1-74 ANSWERS TO QUESTIONS Q1. THROUGH Q46. A-1. Modulation is the impressing of intelligence on a transmission medium. A-2. May be anything that transmits information, such as light, smoke, sound, wire lines, or radio-frequency waves. A-3. Mixing two frequencies across a nonlinear impedance. A-4. The process of recovering intelligence from a modulated carrier. A-5. The sine wave. A-6. To represent quantities that have both magnitude and direction. A-7. Sine != opposite side ÷ hypotenuse. A-8. e = E_{max}sine !. A-9. The value at any given point on the sine wave. A-10. Phase or phase angle. A-11. The rate at which the vector which is generating the sine wave is rotating. A-12. The elapsed time from the beginning of cycle to its completion. A-13. Wavelength = rate of travel period. A-14. Process of combining two signal frequencies in a nonlinear device. A-15. An impedance in which the resulting current is not proportional to the applied voltage. A-16. The display of electromagnetic energy that is arranged according to wavelength or frequency. A-17. At least two different frequencies applied to a nonlinear impedance. A-18. Any method of modulating an electromagnetic carrier frequency by varying its amplitude in accordance with the intelligence. A-19. A method of generating oscillations, a method of turning the oscillations on and off (keying), and an antenna to radiate the energy. A-20. Plate keying and cathode keying. A-21. Machine keying. A-22. A high degree of clarity even under severe noise conditions, long-range operation, and narrow bandwidth. A-23. Antenna-to-ground capacitance can cause the oscillator frequency to vary. A-24. To isolate the oscillator from the antenna and increase the amplitude of the rf oscillations to the required output level. A-25. To raise the low frequency of a stable oscillator to the vhf range.