• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
Appendix I - Continued - 14184_192
Appendix I - Continued - 14184_194

Neets Module 12-Modulation Principles
Page Navigation
  174    175    176    177    178  179  180    181    182    183    184  
AI-5 PHASE or PHASE ANGLE—The angle that exists between the starting point of a vector and its position at that instant. An indication of how much of a cycle has been completed at any given instant in time. PHASE-SHIFT DISCRIMINATOR—See Foster-Seeley discriminator. PHASE-SHIFT KEYING—Similar to ON-OFF cw keying in AM systems and frequency-shift keying in fm systems. Each time a mark is received, the phase is reversed. No phase reversal takes place when a space is received. PLATE KEYING—A keying system in which the plate supply is interrupted. PLATE MODULATOR—An electron-tube modulator in which the modulating voltage is applied to the plate circuit of the tube. POSITIVE ALTERNATION—That part of a sine wave that is above the reference line. PULSE DURATION (pd)—The period of time during which a pulse is present. PULSE MODULATION—A form of modulation in which one of the characteristics of a pulse train is varied. PULSE WIDTH (pw)—The period of time during which a pulse occurs. PULSE—A surge of plate current that occurs when a tube is momentarily saturated. PULSE-AMPLITUDE MODULATION (pam)—Pulse modulation in which the amplitude of the pulses is varied by the modulating signal. PULSE-CODE MODULATION (pcm)—A modulation system in which the standard values of a quantized wave are indicated by a series of coded pulses. PULSE-DURATION MODULATION (pdm)—Pulse modulation in which the time duration of the pulses is changed by the modulating signal. PULSE-FORMING NETWORK (pfn)—A circuit used for storing energy. Essentially a short section of artificial transmission line. PULSE-FREQUENCY MODULATION (pfm)—Pulse modulation in which the modulating voltage varies the repetition rate of a pulse train. PULSE-POSITION MODULATION (ppm)—Pulse modulation in which the position of the pulses is varied by the modulating voltage. PULSE-REPETITION FREQUENCY—The rate, in pulses per second, at which the pulses occur. PULSE-REPETITION TIME (prt)—The total time for one complete pulse cycle of operation (rest time plus pulse width). PULSE-TIME MODULATION (ptm)—Pulse modulation that varies one of the time characteristics of a pulse train (pwm, pdm, ppm, and pfm). PULSE-WIDTH MODULATION (pwm)—Pulse modulation in which the duration of the pulses is varied by the modulating voltage.






Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.