ESAT1. Question: A receiver has a sensitivity of 0.8 V and a blocking dynamic range of 60 db. What is the strongest signal that can be present along with a 0.8 V signal without blocking taking place?

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2. Question: The moon revolves the earth with a period of approximately 28 days. How far away is it? Assume circular orbit.

Solution: 38400 km

3. Question: For an 8 PSK modulation, data with a carrier frequency of 80 MHz, and an input rate of 10 Mbps, determine the minimum Nyquist Bandwidth.

Solution: =

4. Question: In a certain cellular system, the following information is given: 10 clusters, 7 cells per cluster, and 16 channels per cell. How many channels are available?

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5. Question: Given the DC power input of 1000W. Find the audio power necessary to modulate an RF amplifier of 90%.

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6. Question: A PM transmitter produces a maximum frequency deviation of 12 kHz on a signal-mode frequency that has 400 Hz to 4kHz. What is the maximum phase shift of the system?

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7. Question: In fiber optics communication, find the optical power 45 km from a 0.1 mW source on a modulating frequency of 0.25 dB/km loss.

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8. Question: What is the power density at a distance of 500m with a 1 kW dipole antenna?

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9. Question: For Quarternary Phase Shift Keying (QPSK) Modulation, the data rate has a frequency carrier of 6 MHz and an input rate of 10 Mbps. Determine the minimum Nyquist Bandwidth.

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10. Question: At 20 km of free space from a point source, the power density is 200 W/m2. What is the power density 30 km away from this source?

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11. Question: A telephone signal takes 2 ms to reach its destination. Calculate the Via Net Loss for an acceptable amount of echo.

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12. Question: In transmission lines, what is the physical length of a twin-lead feed line at 31.5 MHz?

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13. Question: In FM broadcasting, what is the carrier frequency in MHz of a station with a channel number of 211?

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14. Question: Light enters glass of refractive index 1.62. From air, if the angle of incidence is 40, determine the angle of refraction?

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15. Question: Calculate the beamwidth between nulls of a 2-m paraboloid reflector used at 6 GHz. Note: such reflectors are often used at that frequency as antennas outside broadcast TV microwave links.

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16. Question: How many Hamming bits are required for a 7-bit ASCII code?

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17. Question: A CDMA mobile measures signal strength from the base of -100 dBm. What should the mobile transmitter power be set to, as first approximation considering -76 dB as mobile power control?

Solution:

= 250 mW

18. Question: What is the length of the path to a geostationary station from an Earth station if the angle of elevation is 30?

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19. Question: By how much should two antennas be separated for space diversity in the 11 GHz band?

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20. Question: What is the frequency deviation constant for a Clapp oscillator frequency-modulated for an unmodulated carrier frequency of 75 MHz with a fixed bias of 20 V and N=0.2?

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21. Question: Determine the electric field strength 20 km from an elementary doublet 20 cm in length with an antenna current of 2 A and operated at 10 MHz.Solution:

22. Question: Calculate the maximum frequency range of a microwave system whose transmitter height is 52 km and receiver height of 32 km.

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23. Question: A system has a loss of 31 dB. If the input power is 5 W then, what is the output power?

Solution:

=

24. Question: Determine the visual carrier frequency of TV channel9.

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25. Question: What is the maximum data rate in Mbps of fiber length of 20 km and a dispersion factor of 25 ns/km?

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26. Question: What is the harmonically related carrier of channel125?

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27. Question: For total capacity of 36 Mbps and 64 QAM of digital modulation, what is the ideal RF beamwidth?

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28. Question: What is the critical frequency of an ionosphere layer if the maximum value of the electron density is 2106 per cm3?

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29. Question: In commercial C-band for satellite communication, the spectrum allocated is 500 MHz divided into 92 channels with a bandwidth of 36 MHz each. What is the center frequency spacing between?

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30. Question: Calculate the power in a 100 mV peak NRZ square wave on a 250-ohm channel of a digital system.

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31. Question: In NTSC standard, line frequency = 15734.264 Hz, what is the equivalent line period?

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32. Question: In tropospheric scatter link, the aperture to medium coupling loss otherwise known as antenna gain degradation occurs because of the very nature of tropospheric scatter in that the antennas used are not doing what is expected of them in using ITU-R suggestion, what is the aperture to medium coupling loss for two 25 ft. antennas one end of the path, with 2 scatter angle and a 5 GHz operating frequency?

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33. Question: In a microwave a communication system, what is the amount loss contributed by a reliability object of 99.95%?

