Description : The ordinary and maximum tolerance limit of sound by human being is – (1) 50 db to 70 db (decibel) (2) 60 db to 80 db (decibel) (3) 65 db to 75 db (decibel) (4) 70 db to 85 db (decibel)
Last Answer : (2) 60 db to 80 db (decibel) Explanation: Normal speech is about 60 dB (decibels). A dangerous sound is anything that is 80 dB or higher which can lead to hearing loss. At 70 dB or ... the risk of harm to healthy ears is negligible. Listening to sound above 80 decibels can cause profound deafness.
Description : The ordinary and maximum tolerance limit of sound by human being is (1) 50 db to 70 db (decibel) (2) 60 db to 80 db (decibel) (3) 65 db to 75 db (decibel) (4) 70 db to 85 db (decibel)
Last Answer : 60 db to 80 db (decibel)
Description : While measuring frequency response, as the signal generator approaches the lowest and highest frequency the recorder can effectively record, the VTVM reading drops to less than - 3 dB. What does this indicate?
Last Answer : The upper and lower limits of the frequency response specification for that tape recorder.
Description : The frequency-response specification of your tape recorder reads within +/ - 3 dB from 150 Hz to 150 kHz at 60 ips. What does this mean?
Last Answer : The recorder can record all frequencies between 150 Hz and 150 kHz at 60 ips without varying the output amplitude more than 3 dB.
Description : For a single mode optical cable with 0.25 dB/km loss, determine the optical power 100 km from a 0.1-mW light source. ∙ A. -45 dBm ∙ B. -15 dBm ∙ C. -35 dBm
Last Answer : ∙ C. -35 dBm
Description : Decibel is the unit used for – (1) Speed of light (2) Intensity of heat (3) Intensity of sound (4) Radio wave frequency
Last Answer : (3) Intensity of sound Explanation: The decibel (abbreviated dB) is the unit used to measure the intensity of a sound. The decibel scale is a little odd because the human ear is incredibly ... of a physical quantity (usually power or intensity) relative to a specified or implied reference level.
Description : ________ is a typeof transmission impairment in which the signal loses strength due to the different propagation speeds of each frequency that makes up the signal. A) Attenuation B) Distortion C) Noise D) Decibel
Last Answer : Distortion
Description : The .............. measures the relative strengths of two signals or a signal at two different points. (A) frequency (B) attenuation (C) throughput (D) decibel
Last Answer : (D) decibel
Description : Decibel is the unit used for (1) Speed of light (2) Intensity of heat (3) Intensity of sound (4) Radio wave frequency
Last Answer : Intensity of sound
Description : Describe an optical fiber cable component (OFCC).
Last Answer : OFCCs are tight-buffer fiber surrounded by arimid yarn and a low-halogen outer jacket.
Description : Describe the operation of an optical detector
Last Answer : It is a transducer that converts an optical signal into an electrical signal. It does this by generating an electrical current proportional to the intensity of incident optical radiation.
Description : Two methods describe how light propagates along an optical fiber. These methods define two theories of light propagation. What do we call these two theories?
Last Answer : The ray theory and the mode theory.
Description : What is the insertion loss of connector type splices for a single mode optical fiber? A. 0.51 dB B. 0.49 dB C. 0.31 dB D. 0.38 db
Last Answer : D. 0.38 db
Description : Developed an optical fiber with losses less that 2 dB/km ∙ A. Kao and Bockham ∙ B. Maiman, Kao and Bockham ∙ C. Maiman and Schawlow ∙ D. Kapron, Keck and Maurer
Last Answer : ∙ A. Kao and Bockham
Description : Developed an optical fiber with losses less that 2 dB/km
Last Answer : Kao and Bockham
Description : In reference to dB meters, 0 dBm represents 1 milliwatt into what value of load?
Last Answer : 600-ohm load.
Description : What is the main difference between a vu and a dB meter?
Last Answer : DB meters are used for measuring sine waves. Vu meters are used to measure the average value of complex waveforms.
Description : Two tape recorders have signal-to-noise ratios (SNRs) of 25-dB RMS and 35-dB RMS respectively. Which of the SNRs can record and reproduce the widest range of input signals and why?
Last Answer : 35-dB RMS because the highest SNR can always record and reproduce the widest range of input signals.
Description : Part of a microwave link can be approximated by free space conditions. The antenna gain are each 40 dB, the frequency is 10 GHz, and the path length is 80 km. Calculate the receive power for a transmitted power of 10 W? A. 0.871 μW B. 871 μW C. 0.871 mW D. 871 nW
Last Answer : A. 0.871 μW
Description : Which type of optical splitter (Y-coupler or T-coupler) splits only a small amount of power from the input fiber to one of the output fibers?
Last Answer : T-coupler
Description : Define the loss in optical power through a connection.
Last Answer : loss = 10log
Description : The amount of optical power coupled into an optical fiber depends on what four factors?
