Patent ID: 6128332
Filing Date: 2000-10-03
Classification: H04B,H04J

Abstract:
A spread spectrum transmitter employing composite spreading codes, comprising:a baseband modulating means for modulating an input digital signal of a predetermined bit rate into at least one baseband signal of a fixed symbol period;clock signal generating means for generating a first clock signal of a predetermined first clock period and a second clock signal of a clock period N times longer than said first clock period, said N being a value larger than 1 but smaller than 8;a short code generating means for repeatedly generating at least one short code of a chip period of the same length as that of said first clock period and of a first repetition period in synchronization with said first clock signal for each chip, said first repetition period of said short code being set equal to said symbol period;a long code generator for repeatedly generating a long code having a chip period longer than the chip period of said short code and longer than a predetermined delay time of a propagation path and having a second repetition period in longer than said first repetition period, synchronization with said second clock signal for each chip, the number of chips of said long code being greater than that of said short code;spreading means for spreading said baseband modulated signal by said at least one short code and said long code to generate a spread baseband modulated signal; anda transmitting part for modulating a carrier signal by said spread baseband modulated signal and for transmitting said modulated carrier signal.