December 17, 2021

In the direct sequence spread spectrum modulation, the pseudo-noise sequence of large bandwidth is multiplied with the narrowband data signal. Therefore the output signal is spreaded over the complete output bandwidth at every instant. The ability to overcome jamming is determined by the processing gain of system. We know that processing Gain = N; length

In the previous subsection we studied the baseband transmission of direct sequence spread spectrum modulated signal. For long distance transmission or transmission over a satellite channel, BPSK can be used. DS-SS BPSK Transmitter Fig. shows the transmitter of Direct Sequence Spread Spectrum with BPSK. The multiplier multiplies the two signals b(t) and c(t). The output

The pseudo-noise (or pseudo random) sequence is a noise like high frequency signal. This signal is binary in nature. Thus it looks like pulses. The sequence is not completely random but it is generated by a well defined logic. The same logic is used at transmitter and receiver. Since the sequence is generated by a

Necessity of Secure Communication There are some applications where it is necessary for the system to resist external interference and to make it difficult for unauthorized receivers to receive the message being transmitted. This type of communication is called secure communication such that noise interference and unwanted receivers should not detect the message. Such communication