Abstract: A mount main body for a parapet-hanging-type antenna is provided with a vertical support column part (or VSC part) that vertically hangs down along an outer wall surface of parapet. The antenna is installed to VSC part so as not to protrude upward from the parapet. A horizontal support column part (or HSC part) that bends and horizontally extends in a direction orthogonal to the parapet is provided at an upper end of VSC part. The mount main body is provided with a cylinder holding HSC part such that HSC part is movable frontward/backward along a central axis thereof and is rotatable about the central axis. VSC part is made pullable to an inner wall side of the parapet by rotating HSC part about the central axis, and moving HSC part to the inner wall side of the parapet along the central axis.

Abstract: Provided is a face-to-face situation determination system in which a first beacon, which is a beacon carried by a first user, transmits a first signal including information identifying the first beacon. A second beacon, which is a beacon carried by a second user, upon receiving the first signal from the first beacon, transmits, toward a control device, a second signal including information identifying the first beacon, a first signal reception intensity, and information identifying the second beacon. The control device receives the second signal and, on the basis of the first signal reception strength included in the second signal, determines that the first user and the second user are facing each other if the first signal reception strength is greater than or equal to a first threshold value for a predetermined period or longer, and determines that the first user and the second user are facing one direction.