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Navigation Voice Prompt Triggering

(Compiled by Hardy 2013, last reviewed 2021-01)

Principle​

  • Far-out prompts are simply triggered based on a lead distance threshold, derived by converting a meaningful lead time via the {% data variables.android-values.default_speed_setting_title %} of the profile.
  • Users can change the {% data variables.android-values.default_speed_setting_title %} of the profile and it will affect the trigger distance for voice prompts.
  • Note: The {% data variables.android-values.default_speed_setting_title %} also affects the calculated route time
  • Another way to change the voice prompt timing is to configure setting {% data variables.android-values.arrival_distance %}. Check column Arrival setting further below to see which voice prompts will be affected. The trigger distance will be multiplied by the following factor
{% data variables.android-values.arrival_distance %}Distance multiplier
{% data variables.android-values.arrival_distance_factor_early %}1.5
{% data variables.android-values.arrival_distance_factor_normally %}1
{% data variables.android-values.arrival_distance_factor_late %}0.5
{% data variables.android-values.arrival_distance_factor_at_last %}0.25
  • For close prompts, both a distance threshold and a time threshold are used (see column Time threshold below). The time threshold ensures that the announcements are triggered early enough even if your current speed exceeds the {% data variables.android-values.default_speed_setting_title %}.
  • In addition, there is a user-configurable overall VOICE_PROMPT_DELAY, particularly needed for output type Phone call audio, where we emulate a call to a car stereo which comes with a noticeable delay. (Also all distances to be used in the prompts anticipate VOICE_PROMPT_DELAY!)
  • We mute prompts immediately once they appear to refer actions already passed, or if your direction of travel seems no in line with a current route.

Base Profile Default Speeds​

While these are now also user-adjustable, the defaults are

  • Driving: 12.5 m/s (45 km/h)
  • Cycling: 2.78 m/s (10 km/h)
  • Walking: 1.11 m/s (4 km/h)
  • Boat: 1.39 m/s (5 km/h)
  • Ski: 1.39 m/s (5 km/h)
  • Aircraft: 40 m/s (144 km/h)

Trigger Behavior​

Prompt typeTrigger time (sec)Trigger distance (m)Time threshold usedArrival settingComment
Turn nowDriving: 7 s Cycling: 3.2 s Walking: 2 sDriving: 45 m Cycling: 10 (12) m Walking: 4 (12) m✔️✔️Dist for 3.6 s, min 12 m Time = max(8, sqrt(speed * 3.6))
Turn in X m22 sDriving: 275 m Cycling: 61 m Walking: 24 m✔️Skipped if less 15 seconds before turn
Prepare to turn in X m115 sDriving: 1438 m Cycling: 319 m Walking: -Skipped if less 150 meters before "Turn in" Skipped if speed < 8 km/h
Long Prepare to turn in X m300 sDriving: - Cycling: - Walking: -Skipped if default speed < 108 km/h
Go Ahead>300 sDriving: 3750 m Cycling: 833 m Walking: 333 mafter route calculation if no other prompt is due, or after a turn if next turn is more than Long Prepare
Arrive at destination or intermediate5 sDriving: 63 m Cycling: 14 m Walking: 6 (12) m✔️Min 12 m
Approaching waypoint / favorite / POI60 sDriving: 750 m Cycling: 167 m Walking: 67 m✔️✔️Limit to max 1 pnt at a time
Passing waypoint / favorite / POI15 sDriving: 188 m Cycling: 42 m Walking: 17 m✔️✔️Limit to max 3 pnts at a time
Standard alarm12 sDriving: 150 m Cycling: 33 m Walking: 13 m✔️✔️
Close alarm7 sDriving: 88 m Cycling: 20 m Walking: 8 m✔️✔️Traffic calming uses pass alarm for approach prompt and filters duplicate in this radius
Off-route announcement20 sDriving: 250 m Cycling: 56 m Walking: 22 m✔️Could be disabled
GPS signal lost20 s-Is played after GPS signal has been lost for continuous 20 s and this was not caused by user action.