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Abstract

A direct sequence spread spectrum (DSSS) radio communication system of the present invention comprises a transmitter and a matching receiver. The transmitter includes a pseudorandom number (PRN) code generator, a chip clock generator and a 16.times. clock generator that runs at sixteen times the chip clock rate. The output of the PRN code generator and chip clock generator are exclusive-OR'ed to derive a Manchester encoding of the DSSS spreading code. A tri-state buffer is used to deliver such Manchester encoded DSSS spreading code to a mixer to spread a biphase shift keyed (BPSK) radio carrier before being transmitted. The tri-state buffer can be a part of the exclusive-OR logic and is connected to place its output in a high impedance state one sixteenth of every chip clock period. This provides for a suppression of the spurious sidebands that otherwise limit adjacent channel packing.

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First Claim