Description : For AM, fc =500kHz , fm = 5 kHz Determine: (i) Upper and lower sideband frequencies (ii) Bandwidth
Last Answer : Given data fc = 500KHz , fm = 5KHz USB =fc+fm USB = 500+5 =505 KHz. LSB =fc – fm LSB = 500 – 5 =495 KHz Bandwidth = 2fm . = 2* 5 =10 KHz
Description : What is the approximate bandwidth of an FM system with 10 kHz of modulating frequency and a 150 kHz of frequency deviation? A. 300 kHz B. 320 kHz C. 150 kHz D. 200 kHz
Last Answer : B. 320 kHz
Description : In a FM system, the maximum deviation is 75KHz. Find bandwidth for modulating frequency i. fm=500Hz ii. fm=5KHz iii. fm=10KHz Draw conclusion for bandwidth of FM from answer.
Last Answer : Given deviation∆=75kHz i) fm=500Hz bandwidth B.W=2(∆+fm) =2(75k+500)=151kHz ii). fm=5KHz bandwidth B.W=2(∆+fm) =2(75k+5k)=160KHz iii) fm=10KHz bandwidth B.W=2(∆+fm) =2(75k+10k)=170KHz As the modulating frequency increases bandwidth also increases.
Description : State the IF frequency and bandwidth of FM receiver.
Last Answer : IF for FM receiver: 10.7 MHz. Bandwidth of FM receiver:88MHz to 108 MHz
Description : Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application
Last Answer : Compare AM and FM on the basis of i)Definition ii)Bandwidth iii) Wave propogation iv)Number of sidebands
Description : Compare AM with FM with respect to following points: a) Definition. b) Modulation index. c) Bandwidth. d) Side band.
Last Answer : Parameters AM FM Definition It is the process in which the amplitude of carrier signal is varied in accordance with the instantaneous value of modulating signal keeping frequency and ... frequency deviation. Side band There are two sidebands Infinite number of sideband
Description : Theoretical bandwidth requirement for FM system is: (1) Same as that of the modulating signal bandwidth (2) Twice of modulating signal Bandwidth (3) Thrice as of modulating signal Bandwidth (4) Infinite
Last Answer : Theoretical bandwidth requirement for FM system is: Infinite
Description : Ideal transmission bandwidth of FM signal is
Last Answer : Ideal transmission bandwidth of FM signal is Infinite
Description : . What are two of the three physical factors that determine the values of capacitance and inductance of a transmission line?
Last Answer : (1) Type of line used, (2) dielectric in the line, and (3) length of line.
Description : What information must be known to determine the component values for a voltage divider?
Last Answer : The source voltage and load requirements (voltage and current).
Description : What type of objects are most easily detected by an fm system?
Last Answer : Stationary.
Description : What factor determines the difference between the transmitted frequency and the received frequency in an fm transmitter?
Last Answer : Travel time.
Description : What is the major difference between direct reproduce electronics and FM reproduce electronics?
Last Answer : FM record electronics must use a limiter and demodulator circuit (figure 5-5) to demodulate the signal intelligence from the carrier frequency.
Description : The head driver circuit of a tape recorder’s FM record electronics (figure 5-4) performs what function?
Last Answer : It amplifies the frequency-modulated output from the record oscillator and sends it to the record head.
Description : How do FM record electronics differ from AM (direct record) electronics?
Last Answer : Instead of recording the signal just as it appears at the recorder’s input, FM record electronics records a frequency-modulated carrier signal from a record oscillator (figure 5-4) onto the magnetic tape
Description : What happens to an fm signal as you increase the frequency of the modulating signal?
Last Answer : Both the bandwidth and the number of significant sidebands increase.
Description : What is the major disadvantage of an fm signal as compared to an AM signal?
Last Answer : Wide bandpass.
Description : In an fm transmitter, when does an oscillator generate only a steady frequency?
Last Answer : When no modulation is present.
Description : Why can phase-modulated signals be detected by fm detectors?
Last Answer : Because of the incidental frequency shift that is caused while phase-shifting a carrier wave that is similar to fm modulation.
Description : What is the function of an fm detector?
Last Answer : Converting frequency variations of received fm signals to amplitude variations
Description : What is the simplest form of fm detector?
Last Answer : Slope detector.
Description : What characteristic of a varactor is used in an fm modulator?
Last Answer : Capacitance.
Description : How is the degree of modulation expressed in an fm system?
Last Answer : As the ratio of the frequency deviation to the maximum frequency deviation allowable.
Description : Receiver bandwidth is defined as those frequencies spread between what two points of the receiver response curve?
Last Answer : Half-power points.
Description : What determines the frequency, bandwidth, and power handling capability of a waveguide probe?
Last Answer : Size and shape
Description : What is the bandwidth of an amplifier?
Last Answer : The difference between the upper and lower frequency limits of an amplifier.
Description : If the unity-gain point of the operational amplifier used in question 24 is 500 kilohertz, what is the bandwidth of the circuit?
