the specified receiver can detect these emitters under the
environmental conditions specified.
SURFACE-SEARCH RADAR
RANGE (SSR)
LEARNING OBJECTIVES Interpret SSR
tables to determine detection ranges of
surface-search radars. Identify limitations and
assumptions. Describe how the output of the
SSR program is displayed.
The SSR program determines the effectiveness of a
surface-search radar against a variety of ship classes.
Input to the program consists of a user-specified radar
antenna height, surface-search radar parameters from
the data base (PDB) file, and a refractivity data set from
the RDF. The retrieved surface-search radar ranges
incorporate the characteristics of the user selected,
surface-search radar and the targets’ radar cross section.
The refractivity data set is composed of a profile of a
modified refractive index (M-unit) with respect to
height, the height of the evaporation duct, and the
surface wind.
APPLICATION
SSR determines the probable effectiveness of
surface-search radar against different size targets. The
determination is based on given atmospheric refractivity
conditions. The detection ranges that are determined
represent a 90 percent probability of detection. Based
on the information output by this program, the tactical
commander can alter the disposition of his or her forces,
as necessary, to maximize the effectiveness of his or her
surface-search effort.
LIMITATIONS AND ASSUMPTIONS
The restrictions as well as the principles taken for
granted in using the SSR program areas follows:
. The SSR Range Tables program assumes
horizontal homogeneity of the atmosphere. (The
program does not account for horizontal changes in the
refractivity structure of the atmosphere.)
. There is no account made for the absorption of
EM energy by oxygen, water vapor, fog, rain, snow, or
other atmospheric particulate matter.
. This program accounts for ducting in
evaporation ducts, surface-based ducts, and
low-elevated ducts, provided the radar antenna is within
the elevated duct. The program does not properly
account for the over-the-horizon region for
low-elevated ducts when the bottom of the duct is above
the radar antenna height. Errors are small and should
be insignificant when the separation between the base
of the low-elevated duct and the radar antenna exceeds
a few thousand feet.
. Prior to running this program, a primary
refractivity data set must be selected.
FUNCTIONAL DESCRIPTION
Output from this program consists of a SSR table
for the user-selected, surface-search radar. Output is
provided in the user-selected units (metric or English),
and is displayed on two screens. Detection ranges are
represented by MIN, AVG, and MAX where MIN is the
range expected if detecting from a bow or stem aspect,
MAX is a broadside aspect, and AVG is a quartering
aspect. Output from this program is classified and
should be labeled as required.
ELECTROMAGNETIC COVER
DIAGRAM (COVER)
LEARNING OBJECTIVES: Interpret COVER
displays of radar detection or communication
coverage.
Identify limitations and
assumptions. Interpret an example of a
surface-system COVER diagram.
The COVER program provides a display of radar
detection or communication coverage in the vertical
plane. Input to the program consists of the radar or
communication system of interest, the height of the
system (if airborne), and a refractivity data set from the
RDF.
The EM system is entered/edited using the platform
option of the EMFILE maintenance program. The
refractivity profile is entered via the environmental
status option of the EM propagation suite of programs.
APPLICATION
COVER provides the capability to determine how
a given EM system will perform under given
atmospheric conditions in detecting or communicating
with a given target or receiver.
It provides the
information necessary to plan flight profiles for airborne
systems to achieve maximum probability of detecting
7-10
