TM 11-5840-281-35/1
CHAPTER 2
FUNCTIONING OF EQUIPMENT
as range mark circuits, sweep generating circuits, cursor
2-1.
Radar Set Description
generating circuits, cursor control circuits, and indicating
circuits.
a.
Radar Set AN/TPN-18 is capable of
radar search coverage through 360 degrees of azimuth
f.
The range mark subsection generates
within a range of 40 nautical miles up to an altitude of
accurately spaced 1-mile range marks for the 5- and 10-
12,000 feet minimum using a C-45 type aircraft. The
mile display ranges, S-mile range marks for the 20- and
radar precision approach coverage is from 40 nautical
40-mile display ranges, and 10-mile range marks for the
miles to within 20 feet of runway touchdown using an 11-
80-mile display range. The sweep generating subsection
degree elevation scan angle (36-degree optional) and a
provides a logarithmic 5- and 10-mile time-base in the
30-degree azimuth scan angle (60-degree optional).
normal (precision) mode, a linear time-base for normal
mode 20- and 40-mile ranges, and a linear time-base for
b.
When auxiliary iff equipment is used with
all search mode ranges. The cursor generating
Radar Set AN/TPN-18, this secondary surveillance radar
subsection produces courseline cursors for the azimuth
is capable of providing positive identification of aircraft
display, and glidepath and height finding cursors for the
and extending the altitude and range above and beyond
elevation display. Refer to paragraph 1-5b(3)(h), (i), and
the radar capability.
(j) in TM 5840-281-12 for technical characteristics of the
cursors. The cursor control subsection uses the antenna
c.
Radar Set AN/TPN-18 consists of seven
angle data and reference voltages to properly time and
functional sections (fig. 2-1). These sections are
switch the cursor generating circuits. The indicating
identified as transmitter, rf, receiver, antenna control and
subsection uses the voltages from the sweep generating
data, control-indicator, receiver-transmitter power supply,
circuits to produce the indicator display required for the
and control-indicator power supplies.
mode selected, and then displays the composite video
signals on the indicator.
d.
The transmitter section generates the rf
radar pulses; the rf section couples the rf radar pulses
g.
Radar Set AN/TPN-18 has six selectable
from the transmitter section to the azimuth and elevation
modes of operation. They are identified as SEARCH,
NORM, 35 EL, 60 AZ, SIMULT, and IFF. When
then couples the reflected rf signals from the feedhorns
SEARCH mode has been selected, azimuth Antenna
back to the receiver section; the receiver section detects
AS-1292/TPN-8 rotates through the full 360-degree
and processes the reflected rf signals for visual
search scan, elevation Antenna AS-1291/TPN-8 is
observation on the control-indicators; the antenna control
inoperative, and Control-Indicator C-6988/TPN-18 uses a
and data section controls the position of the antennas
ppi display. When NORM mode is selected, azimuth
and switches the rf radar pulses between the antennas;
Antenna AS-1292/TPN-8 scans a 30-degree horizontal
the control-indicator section visually dis-
sector, elevation Antenna AS-1291/TPN-8 scans an 11-
plays the relative position of the aircraft to the
degree vertical sector, and Control-Indicator C-
surrounding area; the receiver-transmitter power supply
6988/TPN-18 uses beta scan. When 35EL mode is
section produces the voltages necessary for operation of
selected, azimuth Antenna AS-1292/TPN-8 scans a 30-
the transmitter section, rf section, receiver section, and
degree sector, elevation Antenna AS-1291/TPN-8 scans
the antenna control and data section; and the control-
a 36-degree sector, and Control-Indicator C-6988/TPN-
indicator power supply section produces the voltages
18 uses a beta scan. When 60 AZ mode is selected,
necessary for operation of the indicator circuits.
azimuth
e.
The control-indicator section can be
further divided into five functional subsections identified
2-1
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