THE ANALYSIS OF RADARS AS A FUNCTION OF PHOTOGRAPHIC GROUND RESOLUTION

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04770A000900010004-9
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 46
• Document Creation Date: December 28, 2016
• Document Release Date: June 23, 2006
• Sequence Number: 4
• Publication Date: February 1, 1969
• Content Type: REPORT

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THE ANALYSIIS OF RADARS AS A FUNCTION OF
PHOTOGRAPHIC GROUND RESOLUTION
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THE ANALYSIS OF RADARS AS A FUNCTION OF
PHOTOGRAPHIC GROUND RESOLUTION
Technical Report 723-11
February 1969
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ACKNOWLEDGMENTS
We sincerely appreciate the cooperation
and help we received from the photointerpreters
and radar analysts who participated in this
study.
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TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS . . . . . . . . . . . . . .
LIST OF TABLES . . . . . . . . . . . . . V
INTRODUCTION . . . . . . . . . . . . , 1
METHOD . . . . . ,. 2
The Radars . . . . . . . . 3
The Photographs . . , . ... . . . . . . . 4
Subjects . . . . . . . . . . . . 6
The Procedures . 7
RESULTS . . ... . . . . . . . , . . . 9
DISCUSSION , . . . . . . . . . . . 30
APPENDIX A BASIC RADAR REQUIREMENTS .. . Al
APPENDIX B RADAR RESPONSE CHECKLIST BI
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Table Page
1 .The Radar Targets . . . . . 4
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LIST OF TABLES
2 Description of the Positive Transparencies
3 The Number of Targ-ets for Which Complete
Responses Were Obtained by. Question and
Ground Resolution . . .
Ti Stone Cake
T2 Fan ,Song A . . . . .. 14
T3 Longtalk . . . . . . . . . . .16
T4 Spoon Rest A , . 18
T5 Moon Cone . . . . . .
T6 Firewheel f . . ...
T7 Fan Song E . . . .
.20
24
T8 Barlock . . . . . . . . . . . . . 26
T9 Spon.ge Cake . 28
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INTRODUCTION
-In a previous study' it was concluded that,
"In the analysis of missile sites2
using aerial reconnaissance photography,
most, if not all, of the significant
intelligence information can be obtained
ground-resolution photography.
Ground resolutions of provide
little, if any, additional significant in-
telligence information regarding this. class
of targets." .
In the discussion section of the report of the missile-
site study, the conclusion was -qualified in this way,
"...it must be emphasized that only
missile and missile-related sites were-used
as targets in this study. Had electronic
facilities or tactical targets been used,
the resultslmay have been different. With
such targets, even 0 ground-resolution
photography may_not have yielded all of the
intelligence information that could be
obtained from aerial photography. The
implication is obvious; a similar study must
be done with a different class - of.targets.
In other words, if the class of targets chosen for study
were one characterized by finer detail, then ground resolu-
might have yielded significantly more
information than obtained with
photography.
ground-resolution
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'As suggested by the PIs who participated in the study, this phrase should probably read,
..the analysis of domestic, offensive missile sites......
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Mobile radars are targets with considerably finer detail
than missile sites. So this study was of the effects of
photographic ground resolution on the interpretation and
analysis of mobile radar targets.
The practical significance of this and the previous
research is perhaps obvious but may warrant repeating.
Modern aerial reconnaissance systems are enormously expen-
sive, and obtaining better ground resolutions means even
greater expense. Therefore, it is important to learn what,
if any, additional information will be provided to the
intelligence community by obtaining better, more expensive,
resolutions.
Though it may never be possible to determine the value
of such additional information, it is.quite possible to
determine the minimum resolution required, for different
classes of targets, to maximize the amount of significant
information obtainable by interpretation and analysis. If
a point can be found where improved ground resolution pro-
vides no additional significant information, then the required
ground resolution for aerial reconnaissance systems can be,
specified.
METHOD
The method was similar to that used in the missile-site
study. In brief, an effort was made to simulate operational.
photographic intelligence practices.
