This page contains general information used in the fiber optic world. It is a reference area if you forget the facts. Contained here is a Transmission Rate Table, a Reference Dimensions and Nomenclature for Expressing Values of Physical Quantities, General Fiber Measurement information, tabular Correlation of dB Loss to Percent Loss, a Power to dBm Conversion table, and a Fiber Color Code Chart
| MEDIUM | DESIGNATION | BIT RATE (Mbps) | VOICE CHANNELS | REPEATER SPACING, miles |
| Twisted Pair | ||||
| DS-1 | 1.544 | 24 | 1 | |
| DS-1C | 3.152 | 48 | ||
| DS-2 | 6.312 | 96 | ||
| Coaxial Cable | DS-3 | 44.736 | 672 | |
| Fiber(SONET) | OC-1 | 51.84 | 672 | 25 (LASER) |
| OC-3 | 155.52 | 2016 | 2 (LED) | |
| OC-12 | 622.08 | 8064 | ||
| OC-24 | 1244.16 | 16,128 | ||
| OC-48 | 2488.32 | 32,256 | ||
| OC-96 | 4976.64 | 64,512 | ||
| OC-192 | 9953.28 | 129,024 |
Standard Prefixes
milli (m), thousandths or 1 x 10-3
micro (
m ), millionths or 1 x 10-6 = (0.000001)nano (n), billionths or 1 x 10-9
pico (p), trillionths or 1 x 10-12
kilo (k), thousand or 1 x 103
mega (m), million or 1 x 106
giga (g), billion or 1 x 109
tera (t), trillion or 1 x 1012
1. WAVELENGTHS
1 micron or micrometer, also 1 m = one millionth of a meter (10-6) in length
1 nanometer, also 1 nm = one billionth of a meter (10-9) in length
Example: 800 nm to 900 nm wavelength fiber
2. FIBER DIAMETERS
1 micron or micrometer, also 1 m = one millionth of a meter (10-6) in diameter
Fiber core and cladding dimensions
Example: 62.5/125m fiber
Represents 62.5 micron outside diameter core and 125 micron outside diameter cladding.
3. FREQUENCY MEASUREMENT
One Hertz (Hz) = one cycle
4. BANDWIDTH OF FIBER
MHz . km represents the multimode fiber bandwidth available for 1Km
ps/nm . km expresses the dispersion for SM fibers spectral width
5. SPEED OF LIGHT
Speed at which lightwaves travel in free space.
300 million meters per second or 186,000 miles per second.
6. CORRELATION OF DB LOSS AND PERCENT LOSS
dB Loss =10 log10 Eout/Ein where E is energy (i.e. light)
|
dB Loss |
Percent Loss |
Power Remaining |
|
0.005 |
0.100 |
99.9% |
|
0.05 |
1.000 |
99.0% |
|
0.22 |
5.000 |
95.0% |
|
0.46 |
10.00 |
90.0% |
|
0.97 |
20.00 |
80.0% |
|
1.55 |
30.00 |
70.0% |
|
2.22 |
40.00 |
60.0% |
|
3.01 |
50.00 |
50.0% |
|
3.98 |
60.00 |
40.0% |
|
5.23 |
70.00 |
30.0% |
|
6.99 |
80.00 |
20.0% |
|
10.0 |
90.00 |
10.0% |
|
13.0 |
95.00 |
5.0% |
|
20.0 |
99.00 |
1.0% |
|
30.0 |
99.90 |
0.10% |
|
40.0 |
99.99 |
0.01% |
Sometimes the ratio for calculating loss or gain uses a constant for Eout. In fiber optics this value is usually 1 milliwatt (mW).
dBm = 10 log10 (Eout/1 m W)
dBm means "decibels referenced to a milliwatt". In this case the negative sign is almost always used.
A value of -10 dBm means that E is 10 dB less than 1 mW, or 100 mW.
also 10% of 1mW = 0.1 x 10-3 or 100 x 10-6 = 100 mW
similarly, -3 dBm is 500 mW, since 50% of 1mW = 0.50 x 10-3 or 500 x 10-6 = 500 mW
Various dBm values as related to milliwatt and microwatt levels are shown below.
Power to dBm Conversion
|
10mW |
= |
+10.0 dBm |
|||
|
5mW |
= |
+7.00 dBm |
|||
|
1mW |
= |
0.00 dBm |
|||
|
500mW |
= |
-3.00 dBm |
|||
|
100mW |
= |
-10.0 dBm |
|||
|
50mW |
= |
-13.0 dBm |
|||
|
10mW |
= |
-20.0 dBm |
|||
|
5mW |
= |
-23.0 dBm |
|||
|
1mW |
= |
-30.0 dBm |
|||
|
100nW |
= |
-40.0 dBm |
|||
|
10nW |
= |
-50.0 dBm |
|||
|
1nW |
= |
-60.0 dBm |
|||
|
100pW |
= |
-70.0 dBm |
|||
|
10pW |
= |
-80.0 dBm |
|||
|
1pW |
= |
-90.0 dBm |
|||
7. LENGTHS OR DISTANCES
1 mile = 5,280 feet
1 meter = 39.37 inches = 3.28 feet = 1.093 yards
10 Kilometers = 6.2 miles
8. MISCELLANEOUS
1 million hours = about 113 years
FIBER COLOR CODE
