Modulated spread spectrum in RF identification systems method
US5539775A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 17, 1993 |
| Grant date | Jul 23, 1996 |
| Priority date | — |
| Expiry date | Mar 17, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/707
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for RF communication between transceivers in a radio frequency identification system that improves range, decreases multipath errors and reduces the effect of outside RF source interference by employing spread spectrum techniques. By pulse amplitude modulating a spread spectrum carrier before transmission, the receiver can be designed for simple AM detection, suppressing the spread spectrum carrier and recovering the original data pulse code waveform. The data pulse code waveform has been further encrypted by a direct sequence pseudo-random pulse code. This additional conditioning prevents the original carrier frequency components from appearing in the broadcast power spectra and provides the basis for the clock and transmit carrier of the transceiver aboard an RFID tag. Other advantages include high resolution ranging, hiding transmissions from eavesdroppers, and selective addressing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.