Frequency of sky waves is
A. less then 3 MHzB. more than 3 MHz
C. less than 2 MHz
D. exactly 2 MHz
Description : Tropospheric scatter is a method of sky wave propagation for which of the following frequency bands? A. 300 kHz to 3 MHz B. 3 MHz to 30 MHz C. 30 MHz to 300 MHz D. 300 MHz to 3 GHz
Last Answer : D. 300 MHz to 3 GHz
Description : Which of the following frequency bands is best suited for sky wave propagation? A. 30 to 300 kHz B. 3 MHz to 30 MHz C. 30 MHz to 300 MHz D. 3 GHz to 30 GHz
Last Answer : B. 3 MHz to 30 MHz
Description : Signals with a frequency above30 MHz use_______propagation. A) ground B) sky C) line-of-sight D) none of the above
Last Answer : line-of-sight
Description : Signals with a frequency between 2 MHz and 30 MHz use ______ propagation. A) ground B) sky C) line-of-sight D) none of the above
Last Answer : sky
Description : Signals with a frequency below 2 MHz use _______ propagation. A) ground B) sky C) line-of-sight D) none of the above
Last Answer : ground
Description : What are audible sound waves? (1) Having frequency less than 20 Hz (2) Having frequency between 20 Hz to 20000 Hz (3) Having frequency more than 20000 Hz (4) None of above
Last Answer : (2) Having frequency between 20 Hz to 20000 Hz
Description : Cloudy nights are wanner compared nights, because clouds mainly – (1) Absorb heat from the atmosphere send it towards earth (2) Prevent cold waves from the sky descending on earth (3) Reflect back the heat given by earth (4) Produce heat and radiate it toward earth
Last Answer : (3) Reflect back the heat given by earth Explanation: It is because the night side of Earth will radiate infra-red radiation (heat) back into space. When there is cloud cover, the clouds act like a blanket and trap the heat close to the ground just like a blanket traps heat close to our body.
Description : Cloudy nights are warmer compared nights, because clouds mainly (1) absorb heat from the atmosphere send it towards earth (2) prevent cold waves from the sky descending on earth (3) reflect back the heat given by earth (4) produce heat and radiate it toward earth
Last Answer : reflect back the heat given by earth
Description : The frequency of operation of a dipole antenna cut to a length of 3.4 m. A. 88 MHz B. 44 MHz C. 22 MHz D. 11 MHz
Last Answer : B. 44 MHz
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 : Most satellites operate in which frequency band? A. 30 to 300 MHz B. 300 MHz to 3 GHz C. 3 GHz to 30 GHz D. Above 300 GHz
Last Answer : C. 3 GHz to 30 GHz
Description : The bandwidth of C-band satellite frequency band in U.S. A. 500 GHz B. 1000 GHz C. 1000 MHz D. 500 MHz
Last Answer : D. 500 MHz
Description : What is the local oscillator (mixer) frequency of the satellite with an uplink frequency in GHz band? A. 3500 MHz B. 4500 MHz C. 2225 MHz D. 2555 MHz
Last Answer : C. 2225 MHz
Description : Industrial noise frequency is between _____. A. 0 to 10 KHz B. 160 MHz to 200 MHz C. 15 to 160 MHz D. 200 to 3000 MHz
Last Answer : C. 15 to 160 MHz
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 far is the visual carrier from the lowest frequency in the spectrum of a monochrome TV broadcast channel following the NTSC standard? A. 1.5 MHz B. 1.25 MHz C. 4.5 MHz D. 0.25 MHz
Last Answer : B. 1.25 MHz
Description : What is the most commonly used intermediate frequency of radar receivers? A. 40 MHz B. 60 MHz C. 70 MHz D. 30 MHz
Last Answer : D. 30 MHz
