Radar System Engineering

166 THE GATHERING AND PRESENTATION OF RADAR DATA [SEC. 64
timing equipment. The displays are sometimes subclassified in terms of
the particular type of electronic marker used (see Fig. 6.2).
Sometimes an R-sweep and an A-sweep are shown simultaneously
on the same tube by switching between them on alternate pulses. The
A-sweep is used for general surveillance of targets and for determining
@Q@
(a) R-scope with marker (b) R-scope with step (c) R-scope with notch.
pip.
marker (M-scope).
FIQ. 6.2.—Range scopes. Each displaysa delayed, expanded,range interval.
the proper delay for the R-sweep, either by inspecting the range scale
or by displaying on the A-sweep an electronic marker which indicates
the setting of the R-sweep delay. Such an indicator is called an “A-and-
R-scope.”
One form of deflection-modulated indicator which deserves special
mention is the J-scope, in which the sweep is circular and the deflections
Transmitted
Dulaa
Ground
30 S3?I
~
Echo
signal
11
~o Rlndex
(a) Reading in thousandsof yards. (b) Reading in hundredsof yards.
FIG. 6.3.—Coarseand fine J-scopes. The pair of scopesshownis that usedin the SCR-5s4
(Sec. 614).
are applied radially by means of a central electrode (Fig. 6.3). The
circular sweep is derived by applying a properly phased precision sine
voltage in quadrature to two pairs of deflecting plates at right angles to
one another. The frequency of the sweep sinusoid may be many times
the pulse repetition frequency, in which case the intensity grid of the