초록 ▼

An apparatus for detecting bodies in motion on the ground of a protected area, particularly for military use and the like, wherein, by means of an antenna buried and shielded from the air, an electromagnetic signal in the range of radio frequency is radiated into the ground. Receiver means comprisin

An apparatus for detecting bodies in motion on the ground of a protected area, particularly for military use and the like, wherein, by means of an antenna buried and shielded from the air, an electromagnetic signal in the range of radio frequency is radiated into the ground. Receiver means comprising means for detecting variations of the signal intensity are placed at a known distance from the receiving antenna. The intensity variation is dependent on the presence of bodies in motion within the range of action of the apparatus.

대표청구항 ▼

Apparatus for detecting a body in motion on the ground of a protected area, comprising: (a) transmitter means for transmitting radio frequency elctromagnetic signals including at least a fully buried transmitting antenna, shielded for inhibiting a radio frequency radiation in the air; (b) receiver m

Apparatus for detecting a body in motion on the ground of a protected area, comprising: (a) transmitter means for transmitting radio frequency elctromagnetic signals including at least a fully buried transmitting antenna, shielded for inhibiting a radio frequency radiation in the air; (b) receiver means for receiving said signals including at least a receiving antenna fully shielded to the air and placed at a known distance from said transmitter means; (c) automatic gain control means coupled to said receiver means for adjusting the sensitivity thereof to an average level of an input signal; (d) detector means for detecting amplitude variations of the input signal, for driving said automatic gain control means and for discriminating fast variations due to a body in motion on the ground from slow variations due to physical effects in the ground.