Electronic Communications Systems
ELECTRONIC COMMUNICATIONS SYSTEMS
Wayne Tomasi, 5th edition
Introduction to Electronic Communications
Electricity began in 1837 when Samuel Finley Breese Morse invented the first workable telegraph.
In 1894, Marchese Guglielmo Marconi successfully transmitted the first wireless radio signals through Earth’s atmosphere.
In 1906, Lee DeForest invented the triode vacuum tube.
Commercial radio broadcasting began in 1920 when radio station KDKA began broadcasting amplitude-modulated (AM) signals out of Pittsburgh, Pennsylvania.
In 1931, Major Edwin Howard Armstrong patented frequency modulation (FM).
Commercial broadcasting of monophonic FM began in 1935.
The decibel (abbreviated dB) is a logarithmic unit that can be used to measure ratios of virtually anything.
Zero dB-SPL is the threshold of hearing.
The threshold of pain is approximately 120 dB-SPL.
dB represents the ratio of the signal level at one point in a circuit to the signal level at another point in a circuit.
A power loss is sometimes called attenuation.
dBm is a unit of measurement used to indicate the ratio of a power level with respect to a fixed reference level.
When power levels are given in watts and power gains are given as absolute values, the output power is determined by simply multiplying the input power times the power gain.
Modulation is simply the process of changing one or more properties of the analog carrier in proportion with the information signal.
Digital transmission is a true digital system where digital pulses are transferred between two or more points in a communications system.
Digital radio is the transmittal of digitally modulated analog carriers between two or more points in a communications system.
If the information is analog and the amplitude (V) of the carrier is varied proportional to the information signal, amplitude modulation (AM) is produced. If the frequency (f) is varied proportional to the information signal,
Wayne Tomasi, 5th edition
Introduction to Electronic Communications
Electricity began in 1837 when Samuel Finley Breese Morse invented the first workable telegraph.
In 1894, Marchese Guglielmo Marconi successfully transmitted the first wireless radio signals through Earth’s atmosphere.
In 1906, Lee DeForest invented the triode vacuum tube.
Commercial radio broadcasting began in 1920 when radio station KDKA began broadcasting amplitude-modulated (AM) signals out of Pittsburgh, Pennsylvania.
In 1931, Major Edwin Howard Armstrong patented frequency modulation (FM).
Commercial broadcasting of monophonic FM began in 1935.
The decibel (abbreviated dB) is a logarithmic unit that can be used to measure ratios of virtually anything.
Zero dB-SPL is the threshold of hearing.
The threshold of pain is approximately 120 dB-SPL.
dB represents the ratio of the signal level at one point in a circuit to the signal level at another point in a circuit.
A power loss is sometimes called attenuation.
dBm is a unit of measurement used to indicate the ratio of a power level with respect to a fixed reference level.
When power levels are given in watts and power gains are given as absolute values, the output power is determined by simply multiplying the input power times the power gain.
Modulation is simply the process of changing one or more properties of the analog carrier in proportion with the information signal.
Digital transmission is a true digital system where digital pulses are transferred between two or more points in a communications system.
Digital radio is the transmittal of digitally modulated analog carriers between two or more points in a communications system.
If the information is analog and the amplitude (V) of the carrier is varied proportional to the information signal, amplitude modulation (AM) is produced. If the frequency (f) is varied proportional to the information signal,