This one is a better description, you disable the locator beacon and leave the GPS distress transmission on for covert use or if downed over hostile territory. It uses a modulation system that’s really hard to detect, because it’s modulating an encrypted satellite signal and sending it back, tracking that is hard, but they’re modulating their GPS location and other data onto the signal so if you have the key it’s obvious.
They actually have location beacons but they are meant to be hard to detect, and mostly signal satellites: https://taskaero.com/task_products/survival-locator-beacon/
Not easy to track at all, irregular timing and frequencies and low power.
http://www.wilkoaero.com/uploaded/product/124/catalog_e716f7235e0e04a7b28a3a4cc359d9c30.pdf
This one is a better description, you disable the locator beacon and leave the GPS distress transmission on for covert use or if downed over hostile territory. It uses a modulation system that’s really hard to detect, because it’s modulating an encrypted satellite signal and sending it back, tracking that is hard, but they’re modulating their GPS location and other data onto the signal so if you have the key it’s obvious.