Communication Systems Questions

• Which of the following is taken as reference antenna for directive gain?
• The number of noise sources in a BJT are
• An earth mat for a communication tower consists of
• In CCIR-B system, the time between start of one H syn. pulse and next is
• A cordless telephone using separate frequencies for transmission in base and portable units is known as
• Signal to noise ratio of microphone is defined as the ratio of output when the sound pressure is __________ to the output in the absence of any sound signal.
• Some types of traps used in video IF amplifier of colour TV are
• Consider the following statements The amplitude of an FM wave is constant FM is more immune to noise than AM FM broadcasts operate in upper VHF and UHF frequency ranges FM transmitting and receiving equipments are simpler as compared to AM transmitting and receiving equipments Which of the above are correct?
• The colour subcarrier and sidebands produced by its modulation with the chrominance signals are accommodated in the standard channel width by the process of
• As the frequency increases, the absorption of ground wave by earth's surface
• The velocity of sound waves in air
• Counterpoise is used in coils having
• A modem is classified as low speed if data rate handled is
• A carrier wave carries information.
• A woofer should be fed from the input through a
• A generator is feeding power to a transmission line of characteristic impedance Z0. The line is terminated in impedance ZL. Standing waves will be set up if
• A 400 W carrier is amplitude modulated with m = 0.75. The total power in AM is
• In sound recording the degree of pre-emphasis is about 6 dB/ octave.
• Tracking of extra terrestrial objects requires
• A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. Which of the following frequency is least likely to be present in the output?