Unit 1 Exercise 1
An analog signal is any continuous signal which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal.
A digital signal is a physical signal that is a representation of a sequence of discrete values (a quantified discrete-time signal), for example of an arbitrary bit stream, or of a digitized (sampled and analog-to-digital converted) analog signal.
Half-duplex data transmission means that data can be transmitted in both directions on a signal carrier, but not at the same time.
Full-duplex data transmission means that data can be transmitted in both directions on a signal carrier at the same time.
A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring
Long-distance telephone company, such as MCI (before its absorption by Verizon), Sprint and the former AT&T Corporation (before its merger with SBC in 2005). In the United States, it is defined as any carrier that provides inter-LATA communication, where a LATA is a local access and transport area.
Long Distance central office, central office (CO) is an office in a locality to which subscriber home and business lines are connected on what is called a local loop.
Tandem, telephone switch is a U.S. telephone company central office telephone exchange used to interconnect local exchange carrier offices for long distance communications in the public switched telephone network.