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Positive transparencies were prepared to six specified
ground resolutions. Two PIs independently read out the
transparencies, and each prepared an annotated sketch on an
acetate overlay placed over paper-print enlargements of the
transparencies. Each pair of PIs then worked together to
produce an annotated sketch representing the consensus of
their interpretations.
The positive transparencies,.annotated sketches, and
enlargements were delivered to experienced radar engineers
who were knowledgeable about radar design but were not
familiar with the radars used in the study. From these
materials, the radar engineers prepared a report on each
radar at each of the six ground resolutions.
The.Radars
During the planning phase of=the study, an effort was
made to obtain aerial photographs of real radar sites having
ground resolutions that ranged from a "poor" resolution to a
best: resolution 0 Adequate photographs were not avail-
able, so models of nine Sino-Soviet bloc radars were used as
targets. Table l.shows the,radars and their functions.
Intelligence analysts compared preliminary photographs
of the models with engineering drawings of the radars and
found that at high photographicresolutions.the fidelity
of only two of the models was inadequate. These two models
were modified before the final photographs were.prepared.
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THE RADAR TARGETS
TARGET
NUMBER
NAME
FUNCTION
1.
$TONE CAKE
(HEIGHT FINDER)
2.
FAN SONG (CHINESE VARIENT)
(MISSILE FIRE-CONTROL)
3.
LONG TALK
(GCA)
4.
SPOON REST A
(ACQUISITION)
5.
MOON CONE
(EARLY WARNING)
6.
SHIP WHEEL
(FIRE-CONTROL)
7.
FAN SONG E
(MISSILE FIRE-CONTROL)
8.
BARLOCK
(EARLY WARNING)
9.
SPONGE CAKE
(HEIGHT FINDER)
The Photographs
The models were mounted on a board covered with dark
brown wrapping paper and photographed outdoors with the board
in a vertical position. In bright sunlight the shadows
produced were too pronounced, so the photographs were retaken
in hazy sunlight using a secondary. light source.
Six ground resolutions were studied:
This range of resolution was selected to
include the resolutions of today's better reconnaissance
systems and those of proposed future systems.
Preliminary photographs were taken at different distances
from the models, making it possible to compute the resolving
power of the film-lens system as a function of distance. From
these computations, the distances required to achieve the six
selected resolutions were determined and used in making the
final photographs.
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A pair of final photographs_was then. taken at each dis-
tance, one from 100 to the left of the nadir -and one from-10?
to the right, to provide stereoscopic-pairs with a conver
gence angle of 20?.3
The camera was a 35-mm Kodak Retina 2C with a focal
length of 50-mm. Shutter speed was 1/125 sec., and the aper-
ture setting was f/5.6. Kodak Panatomic-X film was used.
The transparencies were processed with DuPont 228R duplicating
stock.
The scales of the negatives varied from approximately
1:1680 for the highest resolution to approximately 1:36,000
for the lowest. In making the positive transparencies these
scale differences were minimized as much as possible without
altering the ground resolutions.-
Table 2 shows the spatial frequencies, ground resolu-
tions, and scales of the positive transparencies used in the
study.
Note that the ground resolutions actually obtained
differed slightly from those selected for the study but these
differences were considered insignificant. The spatial
frequencies given in the table were based upon resolution
readings of a three-bar target.
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DESCRIPTION OF THE POSITIVE TRANSPARENCIES
RESOLUTION
A
B
SPATIAL FREQUENCY
(LINES/MILLIMETER)
72.0
66.0
66.0
33.3
16.3
10.0
SCALE
1/1,800
1/3,600
1/7,200
1 /7,200
1/7,200
1/7,200
Subjects
Two types of experimental subjects were used, photo-
interpreters (PIs) from, the Center and radar engineers (REs).
The REs played the role of intelligence analysts. Profes-
sional radar intelligence analysts were not used because
their intimate familiarity with the radars used as targets
might have biased the results.
Six PIs participated in the study. All were specialists
in the interpretation of photographs of radars and none had
fewer than four years of professional experience in the
interpretation of electronic facilities.
