Functional Block Diagram - Blonder Tongue Laboratories Inc.

Broadband Specification Guide
CATV Terms & Definitions
Passive
Describing a device which does not contribute energy to the signal
it passes.
Phase Lock
The control of an oscillator such that its output signal maintains a
constant phase angle relative to a second, reference signal.
Photodetector
Any device which detects light, generally producing an electronic signal
with intensity proportional to that of the incident light.
Photodiode
A diode designed to produce photo-current by absorbing light.
Photodiodes are used for the detection of optical power and for the
conversion of optical power to electrical power.
Photon
A quantum of electromagnetic energy.
Pico-
A prefix denoting one millionth of a millionth; one trillionth (10-11).
Pronounced "pie-ko."
Pigtail
A short length of optical fiber, permanently fixed to a component, used to
couple lightwave power between it and the transmission fiber.
PIN Photodiode
A diode with a large intrinsic region sandwiched between p-doped and
n-doped semiconducting regions. Photons absorbed in this region create
electron-hole pairs that are then separated by an electric field, thus
generating an electric current in a load circuit.
Plant
A general term applied to any of the physical property of a
service company, which contributes to the furnishing of power or
communication services.
Polarization
A waveform characteristic of electromagnetic radiation. Two types of
polarizations are used, linear (horizontal and vertical) and circular (right
and left hand).
Power
Energy per unit of time.
Pre-Amplifier
Low noise amplifier usually mounted in close proximity to a receiving
antenna. Used to compensate for down lead losses.
Pulse Broadening
An increase in pulse duration. Note: Pulse broadening may be specified
by the impulse response, the root-mean-square pulse broadening, or the
full-duration-half-maximum pulse broadening.
Pulse Decay Time
The time required for the instantaneous amplitude of an electrical wave
to go from 90% to 10% of the peak amplitude.
Pulse Length
The time duration of the burst of energy emitted by a pulsed laser; also
called pulse width. Usually measured at the "half-power" points (0.707
times the full height of a voltage or current pulse).
Pulse Rise Time
The time required for the instantaneous amplitude of an electrical wave
to go from 10% to 90% of the peak amplitude.
Quadrature Amplitude Modulation (QAM)
QAM is a modulation technique employing both phase and amplitude
modulation. It is widely used to transmit digital CATV programs and cable
Internet service. There are different QAM levels based upon the number
of modulation states used. QAM64 utilizes 6 bits for 64 modulation
states, QAM128 uses 7 bits for 128 states, QAM 256 uses 8 bits for 256
states, etc.
Quadrature Phase Shift Keying (QPSK)
QPSK uses four phase angles to represent each 2 bits input. It is similar
to QAM4 without amplitude modulation. QPSK is used in many CATV
satellite transmissions.
Radiant Energy
Energy (joules) which is transferred via electromagnetic waves; there is
no associated transfer of matter.
Ray
A geometric representation of a light path through an optical device:
a line normal to the wave front indicating the direction of radiant
energy flow.
Rayleigh Scattering
Scattering of a lightwave propagating in a material medium due to the
atomic or molecular structure of the material and variations in the structure
as a function of distance. The scattering losses vary as the reciprocal of
the fourth power of the wavelength. The distances between scattering
centers are small compared to the wavelength. Rayleigh scattering is
the fundamental limit of fiber loss in the operating wavelength region
(0.8-1.6 um) of optical fiber systems.
Ratio
The relative size of two quantities indicated by the quotient obtained by
dividing one quantity by the other.
Receiver
A unit including a detector and signal-processing electronics that converts
optical input into electronic output; often used in communications.
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