Tektronix 1780-R - page 116

Measurements

4–4 1780R-Series Operator’s Manual

Table 4–1: DIFF PHASE Front-Panel Configuration

VECTORSCOPE Vector display enabled, other choices locked out.

WAVEFORM R–Y sweep displayed, all front-panel choices locked out.

(There is no LED to indicate R–Y sweep.)

INPUT Status does not change. All differential modes locked out; if

a differential mode was enabled, input is forced to CH A.

REFERENCE Status does not change.

FILTER Locked out.

WFM SWEEPS Set to One Line when DIFF PHASE is selected. If

<SINGLE> mode is selected, any of the other sweeps can

be selected, using front-panel controls. If <DOUBLE> is

selected, the instrument is set to One Line. The Field, Two

Line and Three Line Sweeps are locked out.

GAINS Vectorscope and Waveform gains can be adjusted while in

DIFF PHASE mode; the new settings will be saved when

the Measurement menu is exited, and reinstated when DIFF

PHASE mode is again enabled.

WAVEFORM POSITION The Horizontal and Vertical Position controls can be

adjusted while in DIFF PHASE mode; the new settings will

be saved when the Measurement menu is exited, and

reinstated when DIFF PHASE mode is again enabled. The

Vertical Position Control range is limited in order to keep the

signal on screen.

VOLT / TIME CURSOR Not available in DIFF PHASE mode.

Noise Reduction. Touch <NOISE REDUCTION> to toggle between

<ON> and <OFF>. When noise reduction is off, the demodulator

output (500 kHz BW) is directly displayed. When noise reduction is

on, noise reduction of about 10–12 dB is accomplished without any

reduction in bandwidth.

Noise reduction can be used in both <SINGLE> and <DOUBLE>

modes.