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Патент USA US3076198

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Jan. 29, 1963
G. w. GODDARD
3,076,189
MULTIPLE-SENSOR AIRBORNE RECONNAISSANCE SYSTE
Ms
Filed Oct. 16, 1958
3 Sheets-Sheet 1
INVENTOR.
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Jan. 29, 1963
G. w. GODDARD
3,076,189
MULTIPLE-SENSOR AIRBORNE RECONNAISSANCE SYSTEMS _
Filed Oct. 16, 1958
5 Sheets-Sheet 2
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INVENTOR.
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Jan- 29, 1963
G. w. GODDARD
3,076,189
MULTIPLE-SENSOR AIRBORNE RECONNAISSANCE SYSTEMS
Filed Oct. 16, 1958
3 Sheets-Sheet 3
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Patented Jan. 29, 1963
2
detailed description to be read in connection with the
MULTIPLEiSENSOR
.
,
accompanying drawing, wherein
ORNE REtIONNAlS
FIG. 1 is a schematic representation of an airborne
SANCE SYSTEMS
multiple-sensor installation in accordance With the in
George W. Goddard, Chevy Chase, Md., assignor to
Bulova Research and Development Laboratories, Inc.,
5 vention.
FIG. 2 is a typical record taken by the system.
Woodside, N.Y., a corporation of New York
FIG. 3 is a block diagram of the installation.
Filed Oct. 16, 1958, Ser. No. 757,627
11 Claims. ((31. 343-5)
FIG. 4 is‘ one preferred embodiment of the dual-image
camera used in the installation, and
The present invention relates generally to multiple 10 FIG. 5 is another preferred embodiment of a dual‘
sensor airborne reconnaissance systems for the ground
image camera.
detection and location of military and other objectives,
Basic Theory
and more particularly to a system adapted to integrate
Referring
now
to
FIG.
1 of the drawing there is shown
in overlay form a photographic image with an image or
indication obtained from a radar device adapted to re
15
spond to the presence of objects which are not optically
a reconnaissance plane 10 having mounted thereon a radar
system, generally designated by numeral 11, operating in
coordination with ‘a strip camera 12. The camera 12 is
mounted on a stabilized platform 13 and is provided with
a slit opening to expose the moving ?lm therein to a strip
1-4lying across the terrain in a direction perpendicular to
are obscured by the existence of natural growth on the 20
the direction of ?ight. The radar ‘system 11 is mounted
terrain or by the use of camou?age techniques. Thus a
on a separate stabilized platform 15 and projects a radar
reconnaissance camera will ordinarily not reveal the pres
visible.
_
>
As is well known, a conventional aerial reconnaissance
camera is incapable of detecting military objectives which
beam which is caused to scan across the same strip to
ence of enemy divisions which have been ‘deployed in
forest areas, nor will it locate ‘camou?aged artillery, acre‘
drornes, munition dumps and the like.
provide simultaneous indications which are superimposed
25 on the photographed ?lm image. The radar beam there—
7
fore scans in a limited sector transverse to the line of
Radar reconnaissance techniques are known whereby
radar pulses propagated toward the e'arth’s surface are
?ight._
Radar pulses propagated toward the terrain produce
re?ections which depend largely on the conductivity of
target or object. Metals have a relatively high con
tation, to provide radar indications. While attempts have 30 the
ductivity and tend ‘to produce stronger radar returns. The
been made to coordinate radar vand photographic data,
energy re?ected by metallic objects is received by the
the results heretofore have not been of practical value,
radar system and converted to corresponding light pulses.
for the information obtained thereby could not be so in
The light pulses are projected on the photographic ?lm
tegrated as to provide indications in simple and convenient
form. For example, it has been known tovapply along 35 which is also optically exposed by the camera. The en
ergy re?ected by "metallic objects therefore forms a clear
the frame edges of a photographic ?lm radar pulse in
re?ected by ground objects in varying degree, depending
upon the speci?c nature of the object and its ‘ground orien—
contrast against any background even when the back
dications, each pulse having a height indicative of
the intensity of re?ection received from an object lying
within the related photographs. This side-by-side rela
ground is constituted by semi-conductive materials, such
as moist or Wet surfaces.
tionship of photographic and radar data is di?icult to 40
interpret and is of little value in quick search missions
by reconnaissance aircraft.
In view of the foregoing, it is the principal object of
the present invention to provide a multiple-sensor data
integration airborne system capable of rapidly identifying
sponding to background level. Only those signal returns
45 rising above the level of suppression are used for record
ground target areas which cannot reliably be detected by
single sensor devices.
