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Measurements
4–18
1780R-Series Operator’s Manual
The 1780R-Series ICPM measurement method is similar to the
Tektronix 1480-Series method. Refer to the 1450 manual for details
on configuring the demodulator for this measurement. The external
low-pass filters (Tektronix P/N 015-0352-00) can be used to improve
the display.
ICPM Measurement Procedure
1. Connect the Quadrature Out of the 1450 or TV1350 Demodulator
to the 1780R-Series EXT HORIZ Input and the Video Out to the
selected 1780R-Series input channel.
2. Push the MEASURE button to enable the Measurement menu.
For in-service ICPM measurements, LINE SELECT can be used
to select the desired line (zero reference pulse, then modulated
staircase signal.) For software versions 1.13 and up: LINE
SELECT can be used to select two lines for an overlaid display.
Push the front-panel LINE SELECT button, then touch the circle
in the lower left portion of the vectorscope CRT to assign large
knob function. Select the line and field where the zero reference
pulse is located. To select the second line, touch the circle in the
lower left portion of the waveform touch screen, and select the
line and field where the modulated staircase signal is located.
Touch the ICPM error readout area of the waveform CRT to
return the large knob assignment to the graticule, then proceed to
step 3.
3. Turn intensity to maximum, to locate the position of the trace off
screen. Use the 1780R-Series Horizontal Position control to
center the signal horizontally, and the Vertical Position control to
set the zero carrier reference point to the center of the electronic
graticule plus mark (+). See Figure 4–5. Turn down intensity for
normal viewing.
4. If no ICPM is present on the carrier, the display between
blanking and zero carrier will line up on the vertical axis. If
ICPM is present, the display will tilt. Use the precision control
(large knob) to adjust the electronic graticule until it just touches
the portion of the signal with the greatest error. Adjust the
Magnification factor as needed to best view the error.
Measurements
4–18
1780R-Series Operator’s Manual
The 1780R-Series ICPM measurement method is similar to the
Tektronix 1480-Series method. Refer to the 1450 manual for details
on configuring the demodulator for this measurement. The external
low-pass filters (Tektronix P/N 015-0352-00) can be used to improve
the display.
ICPM Measurement Procedure
1. Connect the Quadrature Out of the 1450 or TV1350 Demodulator
to the 1780R-Series EXT HORIZ Input and the Video Out to the
selected 1780R-Series input channel.
2. Push the MEASURE button to enable the Measurement menu.
For in-service ICPM measurements, LINE SELECT can be used
to select the desired line (zero reference pulse, then modulated
staircase signal.) For software versions 1.13 and up: LINE
SELECT can be used to select two lines for an overlaid display.
Push the front-panel LINE SELECT button, then touch the circle
in the lower left portion of the vectorscope CRT to assign large
knob function. Select the line and field where the zero reference
pulse is located. To select the second line, touch the circle in the
lower left portion of the waveform touch screen, and select the
line and field where the modulated staircase signal is located.
Touch the ICPM error readout area of the waveform CRT to
return the large knob assignment to the graticule, then proceed to
step 3.
3. Turn intensity to maximum, to locate the position of the trace off
screen. Use the 1780R-Series Horizontal Position control to
center the signal horizontally, and the Vertical Position control to
set the zero carrier reference point to the center of the electronic
graticule plus mark (+). See Figure 4–5. Turn down intensity for
normal viewing.
4. If no ICPM is present on the carrier, the display between
blanking and zero carrier will line up on the vertical axis. If
ICPM is present, the display will tilt. Use the precision control
(large knob) to adjust the electronic graticule until it just touches
the portion of the signal with the greatest error. Adjust the
Magnification factor as needed to best view the error.