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34. Question: What is the refractive index in a Teflon (T2 = 2) medium of a radio wave from air (T1 = 1.0) if the angle of incidence is 45.

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35. Question: A phase locked loop frequency of a VCO has a free-tuning frequency of 16 MHz. As the frequency of the reference input is gradually raised from zero, loops locks at 12 MHz.

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36. Question: The oscillator of a CB transmitter is absolutely accurate to 0.006%. What is the maximum frequency of the actual transmission if it is set to transmit at channel 8 with a nominal carrier frequency of 27.175 MHz.

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37. Question: The maximum voltage standing wave of an RG-11/U foam coaxial cable is 52 V and its minimum voltage is 17 V. How many percent is reflected to the incident power.

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38. Question: What is the maximum and transmitter radiated power if the peak visual transmitter power 120 kW for both.

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39. Question: Determine the bandwidth efficiency of 8-PSK modulation scheme if its transmission rate is 21 MHz.

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40. Question: In a microwave communications system, what is the multipath effect for a distance of 25 km so that the fade margin can be estimated for that particular link using 4 GHz of frequency and an objective of 99.995%?

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41. Question:What is the wavelength of a radio signal traveling at a frequency of 220 MHz in a coaxial cable having Teflon foam as its dielectric, r = 2?

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42. Question: An AM receiver is using a double tuned IF transformer having a coupling constant of 1.5 Kc. The quality factor of the primary and secondary winding is 40 and 30 respectively. What is the bandwidth of the transformer if the IF is 455 kHz?

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43. Question: What is the total waveguide dispersion of a single-mode-step-index fiber with 5 km of length and is utilized for a light source of 1.5 m? Assume spectrum of 5 nm.

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44. Question: Determine the effective isotropic radiated power (EIRP) of a transmitter system with the following data: antenna gain = 30 dB, input power = 100 W and efficiency = 80%.

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45. Question: As per ITU-R Res. V. 431-C Table 1 & 2 wavelength classification. The classification of a Super High Frequency is:

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46. Question: Calculate the video frequency response corresponding to the horizontal resolution of 320 lines of the TV receiver.

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47. Question: In microwave communication, if a passive repeater is fully illuminated, what is its beamwidth when the linear dimension is half the wavelength?

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48. Question: A radio communication link is to be established via ionosphere. The maximum virtual length of the layer is 110 km at the midpoint of the path and the critical frequency is 4 MHz. If the distance between the radio stations is 500 km, what is the suitable value for the optimum working frequency? Use flat terrain analysis.

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49. Question: In CDMA cellular system, what is the radiated mobile phone transmitter power when the signal strength measured from the base is 23.15 W?

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50. Question: The modulating signal of a certain frequency system has produced 36 kHz frequency deviation. Determine the percent modulation if the maximum frequency deviation is 50 kHz.

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51. Question: In acoustic, determine the resonant frequency of a Helmholtz resonator whose cavity volume is 1.5 m3 and radius of 15 cm.

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52. Question: For a BPSK, with a carrier frequency of 100 MHz and a bit rate or 14 Mbps, what is the maximum Nyquist Bandwidth?

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53. Question: What is the maximum aural transmitter radiated power if the peak visual transmitter power is 120 kW?

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54. Question: A CCTV system requires an archive time of 14 days. It is decided that the recorder must operate at a rate of 5 pps and for the proposed machine file capacity of 24 kb per picture in order to obtain an image quality comparable to that of an S-VCD recorder. Determine the required hard disk capacity.

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55. Question: How often is hand off occur in a vehicle that travels through CMTS at 100 kilometer per hour speed if the distance between cell sites is 10 kilometers?

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56. Question: Determine the noise factor of a device if the noise temperature is 290 K?

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57. Question: In an acoustic room, determine the amount of absorption at 9000 Hz by 20,000 m3 of air inside a concert hall when relative humidity of air inside is 50%?

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58. Question: An FM transmitter system uses 1 MHz crystal oscillator to generate a stable 108 MHz final carrier frequency. The output of mixer is fed with X36 multiplier circuit and then mixed with 34.5 MHz signal. The sum output of the mixer is then filtered out while the difference is fed to another multiplier in order to generate stable final carrier frequency. What is the multiplier value?

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59. Question: The reference voltage of a CATV is 1 mV across a 75 . Consider an amplifier with a voltage gain of 20 driving a cable with an attenuation factor of 0.5. Find the final output in dBmV.

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60. Question: Calculate the frequency deviation of an FM modulator that has kf = 30 kHz/V and operates at a carrier frequency of 175 MHz and modulated by a 6 V sine wave.