In lieu of the conventional pictorial radar presentation
of ground ‘echoes, in a preferred form of the invention
exclusive use is made during the scan of those ground
returns whose energy exceeds a signal threshold corre
_
More particularly, it is an object of this invention to
provide a system for concurrently producing aerial photo
and radar recordings of the ‘same target area, the data
being collected and presented with equal scale distortion
and orientation characteristics. Thus the invention elimi
nates inconvenient discrepancies relative to rapid interpre
ing in the form of short ‘dashes.
Since the radar return dashes, as shown by the dash
clusters 16, 17 and 18 in FIG. 2, are superimposed on
the strip photograph taken at the same instant, each
point of high radar re?ectivity appears at its proper place
with respect to ground. The ?lm exposed in this fashion
will then present the exact location of metallic targets
without the need for special interpretive techniques.
In the strip camera, the rate of ?lm travel, the width
tation and assessment of the data. It is a signi?cant fea~
of the exposure slit and the diaphragm control are auto
ture of this invention that thecorrelation of sensor re 55
mati'c'ally adjusted. ‘A variety of ?lms may be used in
cordings is such as to extract the maximum information
‘accordance with the requirements of the mission, such as
panchromatic emulsions, infra-‘red emulsions and camou
Also another object of the invention is to provide an
?a‘ge detection ?lm.
therefrom.
,
v
,
infra-red sensor in synchronism with a radar sensor to
provide integrated recordings for accurate and reliable 60
reconnaissance operations.
Each returning radar pulse above a predetermined mini
mum intensity is marked at the proper spot by means of
a ?ash lamp and an optical scanner or by the use of a
As applied to tactical ‘military operations, use of a
system in accordance with the invention affords a favor
able air situation whereby constant air surveillance of
?ying spot scanner, thereby tracing across the ?lm the
countermeasures. Moreover, it provides data in suitable
form which can be quickly evaluated and coordinated in
close support of ground forces for target guidance and
Referring now to FIG. 3, the system is shown in block
form, the radar device 11 being mounted in the stabilized
platform '15 and the strip camera 12 being mounted in
the ground may be maintained regardless of attempted 65
location.
,
desired radar pattern.
The Multiple-Sensor System
the stabilized platform 13.
For a better understanding of the invention as well as 70
The strip camera 12 requires stabilization to o?set the
‘other objects thereof reference is made to the following J
eifects ‘of aircraft roll and pitch. Stabilization of yawis
3,076,189
A
only passes signals above a predetermined general level,
3
not required for this application, for aircraft generally
this level being determined by the integrator 53. Con
sequently, noise-or background voltages which fall be
exhibit the lowest forces and a high moment of inertia
about the vertical axis. The stabilization is accomplished
low this general level are excluded from the output of
the threshold circuit. Each returning radar pulse from
shaper 54 is then ampli?ed and fed to a gas discharge
lamp 45. By such means, the strong echoes are trans
lated into short light ?ashes which are directly recorded
on the ?lm. The recording of the radar date is accom
plished on the emulsion side of the film, thereby elimi
nating the difficulties of recording on ?lm which may
by means of a gyro control of platform 13. This mount
should be capable of accuracies to within one minute of
arc despite short motions of the aircraft.
Drift rate
and absolute accuracy of such a mount do not in?uence
the resolution signi?cantly and are considered unim
portant in this special application.
The scanning radar antenna also requires some form
of stabilization. Such stabilization is provided by use of
have anti-halation backing.
the slaverplatform 15 (without gyros) operatively coupled
to the camera master platform 13 by two or four systems
of synchros which then actuate the servo motors of the
slave platform.
In practice the discharge
lamp may generate a ?ash of approximately 100 rnicror
15
.To effect stabilization of the camera platform, roll and
pitch gyros 29 and 19, respectively are provided, the
seconds duration.
An optical mechanical scanning technique is used to
distribute the ?ashes across the width of the ?lm in syn
chronism with the scanning operation of the antenna.
