Tektronix DS1001, Руководство пользователя

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Glossary
Glossary–4
DS1000 Series User Manual
States, Canada, and Japan. Now, NTSC is generally used to refer to
that standard.
PAL
Phase Alternate Line. One of the television systems used in Europe
and many other parts of the world. The phase of one of the color
difference signals alternates from line to line to help cancel out
phase errors.
Quadrature AM
A process that allows two signals to modulate a single carrier
frequency. Two signals amplitude modulate carrier signals with the
same frequency but with a phase difference of 90 degrees (hence
the term Quadrature). The two resultant signals are added together
before transmission. Both signals are recovered at the receiver by
demodulating them 90 degrees apart.
Quadrature Distortion
Distortion resulting from the asymmetry of sidebands used in
vestigial sideband television transmission. Quadrature distortion
appears when using envelope detection but can be eliminated by
using a synchronous demodulator.
RF
Radio Frequency. In television applications, the television signal
after the picture carrier modulation process.
RGB
Red, Green and Blue. The three primary colors used in color
television’s additive color reproduction system. These are the three
color components generated by the camera and used by the picture
monitor to produce a picture.
Subcarrier
The high-frequency signal used for quadrature amplitude
modulation of the color difference signals. The subcarrier
frequency is 3,579,545 Hz (NTSC) or 4,433,618.75 Hz (PAL).
Synchronous Detection
A demodulation process in which the original signal is recovered
by multiplying the modulated signal with the output of a
synchronous oscillator locked to the carrier.