Tektronix 1780-R - page 117

Measurements

1780R-Series Operator’s Manual 4–5

NOTE. Freeze only available with Noise Reduction ON.

Freeze. To capture the display (right CRT only), touch <NOISE

REDUCTION> so that <ON> is outlined, then touch <FREEZE>.

<FREEZE> will be outlined.

The captured display remains on the screen even if the input signal is

removed. The display is lost when the DIFF PHASE menu is exited

by any method, including touching <GO TO DIFF GAIN>, pushing

any of the four front-panel menu buttons, pushing the front-panel

LINE SELECT button to enter Line Select mode, changing the

selected line if already in Line Select mode, or turning instrument

power off.

To exit Freeze mode, touch <FREEZE> again.

DIFF PHASE Measurement Information

The 1780R-Series provides two methods of making differential

phase measurements: single- and double-trace.

The single-trace method of differential phase measurement

resembles the single-trace differential phase mode on the 520A-Se-

ries. This method requires the operator to normalize the gains, but

those settings will be stored and recalled at next entry to DIFF

PHASE mode. The amount of distortion is read from the graticule

scale.

The double-trace method of differential phase measurement

resembles the double-trace differential phase in the R520A-Series.

This method requires the operator to null the space between the ends

and individual steps of the two traces. This provides greater accuracy

than the single-trace method, and gives an on-screen readout of the

distortion measurement.

Single-Trace DIFF PHASE Measurement Procedure

1. Apply a staircase signal or a ramp signal with subcarrier to the

1780R-Series.

2. Touch <SINGLE>.