Last Answer : (1) The angles over which the light is emitted. (2) The size of the source's light-emitting area relative to the fiber core size. (3) The alignment of the source and fiber. (4) The coupling characteristics of the fiber (such as the NA and the refractive index profile)
Description : Which semiconductor sources (LD or LED) emit more focused light and are capable of launching sufficient optical power into both single mode and multimode fibers?
Last Answer : LDs.
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 : Which performance parameter is the minimum amount of optical power required to achieve a specific bit-error rate (BER) in digital systems or a given signal-to-noise ratio (SNR) in analog systems?
Last Answer : Receiver sensitivity.
Description : When is an optical power meter measurement recommended for conducting field measurements on installed optical fiber cables or cable plants?
Last Answer : When an installed optical fiber cable or cable plant is less than 50 meters in length.
Description : The amount of backscattered optical power at each point depends on what two properties?
Last Answer : Forward optical power and backscatter capture coefficient.
Description : A cavity that vibrates at its natural frequency produces a louder sound than at other frequencies. What term is used to describe this phenomenon?
Last Answer : Resonance.
Description : What term is used to describe the frequency at which the filter circuit changes from the point of rejecting the unwanted frequencies to the point of passing the desired frequencies?
Last Answer : Frequency cutoff (fco).
Description : What is the term used to describe the basic frequency of a radio wave?
Last Answer : Fundamental frequency.
Description : What is the term used to describe a whole number multiple of the basic frequency of a radio wave?
Last Answer : Harmonic frequency or harmonics.
Description : What term is used to describe the product of pulse width and pulse-repetition frequency?
Last Answer : Duty cycle.
Description : When the elevation angle of a geostationary satellite is 23˚ and the transmitting frequency is 3840 MHz, what is the free space loss in dB? A. 196 dB B. 200 dB C. 150 dB D. 100 dB
Last Answer : A. 196 dB
Description : The total space loss of transmission and reception for two ground stations with uplink frequency 8GHz and a downlink of 6 GHz with angle of elevations of 3˚ and 7˚ A respectively is A. 403 dB B. 100 dB C. 20 dB D. 215 dB
Last Answer : A. 403 dB
Description : What is the required quality factor for an SSB filter with the following data: center frequency= 1 MHz, the desired attenuation level of the unwanted sideband= 80 dB and the separation between sidebands= 200 Hz? A. 1,250 B. 12,500 C. 125,000 D. 25,000
Last Answer : C. 125,000
Description : How does the gain of a parabolic dish type antenna change when the operating frequency is doubled? A. Gain does not change B. Gain is multiplied by 0.707 C. Gain increases 6 dB D. Gain increases 3 dB
Last Answer : C. Gain increases 6 dB
Description : At what loudness level do pitch (in mels) and frequency (in Hz) are numerically equal? A. 0 dB B. 20 dB C. 60 dB D. 40 dB
Last Answer : D. 40 dB
Description : What is the path attenuation between transmitter and receiver at a frequency of 1.2 Ghz and a distance of 11,000 mi? A. 119 dB B. 115dB C. 179dB D. 174dB
Last Answer : C. 179dB
Description : In a 741 Op-Amp, there is 20 dB/decade fall-off starting at a relatively low frequency. This is due to the (A) applied load (B) internal compensation (C) impedance of the source (D) power dissipation in the chip
Last Answer : In a 741 Op-Amp, there is 20 dB/decade fall-off starting at a relatively low frequency. This is due to the internal compensation
Description : Unit of frequency is ________________. A. Hz B. Horton C. dB D. Coulomb
Last Answer : Unit of frequency is Hz.
Description : Which type of fiber optic connector (butt-jointed or expanded beam) brings the prepared ends of two optical fibers into close contact?
Last Answer : Butt-jointed connectors.
Description : What is the basic fiber cleaving technique for preparing optical fibers for coupling?
Last Answer : Score-and-break.
Description : Quality fiber-end preparation is essential for proper system operation. What properties must an optical fiber-end face have to ensure proper fiber connection?
Last Answer : Be flat, smooth, and perpendicular to the fiber axis.
Description : Which type of optical source tends to operate at higher drive currents to produce light?
Last Answer : Laser.
Description : Which type of optical source usually lacks reflective facets and in some cases are designed to suppress reflections back into the active region?
Last Answer : LED.
Description : Which types of LEDs are the preferred optical sources for short-distance, low-data-rate fiber optic systems?
Last Answer : SLEDs and ELEDs.
Description : Which part of a fiber optic transmitter converts the processed electrical signal to an optical signal?
Last Answer : The optical source.
Description : List the three techniques used by manufacturers to buffer optical fibers.
Last Answer : Tight-buffered, loose-tube, and gel-filled loose-tube.
Description : List three benefits that properly cabled optical fibers provide.
Last Answer : a. Protect optical fibers from damage or breakage during installation and over the fiber's lifetime. b. Provide stable fiber transmission characteristics compared with uncabled fibers. c. Maintain the physical integrity of the optical fiber.
Description : List the types of materials used in fabricating low-loss, long wavelength optical fibers.
Last Answer : Heavy-metal fluorides, chalcogenide glasses, and crystalline materials.