Four REs were used in the study. At the time the study
was conducted, all were employed in private industry in the
field of radar research and development, and all were serving
at the time as analysts for OSI.
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The Procedure
The six PIs were divided into three teams of two men
each. Each team was formed in such a way that the skills and
experience of one member complemented those of the other.
For example, offensive radar specialists were teamed with
defensive radar specialists.
Each team was assigned the task of reading-out three of
the nine radar targets at all six resolutions; each of a set
of three was a different type of radar. Team one was assigned
targets 1 through _3; team two, targets 4 through 6; and team
three, targets 7 through 9.
The PIs of each team began by working independently.
They analyzed one radar at a time in steps from
poorest resolution, to
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the best resolution.
After preparing the independent read-outs, each team
discussed its findings and prepared composite read-outs, and
annotated sketches of the radars. To control,scal-e at
each ground resolution, each team prepared its sketches on
tracing paper placed over a paper-print enlargement of one
of each stereo-pair. The enlargement factors used in making
these paper prints were those that resulted in prints of
the maximum dimensions possible without degradation of
photographic coherence. The spatial frequencies of these
enlargements varied between 3.0 lines/mm and-3.6 lines/mm.
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The PIs used stereoscopes, at any desired magnification,
in reading out the positive transparencies. They also used
a guide prepared by professional radar intelligence analysts,
that described the information the analysts wanted about
each radar. The guide served as an Essential Elements of
Information (EEI) type of document (see Appendix A, "Basic
Radar Requirements!').
The positive transparencies,-the paper-print enlarge-
ments, and the annotated sketches prepared by the PIs were
delivered to the REs for analysis. As did the PIs, the.REs
worked side-by-side in teams of two and produced joint
analyses. Each had a copy of the positive transparencies
and a stereoscope. They examined the PI read-outs as well
as the transparencies in making their analyses and, for
guidance, they used ,a checklist that-they had. prepared from
the EEI (see Appendix B, "Radar Response Checklist").
The REs first analyzed all nine read-outs (one for each
radar) at the poorest resolution,
They then pro-
ceeded to the next best resolution, and so on until they had
analyzed all nine targets at each of the six resolutions.
The REs produced an enormous amount of information
about the targets, and for the purposes of this report it
was necessary to.develop summary statements of relevant
information for each question, target, and resolution. The
summary statements prepared by the authors were reviewed by
an experienced radar physicist for accuracy. The final
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summary statements are presented in the tables in the Results
section of the report.
RESULTS
The results of the study were complex and difficult to
interpret and summarize unambiguously. For that reason, the
detailed tables that follow in this section were prepared so
that the reader could make his own interpretation and summary.
Professional analysts in the intelligence community are per-
haps best qualified to make judgments concerning the signifi-
cance of the information produced at each resolution,
However, the authors and some of their engineer colleagues
made an effort to summarize the information produced by the
REs. For each radar target and each resolution, the responses
to each question were compared with the. available ground
truth, if the response at a better resolution contained more
detailed information, partial but correct responses made at
poorer resolutions were considered incomplete. When ground
truth was not available, the response was considered complete
if no additional significant information was added at better
resolutions. The results of the analysis are shown in Table
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As can be seen from Table 3, complete answers were given
for all nine radar targets at a
questions:
ground resolution to these
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THE NUMBER OF TARGETS FOR WHICH
COMPLETE RESPONSES WERE OBTAINED
BY QUESTION AND GROUND RESOLUTION
QUESTION
Number and Type of Vans?
Fixed or Mobile?
Number of Antenna(s)? 4
Type of Antenna(s)? 7 8
Mounting of Antenna(s)? 7 8 9
Frequency of Antenna(s)? 5 5 6*
Horizontal Sector Limits? 9 -
Vertical Sector Limits? 4 -
Beam Patterns,. Horizontal? 7 7
Beam Patterns, Vertical? ~8 -
**Waveguides? 2 4 6
**Feeder Lines? 2 4 8
Function? 9 - -
Cumulative Compl-ete
Responses
Percent of Possible.
