| US 7,385,513 B2 | ||
| Device for monitoring and measuring distance | ||
| A. Wallace Everest, 305 Island Dr., Melbourne Beach, Fla. 32951 (US); Mark B. Godfrey, 5335 Pina Vista, Melbourne, Fla. 32934 (US); and Mark A. Voves, 24861 110th St., Cresco, Iowa 52136 (US) | ||
| Filed on Jan. 27, 2005, as Appl. No. 11/44,104. | ||
| Prior Publication US 2006/0176178 A1, Aug. 10, 2006 | ||
| Int. Cl. G08B 23/00 (2006.01); G01F 17/00 (2006.01); G01S 13/08 (2006.01) | ||
| U.S. Cl. 340—573.1 [701/301; 342/118; 342/134; 342/135] | 4 Claims |
| 1. A device for monitoring distance comprising:
an interrogator;
a transponder in wireless communication with the interrogator, the transponder having a signaling device;
the interrogator having a microprocessor that determines distance between the interrogator and the transponder; and
the interrogator sending a command signal to the transponder that activates the signaling device when the determined distance
nears a pre-determined distance;
wherein the interrogator sends an encoded signal to the transponder and determines the distance to the transponder based on
the phase delay of the transponder's response;
wherein a digital spreading sequence is used with the interrogator to derive a distance measurement.
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