To indicate that the air raid alarm is released, what is the law of the siren?
3. Release the alarm: use: to lift the alarm is in the air raid or war temporarily relieved. Tweets: continuous light for 3 minutes.
2. Air raid alarm: Uses: Air raids are issued when the enemy is going to attack us. Call mode: Ming 6 seconds, stop 6 seconds, repeated 15 times for a cycle. Time is 3 minutes.
1. Pre-alarm: use: pre-alarm is in the enemy attack on our side when there is a warning, requiring personnel to start evacuation. Call mode: Ming 36 seconds, stop 24 seconds, repeated 3 times for a cycle, time for 3 minutes.
