Tektronix 1710J Series, Instruction Manual

Page: 57 / 252

1710J-Series Waveform Monitors
3–1
Reference
This section discusses how to use the graticules to make measurements.
Following the graticules there is more information on the measurements that can
be made with the 1710J-Series Waveform Monitor.
Graticules
There are two graticule patterns available for the 1710J-Series Waveform
Monitors. They are etched into the CRT face and edge illumination. The
graticule used by the 1710J is a 525 line/60 Hz NTSC Composite scale. The
1711J has the CCIR 625 line/50 Hz graticule for the PAL color standard.
Because the internal graticule is on the same plane as the CRT phosphor it
eliminates viewing and photographic parallax errors. The graticule is illumi-
nated, using a front-panel SCALE adjust control, so that the level of graticule
brightness can be adjusted to optimum for viewing or photographing needs.
The major differences between the NTSC and PAL graticules are in the vertical
scales. In the paragraphs that follow each of the vertical graticule scales will be
discussed separately, while the horizontal scales are discussed together.
The NTSC graticule has two main vertical scales to facilitate typical measure-
ments. See Figure 3–1. The left side scale is marked in IRE units and extends
from –50 to +120 IRE in 10 IRE increments. An IRE unit is equal to 7.14 milli-
volts. Black level setup is shown as a dashed line at 7.5 IRE.
There are
±
2 IRE and
±
4 IRE markings at the center of the –40 IRE line (sync
tip) to assist in measuring sync amplitude. This scale is designed to be used with
the 2 line and 2 field sweep rates.
The scale on the right side of the graticule is for measuring depth of modulation.
The scale extends from 0% at the 120 IRE line to 100% at sync tip (–40 IRE
line).
The boxed area slightly to the right of center at the 100 IRE level is scaled in 2%
and 4% increments for precise tilt measurements. This structure is designed to
work with an 18
m
s half-amplitude duration (HAD), 2T bar. Use the set of solid
and short dashed lines, to the left of the bar tilt measurement structure, to
measure pulse-to-bar ratio; the scale is weighted to include K-Factor ratings of
2% and 4%.
NTSC Composite Video
Graticule Vertical Scales