Broadband signals move across the medium in the form of continuous electromagnetic or optical waves, rather than in discrete pulses. Many electronic systems, particularly those dealing with low signal amplitudes or very high frequency required analog approach. The dominance of digital circuits actually increased the amount of analog electronics in existence. Nowdays, most electronic systems contain both analog and digital (called Mixed-signal, also Mixed-signal SoC (System on Chip)). Lots of most challenging design problems are analog. A good analog circuit designers are scarce very well compensated, gain lots of respect, regarded as “artists” because of the “creative” circuit design they do. Fax machines, radios, telephones, and many more all use an analog system.
Broadband transmission systems use a different kind of signaling to transmit information across a cable. Instead of digital pulses, broadband systems use analog techniques to encode information across a continuous range of values. Analog circuits that connect to, create and manipulate arbitrary electrical signals. On broadband systems, signal flow is one-way only, which makes two channels necessary for computers to send and receive data. Multiple analog transmission channels may operate on a single broadband cable. This capability permits your cable television company to send a large number of television channels across a single wire.
The analog system is starting to be out-dated and the cost for switching to digital can be expensive. The FCC decided to push back the transition from analog to digital until June 12th to give people more time to purchase a converter box or buy a HDTV.