Modulation field detection, method and structure
US5448242A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1994 |
| Grant date | Sep 5, 1995 |
| Priority date | — |
| Expiry date | Apr 26, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/767
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Disclosed is a system and method which protects a transponder or tag (14) from being enabled or awakened by spurious RF energy. A modulation detector (64) is provided which detects a modulation signal that is superimposed upon an RF modulation from an interrogator (12). Preferably this superimposed modulation is of a low frequency, below those typically existing as Electro-Magnetic Interference (EMI), such that the transponder (14) is less likely to be erroneously activated by an unintended RF signal. Upon reception of an RF interrogation having the proper modulation superimposed thereupon, the modulation detector (64) is operable to awaken other circuitry within the transponder (14) such that the transponder (14) is then operable to communicate with the interrogator (12).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.