Baseband Signals

• If signals are carried through wires, then so-called baseband signals may be chosen for modulation.
• Example: The simplest baseband signal format use a positive pulse to transmit a ``1'' and a negative pulse to transmit a ``0''.
• Then, the bit sequence 100110 would be transmitted as the signal in Figure 2.23.
• Since this signal set uses two signals that are negatives of each other it is sometimes called an antipodal signal set.
• The frequencies occupied by this signal set are near 0 Hz, or DC.
• This observation explains the term baseband

  

Figure 2.23: Baseband antipodal signals for transmitting bit sequence 100110.