1. A signal s(t) has frequencies in the range 300 Hz to 30 kHz. If it is transmi
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Question
1. A signal s(t) has frequencies in the range 300 Hz to 30 kHz. If it is transmitted through an ideal low pass filter with cut-off frequency fi 40 kHz, will the signal be distorted? Would your answer change if the cut-off frequency/ 20 kHz? 2. Sketch the signals corresponding to the following bit stream: 01000110 assuming a symbol duration T= 1s: a. Unipolar RZ signals b. Antipodal NRZ signals c. Manchester encoding 3. Let us suppose that you have an analog signal that needs conversion to digital. The maximum frequency component in the signal is 2 kHz. a. At what minimum rate should you sample the signal (i.e., at least how many samples per second do you need)? b. If you are quantizing the signal into 32 levels, how many bits do you need per sample? What is the data rate of the digital signal after quantization with 32 levels? What is the data rate after quantization with 64 levels? Hint: data rate= bits per second c. 4. What is amplitude modulation? How is it different from frequency modulation? Consider a transmission medium where the attenuation loss of a signal is SdB per Km. If the transmit power is 50mW, what is the received power at the end of a 5Km line? (Express your final answer in Watts or milliwatts) 5. If I have a 10000 byte file and suppose my channel's digital rate is 2000 bits per sec, how long will it take me to send the entire file? 6. What is the propagation delay to send a 10 MB file on a 1000 mile link with a propagation speed of 2x108m/su miles 1609.34 meters) 7. Continuing from 7) what is the total delay experienced when sending the file if the channel data rate is 1 Mbps? Hint: total delay transmission delay+ propagation delay 8. FocusExplanation / Answer
1) Maximum frequency of signal is 30 KHz and cut off frequency is 40 KHz.Hence signal will not be distorted.
if cut off frequency is 20 KHz which is less than Maximum frequency of signal i.e. 30 KHz Hence signal will be distorted.
3) a) According Shannon's sampling theorem sampling frequency should be atleast twice the maximum frequecy of signal source.since maximum frequency of signal is 2 KHz, sampling frequency shoul be atleast 4 KHz
b)If signal is to be quantized to 32 levels we wll need 5 bits as 5 bits will produce 25 = 32 quantized levels.
c) Since sampling frequency is 4 KHz hence data rate after quantiztion 4 K byte /Sec
Even if quantization level is 64 levels ata rate after quantiztion 4 K byte /Sec
4)Amplitude modulation is a modulation technique used for transmitting information via a carrier wave.In Amplitude Modulation, the amplitude of the carrier wave is varied in proportion to the signal to be transmitted.
Frequency modulation is the encoding of information in a carrier wave by varying the instantaneous frequency of the carrier wave.This contrasts with Amplitude modulation in which the amplitude of the carrier wave varies,while frequency remains constant.
6) 10000 byte file on channel with digital data rate of 2000 bits per second will take 10000/ 2000 = 5 seconds.
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