This is accomplished by means of the ?ash lamp 45, which
output of gyro 19 being applied to a servo mechanism
is shown separately in FIG. 4, is placed at the focus of a
21 to effect correction of platform 13 as to pitch. The out
small condenser lens 46 in a mounting tube 47 to produce
20
put of gyro 20 is fed to an independent servo mechanism
a parallel beam of light. The mounting tube 47 is ar
22 to effect correction as to roll. The platform 15 for the
ranged to oscillate about an axis which passes through the
radar device is stabilized through a slave system coupled
center pupil of a second lens 48 (radar lens) which covers
to the gyros. This is accomplished by a transmitting
the same recording angle and has the same focal length as
selsyn 23 mechanically coupled to the servo motor 21
of the photographic lens 34. This radar lens projects
and electrically linked to a receiving selsyn or synchro 24 25 that
an image of the ?ash lamp through the exposure slit 36
for a servo motor 25, motor 25 effecting roll correction
to the ?lm 35. ' A mirror or prism 49 is used to de?ect the
of platform 15. Similarly servo 22 is mechanically cou—
beam in such fashion as to prevent interference with the
pled to a selsyn 26 which is electrically linked to receiv
optical path of the camera lens. The mirror may be a half
ing selsyn 27 and servo motor 28 for correcting platform
silvered surface or an off-center fully re?ectioned element.
30
15 as to pitch.
If the ?ash scanner rotates synchronously, and is in the
As is well known a synchro system is adapted to trans
proper angular position with the radar re?ector, the ?ash
mit positional information. The transmitter of the syn
signals can thus be made to traverse the length of the ex—
chro, sometimes called a selsyn generator, has a rotor
posure slit. The scanner so synchronized will place the
geared or otherwise linked to the mechanical element in
?ash marks in their proper position during the scanning
motion. The synchro receiver has a rotor which is free
cycle. The synchronous movement of the optical scanner
to rotate and is caused to come into correspondence with
can be accomplished by use of a pair of synchros 50 and
the transmitter rotor.
51. The transmitting synchro 51 is driven by the radar
The radar device 11 is constituted by a radar trans
scan drive motor 33. The receiving synchro 5!} drives the
- mitter 29 whose output is fed to a scanning antenna 30
optical scanner directly for no large forces are required
40
to project periodic exploratory pulses, the re?ected or
for this purpose. To establish proper angular orientation
echo pulses intercepted by the antenna being fed to a
initially, one synchro stator can be rotated.
radar receiver 31. Periodic pulses for the transmitter
The ?ash scanner will produce on the ?lm a recording
originate from a pulse generator 32. The mechanical
in the form of a short dash (black on ?lm, white on the
oscillation of the antenna structure is effected by a scan
print) lying perpendicularly to the direction of the ?lm.
45
ning motor 33.
The width of each mark is equal to the width of the
One important limitation of the reconnaissance sys
exposure slit.
tem deals with the resolution capability of the radar com
In place of an optical mechanical scanning system for
ponents. High resolution can be attained if use is made
impressing the radar marks on the ?lm, a ?ying spot elec
of short wave lengths in conjunction with a re?ector of
a sufficient size.
The camera lens system 34 collects and focuses ground
terrain information on the emulsion of a moving ?lm 35
50
tronic scanner 55 may be used as shown in FIG. 5. The
scanning trace of the scanner may be caused to sweep
across the cathode-ray tube screen by means of a suitable
trigger and time base generator 56 operating in synchro
through an adjustable slit 36. The lens System is provided
nism with the radar antenna. The arrangement is other
with an adjustable diaphragm 37 whose opening is con
trolled automatically by a mechanism 38, which may be 55 wise the same as in FIG. 4 and the ?ying spot data is
superimposed on the camera information.
any electromagnetic device responsive to signals from
The strip camera may be in the form of an infra-red
a photocell 39 when incident light falls thereon.
system rather than the usual photographic arrangement to
The speed of the ?lm isvaried-by a ?lm transport motor
provide a combined radar-infra-red photo overlay record.
40 which in turn is controlled by the ratio of aircraft
information obtained in the plane may be relayed to a
ground velocity to aircraft altitude, as measured by 60 The
ground station by projecting the overlayed optical and
speedometer and altimeter 41 and 42, respectively. The
width of the camera slit is adjusted bya mechanism 43
responsive to a tachometer 44 mechanically coupled to
the ?lm advance motor 40 and is determined by the
radar data on the sensitive surface of a television camera,
rather than on ?lm, and permitting video signals to the
ground station for presentation on a screen.
In order to have the radar information appear in dash
65
product of ground speed, scale and exposure time.
form rather than as straight lines, a shutter may be pro
> The ?lm in passing over the camera exposure slit must
vided in the optical system to break up the code lines of the
be suitably marked with the radar return signals. By
I radar. The same result can also be accomplished by cut
means of the marking device the radar signals are super
ting off the radar tube periodically. Similarly the infra~
imposed with the photographic ground detail. Only those
radar ground returns substantially above an established
suppression level are so recorded. This is effected by a
background suppression or threshold circuit 52 operating
red code can be treated to provide dots or circles.
