EXPANDED SPECTRUM

This technique allows transmitting both analog and digital signals, using an analog signal. It consists of expanding the information of the signal over a bandwidth.

There are two types of spread spectrum:

1. Jump in Frequency

2. Direct Sequence Spread Spectrum

1. Jump in Frequency.

In this scheme the signal is broadcast over a series of apparently random radio frequencies. The receiver will pick up the message by hopping from frequency to frequency synchronously with the transmitter. Unauthorized receivers will hear an unintelligible signal.

2. Direct Sequence Spread Spectrum.

In this scheme, each bit of the original signal is represented by several bits of the transmitted signal, this procedure is called code sharing.