Description : What is the channel number of an FM station with a carrier frequency of 99.5 MHz? A. 256 B. 258 C. 257 D. 259
Last Answer : B. 258
Description : Which of the following systems uses frequency band 870-885 MHz as a transmit band of its base station? A. TACS B. NTT C. NMT D. AMPS
Last Answer : B. NTT
Description : What ionospheric layer has a daytime approximate critical frequency of 8 MHz? A. F2 layer B. F1 layer C. E layer D. D layer
Last Answer : A. F2 layer
Description : What is the approximate critical frequency of the E layer? A. 4 MHz B. 5 MHz C. 6 MHz D. 3 MHz
Last Answer : A. 4 MHz
Description : A radio communications link is to be established via the ionosphere. The maximum virtual height of the layer is 100 km at the midpoint of the path and the critical frequency is 2 MHz. The distance between stations is 600 ... optimum working frequency? A. 6.32 MHz B. 2.1 MHz C. 5.4 MHz D. 1.8 MHz
Last Answer : C. 5.4 MHz
Description : An FM receiver whose intermediate frequency is 10.7 MHz, is experiencing image channel interference from a station transmitting on 121.1 MHz. If the local oscillator is tracking above, the receiver is tuned to A. 131.8 MHz B. 110.4 MHz C. 142.5 MHz D. 99.7 MHz
Last Answer : D. 99.7 MHz
Description : What is the phase coefficient in radians per unit length of a transmission line at the frequency of 10 MHz if the velocity of propagation is 2.5x108 m/s? A. 0.25 B. 2.5 C. 0.35 D. 3.5
Last Answer : A. 0.25
Description : What is the frequency range of an aircraft’s Very High Frequency (VHF) communications? A. 118.000 MHz to 136.975 MHz (worldwide up to 151.975 MHz) B. 108.000 MHz to 117.95 MHz C. 329.15 MHz to 335.00 MHz D. 2.0000 MHz to 29.999 MHz
Last Answer : A. 118.000 MHz to 136.975 MHz (worldwide up to 151.975 MHz)
Description : What is the frequency range of an aircraft’s radio altimeter? A. 962 MHz to 1213 MHz B. 329.15 MHz to 335.00 MHz C. 4250 MHz to 4350 MHz D. 108.00 MHz to 117.95 MHz
Last Answer : C. 4250 MHz to 4350 MHz
Description : Which of the following frequency bands is best suited for ground wave propagation? A. 30 to 300 kHz B. 300 kHz to 3 MHz C. 3 MHz to 30 MHz D. 30 MHz to 300 MHz
Last Answer : A. 30 to 300 kHz
Description : What is the refractive index of an ionospheric layer with 100x105 free electrons per m3 ? Assume frequency to be at 20 MHz. A. 0.99 B. 0.15 C. 0.78 D. 0.85
Last Answer : A. 0.99
Description : At a certain time, the MUF for transmission at an angle of incidence of 75° is 17 MHz. What is the critical frequency? A. 4.4 MHz B. 3.5 MHz C. 6.5 MHz D. 1.5 MHz
Last Answer : A. 4.4 MHz
Description : What is the frequency of a 2-cm sound wave in sea water at 25˚C? A. 76 kHz B. 76 Hz C. 76 MHz D. 76 mHz
Last Answer : A. 76 kHz
Description : Assume a frequency of 4 MHz, determine the phase shift offered by the line in the above problem. A. 108.5˚ B. 106.5˚ C. 115.5˚ D. 166.5˚
Last Answer : D. 166.5˚
Description : If the operating frequency is 450 MHz what length of a pair of conductors is considered to be a transmission line? A. 2.19 ft B. 2.19 m C. 0.219 ft D. 0.219 m
Last Answer : C. 0.219 ft
Description : What is the typical center frequency spacing between adjacent channels (transponders) in satellites? A. 36 MHz B. 40 MHz C. 500 MHz D. 4 MHz
Last Answer : B. 40 MHz
Description : Assuming a UHF frequency range of 405.0125 MHz to 405.0875 MHz at 25 kHz channeling plan, how many channels can you produce? A. 2.5 ch. B. 2 ch. C. 4 ch. D. 3 ch.
