Tektronix 1740A/1750A Instrukcja Użytkownika Pobierz pdf (Strona 90)

Basic Measurements

1740A/1750A Series Waveform/Vector Monitor User Manual

4-9

MakingVectorMeasurements

Chroma Bandwidth

The horizontal and vertical axes of the vector graticule

contain markings for checking chroma bandwidth. A subcar-

rier frequency sine wave (whose amplitude places it on the

outer compass rose) is used as a reference. When the fre-

quency is changed, the diameter of the circle should reduce.

At a point equal to 70% of full amplitude (--3 dB), there are

gaps in the horizontal and vertical axes. This calibration aid

makes it possible to check the --3 dB points of the demodula-

tor output amplifiers.

Differential Phase and Gain

Differential gain (dG) and differential phase (d∅) measure-

ments use the graticule markings located at the outer edge of

the B -- Y or U axis. See Figure 4-5.

2°

dφ

Figure 4-5. Differential Gain and Phase Measurements.

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