- Jan 1, 1970
John said:Hi all,
I have a question about modulating one signal onto another. Take for
example a sine wave and an audio signal. They are easy to combine and
separate. But is this also possible with a random noise signal and an
audio wave. Or are there restrictions to what signals can and can not
be used as a carrier wave for other signals. And if so how are they
Thanks for any help on this.
In direct spread spectrum (DSS) a digitally encoded message is mixed with a
pseudo-random sequence (noise) using an XOR gate. The XOR operation is
reversible, and the intelligence is extracted at the receiving end by
re-generating (and synchronising) an identical pseudo-random sequence, and
XORing it with the signal. Without the correct correlated sequence to
de-spread it, the transmission is just broadband noise.