I think i'm read 3 things here:
- "personall alarms", loud and annoying alarm thingy. to 'scare' people off.
- Avalanch beacons, which transmits radio frequency, which other beacons can read in their 'find' mode. Depending on the model it will show how far and which direction another beacon is. Used by skieers/mountainers to be able to be found and to rescue others. No rescue will be alerted by these beacons, just make you easier to be found.
- Personal Locator Beacons, which uses satelites to alert emergency services.