Complete Responses
115) 71% 78% 88% 90% 90% 90%
*This number indicates that for three targets complete responses
were not obtained at any resolution. -
**For one radar these questions were not appropriate.
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Number and type of vans?_
Fixed or mobile?
-Horizontal sector limits?
Function?
Some questions were not completely answered for all
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radars until
ground resolution photography was avail-
able. And some questions were. not-completely answered for all
radars at the best resolution. Note that some of the-latter
questions such as, Frequency of Antennas?, would probably be
more appropriately asked of an eZint system.
The number of possible complete responses was.115 (nine
targets times 13 questions minus two questions.inappropriate
for one target), -'Note that there was an increase in the
number of complete responses from a.ground resolution
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was-no difference among
II
being small, butthere
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In-the tables following (T1 through T9), the areas of
gray and the notation "same as" indicate that the REs either
added no additional information or added insignificant infor-
mation as compared to the information they had presented at
poorer ground resolutions.
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Target Number 1
No. & Type of Vans
One rotating van with
antenna plus two trucks
Fixed or Mobile
Mobile
.No. of Antennas
One
Type of Antennas
Nodding dish
Mountinq of Antennas
On end of van
Frequency of Antennas-
2578-2666 MHz
Horizontal Sector Limits
360? van rotation
Vertical Sector Limits
0-30?
Beam Patterns--Horizontal
-3.7? beam width,
horizontal polarization
Beam Patterns--Vertical
1.4? (est)
Wave Guides
Yes--horn feed
Feeder Lines
Not specified
Function
Height finding
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Target Number,2
No. & Type of Vans
One'
Fixed or Mobile
Mobile
No. of. Antennas
Four
Type of Antennas
One horiz. trough
One vest. trough
Two O dishes
Mounting of Antennas
Onel dish over horiz.
trougM;j dish at
end on arm;.ver trough at
end
Horizontal S-ector Limits
Vert. trough 17?-20?
Van rotates 360?
Vertical' Sector Limits
Horiz. trough 17?-20?
Beam Patterns-Horizontal
'Horiz. trough 2?
Vert. trough 10?
Dishes 10?-15?
Beam Patterns--Vertical
Horiz. trough 10?
Vert. trough 2
Dishes 10?-15?
Wave Guides
No specified
Feeder Lines
Not specified
Function
Missile guidance and
tracking
Frequency of Antennas
Horiz. trough 2940-3000 MHz
,Vest. trough 3000-3060 MHz
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Target Number 3
No. & Type of Vans
One van (enclosed)
Fixed or Mobile
Mobile
No. of Antennas
Four
Type of Antennas
Curved reflectors--one
each large, medium and
small (one small vert.,
others horiz.)
Horizontal Sector Limits
Large - 3600
Small and medium
not specified
Vertical Sector Limits
Not specified
Beam Patterns--Horizontal
Large - 2.2?
.Medium - 0.64?
Small - 2.1?
Beam Patterns--Vertical
Mounting of Antennas
Large and medium reflectors
at ends on top of van; small
vert. above small horiz.;
off-center of van top
Frequency of Antennas
Large - 820-890 MHz
Medium - 9050-9500 MHz (pos.)
Small - not specified
T3a
Large - not specified
Medium - 0.45?
Small - 4.10
Not specified
Feeder Lines
Not specified
Function
t
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Target Number 4
No. & Type of Vans
One covered truck for
antenna mounting;
One van-truck with
equipment
Fixed or Mobile
Mobile
No. of Antennas
Twelve
Type of Antennas
Yagi
Mounting of Antennas
Two horiz. rows of 6
each on boom--in turn on
lattice mast
Frequency of Antennas
Horizontal Sector Limit-s
360? rotation
Vertical Sector Limits
Tiltable above and
below horizontal
Beam Patterns--Horizontal
5?-10?