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61. Question: What is the range of radar target when time to receive signal is 160 s.

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62. Question: A network with a bandwidth of 10 Mbps can pass only an average of 12,000 frames per minute with each frame carries an average of 10,000 bits. What is the throughput of this network?

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63. Question: A tone is measured 82 dBrnC in the output of a four wire central office. What will it be at a local loop that is at -8 dB TLP in dBa?

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64. Question: Given the energy level of 6.62410-18 imparted to an electron stream by an x-ray device. Calculate the frequency in MHz?

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65. Question: In fiber optic communications, how much is the amount loss when the launching fiber has a numerical aperture of 0.2 and the receiving fiber has a numerical aperture of 0.1?

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66. Question: Calculate the amount of image frequency of an AM broadcast receiver having the following specifications: intermediate frequency is 455 kHz and the receiver is tuned to DZRH station (630 kHz in the AM band).

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67. Question: A system has a noise power of 200 mW with no signal. The output increases to 5000 mW when the signal is applied. Calculate the (S+N)/N as a power ratio in dB.

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68. Question: The input signal of a mu-law compressor is positive with its voltage one-half of the maximum value. What proportion of the maximum voltage is produced?

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69. Question: An SSB transmitter radiated into a 75 load. What is the peak enveloper power (PEP) if the peak-to-peak voltage is 700 V?Solution:

70. Question: If a heart measures 12.5 cm from side to side at its widest point and its image from chest radiograph measures 14.7 cm, what is the magnification factor?

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71. Question: An IPv4 has an address space of how many?

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72. Question: If the temperature is increased to 30 C then what is the change in the velocity of sound in dry air?

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73. Question: For a 16-QAM modulator with an input bit rate (fb) equal to 20 Mbps and a carrier frequency of 200 MHz. Determine the minimum double-side Nyquist Bandwidth (fn)?

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74. Question: A reliever IF filter has a shape factor of 4, a bandwidth of 6 kHz at the 6 dB down point. Calculate the bandwidth of the 60 dB down.

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75. Question: The current of an AM transmitter is 1.8 A when modulated to depth of 50%. If additionally modulated by another sine wave to a depth of 80% then what is the total current of the AM transmitter?

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76. Question: The modulation index of an AM radio transmitter is 0.75. If the carrier power is 500 W, what is the total power transmitted?

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77. Question: Determine the sound power in watts of a banks alarm if a bystander heard the alarm sound pressure level of 100 dB SPL. The bystander is 100 feet away from the bank.

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78. Question: Determine the shot noise for a diode with a forward biased of 1 mA over a 20 MHz bandwidth. (Q = 1.610 false to the minus 19 c)

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79. Question: A group of filters has 1/3 octave of spacing. If the initial frequency is 25 Hz. What is the next frequency available for the filter?

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80. Question: A phone modulator has a Kp = 4 Rad/v. What RMS voltage of a sine wave would cause a peak deviation of 30 degrees?

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81. Question: A transmitter operates from 12 V of power supply with a collector current of 2 A. The modulation transformer has a turn ratio of 4:2. Determine the load impedance seen by the audio amplifier.

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82. Question: A loudspeaker produces an SPL of 85 dB SPL at 1 meter distance and input electrical power of 1W. How loud is the SPL at distance of 20 meters if the speaker is driven to low of electrical power?

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83. Question: +26 dBu is how many volts?

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84. Question: In cable TV, determine the standard frequency carrier of channel 122?

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85. Question: The TV channel has a bandwidth of 6 MHz. Ignoring noise, find the S/N in dB if a 12 level code is used.

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86. Question: A TDR display shows a discontinuity 1.4 s from the start. If the line has a velocity factor of 0.6, how far is the fault from the reflectometer?

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87. Question: Determine the modulation index of an FM system whose carrier swing is 12 kHz and modulating frequency of 6 kHz.

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88. Question: An AM receiver is tuned to a broadcast station of 1000 kHz. Calculate the image frequency refection ratio (IFRR), assuming that the input filter consists of one tuned circuit with a Q of 80. The intermediate frequency of an AM is 455 kHz with a local oscillator frequency of 1355 kHz.

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89. Question: At what frequency a dipole of 3.6 m length is operated?

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90. Question: A rectangular waveguide has a 24 cm. dimension. Determine the cut-off frequency assuming dominant mode of operation.

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91. Question: How many flyback lines are produced during vertical retrace for each field when retrace time is 3% of the vertical trace time in TV receivers?

