Range estimation using floating reference points
Spread spectrum communication system
Spread spectrum communication device
Spread spectrum transmitter for degrading spread spectrum feature detectors
Modulation and demodulation system for spread spectrum transmission Patent #: 5170411
ApplicationNo. 032384 filed on 03/17/1993
US Classes:375/145, Having specific signaling for code synchronization370/342, Combining or distributing information via code word channels using multiple access techniques (e.g., CDMA)375/367Pseudo noise
ExaminersPrimary: Chin, Stephen
Assistant: Vo, Don N.
Attorney, Agent or Firm
International ClassH04B 001/69
AbstractA 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.
Field of SearchPseudo noise