Last Answer : D. 3 ch.
Description : Assume a frequency range of 405.0125 MHz to 405.0875 MHz and 25 kHz channeling plan, determine the center frequency of the second channel from the lower limit. A. 405.030 MHz B. 405.025 MHz C. 405.050 MHz D. 405.075 MHz
Last Answer : C. 405.050 MHz
Description : Assume a frequency range of 401.000 MHz to 401.050 MHz, if you apply 25 kHz channeling plan, determine the center frequency of the first channel from the lower limit. A. 401.010 MHz B. 401.0125 MHz C. 401.025 MHz D. 401.00625 MHz
Last Answer : B. 401.0125 MHz
Description : Determine the lower half-power frequency of a class-C amplifier having upper half-power frequency of 10.025 MHz, a resonant frequency 5 MHz and a circuit Q of 10. A. 1.0025 MHz B. 10.525 MHz C. 0.5 MHz D. 10 MHz
Last Answer : A. 1.0025 MHz
Description : Determine from the following radio frequency that falls under the very high frequency band of the radio spectrum. A. 345.00 MHz B. 144.50 MHz C. 235.50 MHz D. 450.00 MHz
Last Answer : C. 235.50 MHz
Description : The extremely high frequency (EHF) band is in the radio spectrum range of _______. A. 30 to 300 kHz B. 30 to 300 GHz C. 3 to 30 MHz D. 3 to 30 GHz
Last Answer : B. 30 to 300 GHz
Description : A radio frequency in the ultra high frequency band of the radio spectrum band. A. 235.50 MHz B. 450.50 MHz C. 150.50 GHz D. 0.31250 GHz
Last Answer : D. 0.31250 GHz
Description : Which of the following is designated as the international distress, safety and calling frequency for radio telephony for stations of the maritime mobile service when using frequencies in the authorized bands between 156 and 174 MHz? A. 165.8 MHz B. 156.8 MHz C. 158.6 MHz D. 168.5 MHz
Last Answer : B. 156.8 MHz
Description : A satellite receives an uplink frequency of _______ MHz from a ground station of 3700 MHz. A. 8150 MHz B. 1475 MHz C. 2225 MHz D. 5925 MHz
Last Answer : D. 5925 MHz
Description : Which of the following fall under the high frequency band of the radio spectrum? A. 8.2345 MHz B. 150.50 MHz C. 2.4555 MHz D. 35.535 MHz
Last Answer : A. 8.2345 MHz
Description : This type of transmission permits communication in the frequency range from 30 to 60 MHz and over distances from about 1000 to 2000 km. A. Troposcatter B. Ionospheric scatter C. Ducting D. Microwave
Last Answer : B. Ionospheric scatter
Description : The frequency of operation of a dipole antenna cut to length of 3.4 m. A. 42.9 MHz B. 61.3 MHz C. 38.5 MHz D. 53.5 MHz
Last Answer : A. 42.9 MHz
Description : Type of transmission path that permits communication in the frequency range from 30 to 60 MHz and over distances form about 1000 to 2000 km. A. Ducting B. Ionospheric scatter C. Microwave D. Troposcatter
Description : Industrial noise frequency is between _________. A. 200 to 3000 Mhz B. 15 to 160 Mhz C. 0 to 10 Khz D. 20 Ghz
Last Answer : B. 15 to 160 Mhz
Description : The maximum clock frequency is _ a. 45 MHZ b. 50 MHZ c. 52 MHZ d. 68 MHZ
Last Answer : b. 50 MHZ
Description : What frequency range is used for FM radio transmission? A. Very Low Frequency : 3 kHz to 30. kHz B. Low Frequency :30 kHz to 300 kHz C. High Frequency :3 MHz to 30 MHz D. Very High Frequency : 30 MHz to 300 MHz E. None of the above
Last Answer : Very High Frequency : 30 MHz to 300 MHz