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 G 1 = 35dB and G 2 = 15dBm. Using logarithms, find L in dB – (L dB )

4. A t [ms] 2V 2 4 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, 3x10 8 m/s)

5. Question 4 A signal is represented as follows: S(t) = A sin(2.π.f 0.t) + B sin(6.π.f o.t) + C sin (10.π.f o.t) If the fundamental period, T o, is 5  secs find:- the fundamental frequency the frequency of the 1 st harmonic the frequency of the 2 nd harmonic the bandwidth of the signal using up to an additional harmonic. (3 rd )

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 1 sh and 4 th harmonic. The bandwidth of the system if the following upper limit is imposed: The amplitude of the n th 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.