While there has been shown and described what are
believed to be preferred embodiments of the invention, it
is to be understood that many changes and modi?cations
in conjunction with an integrator 53, both coupled to _
may be made therein without departing from the essential
the radar receiver 31 to produce output pulses which are
spirit of the invention as de?ned in the attached claims.
suitably shaped in circuit 54. The threshold circuit 52 75
5
3,076,189
What is claimed is:
1. A multiple-sensor reconnaissance installation com
prising an optical system for obtaining a photographic
image of a given area and including a camera having a
G
I 8. A multiple-sensor aircraft reconnaissance installa
tion comprising an optical system exposed to a given strip
area in the terrain below the aircraft and including a
camera having a moving ?lm on which is projected the
sensitive ?lm therein, a radar system for scanning the 5 resultant photographic image, a ?rst stabilized platform
same area to produce representative light indications, and
for supporting said optical system to offset the effects of
means simultaneously to project said image and said indi
aircraft roll and pitch, a radar system including a scan
cations in overlay relationship on said sensitive ?lm in a
corresponding scale to produce an overlay record.
2. An installation as set forth in claim 1, wherein said
optical system includes a camera responsive to infra-red
energy to provide a combined radar-infra red photo over
lay record.
3. A multiple-sensor reconnaissance aircraft installa
tion comprising an optical system for obtaining an image
of a given strip area below the aircraft, the width of the
strip being transverse to the line of ?ight, the optical sys
tem including a camera having a moving light-sensitive
?lm therein, a radar system for scanning the same area to
produce representative light indications, and means simul~ .
taneously to project said image and said indications in
overlay relationship on said ?lm in a corresponding scale
to produce an overlay record.
4. An installation as set forth in claim 3 including
means to coordinate the movement of said ?lm with the
?ight of said aircraft.
5. A multiple~sensor reconnaissance installation com
prising an optical system for obtaining a photographic
image of a given area and including a camera having a
sensitized ?lm, a radar system for scanning the same
area with periodic pulses to produce representative light
indications, and means simultaneously to project said
image and said indications in the same scale in an overlay
pattern on said sensitized ?lm.
6. An installation as set forth in claim 5, wherein said
radar system includes a receiver to detect return pulses
from said area, and means to suppress return pulses be
low a predetermined level.
7. A multiple-sensor aircraft reconnaissance installa
tion comprising an optical system exposed to a given area
in the terrain below the aircraft and including a camera
having a ?lm on which is projected the resultant photo
graphic image, a ?rst stabilized platform for supporting
ning antenna adapted to sweep said area with a radar
pulse beam, a second stabilized platform synchronized
with the ?rst platform, means to convert the return radar
pulses obtained from said radar system into correspond
ing light values to produce a radar image, and means to
project said radar image onto said ?lm in overlay rela
tionship with said photographic image.
9. An installation as set forth in claim 8, wherein said
means to convert the return radar pulses into correspond
ing light values includes a gas discharge glow tube cou
pled to the output of the radar system, and means to
oscillate said tube in synchronism with the scanning
action of said antenna.
10. An installation as set forth in claim 8, wherein
said means to convert the return pulses into correspond
ing light values includes a ?ying spot electronic tube and
means to apply a sweep voltage thereto in synchronism
with the scanning action of the antenna.
11. A multiple-sensor aircraft reconnaissance installa
tion comprising an optical system exposed to a given strip
area in the terrain below the aircraft and including a
camera having a ?lm on which is projected the resultant
image, the movement of said ?lm being coordinated with
the ?ight of said aircraft, the width of said strip being
transverse to the aircraft ?ight, a ?rst stabilized platform
for supporting said optical system to offset the effects of
aircraft roll and pitch, a radar system including a scan
ning antenna adapted to sweep said area with a radar
beam, a second stabilized platform, a synchro system to
synchronize the second platform with the ?rst platform,
means to convert the return radar pulses obtained from
said radar system into corresponding light values to pro
duce ‘a radar image, and means to project said radar image
onto said ?lm in overlay relationship with said photo
graphic image to produce a dual image in corresponding
scale.
said optical system to offset the e?ects of aircraft roll and
pitch, a radar system including a scanning antenna 45
adapted to sweep said area with a radar beam, a second
stabilized platform, means to convert return radar pulses
obtained from said radar system into corresponding light
values to produce a radar image, and means to project
said radar image onto said ?lm in overlay relationship 50
with said photographic image and in the same scale
therewith.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,462,859
2,526,682
2,705,319
2,873,396
Grieg ________________ .. Mar. 1,
Mulberger et al. ______ __. Oct. 24,
Dauber _____________ __ Mar. 29,
Baldwin _____________ __ Feb. 10,
1949
1950
1955
1959
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