They are ALL line of sight. They ALL work on FM frequencies, therefore they can only operate on line of sight. Only AM frequencies can utilize the skip zone and bounce the signal off the ionosphere. Some, however, have a bit more power thus they can transmit a cleaner signal for a little farther distance without interference from small objects.

Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!

K+E=W (Knowledge Plus Experience = Wisdom.)