Distance determination and alarm system

Details Distance determination and alarm system Distance determination and alarm system

1995-12-12

1997-08-26

Swann, Glen

Communications: electrical

Condition responsive indicating system

Specific condition

340539, 342127, G08B 2100

Patent

active

056614608

ABSTRACT:
A system has a plurality of transceiver units, including a parent unit and one or more portable and wearable child units, for generating an alarm when a child transceiver unit is more than a predetermined distance away from a parent transceiver unit. The distance is determined by the difference in the phase of a reference signal from the time it is transmitted on an rf signal by a parent unit, received and retransmitted by a child unit, and then received again by the parent unit.

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