Here is something which I found interesting....
Optical reconnaissance sensors are undergoing a revolution from primarily daytime-only
film camera based systems to 24-hour, day/night digital sensor systems. The changing
world environment, in terms of technological advances and new operational
requirements, has brought about this transition. There is a worldwide trend to replace film
LOROP (LOng-Range Oblique Photographic) cameras with dual-band E-O/IR (electro-
optical/infrared) systems.
Raytheon Systems Company has developed a dual-band reconnaissance sensor,
designated the DB-110, to meet the requirements of both close-range tactical and LOROP
reconnaissance missions. The system is unique in that two optical systems are
incorporated into a single system. This gives a mission planner the ability to optimize
collections for sorties that previously required different sensors, or possibly even
different platforms, to accomplish.
This paper reviews the traditional categories of reconnaissance sensors as background to
the DB-110 development objectives in Section 2. The characteristics and operations of
the DB-110 system are described in Section 3. Section 4 illustrates the multi-mission
capabilities presented by the DB-110 within a matrix of standard reconnaissance mission
types. Finally, Section 5 presents examples of DB-110 flight test imagery which
demonstrate the performance of the system under day and night collection conditions.
2. BACKGROUND
2.1 Types of Airborne Reconnaissance Sensors
Airborne reconnaissance (recce) sensors are generally categorized by their mission type
and altitude range as illustrated in Figure 1. Descriptions and examples of these
categories follow.
High speed, low-altitude penetrating missions are employed in high threat (wartime)
environments to collect imagery directly over targets (nadir ± 5,000 ft swath width).
Altitude ranges of 200-3,000 ft are typical, as are high velocity/range (V/R) ratio
operation. Due to the short range to target and high V/R, low altitude sensors are based
on short focal length optical systems. The Low Altitude Electro-Optical (LAEO) sensor
(1-inch focal length) used in the US Marine Corps ATARS (Advanced Tactical Air
Reconnaissance System) used in the F-18 platform is one such example.
Medium altitude missions are used to collect imagery for both overflight and standoff
missions. In general, medium altitude operations are in the range of 2,500-25,000 ft. In
high threat environments, an aircraft would fly a low-altitude penetration mission, pop-up
to medium altitude to quickly image the area of interest, and then revert to low-altitude
for safe exit. In lower threat environments, the platform may fly at medium altitude and
image at either nadir (overflight) or at left, right or forward oblique (standoff).
Medium altitude sensors employ focal lengths generally in the 6-18 inch range. In the
ATARS sensor suite, the 12-inch focal length Medium Altitude Electro-Optical (MAEO)
sensor is utilized for side looking oblique (pushbroom) imaging in the daytime. The
Predator UAV (Unmanned Aerial Vehicle) utilizes day and night video sensors with
zoom optics.
LOROP (LOng-range Oblique Photographic) sensors systems are utilized to image at
long-range in peacetime as well as in threat environments. The high altitude category is
generally applied to systems typically operating in the 20,000-50,000 foot range (and
above on special mission platforms). The fundamental design characteristic to support
long-range operations is focal length. LOROP’s employ focal lengths of 36-inches or
greater.
LOROP collections are generally at standoff ranges starting from 5 to 10 miles out to the
horizon. In the United States, the only operational LOROP system is the Raytheon
SYERS (Senior Year Electro-Optical Sensor) operating on the U-2 aircraft. The Global
Hawk UAV is also high-altitude standoff platform utilizing the Raytheon Integrated
Sensor System (ISS). The ISS payload contains an optical sensor with a 70-inch focal
length in both the visible and infrared (IR) spectrums, in addition to an integrated
synthetic aperture radar system.
2.2 DB-110 Design Objectives
Raytheon conducted a survey of reconnaissance users in the early part of the 1990’s to
assess the potential for a new product in the marketplace. It was apparent that a change
would occur worldwide with a transition from film-based reconnaissance to digital
electro-optical sensors. Film systems could not support 24-hour reconnaissance, nor
could they easily support the rapid timelines needed in the modern world from collection
of information to delivery to the warfighter. Logistical and environmental considerations
also favored the transition to an all-electronic system to eliminate the support for wet-
film processing and disposal of chemistry.
In addition to the technological evolution from film to digital systems, the Raytheon
survey also indicated a shift in mission requirements. During the Cold War, the
predominant tactical recce mission anticipated was low-altitude overflight to operate in a
wartime/high-threat environment. Following the Cold War, and with the experience of
Desert Storm, military recce requirements underwent a change in emphasis. Most recce
operations today and in the future will occur during peacetime. Overflying a neighboring
country is unacceptable; a border surveillance mission must be flown in order to collect
intelligence information. Long-range standoff (long focal length) systems are essential to
collect useful imagery. Peacekeeping missions (Bosnia, Southern Watch) are usually
restricted to a minimum altitude (e.g. 10,000 feet), therefore also mandating longer focal
length sensors to achieve high quality imagery.
Still, recce capabilities must be available for crisis and wartime environments. Both low
altitude overflight and medium altitude (pop-up) systems will be used in high threat
environments, as will high altitude standoff sensors which increase survivability by
collecting imagery far from ground-based threats. Flexibility to reprogram missions is an
implicit requirement in order to adjust collection strategies in a dynamic environment, for
example to collect Targets of Opportunity.
Raytheon designed a new sensor, designated as the DB-110 (dual-band 110-inch focal
length), to be responsive and flexible with respect to changing world requirements. Basic
design objectives were to accomplish the following:
· Achieve high performance in both day and night missions
· Support both close range and mid/long standoff range missions in a single sensor
· Minimize size and weight to permit carriage onboard multiple platforms
· Design a stabilization system for high dynamics of tactical aircraft
· Minimize cost by use of COTS equipment where possible
· Produce a modular design to facilitate tailoring to individual customer requirements
