ВУЗ: Казахская Национальная Академия Искусств им. Т. Жургенова
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Radio Receivers 12-3
Doppler Effect
12-34
Transfer Function
12-37
Time Response of Channel Impulse Response & Transfer Function
12-39
References
12-40
Chapter 12.3: AM and FM Receivers
12-41
Introduction
12-41
Superheterodyne Receiver
12-41
Radio Wave Propagation
12-43
AM Band Propagation
12-43
FM Band Propagation
12-43
Radio Receivers
12-44
Antenna Systems
12-45
Antenna Coupling Network
12-45
Whip Antenna
12-45
Loop Antenna
12-46
Filter Types
12-47
LC Filter
12-48
Quartz Crystal Filter
12-48
Monolithic Quartz Filter
12-48
Ceramic Filter
12-49
RF Amplifier and AGC
12-49
The AGC Loop
12-50
Mixer
12-51
Passive Mixer
12-52
Active Mixer
12-53
Local Oscillator
12-54
PLL Synthesizer
12-55
Frequency Divider
12-56
Variable-Frequency Oscillator
12-56
Diode Switching
12-57
Crystal-Controlled Oscillator
12-59
AM-FM Demodulation
12-59
AM Demodulation
12-62
FM Demodulation
12-64
Amplitude Limiter
12-66
Stereo Systems
12-68
FM Stereo
12-68
Generating the Stereo Signal
12-69
Decoding the Stereo Signal
12-70
AM Stereo
12-71
Decoding the C-QUAM Signal
12-71
References
12-73
Bibliography
12-73
Chapter 12.4: Stereo Television
12-75
Introduction
12-75
Audio Chain
12-75
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Radio Receivers
12-4 Section Twelve
Stereo Generator
12-75
Subchannel Filters
12-78
Audio System Specifications and Performance Objectives
12-78
Frequency Response
12-80
Signal-to-Noise Ratio (SNR)
12-80
Total Harmonic Distortion (THD)
12-80
Intermodulation Distortion (IMD)
12-80
Separation
12-81
Headroom
12-81
Channel-to-Channel Amplitude and Phase Tracking
12-81
Stereo Generator Specifications and Performance Objectives
12-81
Separation
12-81
Linear Crosstalk
12-82
Nonlinear Crosstalk
12-82
Spurious Suppression
12-82
Deviation Calibration
12-83
Composite STL Specifications and Performance Objectives
12-83
Signal-to-Noise Ratio
12-83
Distortion
12-83
Amplitude Stability
12-84
Aural Exciter Specifications and Performance Objectives
12-84
Signal-to-Noise Ratio
12-84
Amplitude Stability
12-84
References
12-84
Reference Documents for this Section
Amos, S. W.: “FM Detectors,” Wireless World, vol. 87, no. 1540, pg. 77, January 1981.
Benson, K. Blair, and Jerry C. Whitaker: Television and Audio Handbook for Engineers and
Technicians, McGraw-Hill, New York, N.Y., 1990.
Engelson, M., and J. Herbert: “Effective Characterization of CDMA Signals,” Microwave Jour-
nal, pg. 90, January 1995.
Howald, R.: “Understand the Mathematics of Phase Noise,” Microwaves & RF, pg. 97, Decem-
ber 1993.
Johnson, J. B:, “Thermal Agitation of Electricity in Conduction,” Phys. Rev., vol. 32, pg. 97, July
1928.
Nyquist, H.: “Thermal Agitation of Electrical Charge in Conductors,” Phys. Rev., vol. 32, pg.
110, July 1928.
Pleasant, D.: “Practical Simulation of Bit Error Rates,” Applied Microwave and Wireless, pg. 65,
Spring 1995.
Rohde, Ulrich L.: Digital PLL Frequency Synthesizers, Prentice-Hall, Englewood Cliffs, N.J.,
1983.
Rohde, Ulrich L.: “Key Components of Modern Receiver Design—Part 1,” QST, pg. 29, May
1994.
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Radio Receivers
Radio Receivers 12-5
Rohde, Ulrich L. Rohde and David P. Newkirk: RF/Microwave Circuit Design for Wireless
Applications, John Wiley & Sons, New York, N.Y., 2000.
Rohde, Ulrich L, and Jerry C. Whitaker: Communications Receivers, 3rd ed., McGraw-Hill,
New York, N.Y., 2000.
“Standards Testing: Bit Error Rate,” application note 3SW-8136-2, Tektronix, Beaverton, OR,
July 1993.
Using Vector Modulation Analysis in the Integration, Troubleshooting and Design of Digital RF
Communications Systems, Product Note HP89400-8, Hewlett-Packard, Palo Alto, Calif.,
1994.
Watson, R.: “Receiver Dynamic Range; Pt. 1, Guidelines for Receiver Analysis,” Microwaves &
RF, vol. 25, pg. 113, December 1986.
“Waveform Analysis: Noise and Jitter,” application note 3SW8142-2, Tektronix, Beaverton, OR,
March 1993.
Wilson, E.: “Evaluate the Distortion of Modular Cascades,” Microwaves, vol. 20, March 1981.
Whitaker, Jerry C. (ed.): NAB Engineering Handbook, 9th ed., National Association of Broad-
casters, Washington, D.C., 1999.
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Radio Receivers
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Radio Receivers
12-7
Chapter
12.1
Receiver Characteristics
Ulrich L. Rohde
Jerry C. Whitaker, Editor-in-Chief
12.1.1 Introduction
1
The superheterodyne receiver makes use of the heterodyne principle of mixing an incoming sig-
nal with a signal generated by a local oscillator (LO) in a nonlinear element (Figure 12.1.1).
However, rather than synchronizing the frequencies, the superheterodyne receiver uses a LO fre-
quency offset by a fixed intermediate frequency (IF) from the desired signal. Because a nonlin-
ear device generates identical difference frequencies if the signal frequency is either above or
below the LO frequency (and also a number of other spurious responses), it is necessary to pro-
vide sufficient filtering prior to the mixing circuit so that this undesired signal response (and oth-
ers) is substantially suppressed. The frequency of the undesired signal is referred to as an image
frequency, and a signal at this frequency is referred to as an image. The image frequency is sepa-
rated from the desired signal frequency by a difference equal to twice the IF. The preselection fil-
tering required at the signal frequency is much broader than if the filtering of adjacent channel
signals were required. The channel filtering is accomplished at IF. This is a decided advantage
when the receiver must cover a wide frequency band, because it is much more difficult to main-
tain constant bandwidth in a tunable filter than in a fixed one. Also, for receiving different signal
types, the bandwidth can be changed with relative ease at a fixed frequency by switching filters
of different bandwidths. Because the IF at which channel selectivity is provided is often lower
than the signal band frequencies, it may be easier to provide selectivity at IF, even if wide-band
RF tuning is not required.
1. This chapter is based on: Rohde, Ulrich L., and Jerry C. Whitaker: Communications Receiv-
ers: Principles and Design, 3rd ed., Mcgraw-Hill, New York, N.Y., 2000. Used with permis-
sion.
Source: Standard Handbook of Audio and Radio Engineering
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