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"cell_type": "markdown",
"metadata": {},
"source": [
"# Chapter 25 : Fiber Optic Systems"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 1 : pg 919"
]
},
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"name": "stdout",
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"text": [
"The system margin is 7.011 dB\n"
]
}
],
"source": [
" \n",
"# page no 919\n",
"# prob no 25_1\n",
"#calculate the system margin\n",
"#given\n",
"from math import log10\n",
"span_length = 40#in km\n",
"Pin_mW = 1.5\n",
"signal_strength_dBm = -25\n",
"fiber_length = 2.5#in km\n",
"loss_per_slice_dB = 0.25\n",
"f_loss_dB_per_km = 0.3\n",
"loss_connector_dB = 4\n",
"#calculations\n",
"Pin_dBm = 10 * log10(Pin_mW)\n",
"splices = span_length / fiber_length - 1\n",
"fiber_loss = span_length * f_loss_dB_per_km\n",
"splice_loss = splices * loss_per_slice_dB\n",
"T_loss = fiber_loss + splice_loss + loss_connector_dB\n",
"P_out = Pin_dBm - T_loss\n",
"sys_margin = P_out - signal_strength_dBm\n",
"#results\n",
"print 'The system margin is',round(sys_margin,3),'dB'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 2 : pg 921"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The maximum permissible value for the pulse-spreading constant is 2.22 ns/km\n"
]
}
],
"source": [
" \n",
"# page no 921\n",
"# prob no 25_2\n",
"#calculate the max permissible value\n",
"#given\n",
"L=45;#in km\n",
"dt=100.;#in ns\n",
"#calculations\n",
"#The maximum permissible value for the pulse-spreading constant is \n",
"D=dt/L;\n",
"#results\n",
"print 'The maximum permissible value for the pulse-spreading constant is',round(D,2),'ns/km'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 3 : pg 922"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a) The maximum bit rate for NRZ 0.00743 GHz\n",
"b) The maximum bit rate for NRZ 0.00371 GHz\n"
]
}
],
"source": [
" \n",
"# page no 922\n",
"# prob no 25_3\n",
"#calculate the max bitrate in both cases#given\n",
"#given\n",
"from math import sqrt\n",
"L=45.;\n",
"T_Rtx=50.; T_Rrx=75.; T_Rf=100.;\n",
"#calculations and results\n",
"T_RT=sqrt(T_Rtx**2 + T_Rrx**2 + T_Rf**2);\n",
"# a) for NRZ\n",
"fb=1/T_RT;\n",
"print 'a) The maximum bit rate for NRZ',round(fb,5),'GHz'\n",
"# b) for RZ\n",
"fb=1/(2*T_RT);\n",
"print 'b) The maximum bit rate for NRZ',round(fb,5),'GHz'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 4 : pg 924"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Dispersion is 1.0 ns/km\n",
"Total rise time is 5.0 ns\n"
]
}
],
"source": [
" \n",
"# page no 924\n",
"# prob no 25_4\n",
"#calculate the total rise time and dispersion\n",
"#given\n",
"Bl=500.;#in MHz-km\n",
"L=5.;#in km\n",
"#calculations and results\n",
"# using the bandwidth-distance product formula dispersion is given as\n",
"D=500/Bl;\n",
"print 'Dispersion is',D,'ns/km'\n",
"# Total rise time is given as\n",
"T_rt= D*L;\n",
"print 'Total rise time is',T_rt,'ns'"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 5 : pg 924"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"The maximum acceptable dispersion is 0.139 ns/km\n",
"The bandwidth-distance product is 3608.439 MHz-km\n"
]
}
],
"source": [
" \n",
"# page no 924\n",
"# prob no 25_5\n",
"#calculate the max acceptable dispersion and bandwidth-distance product\n",
"#given\n",
"from math import sqrt\n",
"T_Rrx=3.*10**-9;\n",
"T_Rtx=2.*10**-9;\n",
"fb=100.*10**6;#in bps\n",
"L=25;#in km\n",
"#calculations and results\n",
"T_RT = 1/(2*fb)\n",
"# we have to compute rise time therefore\n",
"T_rf= sqrt(T_RT**2 - T_Rtx**2 - T_Rrx**2)\n",
"# dispersion per km is\n",
"D= T_rf/L;\n",
"print 'The maximum acceptable dispersion is',round(D/10**-9,3),'ns/km'\n",
"# using the bandwidth-distance product\n",
"Bl=500/D;\n",
"print 'The bandwidth-distance product is',round(Bl*10**-9,3),'MHz-km'"
]
}
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