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92. Question: Determine the radio horizon for a transmit antenna that is 200 ft. high and a receiving antenna 100 m high.

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93. Question: Determine the maximum data rate for a channel operated between 300 to 3 kHz if the S/N is 24 dB.

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94. Question: A fiber of core index 1.5 and cladding is dope to have a fractional difference of 0.0035 calculate the intermodal dispersion considering a multimode graded index fiber.

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95. Question: Determine the transmitted data stream of the ff. data and CRC generating the polynomials. G(x) = x raised to the power 7 + x raised to the power 5 + x raised to the power 4 + x raised to the power to the 2nd + x +1. F(x) = x raised to the power 5 + x raised to the power 4 + x + one.

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96. Question: For the following parameters, determine the energy per bit to noise power density ratio. C = 10e-12 W; N = 1.210e-14 W; fb = 60 kbps; B =120 kHz.

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97. Question: In microwave communications, find the optical power 45 km from a 0.1 mW source on a single mode fiber that has 0.25 dB/km loss.

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98. Question: At 20 km in free space from a point source the power density is 200 W/m2. What is the power density at 30 km away from this source?

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99. Question: A transmitter system has an input power of 80 W. If the efficiency of the transmitter is 80% them what is the power density 20 km from the transmitter. Assuming a transmitting antenna gain of 16 dB.

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100. Question: A telephone subscriber line must have anSWRdB above 40. What is the minimum number of bits?

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101. Question: A PM system operates with a modulation index of 1.3 rad. What is the maximum phase shift in degrees?

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102. Question: An isolator has a forward loss of 0.7 dB and return loss of 26 dB. A power source provides 1 to an isolator a load is resistive with SWR of 3. How much power is dissipated on the load?

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103. Question: In digital communication determine the loss when light is released from a bigger fiber core of 40 m diameter to a smaller fiber core of 10 m diameter.

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104. Question: Find the potential generated if blood flows in a vessel with radius 0.9 cm cuts a magnetic field 250 G. Assume the volume rate flow is 175 cubic centimeters per second.

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105. Question: An AM receiver uses double winding IF transformer with a coupling constant of 1.5 Kc. The quality factor of the primary and the secondary windings are 40 and 30 respectively. What is the bandwidth of the transformer if the IF is 10.7 MHz?

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106. Question: A receiver has two uncoupled tune circuit, each having a Q of 65. It has a signal frequency of 100 MHz and an IF of 10.7 MHz. The local oscillator uses high side injection. Determine the image frequency rejection ratio in dB.

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107. Question: A radiographic single phase unit has a maximum capacity of 100 millisecond of 120 kVp and 500 mA. Determine the power rating.

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108. Question: A multiplexer combines 4 100 kHz channels using a time slot of 2 bits. Determine the frame duration.

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109. Question: How much time does it take to sea 20 lines if it takes 60 s to scan 400 lines?

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110. Question: Determine the power in dBm at the receiver with 20 V input voltage and 50 input resistance.

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111. Question: In PCM-TDM system, determine the minimum sampling rate with 6 kHz of bandwidth.

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112. Question: In fiber optics, one of the factor affecting the loss in connectors and splices is optical gap loss that case what is known as Fresnel loss due to the change in refractive index in going from core (n1) to air (n2) and then back to core (n1). If n1 = 1.2 and n2 = 1.3, what is the Fresnel loss.

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113. Question: The European ITU-T TDM system is using the added-channel framing to achieve frame synchronization. If the number of bits per frame is 512 and the number of bits in the frame code is 8, what is the average number of bits needed to acquire frame synchronization?

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114. Question: The efficiency of an antenna is 82%. Its radiation resistance is 30 . What is the value of its loss resistance?

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115. Question: What is the effective radiated power (ERP) of a repeater with 100 W transmitting power output 4 dB feedlineloss, 6 dB circulator loss and feedline antenna gane of 10 dB?

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116. Question: What is the length of a pair of conductor that is considered as transmission line with an operating frequency of 250 MHz?

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117. Question: A radio station operates at an 11 meter wavelength. What is the designated band of stations frequency?

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118. Question: A 5 kW transmitter produces a field strength of 50 V/m while a 15 kW produces how much field strength?

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119. Question: What is the maximum aural transmitter radiated power when the peak visual transmitter radiated power is 10 kW in the American TV standard?

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120. Question: What is the frequency deviation constant for a clap oscillator frequency-modulated for which the unmodulated frequency is 50 MHz with a fixed bias of 15 V and n = 0.1?

