Tektronix 1760 Manual do Utilizador descarregar pdf (Página 118)

Basic Measurements

1760 Series Component Waveform/Vector Monitor User Manual

4-18

of checking timing. The signal source can be adjusted until

the ellipse disappears, providing a very accurate method of

correcting timing errors.

Timing errors are indicated by the trace moving away from

the center timing dot. See Figure 4-15. For wide-band (≥1.5

MHz) component form ats, the smaller spacings of dots repre-

sent approximately 40 ns of error; the larger spacing repre-

sents 80 ns. The timing dots represent proportionally larger

errors for lower ba ndwi dth signals.

For signals decoded from composite (bandwidth of approxi-

mately 500 kHz), the timing dots represent approximately

120 and 240 ns, respectively. The transitions will be “S”

shaped due to the narrow-band col or difference signals. Note

that correct timing is always indicated by a transition through

the center dot, regardless of the signal bandwidth.

If a trace appears “bent” toward the center of the display,

delay of t he c olor difference signal is indicated. “Bending”

away from center indicates an advance of the color differ-

ence signal relative to luminance.

Approximate 80 ns

delay of Channel 2.

Figure 4-15. Lightning display showing delay.

1 2 ... 113 114 115 116 117 118 119 120 121 122 123 ... 179 180

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Tektronix 1760 Manual do Utilizador Página 118