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BPSK Direct Sequence Spread Spectrum
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BPSK DS-SS signals
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Spectrum
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QPSK DS-SS
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Dual Channel QPSK DS-SS
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MSK DS-SS
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MSK DS-SS
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MSK DS-SS
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Frequency Hopping Spread Spectrum
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Spectrum
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Slow FH-SS
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Fast FH-SS
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Hybrid DS FH SS
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Complex envelope model
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Complex-envelope of digital modulations
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Spreading sequence 1. How to choose a spreading sequence?
2. How to generate a spreading sequence? 3. How to choose and generate a set of sequences when more than one sequences are needed, for example, in CDMA systems?
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Some specification 1. Sequence elements should behave like iid random variables, i.e., the sequence should be pseudo-random. 2. It should be easy to distinguish a spreading signal from a time-shifted version of it. 3. It should be easy to distinguish a spreading signal from other spreading signals, including time-shifted versions of them, in the set. 4. It should be easy for the transmitter and the intended receiver to generate the spreading sequence. 5. It should be difficult for any unintended receiver to acquire and regenerate the spreading sequence.
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Cross correlation with modulation
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Binary Linear Feedback Shift Register
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Binary shift register sequence
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maximal-length sequence (m-sequence)
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m-sequence
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m-sequence
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Maximal connected sets
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Gold sequence
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Choice of sequence
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Initial code acquisition
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Radiometer
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Serial Search
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Parallel Search
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Multidwell Search
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