Handbook for Sound Engineers

476 Chapter 15

B. Distortion in decibels (dB).

C. Operating temperature range in degrees Celsius

(°C).

2. If system is digital:
   A. Required BER. Upper BER is usually in mega-
   bits per second (Mbps). Lower BER is usually in
   bits per second (bps).
   B. Operating temperature range in degrees Celsius
   (°C).


3. If system is audio/video:
   A. Bandwidth in hertz (Hz) or megahertz (MHz).
   B. Distortion in decibels (dB).
   C. Crosstalk in decibels (dB) (for multiple channels).
   D. Operating temperature in degrees Celsius (°C).

15.11.1.1 Transmitter Specifications

1. Input impedance in ohms (:).


2. Maximum input signal in dc volts (Vdc), rms or
   effective volts (Vrms), peak-to-peak volts (Vp-p).


3. Optical wavelength in micrometers (μm) or nano-
   meters (nm).


4. Optical power output in microwatts (μW) or (dBm).


5. Optical output rise time in nanoseconds (ns).


6. Required power supply dc voltage, usually
   5 ±0.25 Vdc or 15 ±1 Vdc.

15.11.1.2 Light Source Specifications

1. Continuous forward current in milliamps (mA).


2. Pulsed forward current in milliamps (mA).


3. Peak emission wavelength in nanometers (nm).


4. Spectral width in nanometers (nm).


5. Peak forward voltage in dc volts (Vdc).


6. Reverse voltage in dc volts (Vdc).


7. Operating temperature range in degrees Celsius (°C).


8. Total optical power output in microwatts (μW).


9. Rise/fall times in nanoseconds (ns).

15.11.1.3 Fiber Specifications

1. Mode—single or multimode.


2. Index—step or graded.


3. Attenuation in decibels per kilometer (dB/km).


4. Numerical aperture (NA) (a sine value).


5. Intermodal dispersion in nanoseconds per kilo-
   meter (ns/km).


6. Core and cladding diameters in micrometers (μm).


7. Core and cladding index of refraction (a ratio).


8. Bend radius of fiber in centimeters (cm).


9. Tensile strength in pounds per square inch (psi).

15.11.1.4 Cable Specifications

1. Number of fibers (a unit).


2. Core and cladding diameters in micrometers (μm).


3. Cable diameter in millimeters (mm).


4. Minimum bend radius in centimeters (cm).


5. Weight in kilograms per kilometer (kg/km).

15.11.1.5 Detector Specifications

1. Continuous forward current in milliamps (mA).


2. Pulsed forward current in milliamps (mA).


3. Peak reverse voltage in dc volts (Vdc).


4. Capacitance in picofarads (pF).


5. Wavelength in micrometers (μm) or nanometers
   (nm).


6. Quantum efficiency (K) in percent (%).


7. Responsivity in amps per watt (A/W).


8. Rise/fall time in nanoseconds (ns).


9. Monitor dark current in nanoamperes (nA).


10. Active area diameter in micrometers (μm).


11. Gain coefficient in volts (V) (for APD).


12. Operating temperature in degrees Celsius (°C).

15.11.1.6 Receiver Specifications

1. Output impedance in ohms (:).


2. Output signal in dc volts dc (Vdc), rms or effective
   volts (Vrms), peak-to-peak volts (Vp-p).


3. Optical sensitivity in microwatts (μW), nanowatts
   (nW), decibels referenced to 1 mW (dBm), or
   megabits per second (Mbps).


4. Optical wavelength for rated sensitivity in nanome-
   ters (nm).


5. Maximum optical input power (peak) in micro-
   watts (μW) or (dBm).


6. Analog/digital rise and fall time in nanoseconds (ns).


7. Propagation delay in nanoseconds (ns).


8. Required power supply in dc volts (Vdc).


9. TTL compatibility.


10. Optical dynamic range in decibels (dB).


11. Operating temperature in degrees Celsius (°C).

15.11.2 Design Considerations

Before designing a fiber optic system, certain factors

must be realized.

1. What type of signal information is it?


2. Is signal analog or digital?


3. What is the information bandwidth?


4. What power is required?