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Tuesday, October 4, 2011

CHAPTER 18 COMMUNICATIONS

CHAPTER 18
COMMUNICATIONS


1. The circuit that recovers the modulating signal form 455 kHz intermediate frequency.
Detector

2. Picks up all the radiated signals and feeds them into the RF amplifier.
Antenna

3. Provides a dc level out of the detector that is proportional to the strength of the received signal
Automatic Gain Control (AGC)

4. It brings the high frequency audio signals back to the proper amplitude relationship with the lower frequencies
De-emphasis Network

5. Removes any unwanted variations in the amplitude of the FM signal as it comes out of the IF amplifier and produces a constant amplitude FM output at the 10.7 MHz intermediate frequency
Limiter

6. A feedback circuit consisting of a phase detector, a low pass filter, and a VCO
PLL

7. The range of frequencies over which the PLL can acquire lock with an incoming signal
Capture range

8. The angle that defines whether a light ray will be reflected or refracted as it strikes a surface.
Critical Angle

9. A linear device that produces an output voltage proportional to the product of two input voltages
Four-quadrant Multiplier

10. An optical characteristic of a material that determines the critical angle.
Index of refraction

11. A device for down-converting frequencies in a receiver system
Mixer

12. The RF amplifier, mixer, and local oscillator are tuned simultaneously so that the LO frequency is always 455 kHz above the incoming RF signal frequency.
Gang tuning

13. A special case of the multiplier that is realized by simply applying the same voltage to both inputs by connecting the inputs together.
Squaring circuit

14. Reverse modulation
Demodulation

15. The process of varying a parameter of a carrier signal with an information signal.
Modulation

16. Most VCOs employed in PLLs operate in the principle of ____________ using the varactor diode as a voltage-variable capacitor.
Variable reactance

17. The range of frequencies over which the PLL can maintain lock
Lock range or tracking range

18. Independent of the bandwidth of the low-pass filter because when the PLL is in lock, the difference in frequency is zero or a very low instantaneous value the falls well within the bandwidth.
Hold-in range

19. Uses light pulses to transmit information through fiber-optic cables.
Fiber optics

20. Fiber optic cable in which the diameter of the core is fairly large relative to the diameter of the cladding.
Multimode step index

21. Fiber optic cable in which the diameter core is very small relative to the diameter of the cladding.
Single-mode step index

22. Fiber optic cable in which the diameter of the core is fairly large relative to the diameter of the cladding.
Multimode graded index

23. A linear multiplier can be used as a _________ detector
Phase

24. The output of a linear multiplier is the ________ of the inputs and a scale factor
Product

25. The IF in a standard AM receiver is
455 kHz

26. A form of amplitude modulation in which the carrier is suppressed
Balanced modulation

27. Another term for balanced modulation
Suppresses-carrier modulation

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