Qiz 1 Q1: 1.A periodic signal has a bandwidth of 20 Hz the highest frequency is 60Hz. what is the lowest frequency. a.20 b.40 c.60 d.30 2. find the value of bandwidth of the following signal S(t)=(1/5) sin (2ᴨ 8t +3ᴨ/4)+ sin (2ᴨ 3t+ᴨ/3) sin (2ᴨ 4t). a.8 b.15 c.4 d.5 3.discrete time signals can be obtained by ----------- a continuous-time signal. a. sampling b. digitizing c.defined d. none 4.the --------- signal is the fundamental periodic signal. a. square b. discrete c. sine wave d. analogue 5.the system that has the input output relationship y[n]=x[n]x[n-2] is called. a. memoryless b. memory c. causal d.[b and a] 6.find the length of output sequence y[n]=x[n]*h[n] if X[n] ={2,1, (-1),-2,-3} and h[n]={1,( 2),0,-3}; a.9 b.8 c.7 d. none Q2: An LTI system has the impulse response h[n]={1,(2),-1} and the input x{n]={(4),1,2,5}; the underline locates the n=0 value. Find the output sequence y[n]=x[n]*h[n].expressed both as a list and as a steam plot.
Qiz 2 Q1: 1.in guided media, the characteristics and quality is determined by ------ a. medium b. bandwidth c. transmission d. interference 2.the ratio of the total power radiated by an antenna to the net power accepted by the antenna from the connected transmitter. a. radiation efficiency b. antenna gain c. directionality d. effective aperture 3.------- can be produced from competing signals in overlapping frequency bands. a. bandwidth b. transmission c. interference d. attenuation 4.------- consists of two insulated copper wires arranged in a regular spiral pattern. a. optical fiber b. coaxial cable c. copper coaxial d. twisted pair 5.-----any light ray incident on the boundary above the critical angle will be reflected internally. a. single-mode fiber b. multimode fiber c. optical fiber d. copper coaxial cable 6.fourier series decomposes the 0dd functions periodic input signal as a. b. c. d. Q2: 1.in unguided media the transmission occurs through the atmosphere, outer space,or water ( ) 2.twisted pair generally suffers more impairment then coaxial cable, which in turn suffers more then optical fiber ( ) 3.coax-cable carries signals of lower frequency ranges then those in twisted pair cable ( ) 4.omni-directional antenna has a single peak direction in the radiation pattern ( )
Mid 1 Q1: 1.A time-invariant system has the property that a certain input will always give the same output, without regard to time ( ) 2.Absolute bandwidth narrow band of frequency containing most energy ( ) 3.the system is invertible if the input signal can be uniquely recovered from the output signal ( ) 3.in full duplex both station can be transmit at the same time ( ) 4.attenuation is grater at lower frequencies and this causes distortion ( ) 5.increasing the bit rate can increase the signal guilty ( ) 6.in multi-point more than two devices share the link ( ) 7.the output of causal system is depends on values of the input at the present, past and future ( ) Q2: 1. A periodic signal has a bandwidth of 30Hz the highest frequency is 80Hz. what is the lowest frequency. a.20 b.50 c.60 d.30 2.------- consisting of irregular pulses or spikes of short duration and high amplitude. a. thermal noise b. intermodulation noise c. crosstalk d. impulse noise 3.the power of a signal is 50mW and the power of the noise is 5u W; whet are values of SNRdB. a.40db b.10000 db c.10db d. none 4.the ----- is the distance between two points of corresponding phase of two consecutive cycles. a. wavelength b. frequency c. bandwidth d. none
5.if the two system are in -------- with each other, their order can be interchanged without affecting the overall output of the system. A. cascaded b. parallel c. individual d. none 6.the digital signal has a number of frequencies equal--------- a. infinite b. finite c. one d. none 7.the --------- signal is the fundamental periodic signal. a. square b. discrete c. sine wave d. analogue Q3: 1. An LTI system has the impulse response h[n]={1,(2),0,-3} and the input x{n]={2,1,(-1),-2,-3}; the underline locates the n=0 value. Find the output sequence y[n]=x[n]*h[n].expressed both as a list and as a steam plot. 2. Given a channel with an intended capacity of 20 Mbps, the bandwidth of the channel is 3 Mhz. Assuming white thermal noise, what signal-to-noise ratio is required to achieve this capacity?
3. Given a channel with an intended capacity of 24 Mbps, the bandwidth of the channel is 6 Mhz. Assuming white thermal noise, what signal-to-noise ratio is required to achieve this capacity? Q4: 1. For the following input-output relationship, determine whether the corresponding system is time invariant, or not Y[n]= 10 x[n] 2. Compare between the periodic and aperiodic signals and write the function declare it.
3. Find the following with drawing 1 Find: Amplitude, Freq, phase 1. S(t)= 2sin(2ᴨ5t+3ᴨ/4) with drawing. 2. S(t)= 3sin(2ᴨ3t+3ᴨ/4) with drawing. 2 1. 2U(t+2) 2. 5u(t+5) 3 1. 2U[n-1] 2. 3u[n-1] 4 1. ϐ(t-3) 2. β(t-2) 5 1. ϐ[n-4] 2. ϐ[n-2] 6 Find 1. x[n+3] 2. x[n-5]
Mid2 Q1: 1.one of line coding schemes is ------- which has two voltage, levels, one positive and the other one negative. a. unipolar b. polar c. bipolar d. differential 2.the inverse fourier transform of unit impulse β(w). a. 0 b. 1/2ᴨ c. 1 d. none 3.------- is the process of encoding source data onto a carrier signal with frequency fc. a. demodulation b. decoding c. modulation d. encoding 4.the aperiodic analogue signals be analyzed in terms of frequency components by using. a. fourier transform b. fourier series c. time domain d. none 5.the input source signal m(t) in the modulation is called. a. modulated signal b. modulatating signal c. carrier signal d. digtal signal 6.manchester is an example of -------- conversion. a. digital to digital b. digital to analoge c. analoge to digital d. analoge to analoge 7.lack of synchronization in NRZ-L is occurred when the data contain a long streams of ----- a. 0s b. 1s c. bits d. (a and b) 8. receiver needs to know -------- a. timing of bits b. signal levels c. transmission impairment d. (a.b) 9. image processing can be used --------- to convert the image from time domain into frequency domain. a. encoding b. fourier series c. fourier transform d. discrete fourier transform 10. -------- can be used to replace the original data sequences with filling sequences of the same length to reduce synchronization.
a. bipolar AMI b. pseudonternary c. scrambling b. differential Manchester Q2: 1.find the fourier transform for the following signal X(t)= e bt u(t) 2.Assume a stream of the following string [ 0 1 0 0 1 1 1 0 0 1 1 ]. Encode the stream using the following schemes; NRZ-I, AMI, Manchester, Differential Manchester. using 0 1 0 0 1 1 1 0 0 1 1 NRZ-I AMI Manchester Differential Manchester 3.Sketch the signal waveforms when 11000000001100 is transmitted in the following signal codes. 1. B8ZS 2. HDB3 Using 1 1 0 0 0 0 0 0 0 0 1 1 0 0 B8ZS HDB3
Q3: what are the factors affecting signal interpretation? 1. 2. 3. 4. what are the Satellite communication configuration? 1. 2. what are the Wireless propagation methods? 1. 2. 3. compare between pros and cons of Biphase? pros cons what is the difference between unshielded twisted pair and shielded twisted pair? UTP STP