Beam Patterns--Vertical
Not specified
Wave Guides
Not specified
Feeder Lines
Not specified
Function
Early warning and
SAM acquisition
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Target Number 5
No. & Type of Vans
Type SCR-270
open trailer
Fixed or Mobile
Mobile antenna (fixed
installation use--support
equipment in small building)
No. of Antennas
Three
Type of Antennas
Vertically stacked mattresses
Large bottom with 6 horiz.
rows of 8-12 dipoles, smaller
middle with 4 horiz. rows of
8 dipoles, smallest top with
4 horiz. rows of 4 dipoles
Mounting of Antennas
Mast on pedestal (open
frame work)
Frequency of Antennas
145-161 MHz
Horizontal Sector Limits
360? continuous
Vertical-Sector Limits
Fixed
Beam Patterns--Horizontal
Horiz. polarization
8?-12? beam width
Beam Patterns--Vertical
Two distinct lobes
Lower
lobe MRA 3?
above
Upper
horiz.
lobe. MRA
8?
above
horiz.
Wave Guides
None
Feeder Lines
Type not specified
Function
Early warning
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Target Number 6
No. & Type of Vans
One van (enclosed)
Fixed or Mobile
Mobile
No. of Antennas
Three
Type of Antennas
One 3 meter parabolic dish
Two helical antennas
Mounting of Antennas
Dish on top of and at end
of van, helical antennas
mounted on lower right
side of the dish.
Frequency of Antennas
2695-3020 dish
Helices not specified part
of FOILTWO system
Horizontal Sector Limits
3600 rotation
Vertical Sector Limits
Not specified
Beam Patterns--Horizontal
2.7? circular
and spiral
Beam Patterns--Vertical
2.7? circular
and spiral
Wave Guides
Not specified
Feeder Lines
Not specified;
Dipole fed
Function
Fire control
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Target Number 7
No. & Type of Vans
One
Fixed or.Mobile
Mobile
No. of Antenna's
Five
Type of Antennas
One
One
Two
One
horiz. trough
vert trough
lishes
dish
Mounting of Antennas
TwoO dishes
horiz. trough,
dish at end on arm,
vert. trough at end
Frequency of Antennas
Horiz. trough 4910-49.90 MHz
rough 5010-5090 MHz
dish 723-802 MHz
fishes not specified
Horizontal Sector L.i-mi-ts-
Vert. trough 17,?-20?
Van rotates 360?
Vertical Sector Limits_
Horiz. trough 17?-20
Beam Patterns--Horizontal
Vert..- trough.7.5?--10?
Horiz. trough 1.2?
dish
cular
Beam Patte-rns--Vertical
Vert. trough 1.2?
Horiz. trough 7.5?-1
dish
14? circular
Wave Guides
Not specified
Feeder Lines
Not specified
Function
Missile guidance and
tracking
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Target Number 8
360? van rotation
Vertical Sector Limits
Upper antenna 5.5? up, 7? down
Lower antenna 4? up,. 5.5? down
Beam Patterns--Horizontal
0.8'--l.80 (frequency dependent)-
-Beam Patterns--Vertical.
1.4?-11.4? (frequency.depende.nt)
Wave Guides
Lower antenna fed by 4 S-.band
guides, horn termin.a.ted. -
Upper-antenna fed by 2 S-band
guides; one terminated by
dual or split horn; other
terminates in .8 dipoles
Feeder:.Lines
Not specified.
Function
Early warning
No. & Type of Vans
One
Fixed or Mobile
Mobile
No. of Antennas
Two
Type of Antennas
Truncated parabolic
mesh reflectors
Mounting of Antennas
Horiz.:fore and aft
Frequency of Antennas
Horizontal Sector Limits
t
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Target Number 9
No.& Type of Vans
One rotating van with
antenna plus two trucks
Fixed or Mobile
Mobile
No. of Antennas
Type of Antennas
Similar to-STONE CAKE
but lighter--nodding
dish
Mounting of_Antennas
On end of van
Frequency of Antennas
2689-2763, 2796-2856 MHz
Horizontal Sector Limits
360? van rotation
Vertical Sector Limits
0-30?