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121. Question: Determine the velocity of a satellite 500 km above the earth.

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122. Question: In CATV, what is the increment related channel (IRC) for channel 124?

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123. Question: Determine the carrier swing in a FM system with carrier frequency 100 MHz and frequency deviation of 12 kHz.

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124. Question: In transmission lines, get the inductance in H/ft. for a coaxial line having 50 characteristic impedance. Assume a dielectric constant of 2.3.Solution:

125. Question: Determine the length of the path to a geostationary satellite from an earth antenna where the angle of elevation is 30. (Earth radius = 6400 km, height of the satellite from the earth is 36 103 km.)

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126. Question: Calculate the fc of the rectangular wave guide whose width is 0.6 inch and height is 0.38 inch.

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127. Question: Determine the number of bits to represent 220 possibilities.

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128. Question: An amplifier with an overall gain of 10 dB is impressed with a low signal. Calculate the output power in dBm.

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129. Question: What is the power density at a distance of 500 m from a 1 kW dipole antenna?

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130. Question: A computer monitor has a resolution of 12001000 pixels. If each pixel uses 1024 colors, how many bits are needed to send the complete contents of a screen?

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131. Question: An isolator has a forward loss of 0.2 dB and a return loss of 26 dB. A source provides 1 W to the isolator, and the load is resistive with an SWR of 3. How much power returns to the source?

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132. Question: A TV antenna is located above a tower 800 ft. high. A viewer has a TV receiver on the upper floor of her house 200 ft. above the ground. Calculate the approximate minimum transmission distance.

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133. Question: A diode noise generator has the following information given: input noise voltage = 12 V; input impedance = 75 ; noise frequency = 300 kHz. Determine the current shot noise of the diode.

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134. Question: How far from the transmitter could a signal be received if the transmitting and receiving antennas were 40m and 20 m respectively above level terrain.

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135. Question: The sensitivity of a radio receiver is measure in terms of dBm. If the receiver is receiving 200 mW, what is its corresponding dBm value?

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136. Question: In acoustic find the resonant frequency of a Helmholtz resonator if the cavity volume is 1.5 m3 and a radius of 5 cm.

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137. Question: Given a DC input power of 1000 W, find the audio power necessary to modulate an RF amplifier 90%.

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138. Question: Determine the Hamming distance of the codewords (10101, 11001).

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139. Question: An antenna with noise temperature of 75 K is connected to a receiver with noise temperature of 300 K. Given the reference temp To = 240 K, find the noise figure of the system.

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140. Question: A CATV cable has a loss of 20 dBmV. To compensate, the voltage of the next amplifier should be at least:

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141. Question: A collector modulated class C amplifier has a carrier output power of 100 W, with an efficiency of 50%. Calculate the transistor power dissipation, assuming that all the power dissipation occurs at the transistor.

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142. Question: What is the phase velocity of a rectangular waveguide with a wall separation 3 cm and a desired frequency of operation 6 GHz?

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143. Question: The noise figure of a certain receiver is 40 dB if the S/N input is 20 dB, then what is the output S/N?

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144. Question: In CMTS, what is the radio capcity if the frequency reuse factor is 7 and the total channel capacity is 300?

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145. Question: A power density of 1.5710-4 W/m2 is to be measured 50 meters to a test antenna whose directive gain is 2.15 dB. How much power is fed to the test antenna?

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146. Question: In FM Broadcasting, what is the frequency range of a standard FM receiver?Solution:

147. Question: Determine the time taken for a signal to travel down a 10 m transmission line, if the velocity factor is equal to 0.7.Solution:

148. Question: What is the maximum bit rate of a system with 18 different bits at 10,000 times/second?Solution:

149. Question: For a mammography service, it examined 327 patients during the third calendar quarter of 1996. 719 films were exposed during this period, eight of which were repeated. What is the repeat rate?Solution:

150. Question: Calculate the via net loss (VNL) for a telephone signal that it takes 1.84 ms to reach its destination for a n acceptable amount of echo.Solution:

151. Question: Find the orbital period of a satellite in a circular orbit 36,000 km above the earth surface of the earth radius of 6,400 km.Solution: =

152. Question: Determine the phase shift represented by a 75 ns delay of a 4 MHz signal to a 75 ft. cable with a dielectric constant of 2.3.Solution:

153. Question: What is the total radio horizon distance between an 80 ft. transmitting station and a 20 ft. receiving station?Solution:

154. Question: An FM system has a frequency deviation of 2.5 kHz and a modulating frequency of 500 Hz. Determine the modulation index?Solution: