Pulse or digital communications – Spread spectrum – Chirp
Reexamination Certificate
2005-09-06
2005-09-06
Liu, Shuwang (Department: 2634)
Pulse or digital communications
Spread spectrum
Chirp
C375S130000, C375S146000, C375S152000, C370S307000, C370S441000
Reexamination Certificate
active
06940893
ABSTRACT:
This invention modulates data onto a radio channel in such a way that the deleterious effects of the channel are reduced. This is accomplished in three steps: first, the information signal is modulated using a phase-differential modulation scheme. Second, the modulated signal is spread in both time and frequency by passing it through a dispersive filter, transmitting it through the channel, and removing the spreading using a dispersive filter in the receiver with the opposite characteristics of the filter in the transmitter. The third step, after demodulation, is to pass the signal through a low-pass filter to gather up the signal energy which has been dispersed by the channel. All three of these steps can be implemented with simple functional blocks, making this system very inexpensive to implement. Also included are two methods for enhancing the data throughput of the basic system, making it more bandwidth efficient.
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Nichols Spence T.
Pinkney John A.
Christensen O'Connor Johnson & Kindness PLLC
Liu Shuwang
Telecommunications Research Laboratories
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