ecet hwk chap2

ecet hwk chap2

2-10 Define frequency Spectrum and bandwidth
Frequency spectrum is the wide range of frequencies found in the Frequency domain.
Bandwidth is the specific start and stop of the allowable frequency range.
2-11 Define electrical noise
Any undesirable electrical energy that falls within the pass band of a signal.
2-12 give a brief description of the following forms of electrical noise; man-made, thermal, correlated and impulse
Man-made: noise that is produced by device.
Thermal: is the rapid and random movement of electrons agitating and is present in all electronic components and communications systems.
Correlated: noise that is mutually to the signal and must not be present in a circuit.
Impulse - are high-amplitude peaks of short duration in the total noise spectrum.

2-16 Brief describe the significant of the Shannon limit for information capacity.
Shannon limit indicates that the higher the signal to noise the better the BER.

2-17 What is meant by the M-ary encoding?
M-ary comes from the term "binary", but M represents a digit concerning the number of conditions, levels, or combinations possible for a given number of binary variables.

problem chap2

Problems Chap 2

using shannon-hartley theorem
signal to noise ratio, SNR = 20 dB or 10000
that is , S/N = 10000
Bandwidth, B = 100 kHz

C = B*log(1 + S/N) [log is taken in base 2]
C = 100*log(1+10000) kbps
C = 1328785.66 bps

If by number of conditions it means the number of different combinations then,
for n bits,
number of different conditions = 2^n
for exaple for n = 2 , (00,01,10,11) that is total 2^2 = 4

using this
a. = 2^3 = 8
b. = 2^5 = 32
c. = 2^7 = 128
d. = 2^12 = 4096

M - number of different levels in signal
M = 2^no. of bits = 2^4

B - bandwidth
B = 10000 Hz

highest bit rate possible = 2*B*log(M) [log is in base 2]
highest bit rate possible = 2*10000*log(2^4) bps
highest bit rate possible = 80000 bps

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