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Question 1 Find the following using dB and dBm transformations: a) Power in dB for 22 W

Question 1 Find the following using dB and dBm transformations: a) Power in dB for 22 W b) Power in dBm for 4.8 W c) Power in W for 25 dB. d) Power in mW for -2 dBm e ) Power in dBm for 35 dB f ) Power in dB for -10 dBm. Question 2

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Question 1 Find the following using dB and dBm transformations: a) Power in dB for 22 W

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  1. Question 1 Find the following using dB and dBm transformations: a) Power in dB for 22 W b) Power in dBm for 4.8 W c) Power in W for 25 dB

  2. d) Power in mW for -2 dBm • e) Power in dBm for 35 dB • f) Power in dB for -10 dBm

  3. Question 2 The Free Space Loss (FSL) formula for 2 non-isotropic antennas (which will be looked at further in lectures 2 and 3) is:- The antennas are separated by 300 metres and the wavelength, λ, of the transmitter signal is 1cm (d = 300 m, λ = 0.01 m). Also the gains of the antennas are G1 = 35dB and G2 = 15dBm. Using logarithms, find L in dB – (LdB)

  4. A 2V 2 4 t [ms] Question 3 For the Waveform shown in Figure 1 answer the following questions: • Figure 1 – Sine Wave • What is the Amplitude of the Waveform • What is the frequency, f, of the waveform (Expressed in KHz) • Calculate the wavelength, λ (Express it in cm). • Write the mathematical expression for the waveform. • (Hints: f = 1/T ; λ = c/f , where c = speed of light, 3x108m/s)

  5. Question 4 A signal is represented as follows: S(t) = A sin(2.π.f0.t) + B sin(6.π.fo.t) + C sin (10.π.fo.t) If the fundamental period, T o, is 5 secs find:- • the fundamental frequency • the frequency of the 1st harmonic • the frequency of the 2nd harmonic • the bandwidth of the signal using up to an additional harmonic. (3rd)

  6. Question 5 A periodic signal is used in a binary communications system. The Fourier expansion of the signal is given by the equation: If the amplitude of the signal is 12 Volts and the period is 25 ms, find: • The amplitude of the 1sh and 4th harmonic. • The bandwidth of the system if the following upper limit is imposed: • The amplitude of the nth harmonic is greater than 1/100 of the amplitude of the fundamental.

  7. Calculate how many harmonics are needed to obtain a bandwidth of 0.8KHz • Calculate the wavelength of the signal

  8. Question 6 Draw an approximate graph of the frequency domain representation of the following waveform. Identify on the graph: • the fundamental frequency • the frequency of each harmonic. Calculate the bandwidth of the system.

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