Spread spectrum apparatus

摘要

For use in a spread spectrum communication system there is provided in an embodiment of the invention a spread spectrum transmitter which uses a voltage controlled oscillator (VCO) for generating a carrier signal wherein the frequency of the oscillator is controlled by the output of a correlation code generator and data generator coupled to a varactor in the oscillator. The use of a VCO eliminates the need for sidelobes associated with mixers. In another embodiment the separation of the output of the correlation code generator and data generator coupled to the varactor and the output of a phase detector coupled to the varactor simplifies tuning of the transmitter and in another embodiment the use of a high gain differential amplifier to couple the output of the correlation code generator and data generator to the varactor eliminates tuning the transmitter. In each of the above embodiments, modulating the VCO with a special code as the VCO is coming up to speed, reduces interference with other narrowband receivers. In a spread spectrum receiver there is provided a separate narrow band channel for locking the receiver to a signal received from a transmitter and a separate channel for recovering data from the received signal. The use of the separate channels provide a high interference immunity as well as easier and faster locking and data recovery.