Last Answer : 50 kilohertz (Gain = 10; Gain-Bandwidth Product = 500,000) 500,000(Hz)
Description : What is the advantage of designing a limited bandwidth into a servo amplifier?
Last Answer : Unwanted noise-generated frequencies are rejected
Description : LEDs operating at 850 nm provide sufficient optical power for short-distance, low-bandwidth multimode systems. List three conditions that prevent the use of LEDs in longer distance, higher bandwidth multimode systems.
Last Answer : Multimode fiber dispersion, the relatively high fiber attenuation, and the LED's relatively low optical output power.
Description : While coupled power and bending loss favor a high D, which Dvalue, smaller or larger, improves fiber bandwidth?
Last Answer : Smaller.
Description : Light travels faster in a material with a lower refractive index. Therefore, light rays that travel a longer distance in a lower refractive index travel at a greater average velocity. What effect does this have on multimode graded-index fiber modal dispersion and bandwidth?
Last Answer : Decreases the time difference between light rays, which reduces modal dispersion and increases fiber bandwidth.
Description : Which preamplifier design (high-impedance or transimpedance) provides improvements in bandwidth and greater dynamic range with some degradation in sensitivity from an increase in noise?
Last Answer : Transimpedance.
Description : In a multicavity klystron, tuning all the cavities to the same frequency has what effect on the bandwidth of the tube?
Last Answer : The bandwidth decreases.
Description : Most record and reproduce heads are in one of what three bandwidth categories?
Last Answer : a. Narrowband—100 Hz to 100 kHz. b. Intermediate band—100 Hz to 500 kHz. c. Wideband—400 Hz to 2 mHz.
Description : Modal dispersion affects the bandwidth of multimode systems. It is essential to adjust what three fiber properties to maximize system bandwidth?
Last Answer : Core diameter, NA, and index profile properties.
Description : What category of digital tape recorder is used to record special signals with a bandwidth of less than 500 kHz?
Last Answer : Instrumentation digital tape recorders.
Description : What determines the bandwidth of an AM transmission?
Last Answer : The highest modulating frequency.
Description : The front-end of a television receiver, having a bandwidth of 7Mhz, and operating at a temperature of 27˚C , consists of an amplifier having a gain of 15 followed by a mixer whose gain is 20. The ... equivalent noise resistance for this television receiver. A. 8760 Ω B. 875Ω C. 8.76Ω D. 0.876Ω
Last Answer : B. 875Ω
Description : Most AM broadcasts employ ___ polarization while most FM broadcasts employ ___ polarization of the radio wave. A. vertical, vertical B. vertical, horizontal C. horizontal, vertical D. horizontal, horizontal
Last Answer : B. vertical, horizontal
Description : In FM, frequency of modulated wave varies with A. amplitude B. time C. wavelength D. energy
Last Answer : time
Description : For a 300-m optical fiber cable with a bandwidth distance product of 600 MHz-km, determine the bandwidth. ∙ A. 5 GHz ∙ B. 1 GHz ∙ C. 2 GHz
Last Answer : C. 2 GHz
Description : For the 16-PSK and a transmission system with a 10kHz bandwidth, determine the maximum bit rate
Last Answer : 40,000 bps
Description : The main benefit of light-wave communications over microwaves or any other communications media is a. Lower cost b. Better security c. Wider bandwidth d. Freedom from interference
Last Answer : c. Wider bandwidth
Description : Variation in amplitude or frequency of carrier wave is called A. amplitude modulation B. frequency modulation C. modulation D. bandwidth
Last Answer : modulation
Description : Which of the following methods cannot be used to increase the bandwidth for cascaded RF amplifier stages? A) Wave traps in each stage B) Stagger tuning C) A shunt damping resistor across each tuned circuit D) Doubled tuned transformers with tighter coupling
Last Answer : A) Wave traps in each stage
Description : The main benefit of light wave communications over microwaves or any other communications media are ∙ A. lower cost ∙ B. better security ∙ C. wider bandwidth ∙ D. freedom from interface
Last Answer : C. wider bandwidth
Description : The main benefit of light-wave communications over microwaves or any other communications media is ∙ a. Lower cost ∙ b. Better security ∙ c. Wider bandwidth ∙ d. Freedom from interference
Description : Communications bandwidth that has the highest capacity and is used by microwave, cable and fibre optics lines is known as: (A) hyper-link (B) broadband (C) bus width (D) carrier wave
Last Answer : Answer: B
Description : Three resistors connected in parallel have values of 12 kΩ, 20kΩ, and 30kΩ. What is the equivalent resistance? A37. 6kΩ Q38. Two resistors connected in parallel have values of 10 kΩ and 30kΩ. What is eht equivalent resistance?
Last Answer : 7.5kΩ
Description : Name the modulation system in which the frequency alternates between two discrete values in response to the opening and closing of a key?
Last Answer : . Frequency-shift keying.