Electronic Communications

Electronic Communications

• Electronic communications involves the transmission, reception, and processing of information using electronic circuits.
• Information is defined as knowledge or intelligence that is communicated between two or more points.

Digital Modulation

• Digital modulation is the transmission of digitally modulated analog signals (carriers) between two or more points in a communications system.
• Digital modulation is sometimes called digital radio because it can be propagated through Earth’s atmosphere and used in wireless communications systems.

Types of Digital Modulation

• Amplitude Shift Keying (ASK): the amplitude of the carrier is varied proportional to the information signal.
• Frequency Shift Keying (FSK): the frequency of the carrier is varied proportional to the information signal.
• Phase Shift Keying (PSK): the phase of the carrier is varied proportional to the information signal.
• Quadrature Amplitude Modulation (QAM): both the amplitude and the phase are varied proportional to the information signal.

Information Theory

• Information theory is a highly theoretical study of the efficient use of bandwidth to propagate information through electronic communications systems.
• Information capacity is a measure of how much information can be propagated through a communications system and is a function of bandwidth and transmission time.

Digital Symbols

• The most basic digital symbol used to represent information is the binary digit, or bit.
• Bit rate is the number of bits transmitted during one second and is expressed in bits per second (bps).
• M-ary is a term that represents a digit that corresponds to the number of conditions, levels, or combinations possible for a given number of binary variables.

Baud and Bit Rate

• Baud is a unit of transmission rate, modulation rate, or symbol rate, and is often used interchangeably with symbols per second.
• Baud is not the same as bit rate, as the baud of a data communications system may be less than the bit rate.
• In binary systems, baud and bits per second are equal, but in higher-level systems, bps is always greater than baud.

Minimum Nyquist Bandwidth

• The minimum theoretical bandwidth necessary to propagate a signal is called the minimum Nyquist bandwidth or minimum Nyquist frequency.
• fb = 2 B, where fb is the bit rate in bps and B is the ideal Nyquist bandwidth.

Amplitude-Shift Keying (ASK)

• Amplitude-Shift Keying (ASK) is the simplest digital modulation technique.
• In ASK, a binary information signal directly modulates the amplitude of an analog carrier.
• ASK is sometimes called digital amplitude modulation (DAM) or on-off keying (OOK).

This quiz covers the basics of electronic communications, including the transmission, reception, and processing of information using electronic circuits. It also explores digital modulation and its role in communications systems.