Category: DATA TRANSMISSION

Modem Definition

Modem Definition: The term Modem Definition is an acronym for modulator-demodulator. The primary modem function is to convert digital data into an analog form which is suitable for transmission on common carrier circuits (example telephone lines). Modulation is the D/A conversion in which the digital data is placed on the transmission line by modulation of […]

Pulse Wave Code Format

Pulse Wave Code Format: There are many different code formats of pulse wave. The classification is based on three criteria, namely, form of information transmission, relation to zero level, and direction. Based on the form of information transmission, the format used can be any one of the following Full binary transmission, where both 0 and […]

Delta Modulation

Delta Modulation(DM): Delta modulation(DM) is process of modulation in which train of fixed width pulses is transmitted. Their polarity indicates whether the demodulator output should rise or fall at each pulse. The input is caused to rise or fall by a fixed step height at each pulse. Figure 18.20 shows the block diagram of a […]

Pulse Code Modulation

Pulse Code Modulation(PCM): Pulse Code Modulation(PCM) is different from the other forms of pulse modulation studied so far, PCM also uses sampling techniques, but it differs from the others in that it is a digital process. Instead of sending a pulse train capable of continuously varying one of the parameters, the PCM generator produces a […]

Pulse Position Modulation

Pulse Position Modulation(PPM): In this Pulse Position Modulation system, the amplitude and width of pulses is kept constant, while the position of each pulse, in relation to the position of a recurrent reference pulse, is varied by each instantaneous sampled value of the modulating wave. PPM may be obtained very simply from PWM, as shown […]

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