56451. For an RC low pass filter, the relation between noise bandwidth BN and 3-dB bandwidth B3dB is
56452. In FM and AM the ratio of signal to noise ratio at the detector output least depends upon
56453. Which of the following can provide two or more voice circuits with the same carrier?
56454. A linear diode detector uses RC filter. As modulation index increases the maximum permissible value of time constant RC
56455. In SSB generation, the most commonly used filter is
56456. The FM broadcast band is from
56457. If k is Boltzmann's constant, T0 is standard ambient temperature, δf is bandwidth of receiver, F is noise figure, the minimum receivable signal in a radar receiver is given by
56458. The purpose of source coding is to
56459. If a source of information generates messages at the rate of r messages per second and H is entropy, the information rate is
56460. The noise generated by a resistor depends upon
56461. A source has two symbols x1 and x2 with probabilities pi and pr. If a new source with four symbols is generated from the above source, the new symbol probabilities will be (∈ is a number such that 0 < ∈ < 1)
56462. Coupling and bypass filters can be a source of
56463. Assertion (A): SSB transmitter is generally smaller than AM transmitter Reason (R): SSB systems mostly use combined transmitter receiver.
56464. The VLF, LF and MF antennas are
56465. The block diagram of AM transmitter in which high level modulation is used as shown in figure. The block X could be
56466. In FM 'guard band' is provided
56467. Assertion (A): FM requires more bandwidth than AMReason (R): Wide band FM is used for broadcast transmissions.
56468. When E1, E2, E3 etc. are the simultaneous modulating voltages, then the total modulating voltage Et will be
56469. A frequency doubler has an FM signal input at 13 MHz with a deviation of 5 kHz. The output, frequency for the carrier will be
56470. In MF range, increasing the transmitter power
56471. The most frequent users of long distance VLF transmission is
56472. BFO stands for
56473. SSB-SC stands for
56474. A lens has a hyperfocal distance of 7.5 m. It is focused at 7.5 m. Then
56475. In a 4-ary FSK, the frequencies are separated by fs. Then they are
56476. In cell communication, cell stands for
56477. In which of the following frequency bands are the standard AM radio broadcast stations?
56478. The frequency tolerance for the RF carrier in the standard AM radio broadcast band is
56479. If carrier is modulated by a digital bit stream having one of the possible phases of 0°, 90°, 180°, and 270°, then modulation is called
56480. In FM, the frequency deviation is
56481. If fh(t) is the Hilbert transform of f(t), and f(t) is a real valued signal, the pre-envelope of f(t) is
56482. Speech amplifiers are usually operated as
56483. In which frequency range is the noise figure in a transistor independent of frequency
56484. Which of the following is likely to be associated with FM radio broadcasting?
56485. If D is diagonal and F is focal length, lens angle θ is
56486. Present day stereophonic systems have
56487. RF choke used for suppressing interference in TV is generally
56488. Indicate the false statement: To combat noise
56489. Audio and video signals are called modulating waves.
56490. In AM, if modulation index is more than 100%, then
56491. The width of air gap on recording head in a tape recorder is about
56492. In a stereo tape recorder the speed of the tape is
56493. Which of the following refers to SSB suppressed carrier amplitude modulated system?
56494. The frequency at which the piezoelectric effect occurs is primarily determined by
56495. Which of the following statement regarding the advantages of the phase discriminator over the slope detector is false?
56496. The highest modulating frequency typically used in AM systems is
56497. The line of sight communication requires the transmit and receive antennas to face each other. If the transmit antenna is vertically polarized, for best reception to the receive antenna should be
56498. The bandwidth of FM for Commercial Purpose is
56499. In home tape recorders the tape width is 2 inches.
56500. If e = 10 sin(108 t + 3 sin 104 t) then carrier frequency is