Beam Patterns---Horizontal
3.7? same as. STONE
CAKE
Beam Patterns--Vertical
1.4? (est) same as
STONE CAKE -
Wav-e Guides -
Yes--horn feed
Feeder Lines
Not speci-fied
Function
Height finding. -
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DISCUSSION
The purpose of the study was to attempt to determine what
information could be learned about mobile radar targets as a
function of the ground resolution of aerial photography. Addi-
tional information was obtained as resolution improved, but
the question is: How valuable is the addition-al information.
to our national security in light of the significant, addi-
tional system costs? The authors have-left the burden of
answering that question to.the reader.
Precise measures are required to infe-r-.electronic charac-,
teristics of radars of this type. It was not_entir-ely possible
to determine the accuracy of,the.models for the purposes of a-
mensuration study. Consequently this study.:wa-s limited to
"interpretation" without measures, However,-the REs-did make
measurements and, at the better resolutions,. model-i-naccura
cies could have led to measurements that in'-turn led to erro-
neous inferences about-electronic characteristics.
It was not ,possible in -analyzing the data. to distinguish
inferences from what was actually seen. The PIs produced an-
notated overlays-so their responses probably reflected what
they saw. But the REs, in some instances,.may have inferred
the presence of some features of the radars-on the basis-of
their knowledge of radar functions. -
.The "open-end" format of the questions askedthe.PIs and
REs made very difficult the task of reducing- the.e.normous
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amount of data produced in the study, The amount of data
.wasn't the only difficulty: difference.s
in terminology also
had to be resolved. If a .similar study were to be done with-
a different class of targets, the experimenter should consider
the possibility of adding greater structure to the response
requirements, perhaps a structure similar to a multiple-choice
31,
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.BASIC RADAR REQUIREMENTS
Used by the PIs in preparing their
annotated sketch read-outs
Generally speaking, the intelligence community wants
the answers to two fundamental questions regarding the radars
of potential enemies:
1. What is its function? For example, fire control,
missile guidance, early warning, etc. The answer
to the question is generally inferred by the
intelligence.analysts.from the configuration and
general description of the radar, from its loca-
tion, from its association with or relation to
other equipment, from the number of apertures or
elements, from descriptions of the feeds, and from
gross measurements.
2. What are its basic technical and performance
characteristics? For example, antenna pattern and
gain, antenna scanning modes and volume of.coverage.
The answers to this question are inferred by the
intelligence analysts from numerous factors.
a. Description and'size of the antenna or
antennas (bedspring, yagi, parabolic reflector--
mesh or solid--etc.).
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b. Description, size, and orientation of,feed
mechanisms (horn, dipole, line source, scanner,
etc.; f/D ratio, feed tilt, etc.).
c. Description and dimensions of r.f. lines
(waveguide, coax).
d. Description. of site.
e. Identification of any appendages related to
beam shapin-g.
f. Mechanical connection of antenna to its mount.
(circular scan., vertical sector, horizontal
sector, etc_.) .
-Mechanical relationship between multiple
antennas on a single mount. (For example,
are they capable-of independent motion?)
h. Limits of mechanical motion. (For example,,
sector limits of a nodding height finder.)
i. Detailed description of any scanning feed
mechanism, including r.f. connections,
electrical connections, mechanical drives,
etc.
j. Identification.and dimensions of feed aper-,
ture.
k. Identification of type of scanner.
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signal characteristics, such as transmission frequency, PRF,
scan rate, 'etc., which may not be available from-reconnais-
.sance photography.
From all.,of this information., the analysts try to infer
the capabilities, limitations, and vulnerabilities of a radar.
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APPENDIX B
RADAR RESPONSE CHECKLIST
Used by the REs in
analyzing the targets
1. Type of van? -
2, Fixed or mobile?
3. -Number of antennas?
4. Type of antennas?
5. Mounting of antennas?
6. Size of, antennas?
.7. Frequency of antennas ?
8. Horizontal sector limits?
9. Vertical sector limits?
10. Beam patterns, horizontal?
11. Beam patterns, vertical?
12. Wave guides?
13, Feeder lines?
14. Function?
IS., Comments
16. Significance
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