preference in Visual preferences.

In MyTrails 1.3.23 and later, you can work around this problem by using the toggle alternate distance hidden option.

My GPS stopped working

This article has been superseded by this new and expanded version.

GPS signal is tricky: it’s affected by the quality of the phone (the Samsung Galaxy S had notoriously bad GPS reception) and by the environment it’s in (indoors, urban canyons or dense forest reduce the quality of the GPS signal).

However, all other parameters being equal, if your GPS suddenly seems much worse (the GPS arrow no longer appears even if you’re moving faster than 5km/h, MyTrails no longer reports the speed, or the GPS signal quality meter remains red), you may need to reset your GPS.

MyTrails doesn’t do this for you, but you can install the GPS Test app, go into its settings and tap the Clear AGPS, then Update AGPS buttons.

One some devices, setting the Temporal resolution to a value greater than 1s (in MyTrails > Preferences > Behavior) causes the device to stop updating the GPS. This is a bug on your device, and you can work around it by setting the temporal resolution back to its default of 1s.

Some devices disable the GPS when the battery is low. Some Kyocera phones for example, disable it below 20% battery, without any visible indications. This may be configurable in the phone’s battery saving settings.

How can I plan a track?

In-application track planning is… planned for MyTrails 2.1. In the meantime, you can use the www.mytrails.com.au (My Trails) web site to plan a track on your computer, and import it into MyTrails. Note that the web site (My Trails) is developed and administered separately from the application (MyTrails, no space) and this web site.

  1. If you don’t already have an account on the My Trails web site, create one
  2. Log in to the My Trails site
  3. In the menu, select either Draw new trail (for freehand trail definitions, with the option to also snap to roads) or Navigate (to always snap the trail to what Google considers to be navigable)
  4. Create your trail and save it (on the Navigate page, you have the option of sending the trail via email directly to your device so you can open it straight into MyTrails)
    1. After saving the trail, you can view it in My Trails and email it to yourself.
  5. If you saved the trail rather than send it via email
    1. run MyTrails
    2. in Preferences > Accounts > My Trails, log in to your My Trails account
    3. open the Track Manager, then tap the Download button and select My Trails as the source
    4. the search function looks for tracks around a certain location (current GPS location, current map location or a waypoint): you may have to shift the map to the approximate location of the track first
  6. If you sent the trail via email, just open your email client on your device and open the attachment. MyTrails should be one of the applications that offers to open the document.

Why does my phone sometime stop recording the track?

In order to minimize battery impact on the device when recording a track while the screen is off, MyTrails uses the standard method offered by Android where the application is woken up by the OS only when a new track point is ready to be recorded.

The top reasons for this are:

  • Android Marshmallow and later have the ability to stop background apps (to save battery) when the device is not moving. This shouldn’t affect MyTrails, except some versions of Android do this incorrectly and also stop apps when you’re hiking. In these cases, allowing MyTrails to keep running in the background may help: Android Settings > Apps > gear icon (Configure apps) > Battery optimization > All apps > MyTrails > Don’t optimize. Because this is a bit convoluted, I made short animation below.
  • Similarly, some customized Android versions such as Samsung’s include an Energy Saver feature that disables background GPS. Please check that it is disabled (it sometimes becomes enabled after a system update).
  • For other devices, see more info compiled by another GPS tracker app, Strava.

Other things you can try:

  • On some phones, Android may occasionally lose track of this, and forget to wake MyTrails up. This would result on a track where no recording takes place  during some stretches where the screen was off. Because this is a platform bug and so far has been reported only once, I do not intend to add a potentially harmful work-around to MyTrails.
    You can implement the work-around on your phone by downloading Wake Lock from the Play Store and using it to keep a PARTIAL_WAKE_LOCK when running MyTrails.
  • Some phones may incorrectly stop recording the track when the Temporal resolution preference in MyTrails is set to something other than 1s.
  • You can even use the TRACKER_OPTIMIZATION hidden option (disable it).
  • System optimizers such as Juice Defender may also stop the GPS when the screen is turned off. Disabling that dubious optimization restores the recording functionality.
  • Some devices disable the GPS when the battery is low.
  • Some users have reported that using GPS Test to clear and reload the AGPS data may help restore GPS operation for all apps.

If you do experience this, please contact me or add a comment below so I can keep track of the affected users and phone models.