| 摘要 |
<p>A personal emergency communicator (1) able to be readily carried by an underground miner, generates a signal transmitted through the ground via a ground antenna where it can be intercepted and received by a through the ground receiver equipped with an equivalent antenna. In one form, the ground antenna comprises an earth current antenna provided by ground engagement spikes (6) receiving the signal from the communicator (1) via wires (5). The signal is preferably digitally generated from a keypad (3), shown in a screen (4), and the device may be powered by a battery or a crank and generator assembly (2). In an alterative form, the ground antennae are provided in the form of a loop antennae.</p> |
