Crash site locator beacon

Abstract

The Locator Beacon (LB) is an 18 inch diameter hemispherical unit designed to be air dropped via parachute from a search aircraft near an aircraft crash site. The LB is self uprighting when it lands on the ground and its antenna is always oriented for maximum efficiency. When activated, the LB sends out a radio frequency signal on 121.6 Mhz and 243.2 Mhz, this signal can be tracked by aircraft or by ground parties equipped with directional locating equipment. The LB also contains a strobe light beacon to aid in visual acquisition of the unit. The LB remains in the active (broadcast) mode for approximately 20 minutes before resetting itself to the listening mode. External VHF activation of the LB repeats the LB broadcast and strobe light cycle for another 20 minutes.

We claim: 
     
       1. A radio beacon unit comprising: radio electronics contained in a housing and an external antenna designed to be air dropped via parachute; wherein the housing comprises: a top portion having a flat upper surface, and a bottom portion having a hemispherical lower surface, with said antenna mounted on said upper surface perpendicular thereto, means for providing a relatively low center of gravity, so that when the beacon unit is in any position on the hemispherical lower surface the beacon unit will upright itself so that the antenna is oriented for maximum efficiency;   wherein said radio beacon unit is a locator beacon which has mounted inside said housing a first subunit comprising a receiver and a power relay, a second subunit comprising a transmitter for sending radio signals on given frequencies so that the radio beacon unit can be tracked with directional locating equipment, a third subunit comprising an RF antenna switch which normally connects the antenna to the receiver, and a fourth subunit comprising a main battery pack;   a mode switch mounted on said upper surface, said mode switch having an OFF position in which the main battery pack is disconnected, and an ACTIVE position in which the main battery pack is connected to the receiver and to a first terminal of the power relay in the first subunit;   wherein the first subunit includes means for detecting a given number of RF pulses received via said antenna and in response thereto activating the power relay to extend the connection of the main battery pack from said first terminal to the second and third subunits, so the transmitter and the RF antenna switch are activated to transmit a beacon signal and to disconnect the receiver from the antenna;   wherein the first subunit further includes timing means to deactivate the power relay after a given period of time, to thereby disconnect the transmitter and RF antenna switch from the main battery pack, and to reconnect the receiver via the RF antenna switch to the antenna so that further RF pulses can be detected.   
     
     
       2. A radio beacon unit according to claim 1, wherein said top portion includes a sloping surface connecting the upper surface to an outer rim at the top of the bottom portion; and wherein the radio beacon unit further includes a strobe light mounted on said upper surface, a strobe-light battery pack, wherein said mode switch has first and second poles, with the first pole in the ACTIVE position providing said connection of the main battery pack to the receiver and to said first terminal, and the second pole connecting the strobe-light battery pack to a second terminal of the power relay, so that when the power relay is activated the strobe light is energized.