Page 150 - Radar Technology Encyclopedia

140 display, alphanumeric (data) display, bright

character synthesizing displays: that is, displays designed to in the plane of the specified angular coordinate. The ampli-
display information in the form of mnemocircuits. tude-differential display is used with the equal signal method
Segment character-synthesizing displays only allow the of measurement. The operator (or automatic tracker) turns the
display of numbers (numerical character-synthesizing dis- antenna until the difference of the mean values of the video
plays), or numbers and letters (alphanumeric character-syn- signals is zero.
thesizing displays). In a number of cases, scale and digital- In two-dimensional displays the azimuth and elevation
analog character-synthesizing displays with an analog form discrepancy signals are fed to the horizontal and vertical
of information presentation are used. Character-synthesizing deflecting plates of the CRT. This type of display is also
displays can be constructed using gas discharge, semiconduc- called a K-scope. IAM
tor, and other types of displays. In particular, in CRT charac- Ref.: Barton (1964), p. 8; Vasin (1977), p. 193.
ter-synthesizing displays the characters are synthesized from
analog display (see raw-video display).
Lissajous figures. These types of displays can be used for dis-
playing information provided by radar control and monitoring An azimuth-elevation display is a two-dimensional display
subsystems (see SUBSYSTEM, radar). IAM for presenting and measuring the azimuth and elevation based
on the bright blip of the target. The sweep of the beam in the
Ref.: Poole (1966), Ch. 13; Bystrov (1985), p. 6; Stevens (1988), p. 4.
CRT display is carried out by two sweep generators that pro-
An altitude-range display shows target position in altitude
cess voltage, the linearity of which depends on the angle of
(height)-range coordinates. The current of the horizontal
rotation in the plane of the azimuth and elevation, respec-
sweep of the display is proportional to the horizontal range to
tively. The azimuth-elevation display has no range resolution.
the target; the current of the vertical sweep is proportional to
Therefore, for the individual monitoring of targets that have
its altitude. If a small elevation sector is displayed, time (slant
the same angular coordinates, gating of the receiver is used
range) may be used as the horizontal coordinate, and the sine
for the time of the reception of the reflected pulse of the target
of the elevation angle as the vertical coordinate.
located at the specific range. In this case the capability for
When determining the altitude relative to the earth's sur-
simultaneous monitoring of all the targets in the scanning sec-
face, the current in the vertical deflection coils should have a
tor is lost. For the approximate determination of the range to
supplemental parabolic component to compensate for the cur-
the dot of the blip, dashes are added to the right and the left,
vature of the earth and the refraction of the radio waves. In
the length of which is inversely proportional to the range.
contrast to the elevation-range display, reading of the altitude
This type of display is also termed a C-scope. IAM
becomes easier in altitude-range displays as the elevation
Ref.: Barton (1964), p. 7; Vasin (1977), p. 195
increases. This display is also termed a range-height indica-
tor (RHI). IAM An azimuth-range display is a two-dimensional display for
the recording and measurement of azimuth and range based
Ref.: IEEE (1993), p. 1066; Druzhinin (1967), p. 415; Sauvageot (1992),
p. 15. on the bright blip of the target. In azimuth-range displays,
either a panoramic sweep (plan-position indicator) or a sweep
An amplitude display is a display with an amplitude blip
in rectangular coordinates (B-scope) is used. In the latter
used to determine the angular coordinate. Amplitude displays
case, the azimuth sweep is shaped by voltage that is a func-
are employed using the equal signal method and the method
tion of the angular displacement of the antenna based on the
of dividing the envelope of the signal burst. In the first
azimuth. This is achieved using a transmitter in the form of a
method the blips of the video signals of the target are
variable capacitor, a circular potentiometer, or a synchro in
observed on the CRT. These blips correspond to the extreme
the sweep generator.
positions of the beam scanning in the plane determined by the
The advantages of the azimuth-range rectangular sweep
angular coordinate. The operator or the automatic tracker
are the even and higher resolution in the azimuth and the ease
turns the antenna until the heights (amplitudes) of the blips
in changing the scale, which gives it preferred usage in guid-
are aligned. In the method of dividing the envelope a tempo-
ance radar compared with the PPI often used in search radars.
rary angular sweep is created in the amplitude display along a
IAM
specific angular coordinate synchronized with the shifting of
the beam in the plane of that coordinate. The operator or auto- Ref.: Barton (1964), p. 7; Vasin (1997), p. 193.
matic tracker reads the coordinate according to the position of An A-(scope) display is one “in which targets appear as verti-
the center of the signal burst blip on the sweep line or turns cal deflections from a horizontal line representing a time base
the antenna until it is pointed at the target along the specified (Fig. D47). Target distance [range] is indicated by the hori-
coordinate. IAM zontal position of the deflection from one end of the time
Ref.: Skolnik (1962), p. 391; Barton (1964), p. 6; Rakov (1970), vol 2, p. base. The amplitude of the vertical deflection is a function of
385. the signal intensity.”
An amplitude-differential display is a display with an Ref.: IEEE (1993), p. 18.
amplitude blip for determining the angular coordinate based A bright display is used in applications where it is not possi-
on the observed difference of the video signal voltages, ble or convenient to use a conventional CRT in a darkened
obtained at the two extreme positions of the beam, scanning environment. An example of such applications is the aircraft