中文说明：这个
English Description：
This is probably the most widely recognized form of spread spectrum. The DSSS process is performed by effectively multiplying an RF carrier and a pseudo-noise (PN) digital signal. First the PN code is modulated onto the information signal using one of several modulation techniques (eg. BPSK, QPSK, etc ). Then, a doubly balanced mixer is used to multiply the RF carrier and PN modulated information signal. This process causes the RF signal to be replaced with a very wide bandwidth signal with the spectral equivalent of a noise signal. The demodulation process (for the BPSK case) is then simply the mixing/multiplying of the same PN modulated carrier with the incoming RF signal. The output is a signal that is a maximum when the two signals exactly equal one another or are "correlated". The correlated signal is then filtered and sent to a