What do the sounds mean?

Tertill plays various sounds when it transitions from one mode to another.

• Ascending Three Tones - Powering on. Tertill will wait for the next button press and release to begin Patrolling.
• Descending Three Tones - Powering off, Tertill will not wake itself up. Off is the mode you want Tertill to be in for storage.
• Descending Two Tones - Entering Hold mode, Tertill will remain on but will not do any work. Tertill will wait for the next button press and release to begin Patrolling.
• Cavalry Charge - Entering Patrol mode, Tertill will begin weeding. Make sure the robot is in an appropriate place, e.g. not a table top or an accessible cliff.
• Lullaby - Entering AutoCharge mode. Tertill will wake itself up periodically and check the battery state. When Tertill sees its battery adequately charged it will begin Patrolling.
• French Police Siren - Tertill has encountered a problem and cannot continue without help. It will power off automatically after sounding the siren.